# yugo.click · design system reference

> A design system for React with principles, components, and motion finished until they feel inevitable. Every component below is one self-contained file whose only dependency is motion, shipped as a headless hook plus a styled example.

Source code: https://github.com/iBz-04/yugo

## Copy Button · Action Feedback

Copy to tick, width locked, reverts after 2s.

Docs: https://yugo.click/docs/copy-button
Install: `bun add motion`, then copy the source below into `components/yugo/copy-button.tsx` · or `bunx shadcn@latest add https://yugo.click/r/copy-button.json`.

Guarantees:
- The three labels: rest, success, failure: occupy one grid cell, so the button is sized to its widest reachable state before the first click and neighbours never shift when the tick arrives.
- A second click while the tick is showing restarts the two-second revert instead of stacking a second timer, and every timer is cleared on unmount, so a button removed mid-countdown cannot set state on a dead component.
- The write is attempted through the async clipboard API and falls back to a detached textarea selection, restoring the user's prior selection range afterwards; when both refuse, the button says so rather than showing a tick it did not earn.
- The accessible name is fixed to the resting label and the outcome is announced once through a polite live region, so a screen reader hears "Copied" a single time instead of a renamed control.
- prefers-reduced-motion collapses the crossfade and the tick draw to zero duration: the state still changes, only the trip is skipped, and nothing is hidden.
- Only opacity, scale, transform and stroke length are animated, and no state is written from an animation callback, so a rapid double click interrupts the spring from its current position instead of restarting it.


### Usage

```tsx
import { CopyButton } from "@/components/yugo/copy-button";

export function ApiKeyRow({ token }: { token: string }) {
  return (
    <div className="flex items-center gap-3 rounded-[11px] border border-stone-200 p-[5px] pl-3 dark:border-white/[0.16]">
      <code className="min-w-0 flex-1 truncate font-mono text-[12px] text-stone-500 dark:text-stone-400">
        {token}
      </code>
      <CopyButton
        value={token}
        label="Copy key"
        timeout={2000}
        onCopy={() => track("api_key_copied")}
      />
    </div>
  );
}
```

### Source (`components/yugo/copy-button.tsx`)

```tsx
"use client";

import { useCallback, useEffect, useRef, useState } from "react";
import { motion, useReducedMotion } from "motion/react";

const EASE = [0.23, 1, 0.32, 1] as const;
const CELL = { type: "spring", stiffness: 520, damping: 34, mass: 0.45 } as const;
const CROSSFADE = { type: "spring", stiffness: 260, damping: 34, mass: 0.8 } as const;
const DRAW = { duration: 0.26, ease: EASE } as const;
const INSTANT = { duration: 0 } as const;

export type CopyStatus = "idle" | "copied" | "error";

export type UseCopyToClipboardOptions = {
  timeout?: number;
  onCopy?: (value: string) => void;
  onError?: (reason: unknown) => void;
};

function writeFallback(text: string): boolean {
  const area = document.createElement("textarea");
  area.value = text;
  area.setAttribute("readonly", "");
  area.style.position = "fixed";
  area.style.top = "0";
  area.style.left = "0";
  area.style.opacity = "0";
  document.body.appendChild(area);

  const selection = document.getSelection();
  const previous =
    selection && selection.rangeCount > 0 ? selection.getRangeAt(0) : null;

  area.select();
  let ok = false;
  try {
    ok = document.execCommand("copy");
  } catch {
    ok = false;
  }

  document.body.removeChild(area);
  if (selection && previous) {
    selection.removeAllRanges();
    selection.addRange(previous);
  }
  return ok;
}

export function useCopyToClipboard({
  timeout = 2000,
  onCopy,
  onError,
}: UseCopyToClipboardOptions = {}) {
  const [status, setStatus] = useState<CopyStatus>("idle");
  const [ticket, setTicket] = useState(0);

  const mounted = useRef(true);
  const copied = useRef(onCopy);
  copied.current = onCopy;
  const failed = useRef(onError);
  failed.current = onError;

  useEffect(() => {
    mounted.current = true;
    return () => {
      mounted.current = false;
    };
  }, []);

  const reset = useCallback(() => {
    setStatus("idle");
    setTicket(0);
  }, []);

  const copy = useCallback(async (text: string) => {
    if (!text) return false;

    let ok = false;
    let reason: unknown = null;

    try {
      if (typeof navigator !== "undefined" && navigator.clipboard?.writeText) {
        await navigator.clipboard.writeText(text);
        ok = true;
      } else {
        ok = writeFallback(text);
      }
    } catch (error) {
      reason = error;
      try {
        ok = writeFallback(text);
      } catch {
        ok = false;
      }
    }

    if (!mounted.current) return ok;

    setStatus(ok ? "copied" : "error");
    setTicket((t) => t + 1);

    if (ok) copied.current?.(text);
    else failed.current?.(reason);

    return ok;
  }, []);

  useEffect(() => {
    if (ticket === 0 || status === "idle") return;
    const id = setTimeout(() => setStatus("idle"), timeout);
    return () => clearTimeout(id);
  }, [ticket, status, timeout]);

  return { copy, reset, status, copied: status === "copied" };
}

export type CopyButtonProps = {
  value: string;
  label?: string;
  copiedLabel?: string;
  errorLabel?: string;
  timeout?: number;
  onCopy?: (value: string) => void;
  onError?: (reason: unknown) => void;
  disabled?: boolean;
  className?: string;
};

export function CopyButton({
  value,
  label = "Copy",
  copiedLabel = "Copied",
  errorLabel = "Failed",
  timeout = 2000,
  onCopy,
  onError,
  disabled = false,
  className = "",
}: CopyButtonProps) {
  const { copy, status } = useCopyToClipboard({ timeout, onCopy, onError });
  const reduced = useReducedMotion();

  const fade = reduced ? INSTANT : CROSSFADE;
  const draw = reduced ? INSTANT : DRAW;

  const labels: Array<[CopyStatus, string]> = [
    ["idle", label],
    ["copied", copiedLabel],
    ["error", errorLabel],
  ];

  return (
    <motion.button
      type="button"
      disabled={disabled}
      aria-label={label}
      onClick={() => {
        void copy(value);
      }}
      whileTap={disabled || reduced ? undefined : { y: 1 }}
      transition={CELL}
      style={{ borderRadius: 9, touchAction: "manipulation" }}
      className={`inline-flex h-9 select-none items-center gap-2 rounded-[9px] border border-stone-200 bg-white px-3 text-[13px] font-medium text-stone-700 shadow-[inset_0_1.5px_0_rgba(255,255,255,0.95),inset_0_-1px_0_rgba(28,25,23,0.06),0_1px_2px_rgba(28,25,23,0.08)] outline-none transition-[border-color,box-shadow,background-color] duration-150 hover:bg-stone-50 focus-visible:border-[#4568FF] focus-visible:shadow-[0_1px_2px_rgba(28,25,23,0.08),0_10px_20px_-14px_rgba(69,104,255,0.6)] disabled:opacity-50 dark:border-white/[0.16] dark:bg-[#252522] dark:text-stone-200 dark:shadow-[inset_0_1px_0_rgba(255,255,255,0.07),0_1px_2px_rgba(0,0,0,0.4)] dark:hover:bg-[#2A2A27] dark:focus-visible:border-[#93B0FF] dark:focus-visible:shadow-[0_10px_20px_-14px_rgba(147,176,255,0.5)] ${className}`}
    >
      <span className="grid size-[14px] shrink-0" aria-hidden="true">
        <motion.svg
          viewBox="0 0 14 14"
          fill="none"
          stroke="currentColor"
          strokeWidth={1.5}
          strokeLinecap="round"
          strokeLinejoin="round"
          className="col-start-1 row-start-1 size-[14px]"
          initial={false}
          animate={{
            opacity: status === "idle" ? 1 : 0,
            scale: status === "idle" ? 1 : 0.92,
          }}
          transition={fade}
        >
          <path d="M9.6 5.1V3.7A1.7 1.7 0 0 0 7.9 2H3.7A1.7 1.7 0 0 0 2 3.7v4.2a1.7 1.7 0 0 0 1.7 1.7h1.4" />
          <rect x="5.1" y="5.1" width="6.9" height="6.9" rx="1.7" />
        </motion.svg>

        <motion.svg
          viewBox="0 0 14 14"
          fill="none"
          stroke="currentColor"
          strokeWidth={1.5}
          strokeLinecap="round"
          strokeLinejoin="round"
          className="col-start-1 row-start-1 size-[14px]"
          initial={false}
          animate={{
            opacity: status === "copied" ? 1 : 0,
            scale: status === "copied" ? 1 : 0.92,
          }}
          transition={fade}
        >
          <motion.path
            d="M2.9 7.4 5.6 10.1 11.1 4"
            initial={false}
            animate={{ pathLength: status === "copied" ? 1 : 0 }}
            transition={draw}
          />
        </motion.svg>

        <motion.svg
          viewBox="0 0 14 14"
          fill="none"
          stroke="currentColor"
          strokeWidth={1.5}
          strokeLinecap="round"
          strokeLinejoin="round"
          className="col-start-1 row-start-1 size-[14px]"
          initial={false}
          animate={{
            opacity: status === "error" ? 1 : 0,
            scale: status === "error" ? 1 : 0.92,
          }}
          transition={fade}
        >
          <path d="M3.6 3.6 10.4 10.4" />
          <path d="M10.4 3.6 3.6 10.4" />
        </motion.svg>
      </span>

      <span aria-hidden="true" className="relative grid">
        {labels.map(([key, text]) => (
          <motion.span
            key={key}
            initial={false}
            animate={
              key === status
                ? { opacity: 1, y: 0, filter: "blur(0px)" }
                : { opacity: 0, y: 3, filter: "blur(3px)" }
            }
            transition={fade}
            className="col-start-1 row-start-1 whitespace-nowrap"
          >
            {text}
          </motion.span>
        ))}
      </span>

      <span role="status" aria-live="polite" className="sr-only">
        {status === "copied" ? copiedLabel : status === "error" ? errorLabel : ""}
      </span>
    </motion.button>
  );
}
```

---

## Loading Button · Action Feedback

Label to state without layout shift.

Docs: https://yugo.click/docs/loading-button
Install: `bun add motion`, then copy the source below into `components/yugo/loading-button.tsx` · or `bunx shadcn@latest add https://yugo.click/r/loading-button.json`.

Guarantees:
- All four labels are rendered into a single grid cell, so the widest one reserves the button's width before the first click; "Publish" becoming "Publishing…" cannot grow the button or shove the controls beside it.
- The button is never given the native disabled attribute while a request is in flight: it carries aria-busy and aria-disabled instead: so a keyboard user's focus is not dropped onto the body the moment they press Enter.
- A second click during flight is ignored, and every run carries an id, so a slow first response can never overwrite the result of the run that replaced it.
- Pending is indeterminate, because the button does not know how long the request will take. A meter filling against a guessed duration claims progress it cannot know, so the wait is shown as a wait.
- The rAF loop and the reset timer are cancelled on unmount and every settlement checks an alive flag, so a promise resolving after navigation sets no state.
- Under prefers-reduced-motion the meter's rAF never starts and the state lands instantly; the label still changes and a polite status region announces success or failure exactly once, not on every tick.


### Usage

```tsx
import { useRouter } from "next/navigation";
import { LoadingButton } from "@/components/yugo/loading-button";

export function PublishRelease({ id }: { id: string }) {
  const router = useRouter();

  return (
    <div className="flex items-center justify-end gap-2">
      <button type="button" className="h-9 rounded-[9px] px-3 text-[13px]">
        Cancel
      </button>

      <LoadingButton
        onAction={async () => {
          const res = await fetch(`/api/releases/${id}/publish`, { method: "POST" });
          if (!res.ok) throw new Error(await res.text());
          router.refresh();
        }}
        pendingLabel="Publishing…"
        successLabel="Published"
        errorLabel="Retry"
        expected={2400}
        onError={(error) => console.error(error)}
      >
        Publish
      </LoadingButton>
    </div>
  );
}
```

### Source (`components/yugo/loading-button.tsx`)

```tsx
"use client";

import { useCallback, useEffect, useRef, useState } from "react";
import { motion, useReducedMotion } from "motion/react";

const CELL = { type: "spring", stiffness: 520, damping: 34, mass: 0.45 } as const;
const CROSSFADE = { type: "spring", stiffness: 260, damping: 34, mass: 0.8 } as const;
const INSTANT = { duration: 0 } as const;

export type AsyncActionStatus = "idle" | "pending" | "success" | "error";

export type UseAsyncActionOptions = {
  action: () => unknown;
  resetAfter?: number;
  onError?: (error: unknown) => void;
};

export function useAsyncAction({
  action,
  resetAfter = 1400,
  onError,
}: UseAsyncActionOptions) {
  const [status, setStatus] = useState<AsyncActionStatus>("idle");

  const phase = useRef<AsyncActionStatus>("idle");
  const runId = useRef(0);
  const timer = useRef<ReturnType<typeof setTimeout> | null>(null);
  const alive = useRef(true);

  const act = useRef(action);
  const fail = useRef(onError);

  useEffect(() => {
    act.current = action;
    fail.current = onError;
  });

  const clear = useCallback(() => {
    if (timer.current) {
      clearTimeout(timer.current);
      timer.current = null;
    }
  }, []);

  const reset = useCallback(() => {
    runId.current += 1;
    clear();
    phase.current = "idle";
    setStatus("idle");
  }, [clear]);

  const run = useCallback(() => {
    if (phase.current === "pending") return;

    clear();
    const id = ++runId.current;
    phase.current = "pending";
    setStatus("pending");

    const settle = (next: "success" | "error") => {
      if (!alive.current || id !== runId.current) return;
      clear();
      phase.current = next;
      setStatus(next);
      timer.current = setTimeout(() => {
        if (!alive.current || id !== runId.current) return;
        phase.current = "idle";
        setStatus("idle");
      }, resetAfter);
    };

    Promise.resolve()
      .then(() => act.current())
      .then(
        () => settle("success"),
        (error: unknown) => {
          fail.current?.(error);
          settle("error");
        },
      );
  }, [clear, resetAfter]);

  useEffect(() => {
    alive.current = true;
    return () => {
      alive.current = false;
      clear();
    };
  }, [clear]);

  return {
    status,
    run,
    reset,
    pending: status === "pending",
  };
}

function Spinner({ still }: { still: boolean }) {
  return (
    <motion.svg
      width="12"
      height="12"
      viewBox="0 0 12 12"
      fill="none"
      aria-hidden="true"
      className="shrink-0"
      animate={still ? undefined : { rotate: 360 }}
      transition={
        still ? undefined : { duration: 0.85, repeat: Infinity, ease: "linear" }
      }
    >
      <circle
        cx="6"
        cy="6"
        r="4.5"
        stroke="currentColor"
        strokeWidth="1.5"
        strokeOpacity="0.22"
      />
      <path
        d="M10.5 6A4.5 4.5 0 0 0 6 1.5"
        stroke="currentColor"
        strokeWidth="1.5"
        strokeLinecap="round"
      />
    </motion.svg>
  );
}

function CheckMark() {
  return (
    <svg
      width="12"
      height="12"
      viewBox="0 0 12 12"
      fill="none"
      aria-hidden="true"
      className="shrink-0"
    >
      <path
        d="M2.6 6.3 4.9 8.6 9.4 3.6"
        stroke="currentColor"
        strokeWidth="1.7"
        strokeLinecap="round"
        strokeLinejoin="round"
      />
    </svg>
  );
}

function AlertMark() {
  return (
    <svg
      width="12"
      height="12"
      viewBox="0 0 12 12"
      fill="none"
      aria-hidden="true"
      className="shrink-0"
    >
      <path d="M6 2.9v3.5" stroke="currentColor" strokeWidth="1.7" strokeLinecap="round" />
      <path d="M6 9.05h.01" stroke="currentColor" strokeWidth="1.9" strokeLinecap="round" />
    </svg>
  );
}

export type LoadingButtonProps = {
  onAction: () => unknown;
  children: string;
  pendingLabel?: string;
  successLabel?: string;
  errorLabel?: string;
  resetAfter?: number;
  disabled?: boolean;
  onError?: (error: unknown) => void;
  className?: string;
};

export function LoadingButton({
  onAction,
  children,
  pendingLabel = children,
  successLabel = "Done",
  errorLabel = "Try again",
  resetAfter = 1400,
  disabled = false,
  onError,
  className = "",
}: LoadingButtonProps) {
  const reduced = useReducedMotion();

  const { status, run, pending } = useAsyncAction({
    action: onAction,
    resetAfter,
    onError,
  });

  const fade = reduced ? INSTANT : CROSSFADE;


  const label =
    status === "pending"
      ? pendingLabel
      : status === "success"
        ? successLabel
        : status === "error"
          ? errorLabel
          : children;

  const faces = [
    {
      key: "idle",
      text: children,
      tone: "text-stone-700 dark:text-stone-200",
      icon: null,
    },
    {
      key: "pending",
      text: pendingLabel,
      tone: "text-stone-500 dark:text-stone-400",
      icon: <Spinner still={reduced === true || status !== "pending"} />,
    },
    {
      key: "success",
      text: successLabel,
      tone: "text-emerald-600 dark:text-emerald-400",
      icon: <CheckMark />,
    },
    {
      key: "error",
      text: errorLabel,
      tone: "text-red-600 dark:text-red-400",
      icon: <AlertMark />,
    },
  ];

  return (
    <>
      <motion.button
        type="button"
        disabled={disabled}
        aria-label={label}
        aria-busy={pending || undefined}
        aria-disabled={pending || undefined}
        whileTap={disabled || pending || reduced ? undefined : { y: 1 }}
        transition={CELL}
        onClick={(event) => {
          if (pending) {
            event.preventDefault();
            return;
          }
          run();
        }}
        className={`relative inline-flex h-9 select-none items-center justify-center rounded-[9px] border border-stone-200 bg-white px-3.5 text-[13px] font-medium text-stone-700 shadow-[inset_0_1.5px_0_rgba(255,255,255,0.95),inset_0_-1px_0_rgba(28,25,23,0.06),0_1px_2px_rgba(28,25,23,0.08)] outline-none transition-[border-color,box-shadow,background-color] duration-150 hover:bg-stone-50 focus-visible:border-[#4568FF] focus-visible:shadow-[0_1px_2px_rgba(28,25,23,0.08),0_10px_20px_-14px_rgba(69,104,255,0.6)] disabled:opacity-50 dark:border-white/[0.16] dark:bg-[#252522] dark:text-stone-200 dark:shadow-[inset_0_1px_0_rgba(255,255,255,0.07),0_1px_2px_rgba(0,0,0,0.4)] dark:hover:bg-[#2A2A27] dark:focus-visible:border-[#93B0FF] dark:focus-visible:shadow-[0_10px_20px_-14px_rgba(147,176,255,0.5)] ${className}`}
        style={{ borderRadius: 9, touchAction: "manipulation" }}
      >
        <span aria-hidden className="relative grid place-items-center">
          {faces.map((face) => (
            <motion.span
              key={face.key}
              initial={false}
              animate={
                face.key === status
                  ? { opacity: 1, y: 0, filter: "blur(0px)" }
                  : { opacity: 0, y: 3, filter: "blur(3px)" }
              }
              transition={fade}
              className={`col-start-1 row-start-1 flex items-center justify-center gap-1.5 whitespace-nowrap ${face.tone}`}
            >
              {face.icon}
              {face.text}
            </motion.span>
          ))}
        </span>
      </motion.button>

      <span role="status" aria-live="polite" className="sr-only">
        {status === "success" ? successLabel : status === "error" ? errorLabel : ""}
      </span>
    </>
  );
}
```

---

## Hold to Confirm · Action Feedback

A guard rail in front of destructive actions.

Docs: https://yugo.click/docs/hold-to-confirm
Install: `bun add motion`, then copy the source below into `components/yugo/hold-to-confirm.tsx` · or `bunx shadcn@latest add https://yugo.click/r/hold-to-confirm.json`.

Guarantees:
- A click cannot confirm: the click event is prevented at every stage, so a mis-aimed pointer, a double-click on the row underneath, or a stray Enter on a focused button destroys nothing.
- Releasing early does not snap the progress to zero, it drains at a bounded rate, and pressing again resumes from whatever is left rather than restarting the count.
- The label does not change while you hold. A block sweeps across the button and the same text inverts inside it, so the only thing moving is the progress itself, and the button never changes width. Layout never reflows when the state changes.
- Progress arrives as twenty discrete steps rather than a float, so a 1.2 second hold costs twenty renders instead of eighty, and no React state is written per animation frame.
- Losing the window, hiding the tab, dragging past the move tolerance, or blurring the button all release the hold, so a hold can never survive in the background and fire when nobody is watching.
- Screen readers get a static hint naming the required hold time and one polite announcement at commit, never a stream of progress updates, and prefers-reduced-motion removes the springs while leaving the hold itself intact, because the delay is the guard rail and not decoration.


### Usage

```tsx
"use client";

import { useRouter } from "next/navigation";
import { useState } from "react";
import { HoldToConfirm } from "@/components/yugo/hold-to-confirm";

export function DangerZone({ workspaceId }: { workspaceId: string }) {
  const router = useRouter();
  const [pending, setPending] = useState(false);

  return (
    <section className="rounded-[14px] border border-stone-200 p-4 dark:border-white/[0.16]">
      <h2 className="text-[13px] font-medium text-stone-700 dark:text-stone-200">
        Delete this workspace
      </h2>
      <p className="mb-3 mt-1 text-[12.5px] text-stone-500 dark:text-stone-400">
        Members, files and history go with it. There is no undo.
      </p>

      <HoldToConfirm
        duration={1400}
        disabled={pending}
        holdLabel="Keep holding"
        confirmLabel="Workspace deleted"
        onAbort={() => track("workspace.delete.abandoned", { workspaceId })}
        onConfirm={async () => {
          setPending(true);
          await fetch(`/api/workspaces/${workspaceId}`, { method: "DELETE" });
          router.push("/workspaces");
        }}
      >
        Delete workspace
      </HoldToConfirm>
    </section>
  );
}
```

### Source (`components/yugo/hold-to-confirm.tsx`)

```tsx
"use client";

import { useCallback, useEffect, useId, useRef, useState } from "react";
import {
  animate,
  motion,
  useMotionValue,
  useReducedMotion,
  useTransform,
} from "motion/react";

const FACE = { type: "spring", stiffness: 260, damping: 34, mass: 0.8 } as const;


export type HoldPhase = "idle" | "holding" | "releasing" | "committed";

export type UseHoldToConfirmOptions = {
  onConfirm: () => void;
  onAbort?: () => void;
  duration?: number;
  steps?: number;
  releaseRate?: number;
  moveTolerance?: number;
  haptic?: boolean;
  disabled?: boolean;
};

export function useHoldToConfirm({
  onConfirm,
  onAbort,
  duration = 1800,
  steps = 20,
  releaseRate = 2.5,
  moveTolerance = 10,
  haptic = true,
  disabled = false,
}: UseHoldToConfirmOptions) {
  const [step, setStep] = useState(0);
  const [phase, setPhase] = useState<HoldPhase>("idle");

  const phaseRef = useRef<HoldPhase>("idle");
  const down = useRef(false);
  const elapsed = useRef(0);
  const last = useRef(0);
  const raf = useRef(0);
  const origin = useRef<{ x: number; y: number } | null>(null);

  const confirm = useRef(onConfirm);
  confirm.current = onConfirm;
  const abort = useRef(onAbort);
  abort.current = onAbort;

  const move = useCallback((next: HoldPhase) => {
    phaseRef.current = next;
    setPhase(next);
  }, []);

  const reset = useCallback(() => {
    cancelAnimationFrame(raf.current);
    raf.current = 0;
    down.current = false;
    elapsed.current = 0;
    origin.current = null;
    setStep(0);
    move("idle");
  }, [move]);

  const begin = useCallback(
    (point?: { x: number; y: number }) => {
      if (disabled) return;
      if (phaseRef.current === "committed" || phaseRef.current === "holding") {
        return;
      }

      origin.current = point ?? null;
      down.current = true;
      move("holding");
      if (raf.current) return;

      last.current = performance.now();

      const loop = (now: number) => {
        const dt = Math.min(64, now - last.current);
        last.current = now;
        elapsed.current += down.current ? dt : -dt * releaseRate;

        if (elapsed.current >= duration) {
          raf.current = 0;
          elapsed.current = duration;
          down.current = false;
          origin.current = null;
          setStep(steps);
          move("committed");
          if (haptic) navigator.vibrate?.(14);
          confirm.current();
          return;
        }

        if (elapsed.current <= 0) {
          raf.current = 0;
          elapsed.current = 0;
          origin.current = null;
          setStep(0);
          move("idle");
          return;
        }

        const s = Math.min(
          steps,
          Math.floor((elapsed.current / duration) * steps),
        );
        setStep((prev) => (prev === s ? prev : s));
        raf.current = requestAnimationFrame(loop);
      };

      raf.current = requestAnimationFrame(loop);
    },
    [disabled, duration, steps, releaseRate, haptic, move],
  );

  const release = useCallback(() => {
    if (phaseRef.current !== "holding") return;
    down.current = false;
    origin.current = null;
    move("releasing");
    abort.current?.();
  }, [move]);

  useEffect(() => {
    const bail = () => release();
    const onVisibility = () => {
      if (document.hidden) release();
    };
    window.addEventListener("blur", bail);
    document.addEventListener("visibilitychange", onVisibility);
    return () => {
      window.removeEventListener("blur", bail);
      document.removeEventListener("visibilitychange", onVisibility);
      cancelAnimationFrame(raf.current);
      raf.current = 0;
    };
  }, [release]);

  const bind = {
    onPointerDown: (e: React.PointerEvent) => {
      if (e.pointerType === "mouse" && e.button !== 0) return;
      e.currentTarget.setPointerCapture?.(e.pointerId);
      begin({ x: e.clientX, y: e.clientY });
    },
    onPointerMove: (e: React.PointerEvent) => {
      const from = origin.current;
      if (phaseRef.current !== "holding" || !from) return;
      if (Math.hypot(e.clientX - from.x, e.clientY - from.y) > moveTolerance) {
        release();
      }
    },
    onPointerUp: release,
    onPointerCancel: release,
    onPointerLeave: release,
    onKeyDown: (e: React.KeyboardEvent) => {
      if (e.key === "Escape") {
        if (phaseRef.current === "holding" || phaseRef.current === "releasing") {
          e.preventDefault();
          reset();
        }
        return;
      }
      if (e.repeat) return;
      if (e.key === " " || e.key === "Enter") {
        e.preventDefault();
        begin();
      }
    },
    onKeyUp: (e: React.KeyboardEvent) => {
      if (e.key === " " || e.key === "Enter") release();
    },
    onBlur: release,
    onClick: (e: React.MouseEvent) => {
      e.preventDefault();
      if (phaseRef.current === "committed") e.stopPropagation();
    },
    onContextMenu: (e: React.MouseEvent) => e.preventDefault(),
  };

  return {
    bind,
    step,
    steps,
    phase,
    progress: step / steps,
    reset,
  };
}

export type HoldToConfirmProps = {
  onConfirm: () => void;
  children: React.ReactNode;
  onAbort?: () => void;
  confirmLabel?: string;
  duration?: number;
  resetAfter?: number;
  steps?: number;
  releaseRate?: number;
  disabled?: boolean;
  className?: string;
};

export function HoldToConfirm({
  onConfirm,
  children,
  onAbort,
  confirmLabel = "Confirmed",
  duration = 1800,
  resetAfter = 1600,
  steps = 20,
  releaseRate = 2.5,
  disabled = false,
  className = "",
}: HoldToConfirmProps) {
  const { bind, phase, reset } = useHoldToConfirm({
    onConfirm,
    onAbort,
    duration,
    steps,
    releaseRate,
    disabled,
  });

  const reduced = useReducedMotion();
  const hintId = useId();

  const committed = phase === "committed";
  const seconds = Math.round(duration / 100) / 10;

  const swept = useMotionValue(0);
  const clipPath = useTransform(
    swept,
    (v) => `inset(0 ${(1 - v) * 100}% 0 0)`,
  );

  useEffect(() => {
    if (phase !== "committed" || resetAfter <= 0) return;
    const back = setTimeout(reset, resetAfter);
    return () => clearTimeout(back);
  }, [phase, resetAfter, reset]);

  useEffect(() => {
    if (reduced) {
      swept.set(phase === "holding" || phase === "committed" ? 1 : 0);
      return;
    }

    if (phase === "committed") {
      const controls = animate(swept, 1, { duration: 0.12, ease: "linear" });
      return () => controls.stop();
    }

    const from = swept.get();

    if (phase === "holding") {
      const controls = animate(swept, 1, {
        duration: (duration * (1 - from)) / 1000,
        ease: "linear",
      });
      return () => controls.stop();
    }

    const controls = animate(swept, 0, {
      duration: (duration * from) / releaseRate / 1000,
      ease: [0.23, 1, 0.32, 1],
    });
    return () => controls.stop();
  }, [phase, duration, releaseRate, reduced, swept]);

  return (
    <button
      type="button"
      aria-disabled={disabled || committed}
      aria-describedby={hintId}
      {...bind}
      style={{ touchAction: "manipulation", WebkitTouchCallout: "none" }}
      className={`relative isolate inline-grid h-10 select-none place-items-center overflow-hidden rounded-[9px] border border-stone-200 bg-white px-4 text-[13px] font-medium text-stone-700 outline-none focus-visible:ring-2 focus-visible:ring-stone-400 dark:border-white/[0.16] dark:bg-[#1D1D1A] dark:text-stone-200 dark:focus-visible:ring-stone-500 ${
        disabled ? "cursor-not-allowed opacity-50" : "cursor-pointer"
      } ${className}`}
    >
      <Faces committed={committed} confirmLabel={confirmLabel}>
        {children}
      </Faces>

      <motion.span
        aria-hidden
        style={{ clipPath }}
        className="absolute inset-0 grid place-items-center bg-stone-800 px-4 text-white dark:bg-stone-100 dark:text-stone-900"
      >
        <Faces committed={committed} confirmLabel={confirmLabel}>
          {children}
        </Faces>
      </motion.span>

      <span id={hintId} className="sr-only">
        Press and hold for {seconds} seconds to confirm. Releasing early cancels
        and nothing happens.
      </span>

      <span role="status" aria-live="polite" className="sr-only">
        {committed ? confirmLabel : ""}
      </span>
    </button>
  );
}

function Faces({
  committed,
  confirmLabel,
  children,
}: {
  committed: boolean;
  confirmLabel: string;
  children: React.ReactNode;
}) {
  return (
    <span className="col-start-1 row-start-1 grid">
      <motion.span
        initial={false}
        animate={{ opacity: committed ? 0 : 1 }}
        transition={FACE}
        className="col-start-1 row-start-1 flex items-center justify-center whitespace-nowrap"
      >
        {children}
      </motion.span>
      <motion.span
        initial={false}
        animate={{ opacity: committed ? 1 : 0 }}
        transition={FACE}
        className="col-start-1 row-start-1 flex items-center justify-center gap-1.5 whitespace-nowrap"
      >
        <svg
          width="12"
          height="12"
          viewBox="0 0 12 12"
          fill="none"
          stroke="currentColor"
          strokeWidth="1.7"
          strokeLinecap="round"
          strokeLinejoin="round"
          aria-hidden="true"
        >
          <path d="M2.5 6.4 4.7 8.6 9.5 3.5" />
        </svg>
        {confirmLabel}
      </motion.span>
    </span>
  );
}
```

---

## Like Burst · Action Feedback

Optimistic like that survives rapid taps.

Docs: https://yugo.click/docs/like-burst
Install: `bun add motion`, then copy the source below into `components/yugo/like-burst.tsx` · or `bunx shadcn@latest add https://yugo.click/r/like-burst.json`.

Guarantees:
- Nine taps produce one request. Intent is debounced by settle, and a burst that returns to the confirmed state sends nothing at all, so a double tap is not a write followed by an undo write.
- Responses that arrive out of order cannot win. Every flush increments a sequence number and aborts the previous controller, so a slow unlike landing after a fast like is discarded rather than applied.
- A rejected commit rolls the count and the fill back to the last confirmed value, not to zero and not to a guess, so the number on screen is never a lie the user has to reload to discover.
- The button never changes width. Both labels share one grid cell, and the count cell reserves the wider of base and base + 1 up front, so a like at 999 does not shove the row.
- Screen readers get the settled value once from a polite status region; the optimistic count and the burst are aria-hidden, so a fast tapper does not queue nine announcements.
- Under prefers-reduced-motion the sparks are not rendered and the fill switches with no transition. The state still arrives, only the trip is skipped.


### Usage

```tsx
"use client";

import { LikeBurst } from "@/components/yugo/like-burst";

export function PostActions({ postId, likes, liked }: { postId: string; likes: number; liked: boolean }) {
  return (
    <LikeBurst
      initialLiked={liked}
      initialCount={likes}
      settle={400}
      onCommit={async (next, signal) => {
        const res = await fetch(`/api/posts/${postId}/like`, {
          method: next ? "POST" : "DELETE",
          signal,
        });
        if (!res.ok) throw new Error("like failed");
      }}
      onError={() => toast("Could not save your like")}
    />
  );
}
```

### Source (`components/yugo/like-burst.tsx`)

```tsx
"use client";

import {
  useCallback,
  useEffect,
  useImperativeHandle,
  useRef,
  useState,
} from "react";
import { AnimatePresence, motion, useReducedMotion } from "motion/react";

const EASE = [0.23, 1, 0.32, 1] as const;
const CELL = { type: "spring", stiffness: 520, damping: 34, mass: 0.45 } as const;
const CROSSFADE = { type: "spring", stiffness: 260, damping: 34, mass: 0.8 } as const;
const INSTANT = { duration: 0 } as const;

const HEART =
  "M12 20.3 4.3 12.6a4.8 4.8 0 0 1 6.8-6.8l.9.9.9-.9a4.8 4.8 0 0 1 6.8 6.8Z";

const SPARKS = Array.from({ length: 8 }, (_, i) => {
  const h = (((i + 1) * 2654435761) % 997) / 997;
  const angle = (i / 8) * Math.PI * 2 - Math.PI / 2 + (h - 0.5) * 0.4;
  const distance = 13 + h * 9;
  return {
    x: Math.round(Math.cos(angle) * distance * 10) / 10,
    y: Math.round(Math.sin(angle) * distance * 10) / 10,
    size: h > 0.5 ? 4 : 3,
    delay: Math.round(h * 50) / 1000,
  };
});

const DEFAULT_FORMAT = (value: number) =>
  new Intl.NumberFormat("en-US").format(value);

export type LikeCommit = (
  liked: boolean,
  signal: AbortSignal,
) => Promise<unknown>;

export type LikeBurstHandle = {
  toggle: () => void;
};

export type UseOptimisticLikeOptions = {
  initialLiked?: boolean;
  initialCount?: number;
  onCommit?: LikeCommit;
  onError?: (error: unknown) => void;
  settle?: number;
};

export type OptimisticLike = {
  liked: boolean;
  count: number;
  base: number;
  pending: boolean;
  burst: number;
  settled: { liked: boolean; count: number };
  toggle: () => void;
};

export function useOptimisticLike({
  initialLiked = false,
  initialCount = 0,
  onCommit,
  onError,
  settle = 400,
}: UseOptimisticLikeOptions = {}): OptimisticLike {
  const [liked, setLiked] = useState(initialLiked);
  const [count, setCount] = useState(initialCount);
  const [pending, setPending] = useState(false);
  const [burst, setBurst] = useState(0);
  const [settled, setSettled] = useState({
    liked: initialLiked,
    count: initialCount,
  });

  const likedNow = useRef(initialLiked);
  const countNow = useRef(initialCount);
  const truth = useRef({ liked: initialLiked, count: initialCount });
  const timer = useRef<ReturnType<typeof setTimeout> | null>(null);
  const inFlight = useRef<AbortController | null>(null);
  const seq = useRef(0);

  const commit = useRef(onCommit);
  commit.current = onCommit;
  const failed = useRef(onError);
  failed.current = onError;

  const flush = useCallback(() => {
    timer.current = null;
    inFlight.current?.abort();
    inFlight.current = null;
    seq.current += 1;

    const intent = likedNow.current;

    if (intent === truth.current.liked) {
      countNow.current = truth.current.count;
      setLiked(truth.current.liked);
      setCount(truth.current.count);
      setPending(false);
      return;
    }

    const target = { liked: intent, count: countNow.current };
    const run = commit.current;

    if (!run) {
      truth.current = target;
      setSettled(target);
      setPending(false);
      return;
    }

    const controller = new AbortController();
    const id = seq.current;
    inFlight.current = controller;
    setPending(true);

    run(intent, controller.signal).then(
      () => {
        if (id !== seq.current) return;
        inFlight.current = null;
        truth.current = target;
        setSettled(target);
        setPending(false);
      },
      (error: unknown) => {
        if (id !== seq.current) return;
        inFlight.current = null;
        likedNow.current = truth.current.liked;
        countNow.current = truth.current.count;
        setLiked(truth.current.liked);
        setCount(truth.current.count);
        setPending(false);
        failed.current?.(error);
      },
    );
  }, []);

  const toggle = useCallback(() => {
    const next = !likedNow.current;
    likedNow.current = next;
    countNow.current += next ? 1 : -1;

    setLiked(next);
    setCount(countNow.current);
    setPending(true);
    if (next) setBurst((b) => b + 1);

    if (timer.current) clearTimeout(timer.current);
    timer.current = setTimeout(flush, settle);
  }, [flush, settle]);

  useEffect(
    () => () => {
      if (timer.current) clearTimeout(timer.current);
      timer.current = null;
      seq.current += 1;
      inFlight.current?.abort();
      inFlight.current = null;
    },
    [],
  );

  return {
    liked,
    count,
    base: liked ? count - 1 : count,
    pending,
    burst,
    settled,
    toggle,
  };
}

export type LikeBurstProps = {
  initialLiked?: boolean;
  initialCount?: number;
  onCommit?: LikeCommit;
  onError?: (error: unknown) => void;
  onToggle?: (liked: boolean) => void;
  settle?: number;
  label?: string;
  activeLabel?: string;
  format?: (value: number) => string;
  disabled?: boolean;
  className?: string;
};

export function LikeBurst({
  initialLiked = false,
  initialCount = 0,
  onCommit,
  onError,
  onToggle,
  settle = 400,
  label = "Like",
  activeLabel = "Liked",
  format = DEFAULT_FORMAT,
  disabled = false,
  className = "",
  ref,
}: LikeBurstProps & { ref?: React.Ref<LikeBurstHandle> }) {
  const reduced = useReducedMotion();
  const { liked, count, base, pending, burst, settled, toggle } =
    useOptimisticLike({ initialLiked, initialCount, onCommit, onError, settle });

  useImperativeHandle(ref, () => ({ toggle }), [toggle]);

  const low = format(base);
  const high = format(base + 1);
  const widest = high.length >= low.length ? high : low;
  const shown = format(count);

  return (
    <span className={`inline-flex items-center ${className}`}>
      <button
        type="button"
        disabled={disabled}
        aria-pressed={liked}
        aria-busy={pending}
        aria-label={label}
        onClick={() => {
          toggle();
          onToggle?.(!liked);
        }}
        style={{ touchAction: "manipulation" }}
        className="inline-flex h-9 select-none items-center gap-2 rounded-[9px] border border-stone-200 bg-white px-3 text-[13px] font-medium text-stone-700 outline-none focus-visible:ring-2 focus-visible:ring-stone-400 disabled:opacity-50 dark:border-white/[0.16] dark:bg-[#1D1D1A] dark:text-stone-200 dark:focus-visible:ring-stone-500"
      >
        <span aria-hidden className="relative block size-[18px]">
          <motion.svg
            viewBox="0 0 24 24"
            fill="none"
            stroke="currentColor"
            strokeWidth={1.7}
            strokeLinejoin="round"
            className="absolute inset-0 size-[18px] text-stone-500 dark:text-stone-400"
            initial={false}
            animate={{ opacity: liked ? 0 : 1 }}
            transition={reduced ? INSTANT : CROSSFADE}
          >
            <path d={HEART} />
          </motion.svg>

          <motion.svg
            viewBox="0 0 24 24"
            fill="currentColor"
            className="absolute inset-0 size-[18px] text-stone-800 dark:text-stone-100"
            initial={false}
            animate={{ opacity: liked ? 1 : 0, scale: liked ? 1 : 0.55 }}
            transition={reduced ? INSTANT : CELL}
          >
            <path d={HEART} />
          </motion.svg>

          {!reduced && burst > 0 ? (
            <span
              key={burst}
              className="pointer-events-none absolute left-1/2 top-1/2 block size-0"
            >
              {SPARKS.map((spark, i) => (
                <motion.span
                  key={i}
                  className="absolute block rounded-[1.5px] bg-stone-800 dark:bg-stone-100"
                  style={{
                    width: spark.size,
                    height: spark.size,
                    marginLeft: -spark.size / 2,
                    marginTop: -spark.size / 2,
                  }}
                  initial={{ x: 0, y: 0, scale: 0.6, opacity: 0.85 }}
                  animate={{ x: spark.x, y: spark.y, scale: 1, opacity: 0 }}
                  transition={{ duration: 0.44, delay: spark.delay, ease: EASE }}
                />
              ))}
            </span>
          ) : null}
        </span>

        <span aria-hidden className="grid">
          <motion.span
            className="col-start-1 row-start-1"
            initial={false}
            animate={{ opacity: liked ? 0 : 1 }}
            transition={reduced ? INSTANT : CROSSFADE}
          >
            {label}
          </motion.span>
          <motion.span
            className="col-start-1 row-start-1"
            initial={false}
            animate={{ opacity: liked ? 1 : 0 }}
            transition={reduced ? INSTANT : CROSSFADE}
          >
            {activeLabel}
          </motion.span>
        </span>

        <span
          aria-hidden
          className="grid overflow-hidden text-[12px] tabular-nums text-stone-500 dark:text-stone-400"
        >
          <span className="invisible col-start-1 row-start-1">{widest}</span>
          <AnimatePresence initial={false}>
            <motion.span
              key={shown}
              className="col-start-1 row-start-1 justify-self-end"
              initial={{ opacity: 0, y: reduced ? 0 : -7 }}
              animate={{ opacity: 1, y: 0 }}
              exit={{ opacity: 0, y: reduced ? 0 : 7 }}
              transition={reduced ? INSTANT : CROSSFADE}
            >
              {shown}
            </motion.span>
          </AnimatePresence>
        </span>

      </button>

      <span role="status" aria-live="polite" className="sr-only">
        {`${format(settled.count)} likes, ${settled.liked ? "liked" : "not liked"}`}
      </span>
    </span>
  );
}
```

---

## Ripple · Action Feedback

Touch feedback from the pointer origin.

Docs: https://yugo.click/docs/ripple
Install: `bun add motion`, then copy the source below into `components/yugo/ripple.tsx` · or `bunx shadcn@latest add https://yugo.click/r/ripple.json`.

Guarantees:
- A tap released in forty milliseconds still gets a whole bloom: the fade cannot begin until the ripple has been visible for its minimum window, so the fastest presses are the ones most implementations swallow and this one does not.
- The bloom is spawned at the pointer's coordinates inside the element rect and scaled to the distance of the farthest corner, so a press on an edge fills the surface instead of stopping short of the opposite side.
- Nothing that moves is a layout property: the ripple is a fixed 40px patch, absolutely positioned inside an aria-hidden overlay, driven only by transform and opacity, so no press can shift the content sitting above it.
- Pointer capture, lost capture, pointer cancel, blur, and tab hide all release through one path, so dragging off the control, scrolling the list out from under a finger, or switching tabs mid-press never strands a ripple on screen.
- Space and Enter spawn from the element's centre and release on key up, so keyboard activation is acknowledged exactly like a finger, while the overlay stays aria-hidden and the button announces itself once rather than once per bloom.
- Under prefers-reduced-motion the patch arrives already at full size and only fades, so the press is still confirmed and only the travel is skipped.


### Usage

```tsx
"use client";

import { Ripple, useRipple } from "@/components/yugo/ripple";

export function PinPad({ onDigit }: { onDigit: (d: string) => void }) {
  return (
    <div className="grid grid-cols-3 gap-2">
      {["1", "2", "3", "4", "5", "6", "7", "8", "9"].map((d) => (
        <Ripple key={d} onPress={() => onDigit(d)} className="h-12 w-full font-mono">
          {d}
        </Ripple>
      ))}
    </div>
  );
}

export function TrackRow({ title, onPlay }: { title: string; onPlay: () => void }) {
  const { bind, ripples, fadeDuration } = useRipple({ max: 2 });

  return (
    <div
      role="button"
      tabIndex={0}
      onClick={onPlay}
      {...bind}
      className="relative isolate flex h-14 items-center rounded-[11px] px-3 text-[13px] text-stone-700 dark:text-stone-200"
    >
      <span aria-hidden className="pointer-events-none absolute inset-0 overflow-hidden rounded-[inherit]">
        {ripples.map((r) => (
          <span
            key={r.id}
            className="absolute block size-10 rounded-[14px] bg-stone-800/10 dark:bg-white/15"
            style={{
              left: r.x - 20,
              top: r.y - 20,
              transform: `scale(${r.scale})`,
              opacity: r.released ? 0 : 1,
              transition: `opacity ${fadeDuration}s linear`,
            }}
          />
        ))}
      </span>
      <span className="relative">{title}</span>
    </div>
  );
}
```

### Source (`components/yugo/ripple.tsx`)

```tsx
"use client";

import { useCallback, useEffect, useRef, useState } from "react";
import { motion, useReducedMotion } from "motion/react";

const EASE = [0.23, 1, 0.32, 1] as const;
const BLOOM = { duration: 0.5, ease: "linear" } as const;
const BASE = 40;

export type RippleSpec = {
  id: number;
  x: number;
  y: number;
  scale: number;
  released: boolean;
};

export type UseRippleOptions = {
  disabled?: boolean;
  max?: number;
  minVisible?: number;
  fade?: number;
};

export function useRipple({
  disabled = false,
  max = 4,
  minVisible = 220,
  fade = 320,
}: UseRippleOptions = {}) {
  const [ripples, setRipples] = useState<RippleSpec[]>([]);

  const list = useRef<RippleSpec[]>([]);
  const seq = useRef(0);
  const born = useRef(new Map<number, number>());
  const timers = useRef(new Map<number, ReturnType<typeof setTimeout>[]>());
  const pointers = useRef(new Map<number, number>());
  const keyed = useRef<number | null>(null);

  const commit = useCallback((next: RippleSpec[]) => {
    list.current = next;
    setRipples(next);
  }, []);

  const forget = useCallback((id: number) => {
    timers.current.get(id)?.forEach(clearTimeout);
    timers.current.delete(id);
    born.current.delete(id);
  }, []);

  const spawn = useCallback(
    (el: HTMLElement, clientX?: number, clientY?: number) => {
      const rect = el.getBoundingClientRect();
      const x = Math.round(
        clientX === undefined ? rect.width / 2 : clientX - rect.left,
      );
      const y = Math.round(
        clientY === undefined ? rect.height / 2 : clientY - rect.top,
      );
      const reach = Math.max(
        Math.hypot(x, y),
        Math.hypot(rect.width - x, y),
        Math.hypot(x, rect.height - y),
        Math.hypot(rect.width - x, rect.height - y),
      );

      let next = list.current;
      while (next.length >= max) {
        forget(next[0].id);
        next = next.slice(1);
      }

      const id = (seq.current += 1);
      born.current.set(id, performance.now());
      commit([
        ...next,
        {
          id,
          x,
          y,
          scale: Math.round((reach * 200) / BASE) / 100,
          released: false,
        },
      ]);
      return id;
    },
    [commit, forget, max],
  );

  const release = useCallback(
    (id: number) => {
      if (timers.current.has(id)) return;
      if (!list.current.some((r) => r.id === id)) return;

      const wait = Math.max(
        0,
        minVisible - (performance.now() - (born.current.get(id) ?? 0)),
      );

      const start = setTimeout(() => {
        commit(
          list.current.map((r) => (r.id === id ? { ...r, released: true } : r)),
        );
      }, wait);

      const drop = setTimeout(() => {
        forget(id);
        commit(list.current.filter((r) => r.id !== id));
      }, wait + fade);

      timers.current.set(id, [start, drop]);
    },
    [commit, fade, forget, minVisible],
  );

  const releaseAll = useCallback(() => {
    pointers.current.forEach((id) => release(id));
    pointers.current.clear();
    if (keyed.current !== null) {
      release(keyed.current);
      keyed.current = null;
    }
  }, [release]);

  const endPointer = useCallback(
    (pointerId: number) => {
      const id = pointers.current.get(pointerId);
      if (id === undefined) return;
      pointers.current.delete(pointerId);
      release(id);
    },
    [release],
  );

  useEffect(() => {
    const bail = () => releaseAll();
    const onVisibility = () => document.hidden && releaseAll();
    window.addEventListener("blur", bail);
    document.addEventListener("visibilitychange", onVisibility);
    return () => {
      window.removeEventListener("blur", bail);
      document.removeEventListener("visibilitychange", onVisibility);
    };
  }, [releaseAll]);

  useEffect(() => {
    const pending = timers.current;
    return () => {
      pending.forEach((set) => set.forEach(clearTimeout));
      pending.clear();
    };
  }, []);

  const bind = {
    onPointerDown: (e: React.PointerEvent<HTMLElement>) => {
      if (disabled) return;
      if (e.pointerType === "mouse" && e.button !== 0) return;
      if (pointers.current.has(e.pointerId)) return;
      e.currentTarget.setPointerCapture?.(e.pointerId);
      pointers.current.set(
        e.pointerId,
        spawn(e.currentTarget, e.clientX, e.clientY),
      );
    },
    onPointerUp: (e: React.PointerEvent<HTMLElement>) => endPointer(e.pointerId),
    onPointerCancel: (e: React.PointerEvent<HTMLElement>) =>
      endPointer(e.pointerId),
    onLostPointerCapture: (e: React.PointerEvent<HTMLElement>) =>
      endPointer(e.pointerId),
    onKeyDown: (e: React.KeyboardEvent<HTMLElement>) => {
      if (disabled || e.repeat || keyed.current !== null) return;
      if (e.key !== " " && e.key !== "Enter") return;
      keyed.current = spawn(e.currentTarget);
    },
    onKeyUp: (e: React.KeyboardEvent<HTMLElement>) => {
      if (keyed.current === null) return;
      if (e.key !== " " && e.key !== "Enter" && e.key !== "Escape") return;
      release(keyed.current);
      keyed.current = null;
    },
    onBlur: () => releaseAll(),
  };

  return { bind, ripples, fadeDuration: fade / 1000 };
}

export type RippleProps = {
  children: React.ReactNode;
  onPress?: () => void;
  disabled?: boolean;
  max?: number;
  tintClassName?: string;
  className?: string;
};

export function Ripple({
  children,
  onPress,
  disabled = false,
  max = 4,
  tintClassName = "bg-stone-800/15 dark:bg-white/20",
  className = "",
}: RippleProps) {
  const { bind, ripples, fadeDuration } = useRipple({ disabled, max });
  const reduced = useReducedMotion();

  return (
    <button
      type="button"
      disabled={disabled}
      onClick={onPress}
      style={{ touchAction: "manipulation", WebkitTapHighlightColor: "transparent" }}
      className={`relative isolate inline-flex select-none items-center justify-center gap-2 rounded-[9px] border border-stone-200 bg-white px-3.5 py-2 text-[13px] font-medium text-stone-700 outline-none focus-visible:ring-2 focus-visible:ring-stone-400 disabled:opacity-50 dark:border-white/[0.16] dark:bg-[#1D1D1A] dark:text-stone-200 dark:focus-visible:ring-white/25 ${className}`}
      {...bind}
    >
      <span
        aria-hidden
        className="pointer-events-none absolute inset-0 overflow-hidden rounded-[inherit]"
      >
        {ripples.map((r) => (
          <motion.span
            key={r.id}
            className={`absolute block rounded-full ${tintClassName}`}
            style={{
              left: r.x - BASE / 2,
              top: r.y - BASE / 2,
              width: BASE,
              height: BASE,
              willChange: "transform, opacity",
            }}
            initial={{ scale: reduced ? r.scale : 0, opacity: 0 }}
            animate={{ scale: r.scale, opacity: r.released ? 0 : 1 }}
            transition={{
              scale: reduced ? { duration: 0 } : BLOOM,
              opacity: {
                duration: r.released ? fadeDuration : 0.07,
                ease: r.released ? EASE : "linear",
              },
            }}
          />
        ))}
      </span>

      <span className="relative">{children}</span>
    </button>
  );
}
```

---

## Icon Morph · Action Feedback

Play/pause, menu/close as one mechanism.

Docs: https://yugo.click/docs/icon-morph
Install: `bun add motion`, then copy the source below into `components/yugo/icon-morph.tsx` · or `bunx shadcn@latest add https://yugo.click/r/icon-morph.json`.

Guarantees:
- Two icons crossfaded over each other draw both shapes at once through the middle of the transition; this renders one path list and interpolates its coordinates, so there is never a second icon on screen to catch.
- Every state is padded to the same slot count, and a slot a state does not use collapses to a zero-length path and fades, so the number of paths never changes mid-flight and no stroke pops into existence.
- The icon box and the label cell are reserved before the first paint: all labels stack in one grid cell: so swapping Play for Pause or Menu for Close cannot widen the button or push the row beside it.
- Activating the control mid-transition resumes the spring from the geometry currently on screen, rather than snapping back to the previous shape and replaying.
- Under prefers-reduced-motion the target geometry is applied in one frame; the icon still shows the correct state instead of being hidden or left mid-morph.
- It is a real button with aria-pressed or aria-expanded and an accessible name that changes once per state, so a screen reader announces the new state on activation and nothing repeats it.


### Usage

```tsx
"use client";

import { useState } from "react";
import { IconMorph } from "@/components/yugo/icon-morph";

export function PlayerBar() {
  const [playing, setPlaying] = useState(false);
  const [open, setOpen] = useState(false);

  return (
    <div className="flex items-center gap-2">
      <IconMorph
        preset="play-pause"
        semantics="pressed"
        showLabel
        active={playing}
        onActiveChange={(i) => setPlaying(i === 1)}
      />

      <IconMorph
        preset="menu-close"
        semantics="expanded"
        active={open}
        onActiveChange={(i) => setOpen(i === 1)}
      />

      <IconMorph
        labels={["Expand", "Collapse"]}
        shapes={[
          { d: ["M 5 12 L 19 12", "M 12 5 L 12 19"], rotate: 0 },
          { d: ["M 5 12 L 19 12", "M 5 12 L 19 12"], rotate: 180 },
        ]}
      />
    </div>
  );
}
```

### Source (`components/yugo/icon-morph.tsx`)

```tsx
"use client";

import { useCallback, useMemo, useState } from "react";
import { motion, useReducedMotion } from "motion/react";

const CELL = { type: "spring", stiffness: 520, damping: 34, mass: 0.45 } as const;
const CROSSFADE = { type: "spring", stiffness: 260, damping: 34, mass: 0.8 } as const;
const INSTANT = { duration: 0 } as const;

const NUMBER = /-?\d*\.?\d+/g;
const CENTER = "12";

export type MorphShape = {
  d: readonly string[];
  rotate?: number;
};

export type IconMorphMode = "stroke" | "fill";

export type IconMorphPreset =
  | "menu-close"
  | "play-pause"
  | "plus-minus"
  | "check-close";

export type IconMorphSlot = {
  key: number;
  d: string;
  visible: boolean;
};

export type IconMorphSemantics = "label" | "pressed" | "expanded";

export const iconMorphPresets: Record<
  IconMorphPreset,
  { mode: IconMorphMode; labels: readonly string[]; shapes: readonly MorphShape[] }
> = {
  "menu-close": {
    mode: "stroke",
    labels: ["Menu", "Close"],
    shapes: [
      {
        rotate: 0,
        d: ["M 4 7 L 20 7", "M 4 12 L 20 12", "M 4 17 L 20 17"],
      },
      {
        rotate: 90,
        d: ["M 6.5 6.5 L 17.5 17.5", "M 12 12 L 12 12", "M 6.5 17.5 L 17.5 6.5"],
      },
    ],
  },
  "play-pause": {
    mode: "fill",
    labels: ["Play", "Pause"],
    shapes: [
      {
        d: [
          "M 8 5 L 14 8.5 L 14 15.5 L 8 19 Z",
          "M 14 8.5 L 20 12 L 20 12 L 14 15.5 Z",
        ],
      },
      {
        d: [
          "M 8 5 L 11.5 5 L 11.5 19 L 8 19 Z",
          "M 15 5 L 18.5 5 L 18.5 19 L 15 19 Z",
        ],
      },
    ],
  },
  "plus-minus": {
    mode: "stroke",
    labels: ["Add", "Remove"],
    shapes: [
      { rotate: 0, d: ["M 5 12 L 19 12", "M 12 5 L 12 19"] },
      { rotate: 180, d: ["M 5 12 L 19 12", "M 5 12 L 19 12"] },
    ],
  },
  "check-close": {
    mode: "stroke",
    labels: ["Confirm", "Cancel"],
    shapes: [
      { d: ["M 5 12.5 L 10 17.5 L 19.5 7", "M 12 12 L 12 12 L 12 12"] },
      { d: ["M 6.5 6.5 L 12 12 L 17.5 17.5", "M 17.5 6.5 L 12 12 L 6.5 17.5"] },
    ],
  },
};

function isCollapsed(d: string): boolean {
  const nums = d.match(NUMBER);
  if (!nums || nums.length < 4) return false;
  return nums.every((n, i) => n === nums[i % 2]);
}

function normalize(shapes: readonly MorphShape[]): IconMorphSlot[][] {
  const slots = shapes.reduce((most, s) => Math.max(most, s.d.length), 0);

  return shapes.map((shape) =>
    Array.from({ length: slots }, (_, i) => {
      const own = shape.d[i];
      const sibling = shapes.find((s) => s.d[i] !== undefined)?.d[i] ?? "";
      const d = own ?? sibling.replace(NUMBER, CENTER);
      return { key: i, d, visible: !isCollapsed(d) };
    }),
  );
}

function toIndex(value: number | boolean): number {
  return typeof value === "boolean" ? (value ? 1 : 0) : Math.trunc(value);
}

export type UseIconMorphOptions = {
  preset?: IconMorphPreset;
  shapes?: readonly MorphShape[];
  mode?: IconMorphMode;
  labels?: readonly string[];
  active?: number | boolean;
  defaultActive?: number | boolean;
  onActiveChange?: (index: number) => void;
};

export function useIconMorph({
  preset = "menu-close",
  shapes,
  mode,
  labels,
  active,
  defaultActive = 0,
  onActiveChange,
}: UseIconMorphOptions = {}) {
  const base = iconMorphPresets[preset];
  const source = shapes ?? base.shapes;
  const names = labels ?? base.labels;
  const count = source.length;

  const [internal, setInternal] = useState(() => toIndex(defaultActive));
  const reduced = useReducedMotion();

  const raw = active === undefined ? internal : toIndex(active);
  const index = count === 0 ? 0 : Math.min(Math.max(raw, 0), count - 1);

  const frames = useMemo(() => normalize(source), [source]);

  const setIndex = useCallback(
    (next: number) => {
      if (count === 0) return;
      const wrapped = ((next % count) + count) % count;
      if (active === undefined) setInternal(wrapped);
      onActiveChange?.(wrapped);
    },
    [active, count, onActiveChange],
  );

  const toggle = useCallback(() => setIndex(index + 1), [setIndex, index]);

  return {
    index,
    count,
    slots: frames[index] ?? [],
    rotate: source[index]?.rotate ?? 0,
    mode: mode ?? base.mode,
    label: names[index] ?? "",
    labels: names,
    transition: reduced ? INSTANT : CELL,
    labelTransition: reduced ? INSTANT : CROSSFADE,
    setIndex,
    toggle,
  };
}

export type IconMorphProps = UseIconMorphOptions & {
  size?: number;
  strokeWidth?: number;
  showLabel?: boolean;
  semantics?: IconMorphSemantics;
  disabled?: boolean;
  className?: string;
};

export function IconMorph({
  size = 20,
  strokeWidth = 1.75,
  showLabel = false,
  semantics = "label",
  disabled = false,
  className = "",
  ...options
}: IconMorphProps) {
  const {
    index,
    slots,
    rotate,
    mode,
    label,
    labels,
    transition,
    labelTransition,
    toggle,
  } = useIconMorph(options);

  const stroked = mode === "stroke";

  return (
    <motion.button
      type="button"
      disabled={disabled}
      onClick={toggle}
      aria-label={label}
      aria-pressed={semantics === "pressed" ? index === 1 : undefined}
      aria-expanded={semantics === "expanded" ? index === 1 : undefined}
      whileTap={disabled ? undefined : { y: 1 }}
      transition={transition}
      className={`inline-flex h-9 shrink-0 select-none items-center justify-center gap-2 rounded-[9px] border border-stone-200 bg-white text-[13px] font-medium text-stone-700 outline-none focus-visible:ring-2 focus-visible:ring-stone-400 disabled:opacity-50 dark:border-white/[0.16] dark:bg-[#1D1D1A] dark:text-stone-200 dark:focus-visible:ring-white/30 ${
        showLabel ? "px-3" : "w-9"
      } ${className}`}
      style={{ touchAction: "manipulation" }}
    >
      <motion.span
        aria-hidden="true"
        initial={false}
        animate={{ rotate }}
        transition={transition}
        className="grid shrink-0 place-items-center"
        style={{ width: size, height: size }}
      >
        <svg
          viewBox="0 0 24 24"
          width={size}
          height={size}
          focusable="false"
          fill={stroked ? "none" : "currentColor"}
          stroke={stroked ? "currentColor" : "none"}
          strokeWidth={stroked ? strokeWidth : undefined}
          strokeLinecap="round"
          strokeLinejoin="round"
          style={{ display: "block" }}
        >
          {slots.map((slot) => (
            <motion.path
              key={slot.key}
              initial={false}
              animate={{ d: slot.d, opacity: slot.visible ? 1 : 0 }}
              transition={transition}
            />
          ))}
        </svg>
      </motion.span>

      {showLabel && (
        <span aria-hidden="true" className="grid">
          {labels.map((text, i) => (
            <motion.span
              key={i}
              initial={false}
              animate={{
                opacity: i === index ? 1 : 0,
                y: i === index ? 0 : i < index ? -3 : 3,
              }}
              transition={labelTransition}
              className="col-start-1 row-start-1 whitespace-nowrap"
            >
              {text}
            </motion.span>
          ))}
        </span>
      )}
    </motion.button>
  );
}
```

---

## Press Depth · Action Feedback

The feeling that the press landed.

Docs: https://yugo.click/docs/press-depth
Install: `bun add motion`, then copy the source below into `components/yugo/press-depth.tsx` · or `bunx shadcn@latest add https://yugo.click/r/press-depth.json`.

Guarantees:
- The key reserves its travel as bottom padding before the first press, so depressing it moves a transform and never the layout around it.
- Press state is tracked on the window rather than the element, so a pointer that leaves the key mid-hold lifts it, and a pointer that comes back presses it again: the visual state and the browser's own click suppression agree.
- A press that is interrupted by a scroll, a tab switch, a window blur, or a disabled prop arriving mid-hold releases instead of sticking down forever.
- Activation stays with the browser: Enter and Space fire a real click on a real button, so no synthetic handler double-fires and no keyboard path is invented.
- Auto-repeat is ignored, so holding Enter presses once instead of hammering the key sixty times a second.
- Under prefers-reduced-motion the key still lands at full depth, instantly: the confirmation survives, only the spring is dropped.


### Usage

```tsx
"use client";

import { useState } from "react";
import { PressDepth, usePressDepth } from "@/components/yugo/press-depth";

export function AmountPad({ onSubmit }: { onSubmit: (cents: number) => void }) {
  const [digits, setDigits] = useState("");
  const { pressed, ref, bind } = usePressDepth();

  return (
    <div className="space-y-3">
      <p className="text-[13px] tabular-nums text-stone-700 dark:text-stone-200">
        ${(Number(digits || "0") / 100).toFixed(2)}
      </p>

      <div className="flex gap-2">
        {["1", "2", "3"].map((d) => (
          <PressDepth
            key={d}
            depth={2}
            aria-label={`Digit ${d}`}
            onClick={() => setDigits((v) => (v + d).slice(0, 6))}
          >
            {d}
          </PressDepth>
        ))}
      </div>

      <button
        ref={ref}
        {...bind}
        type="button"
        disabled={digits.length === 0}
        onClick={() => onSubmit(Number(digits))}
        style={{ transform: `translateY(${pressed ? 2 : 0}px)` }}
        className="h-9 rounded-[9px] bg-stone-800 px-3.5 text-[13px] font-medium text-white disabled:opacity-50 dark:bg-stone-100 dark:text-stone-900"
      >
        Charge
      </button>
    </div>
  );
}
```

### Source (`components/yugo/press-depth.tsx`)

```tsx
"use client";

import { useCallback, useEffect, useRef, useState } from "react";
import { motion, useReducedMotion } from "motion/react";

const PRESS = { type: "spring", stiffness: 520, damping: 34, mass: 0.45 } as const;

export type UsePressDepthOptions = {
  disabled?: boolean;
  onPressStart?: () => void;
  onPressEnd?: () => void;
};

export type PressOrigin = { x: number; y: number };

export type UsePressDepthResult = {
  pressed: boolean;
  origin: PressOrigin | null;
  ref: (node: HTMLElement | null) => void;
  bind: {
    onPointerDown: (event: React.PointerEvent) => void;
    onKeyDown: (event: React.KeyboardEvent) => void;
    onKeyUp: (event: React.KeyboardEvent) => void;
    onBlur: () => void;
  };
};

export function usePressDepth(
  options: UsePressDepthOptions = {},
): UsePressDepthResult {
  const { disabled = false, onPressStart, onPressEnd } = options;

  const [pressed, setPressed] = useState(false);
  const [tracking, setTracking] = useState(false);
  const [origin, setOrigin] = useState<PressOrigin | null>(null);

  const node = useRef<HTMLElement | null>(null);
  const pointer = useRef<number | null>(null);
  const down = useRef(false);

  const began = useRef(onPressStart);
  began.current = onPressStart;
  const ended = useRef(onPressEnd);
  ended.current = onPressEnd;

  const setDown = useCallback((next: boolean) => {
    if (down.current === next) return;
    down.current = next;
    setPressed(next);
    if (next) began.current?.();
    else ended.current?.();
  }, []);

  const stop = useCallback(() => {
    pointer.current = null;
    setTracking(false);
    setOrigin(null);
    setDown(false);
  }, [setDown]);

  useEffect(() => {
    if (!tracking) return;

    const contains = (event: PointerEvent) => {
      const el = node.current;
      if (!el) return false;
      const r = el.getBoundingClientRect();
      return (
        event.clientX >= r.left &&
        event.clientX <= r.right &&
        event.clientY >= r.top &&
        event.clientY <= r.bottom
      );
    };

    const move = (event: PointerEvent) => {
      if (event.pointerId !== pointer.current) return;
      setDown(contains(event));
    };
    const lift = (event: PointerEvent) => {
      if (event.pointerId !== pointer.current) return;
      stop();
    };
    const bail = () => stop();
    const hidden = () => {
      if (document.hidden) stop();
    };

    window.addEventListener("pointermove", move);
    window.addEventListener("pointerup", lift);
    window.addEventListener("pointercancel", lift);
    window.addEventListener("blur", bail);
    document.addEventListener("visibilitychange", hidden);

    return () => {
      window.removeEventListener("pointermove", move);
      window.removeEventListener("pointerup", lift);
      window.removeEventListener("pointercancel", lift);
      window.removeEventListener("blur", bail);
      document.removeEventListener("visibilitychange", hidden);
    };
  }, [tracking, setDown, stop]);

  useEffect(() => {
    if (disabled) stop();
  }, [disabled, stop]);

  const ref = useCallback((next: HTMLElement | null) => {
    node.current = next;
  }, []);

  const bind = {
    onPointerDown: (event: React.PointerEvent) => {
      if (disabled) return;
      if (event.pointerType === "mouse" && event.button !== 0) return;
      const r = event.currentTarget.getBoundingClientRect();
      setOrigin({
        x: Math.max(-1, Math.min(1, ((event.clientX - r.left) / r.width) * 2 - 1)),
        y: Math.max(-1, Math.min(1, ((event.clientY - r.top) / r.height) * 2 - 1)),
      });
      pointer.current = event.pointerId;
      setTracking(true);
      setDown(true);
    },
    onKeyDown: (event: React.KeyboardEvent) => {
      if (disabled || event.repeat) return;
      if (event.key === " " || event.key === "Enter") setDown(true);
    },
    onKeyUp: (event: React.KeyboardEvent) => {
      if (event.key === " " || event.key === "Enter" || event.key === "Escape") {
        setDown(false);
      }
    },
    onBlur: () => stop(),
  };

  return { pressed, origin, ref, bind };
}

export type PressDepthProps = {
  children: React.ReactNode;
  depth?: number;
  tilt?: number;
  disabled?: boolean;
  type?: "button" | "submit" | "reset";
  onClick?: React.MouseEventHandler<HTMLButtonElement>;
  className?: string;
  "aria-label"?: string;
};

export function PressDepth({
  children,
  depth = 4,
  tilt = 7,
  disabled = false,
  type = "button",
  onClick,
  className = "",
  "aria-label": ariaLabel,
}: PressDepthProps) {
  const reduced = useReducedMotion();
  const { pressed, origin, ref, bind } = usePressDepth({ disabled });

  const lean = pressed && origin && !reduced ? origin : null;

  return (
    <button
      ref={ref}
      type={type}
      disabled={disabled}
      aria-label={ariaLabel}
      data-pressed={pressed ? "" : undefined}
      onClick={onClick}
      style={{
        paddingBottom: depth,
        touchAction: "manipulation",
        WebkitTapHighlightColor: "transparent",
      }}
      className="group relative inline-flex select-none rounded-[9px] align-middle outline-none disabled:opacity-50"
      {...bind}
    >
      <span
        aria-hidden
        style={{ top: depth }}
        className="absolute inset-x-0 bottom-0 rounded-[9px] bg-stone-300 dark:bg-white/25"
      />
      <motion.span
        initial={false}
        animate={{
          y: pressed ? depth : 0,
          rotateX: lean ? -lean.y * tilt : 0,
          rotateY: lean ? lean.x * tilt : 0,
        }}
        transition={reduced ? { duration: 0 } : PRESS}
        style={{ transformPerspective: 340 }}
        className={`relative inline-flex h-9 items-center justify-center gap-2 rounded-[9px] border border-stone-200 bg-white px-3.5 text-[13px] font-medium text-stone-700 group-focus-visible:ring-2 group-focus-visible:ring-stone-400 dark:border-white/[0.16] dark:bg-[#1D1D1A] dark:text-stone-200 dark:group-focus-visible:ring-stone-500 ${className}`}
      >
        <motion.span
          aria-hidden
          initial={false}
          animate={{ opacity: pressed ? 0 : 1 }}
          transition={reduced ? { duration: 0 } : PRESS}
          className="pointer-events-none absolute inset-0 rounded-[9px] shadow-[inset_0_1.5px_0_rgba(255,255,255,0.95),inset_0_-1px_0_rgba(28,25,23,0.06)] dark:shadow-[inset_0_1.5px_0_rgba(255,255,255,0.09)]"
        />
        {children}
      </motion.span>
    </button>
  );
}
```

---

## Floating Label · Input

The label makes room instead of disappearing.

Docs: https://yugo.click/docs/floating-label
Install: `bun add motion`, then copy the source below into `components/yugo/floating-label.tsx` · or `bunx shadcn@latest add https://yugo.click/r/floating-label.json`.

Guarantees:
- The label makes room instead of disappearing: the field reserves the raised row and the hint row at mount, so it stands 52px tall in every reachable state and a counter, an error color or a hint arriving on blur cannot push the submit button down the page.
- The label travels on transform only: y and scale, origin pinned to its left edge: so raising it costs no layout and the spring resumes from wherever the label currently is when you refocus a field you were leaving.
- A value the browser restores on back-navigation, or one a password manager writes without a React change event, still raises the label: the field reads its own node on mount and listens for native input and change, so text is never printed underneath the label.
- The mount-time raise is applied with zero duration, so a field that arrives pre-filled from the server presents its label already raised rather than animating on page load.
- Under prefers-reduced-motion the label still occupies the raised slot and the hint still changes; only the trip is skipped, and nothing is hidden.
- Screen readers get the hint once through aria-describedby and never hear the character counter, which is aria-hidden: the native maxLength attribute carries that information instead of sixty live-region updates.


### Usage

```tsx
"use client";

import { useState } from "react";
import { FloatingLabelInput } from "@/components/yugo/floating-label";

export function BillingContact() {
  const [email, setEmail] = useState("");
  const [reference, setReference] = useState("");
  const [touched, setTouched] = useState(false);

  const bad = touched && !/^[^\s@]+@[^\s@]+\.[^\s@]+$/.test(email);

  return (
    <form className="grid gap-4">
      <FloatingLabelInput
        label="Work email"
        type="email"
        autoComplete="email"
        required
        value={email}
        onChange={setEmail}
        onBlur={() => setTouched(true)}
        invalid={bad}
        hint={bad ? "Needs to look like name@company.com" : "Receipts are sent here."}
      />

      <FloatingLabelInput
        label="Invoice reference"
        value={reference}
        onChange={setReference}
        maxLength={16}
        hint="Printed on the statement header."
      />
    </form>
  );
}
```

### Source (`components/yugo/floating-label.tsx`)

```tsx
"use client";

import {
  useCallback,
  useEffect,
  useId,
  useLayoutEffect,
  useRef,
  useState,
} from "react";
import { motion, useReducedMotion } from "motion/react";

const INSTANT = { duration: 0 } as const;

const LIFT = { type: "spring", stiffness: 760, damping: 46, mass: 0.5 } as const;

const RAISE = -32;
const SLIDE = -12;
const SHRINK = 0.92;

const useIsomorphicLayoutEffect =
  typeof window === "undefined" ? useEffect : useLayoutEffect;

export type UseFloatingLabelOptions = {
  value?: string;
  defaultValue?: string;
  disabled?: boolean;
};

export type UseFloatingLabelReturn = {
  ref: React.RefObject<HTMLInputElement | null>;
  raised: boolean;
  focused: boolean;
  filled: boolean;
  length: number;
  instant: boolean;
  fieldProps: {
    onFocus: () => void;
    onBlur: () => void;
    onChange: (event: React.ChangeEvent<HTMLInputElement>) => void;
  };
};

type Fill = { length: number; instant: boolean };

export function useFloatingLabel({
  value,
  defaultValue,
  disabled = false,
}: UseFloatingLabelOptions = {}): UseFloatingLabelReturn {
  const ref = useRef<HTMLInputElement | null>(null);
  const mounted = useRef(false);

  const [focused, setFocused] = useState(false);
  const [fill, setFill] = useState<Fill>({
    length: (value ?? defaultValue ?? "").length,
    instant: true,
  });

  const settle = useCallback((next: number, instant: boolean) => {
    setFill((prev) =>
      prev.length === next && prev.instant === instant ? prev : { length: next, instant },
    );
  }, []);

  useIsomorphicLayoutEffect(() => {
    const el = ref.current;
    const next = value !== undefined ? value.length : el ? el.value.length : 0;
    settle(next, !mounted.current);
    mounted.current = true;
  }, [value, settle]);

  useEffect(() => {
    setFill((prev) => (prev.instant ? { ...prev, instant: false } : prev));
  }, []);

  useEffect(() => {
    const el = ref.current;
    if (!el || value !== undefined) return;
    const read = () => settle(el.value.length, false);
    el.addEventListener("input", read);
    el.addEventListener("change", read);
    return () => {
      el.removeEventListener("input", read);
      el.removeEventListener("change", read);
    };
  }, [value, settle]);

  useEffect(() => {
    if (disabled) setFocused(false);
  }, [disabled]);

  const onFocus = useCallback(() => setFocused(true), []);
  const onBlur = useCallback(() => setFocused(false), []);
  const onChange = useCallback(
    (event: React.ChangeEvent<HTMLInputElement>) =>
      settle(event.currentTarget.value.length, false),
    [settle],
  );

  return {
    ref,
    raised: focused || fill.length > 0,
    focused,
    filled: fill.length > 0,
    length: fill.length,
    instant: fill.instant && !focused,
    fieldProps: { onFocus, onBlur, onChange },
  };
}

export type FloatingLabelInputProps = {
  label: string;
  value?: string;
  defaultValue?: string;
  onChange?: (value: string, event: React.ChangeEvent<HTMLInputElement>) => void;
  onFocus?: () => void;
  onBlur?: () => void;
  hint?: string;
  invalid?: boolean;
  id?: string;
  name?: string;
  type?: "text" | "email" | "password" | "search" | "tel" | "url";
  autoComplete?: string;
  inputMode?: React.ComponentProps<"input">["inputMode"];
  maxLength?: number;
  required?: boolean;
  disabled?: boolean;
  readOnly?: boolean;
  inputRef?: React.Ref<HTMLInputElement>;
  className?: string;
};

export function FloatingLabelInput({
  label,
  value,
  defaultValue,
  onChange,
  onFocus,
  onBlur,
  hint,
  invalid = false,
  id,
  name,
  type = "text",
  autoComplete,
  inputMode,
  maxLength,
  required = false,
  disabled = false,
  readOnly = false,
  inputRef,
  className = "",
}: FloatingLabelInputProps) {
  const auto = useId();
  const fieldId = id ?? `${auto}-field`;
  const hintId = `${auto}-hint`;

  const reduced = useReducedMotion();
  const { ref, raised, focused, length, instant, fieldProps } = useFloatingLabel({
    value,
    defaultValue,
    disabled,
  });

  const move = reduced || instant ? INSTANT : LIFT;

  const attach = useCallback(
    (node: HTMLInputElement | null) => {
      ref.current = node;
      if (typeof inputRef === "function") inputRef(node);
      else if (inputRef) inputRef.current = node;
    },
    [ref, inputRef],
  );

  return (
    <div className={`w-full ${className}`}>
      <div className="relative pt-[20px]">
        <div
          className={`relative h-10 rounded-[10px] border-2 transition-[background-color,border-color,box-shadow] duration-150 ${
            invalid
              ? "border-red-500 bg-white dark:border-red-400 dark:bg-[#252522]"
              : focused
                ? "border-[#4568FF] bg-white dark:border-[#93B0FF] dark:bg-[#252522]"
                : "border-stone-200 bg-stone-100/70 shadow-[inset_0_1px_2px_rgba(28,25,23,0.07)] dark:border-white/[0.08] dark:bg-[#1D1D1A] dark:shadow-[inset_0_1px_2px_rgba(0,0,0,0.45)]"
          } ${disabled ? "opacity-55" : ""}`}
        >
          <input
          ref={attach}
          id={fieldId}
          name={name}
          type={type}
          value={value}
          defaultValue={defaultValue}
          autoComplete={autoComplete}
          inputMode={inputMode}
          maxLength={maxLength}
          required={required}
          disabled={disabled}
          readOnly={readOnly}
          aria-required={required || undefined}
          aria-invalid={invalid || undefined}
          aria-describedby={hint ? hintId : undefined}
          onFocus={() => {
            fieldProps.onFocus();
            onFocus?.();
          }}
          onBlur={() => {
            fieldProps.onBlur();
            onBlur?.();
          }}
          onChange={(event) => {
            fieldProps.onChange(event);
            onChange?.(event.currentTarget.value, event);
          }}
            className="absolute inset-0 h-full w-full rounded-[9px] bg-transparent px-3 py-0 text-[13px] leading-[20px] text-stone-700 outline-none focus-visible:outline-none disabled:cursor-not-allowed dark:text-stone-200"
          />
        </div>

        <motion.label
          htmlFor={fieldId}
          initial={false}
          animate={{
            y: raised ? RAISE : 0,
            x: raised ? SLIDE : 0,
            scale: raised ? SHRINK : 1,
          }}
          transition={move}
          style={{ originX: 0, originY: 0, willChange: "transform" }}
          className={`absolute left-3 top-[32px] block cursor-text select-none text-[13px] leading-[16px] ${
            invalid
              ? "text-red-600 dark:text-red-400"
              : raised
                ? "text-stone-600 dark:text-stone-300"
                : "text-stone-400 dark:text-stone-500"
          }`}
        >
          {label}
          {required ? (
            <span aria-hidden className="ml-0.5 text-stone-400 dark:text-stone-500">
              *
            </span>
          ) : null}
        </motion.label>
      </div>

      <div className="mt-1.5 flex h-[16px] items-start gap-3">
        <p
          aria-hidden
          className={`min-w-0 flex-1 truncate text-[11.5px] leading-[16px] ${
            invalid
              ? "text-red-600 dark:text-red-400"
              : "text-stone-500 dark:text-stone-400"
          }`}
        >
          {hint}
        </p>

        {maxLength !== undefined ? (
          <span
            aria-hidden
            className="grid shrink-0 justify-items-end font-mono text-[10.5px] leading-[16px] tabular-nums text-stone-400 dark:text-stone-500"
          >
            <span className="invisible col-start-1 row-start-1">
              {maxLength} / {maxLength}
            </span>
            <span className="col-start-1 row-start-1">
              {length} / {maxLength}
            </span>
          </span>
        ) : null}

        {hint ? (
          <span id={hintId} className="sr-only">
            {hint}
          </span>
        ) : null}
      </div>
    </div>
  );
}
```

---

## Inline Validation · Input

Error message that does not shove the form.

Docs: https://yugo.click/docs/inline-validation
Install: `bun add motion`, then copy the source below into `components/yugo/inline-validation.tsx` · or `bunx shadcn@latest add https://yugo.click/r/inline-validation.json`.

Guarantees:
- The message slot is measured and reserved before anything is wrong, so an error arriving never pushes the next field, the footer or the submit button down the page.
- Validation waits for the first blur; a field you have not finished with is never told it is wrong halfway through the first word.
- After that first blur a value that becomes correct clears the message immediately, while a value that is still wrong waits out the debounce, so the text under the input cannot flicker once per keystroke.
- Hint and error occupy the same grid cell and only opacity and three pixels of travel move between them, so swapping one for the other cannot change the row's width or height.
- A long message clamps inside its reserved lines rather than animating to an unbounded height, so no validator can make the form taller than it declared it would be.
- The announcement lives in one polite region carrying only the settled message, so a screen reader hears the error once instead of on every keypress, and under prefers-reduced-motion the message and the status glyph arrive at full opacity with no travel.


### Usage

```tsx
"use client";

import { useState } from "react";
import { InlineValidation } from "@/components/yugo/inline-validation";

const checkEmail = (v: string) => {
  if (v.trim() === "") return "A work email is required.";
  if (!/^[^\s@]+@[^\s@]+\.[^\s@]+$/.test(v)) return "That is not a complete email address.";
  return null;
};

export function InviteForm({ onInvite }: { onInvite: (email: string) => void }) {
  const [email, setEmail] = useState("");

  return (
    <form
      className="w-full max-w-sm"
      onSubmit={(e) => {
        e.preventDefault();
        if (checkEmail(email)) return;
        onInvite(email);
      }}
    >
      <InlineValidation
        label="Work email"
        type="email"
        value={email}
        onChange={setEmail}
        validate={checkEmail}
        hint="Only used to send the invite."
        autoComplete="email"
        required
      />

      <button
        type="submit"
        className="mt-3 h-9 rounded-[9px] bg-stone-800 px-3 text-[13px] font-medium text-white dark:bg-stone-100 dark:text-stone-900"
      >
        Send invite
      </button>
    </form>
  );
}
```

### Source (`components/yugo/inline-validation.tsx`)

```tsx
"use client";

import { useCallback, useEffect, useId, useRef, useState } from "react";
import { motion, useReducedMotion } from "motion/react";

const CROSSFADE = { type: "spring", stiffness: 260, damping: 34, mass: 0.8 } as const;
const INSTANT = { duration: 0 } as const;

const LINE = 16;

export type ValidationStatus = "idle" | "pending" | "valid" | "invalid";

export type Validator = (value: string) => string | null;

export type UseInlineValidationOptions = {
  value: string;
  validate: Validator;
  debounce?: number;
};

export type UseInlineValidationReturn = {
  status: ValidationStatus;
  error: string | null;
  message: string;
  touched: boolean;
  commit: () => void;
  reset: () => void;
  fieldProps: {
    onBlur: () => void;
    "aria-invalid": boolean;
  };
};

type Settled = {
  status: ValidationStatus;
  error: string | null;
  message: string;
};

const CLEAN: Settled = { status: "idle", error: null, message: "" };

export function useInlineValidation({
  value,
  validate,
  debounce = 400,
}: UseInlineValidationOptions): UseInlineValidationReturn {
  const [touched, setTouched] = useState(false);
  const [settled, setSettled] = useState<Settled>(CLEAN);

  const check = useRef(validate);
  const latest = useRef(value);

  useEffect(() => {
    check.current = validate;
    latest.current = value;
  });

  useEffect(() => {
    if (!touched) return;

    const next = check.current(value);
    const resolved: ValidationStatus = value.length > 0 ? "valid" : "idle";

    if (next === null) {
      setSettled((prev) =>
        prev.status === resolved && prev.error === null
          ? prev
          : { status: resolved, error: null, message: prev.message },
      );
      return;
    }

    setSettled((prev) =>
      prev.status === "invalid"
        ? prev
        : { status: "pending", error: null, message: prev.message },
    );

    const t = setTimeout(() => {
      setSettled((prev) =>
        prev.error === next ? prev : { status: "invalid", error: next, message: next },
      );
    }, debounce);

    return () => clearTimeout(t);
  }, [value, touched, debounce]);

  const commit = useCallback(() => {
    setTouched(true);
    const v = latest.current;
    const next = check.current(v);
    setSettled((prev) =>
      next === null
        ? { status: v.length > 0 ? "valid" : "idle", error: null, message: prev.message }
        : { status: "invalid", error: next, message: next },
    );
  }, []);

  const reset = useCallback(() => {
    setTouched(false);
    setSettled(CLEAN);
  }, []);

  return {
    status: settled.status,
    error: settled.error,
    message: settled.message,
    touched,
    commit,
    reset,
    fieldProps: { onBlur: commit, "aria-invalid": settled.status === "invalid" },
  };
}

export type InlineValidationProps = {
  label: string;
  value: string;
  onChange: (value: string) => void;
  validate: Validator;
  hint?: string;
  id?: string;
  name?: string;
  type?: "text" | "email" | "password" | "tel" | "url" | "search";
  placeholder?: string;
  autoComplete?: string;
  inputMode?: React.ComponentProps<"input">["inputMode"];
  debounce?: number;
  reserveLines?: number;
  disabled?: boolean;
  required?: boolean;
  className?: string;
};

export function InlineValidation({
  label,
  value,
  onChange,
  validate,
  hint,
  id,
  name,
  type = "text",
  placeholder,
  autoComplete,
  inputMode,
  debounce = 400,
  reserveLines = 1,
  disabled = false,
  required = false,
  className = "",
}: InlineValidationProps) {
  const reduced = useReducedMotion();
  const fade = reduced ? INSTANT : CROSSFADE;

  const auto = useId();
  const fieldId = id ?? `${auto}-field`;
  const hintId = `${auto}-hint`;
  const errorId = `${auto}-error`;

  const { status, error, message, fieldProps } = useInlineValidation({
    value,
    validate,
    debounce,
  });

  const invalid = status === "invalid";
  const valid = status === "valid";

  const described = [hint ? hintId : null, invalid ? errorId : null]
    .filter(Boolean)
    .join(" ");

  const clamp = {
    display: "-webkit-box" as const,
    WebkitBoxOrient: "vertical" as const,
    WebkitLineClamp: reserveLines,
    overflow: "hidden" as const,
  };

  return (
    <div className={`w-full ${className}`}>
      <label
        htmlFor={fieldId}
        className="block text-[13px] font-medium text-stone-700 dark:text-stone-200"
      >
        {label}
      </label>

      <div className="relative mt-1.5">
        <input
          id={fieldId}
          name={name}
          type={type}
          value={value}
          placeholder={placeholder}
          autoComplete={autoComplete}
          inputMode={inputMode}
          disabled={disabled}
          required={required}
          aria-required={required || undefined}
          aria-describedby={described || undefined}
          onChange={(e) => onChange(e.target.value)}
          {...fieldProps}
          className={`h-10 w-full rounded-[10px] border-2 pl-3 pr-9 text-[13px] text-stone-700 outline-none transition-[background-color,border-color,box-shadow] duration-150 placeholder:text-stone-400 focus-visible:outline-none disabled:opacity-50 dark:text-stone-200 dark:placeholder:text-stone-500 ${
            invalid
              ? "border-red-500 bg-white dark:border-red-400 dark:bg-[#1D1D1A]"
              : "border-stone-200 bg-stone-100/70 shadow-[inset_0_1px_2px_rgba(28,25,23,0.07)] focus:border-[#4568FF] focus:bg-white focus:shadow-none dark:border-white/[0.08] dark:bg-[#1D1D1A] dark:shadow-[inset_0_1px_2px_rgba(0,0,0,0.45)] dark:focus:border-[#93B0FF] dark:focus:bg-[#252522]"
          }`}
        />

        <span
          className="pointer-events-none absolute right-3 top-1/2 grid size-3.5 -translate-y-1/2 place-items-center"
          aria-hidden
        >
          <motion.svg
            viewBox="0 0 12 12"
            width="14"
            height="14"
            fill="none"
            className="col-start-1 row-start-1 text-stone-500 dark:text-stone-400"
            initial={false}
            animate={{ opacity: valid ? 1 : 0, scale: valid ? 1 : 0.7 }}
            transition={fade}
          >
            <path
              d="M2 6.3 4.7 9 10 3.2"
              stroke="currentColor"
              strokeWidth="1.6"
              strokeLinecap="round"
              strokeLinejoin="round"
            />
          </motion.svg>
          <motion.svg
            viewBox="0 0 12 12"
            width="14"
            height="14"
            fill="none"
            className="col-start-1 row-start-1 text-red-700 dark:text-red-400"
            initial={false}
            animate={{ opacity: invalid ? 1 : 0, scale: invalid ? 1 : 0.7 }}
            transition={fade}
          >
            <path d="M6 2v4.4" stroke="currentColor" strokeWidth="1.7" strokeLinecap="round" />
            <rect x="5.15" y="8.4" width="1.7" height="1.7" rx="0.5" fill="currentColor" />
          </motion.svg>
        </span>
      </div>

      <div className="relative mt-1.5 grid" style={{ height: reserveLines * LINE }}>
        {hint ? (
          <motion.p
            aria-hidden
            style={clamp}
            className="col-start-1 row-start-1 text-[11.5px] leading-[16px] text-stone-500 dark:text-stone-400"
            initial={false}
            animate={{ opacity: invalid ? 0 : 1, y: invalid ? 3 : 0 }}
            transition={fade}
          >
            {hint}
          </motion.p>
        ) : null}

        <motion.p
          aria-hidden
          style={clamp}
          className="col-start-1 row-start-1 text-[11.5px] leading-[16px] text-red-700 dark:text-red-400"
          initial={false}
          animate={{ opacity: invalid ? 1 : 0, y: invalid ? 0 : -3 }}
          transition={fade}
        >
          {error ?? message}
        </motion.p>

        {hint ? (
          <span id={hintId} className="sr-only">
            {hint}
          </span>
        ) : null}

        <span
          id={errorId}
          role="status"
          aria-live="polite"
          aria-atomic="true"
          className="sr-only"
        >
          {error ?? ""}
        </span>
      </div>
    </div>
  );
}
```

---

## Password Strength · Input

Strength read segment by segment.

Docs: https://yugo.click/docs/password-strength
Install: `bun add motion`, then copy the source below into `components/yugo/password-strength.tsx` · or `bunx shadcn@latest add https://yugo.click/r/password-strength.json`.

Guarantees:
- Strength is a whole number of segments, never a percentage, so the meter cannot report a change too small to name; the cells, the label and the count move together or not at all.
- The five verdict labels occupy one grid cell and the requirement list is fixed length, so nothing below the field, including the submit button, moves while a password is typed.
- A screen reader hears the verdict once, after typing stops, from a polite region that names the level and the requirements still outstanding, instead of a new announcement per keystroke.
- Meaning is never carried by color: the number of filled cells, the label, and a per-row met or not met string each state it, so the component survives greyscale and low vision.
- Segments fill with transform rather than width, and each cell springs from wherever it currently is, so deleting three characters reverses the fill mid-flight instead of restarting it.
- Common passwords, four-character repeats and keyboard walks are capped at one segment, because a meter that calls Passw0rd! strong is worse than no meter at all.


### Usage

```tsx
"use client";

import { useState } from "react";
import {
  PasswordStrength,
  usePasswordStrength,
} from "@/components/yugo/password-strength";

export function SignUpForm() {
  const [password, setPassword] = useState("");
  const { score, max } = usePasswordStrength(password);

  return (
    <form onSubmit={(e) => e.preventDefault()} className="w-full max-w-sm">
      <label htmlFor="password" className="text-[12.5px] text-stone-500">
        New password
      </label>
      <input
        id="password"
        type="password"
        value={password}
        autoComplete="new-password"
        onChange={(e) => setPassword(e.target.value)}
        className="mt-2 h-9 w-full rounded-[9px] border border-stone-200 px-3 text-[13px] dark:border-white/[0.16]"
      />

      <PasswordStrength value={password} className="mt-3" />

      <button type="submit" disabled={score < max} className="mt-4 h-9 w-full rounded-[9px]">
        Create account
      </button>
    </form>
  );
}
```

### Source (`components/yugo/password-strength.tsx`)

```tsx
"use client";

import { useEffect, useMemo, useState } from "react";
import { motion, useReducedMotion } from "motion/react";

const CELL = { type: "spring", stiffness: 520, damping: 34, mass: 0.45 } as const;
const CROSSFADE = { type: "spring", stiffness: 260, damping: 34, mass: 0.8 } as const;
const INSTANT = { duration: 0 } as const;

const COMMON = /^(?:password|passw0rd|qwerty|letmein|welcome|admin|iloveyou|monkey|dragon|abc123|111111|123123|123456)/i;
const RUN = /(.)\1{3,}/;
const RUN_UP = /(?:0123|1234|2345|3456|4567|5678|6789|abcd|bcde|cdef|defg|qwer|wert|erty|asdf)/i;
const SYMBOL = /[!-/:-@[-`{-~]/;

export type PasswordRule = {
  id: string;
  label: string;
  test: (value: string) => boolean;
};

export type EvaluatedRule = PasswordRule & { met: boolean };

export type UsePasswordStrengthOptions = {
  rules?: readonly PasswordRule[];
  labels?: readonly string[];
  announceDelay?: number;
};

export type PasswordStrengthState = {
  score: number;
  max: number;
  label: string;
  rules: EvaluatedRule[];
  guessable: boolean;
  announcement: string;
};

export const defaultPasswordRules: readonly PasswordRule[] = [
  { id: "length", label: "12 characters or more", test: (v) => v.length >= 12 },
  {
    id: "case",
    label: "Upper and lower case",
    test: (v) => /[a-z]/.test(v) && /[A-Z]/.test(v),
  },
  { id: "digit", label: "A number", test: (v) => /\d/.test(v) },
  { id: "symbol", label: "A symbol", test: (v) => SYMBOL.test(v) },
];

const defaultLabels = ["Empty", "Weak", "Fair", "Good", "Strong"] as const;

export function usePasswordStrength(
  value: string,
  {
    rules = defaultPasswordRules,
    labels = defaultLabels,
    announceDelay = 700,
  }: UsePasswordStrengthOptions = {},
): PasswordStrengthState {
  const state = useMemo(() => {
    const evaluated = rules.map((rule) => ({ ...rule, met: rule.test(value) }));
    const passed = evaluated.reduce((n, r) => n + (r.met ? 1 : 0), 0);
    const guessable =
      value.length > 0 && (COMMON.test(value) || RUN.test(value) || RUN_UP.test(value));

    const score =
      value.length === 0 ? 0 : guessable ? 1 : Math.min(rules.length, Math.max(1, passed));

    const label = labels[Math.min(score, labels.length - 1)] ?? "";
    const unmet = evaluated.filter((r) => !r.met);

    const announcement =
      value.length === 0
        ? ""
        : [
            `Password strength ${label.toLowerCase()}.`,
            guessable ? "This is a commonly guessed pattern." : "",
            unmet.length === 0
              ? "All requirements met."
              : `Still needed: ${unmet.map((r) => r.label.toLowerCase()).join(", ")}.`,
          ]
            .filter(Boolean)
            .join(" ");

    return { score, max: rules.length, label, rules: evaluated, guessable, announcement };
  }, [value, rules, labels]);

  const [settled, setSettled] = useState("");

  useEffect(() => {
    if (state.announcement === "") {
      setSettled("");
      return;
    }
    const id = setTimeout(() => setSettled(state.announcement), announceDelay);
    return () => clearTimeout(id);
  }, [state.announcement, announceDelay]);

  return { ...state, announcement: settled };
}

export type PasswordStrengthProps = {
  value: string;
  rules?: readonly PasswordRule[];
  labels?: readonly string[];
  announceDelay?: number;
  showRules?: boolean;
  className?: string;
};

const TONES = {
  none: { bar: "bg-stone-300 dark:bg-white/20", text: "text-stone-500 dark:text-stone-400" },
  danger: { bar: "bg-red-500", text: "text-red-600 dark:text-red-400" },
  caution: { bar: "bg-amber-500", text: "text-amber-600 dark:text-amber-400" },
  safe: { bar: "bg-emerald-500", text: "text-emerald-600 dark:text-emerald-400" },
} as const;

function toneFor(score: number, max: number) {
  if (score === 0) return TONES.none;
  const ratio = score / max;
  if (ratio <= 0.34) return TONES.danger;
  if (ratio <= 0.67) return TONES.caution;
  return TONES.safe;
}

export function PasswordStrength({
  value,
  rules = defaultPasswordRules,
  labels = defaultLabels,
  announceDelay = 700,
  showRules = true,
  className = "",
}: PasswordStrengthProps) {
  const {
    score,
    max,
    label,
    rules: evaluated,
    guessable,
    announcement,
  } = usePasswordStrength(value, { rules, labels, announceDelay });
  const reduced = useReducedMotion();
  const tone = toneFor(score, max);

  return (
    <div className={`w-full ${className}`}>
      <div
        role="meter"
        aria-label="Password strength"
        aria-valuemin={0}
        aria-valuemax={max}
        aria-valuenow={score}
        aria-valuetext={label}
        className="grid gap-1.5"
        style={{ gridTemplateColumns: `repeat(${max}, minmax(0, 1fr))` }}
      >
        {Array.from({ length: max }, (_, i) => (
          <div
            key={i}
            className="relative h-1.5 overflow-hidden rounded-[2px] bg-stone-200 dark:bg-white/12"
          >
            <motion.span
              className={`absolute inset-0 origin-left rounded-[2px] transition-colors duration-200 ${tone.bar}`}
              initial={false}
              animate={{ scaleX: i < score ? 1 : 0 }}
              transition={
                reduced ? INSTANT : { ...CELL, delay: i < score ? i * 0.03 : 0 }
              }
            />
          </div>
        ))}
      </div>

      <div className="mt-2 flex h-5 items-center justify-between gap-3">
        <span className="inline-grid text-[12.5px] font-medium leading-5">
          {labels.map((text, i) => (
            <motion.span
              key={text}
              aria-hidden
              className={`col-start-1 row-start-1 whitespace-nowrap transition-colors duration-200 ${tone.text}`}
              initial={false}
              animate={{ opacity: i === Math.min(score, labels.length - 1) ? 1 : 0 }}
              transition={reduced ? INSTANT : CROSSFADE}
            >
              {text}
            </motion.span>
          ))}
        </span>

        <motion.span
          aria-hidden
          className="whitespace-nowrap text-[11.5px] leading-5 text-amber-600 dark:text-amber-400"
          initial={false}
          animate={{ opacity: guessable ? 1 : 0 }}
          transition={reduced ? INSTANT : CROSSFADE}
        >
          Commonly guessed
        </motion.span>
      </div>

      {showRules && (
        <ul className="mt-3 grid gap-1.5">
          {evaluated.map((rule) => (
            <li key={rule.id} className="flex items-center gap-2">
              <span className="relative grid size-[14px] shrink-0 place-items-center rounded-[4px] border border-stone-200 text-white dark:border-white/[0.16] dark:text-stone-900">
                <motion.span
                  className="absolute inset-0 rounded-[3px] bg-emerald-500"
                  initial={false}
                  animate={{ opacity: rule.met ? 1 : 0 }}
                  transition={reduced ? INSTANT : CROSSFADE}
                />
                <motion.svg
                  viewBox="0 0 12 12"
                  fill="none"
                  aria-hidden
                  className="relative size-[9px]"
                  initial={false}
                  animate={{ opacity: rule.met ? 1 : 0, scale: rule.met ? 1 : 0.6 }}
                  transition={reduced ? INSTANT : CELL}
                >
                  <path
                    d="M2 6.2 4.7 8.9 10 3.3"
                    stroke="currentColor"
                    strokeWidth={1.9}
                    strokeLinecap="round"
                    strokeLinejoin="round"
                  />
                </motion.svg>
              </span>
              <span
                className={`text-[12.5px] leading-5 transition-colors duration-200 ${
                  rule.met
                    ? "text-stone-700 dark:text-stone-200"
                    : "text-stone-500 dark:text-stone-400"
                }`}
              >
                {rule.label}
              </span>
              <span className="sr-only">{rule.met ? "met" : "not met"}</span>
            </li>
          ))}
        </ul>
      )}

      <p aria-live="polite" className="sr-only">
        {announcement}
      </p>
    </div>
  );
}
```

---

## OTP Input · Input

Auto advance, paste, error recovery.

Docs: https://yugo.click/docs/otp-input
Install: `bun add motion`, then copy the source below into `components/yugo/otp-input.tsx` · or `bunx shadcn@latest add https://yugo.click/r/otp-input.json`.

Guarantees:
- A pasted code fills every cell from one event: paste is intercepted, filtered to the allowed alphabet, and distributed from cell zero whenever the clipboard holds a full-length code, so pasting into the wrong cell is not a failure state.
- Autofilled codes arrive as a single multi-character input event and are distributed the same way, because only the first cell claims autocomplete one-time-code and no cell sets maxLength.
- Rejection never destroys work: the characters stay where they are, focus returns to the first cell with its content selected, and the shake plays once on the false to true edge instead of on every render while the error is up.
- The cell array is the source of truth, so clearing a digit in the middle leaves a hole instead of sliding the digits after it one place left.
- The hint and the error message share one grid cell and only opacity moves, so a wrapped two-line error cannot push the submit button down the page.
- Screen readers get the message once from a polite live region and each cell announces its own position; under prefers-reduced-motion the shake, the sliding focus mark and the character entrance are skipped while the value, the invalid border and the status line still arrive.


### Usage

```tsx
"use client";

import { useState } from "react";
import { OtpInput } from "@/components/yugo/otp-input";

export function VerifyStep({ challengeId }: { challengeId: string }) {
  const [status, setStatus] = useState<"idle" | "checking" | "rejected">("idle");

  async function submit(code: string) {
    setStatus("checking");
    const res = await fetch("/api/verify", {
      method: "POST",
      body: JSON.stringify({ challengeId, code }),
    });
    setStatus(res.ok ? "idle" : "rejected");
  }

  return (
    <OtpInput
      length={6}
      autoFocus
      disabled={status === "checking"}
      error={status === "rejected"}
      errorMessage="That code is wrong. Fix the digit that slipped."
      hint="Paste the whole code into any cell."
      onChange={() => setStatus((s) => (s === "rejected" ? "idle" : s))}
      onComplete={submit}
    />
  );
}
```

### Source (`components/yugo/otp-input.tsx`)

```tsx
"use client";

import {
  useCallback,
  useEffect,
  useId,
  useImperativeHandle,
  useRef,
  useState,
  type ChangeEvent,
  type ClipboardEvent,
  type FocusEvent,
  type KeyboardEvent,
} from "react";
import { AnimatePresence, motion, useReducedMotion } from "motion/react";

const CROSSFADE = { type: "spring", stiffness: 260, damping: 34, mass: 0.8 } as const;
const EASE = [0.23, 1, 0.32, 1] as const;


export type OtpMode = "numeric" | "alphanumeric";

const ALLOW: Record<OtpMode, RegExp> = {
  numeric: /^[0-9]$/,
  alphanumeric: /^[0-9a-zA-Z]$/,
};

export type UseOtpInputOptions = {
  length?: number;
  mode?: OtpMode;
  defaultValue?: string;
  disabled?: boolean;
  onChange?: (value: string) => void;
  onComplete?: (value: string) => void;
};

export type OtpCellProps = {
  ref: (el: HTMLInputElement | null) => void;
  value: string;
  disabled: boolean;
  type: "text";
  inputMode: "numeric" | "text";
  autoComplete: string;
  autoCorrect: "off";
  autoCapitalize: "off";
  spellCheck: false;
  onChange: (e: ChangeEvent<HTMLInputElement>) => void;
  onKeyDown: (e: KeyboardEvent<HTMLInputElement>) => void;
  onPaste: (e: ClipboardEvent<HTMLInputElement>) => void;
  onFocus: (e: FocusEvent<HTMLInputElement>) => void;
  onBlur: (e: FocusEvent<HTMLInputElement>) => void;
};

export type UseOtpInputReturn = {
  chars: string[];
  value: string;
  length: number;
  complete: boolean;
  focusedIndex: number;
  getCellProps: (index: number) => OtpCellProps;
  focusAt: (index: number) => void;
  clear: () => void;
};

export function useOtpInput({
  length = 6,
  mode = "numeric",
  defaultValue = "",
  disabled = false,
  onChange,
  onComplete,
}: UseOtpInputOptions = {}): UseOtpInputReturn {
  const allow = ALLOW[mode];

  const keep = useCallback(
    (text: string) =>
      text
        .split("")
        .filter((c) => allow.test(c))
        .join(""),
    [allow],
  );

  const [chars, setChars] = useState<string[]>(() => {
    const seed = defaultValue
      .split("")
      .filter((c) => ALLOW[mode].test(c))
      .slice(0, length);
    return Array.from({ length }, (_, i) => seed[i] ?? "");
  });
  const [focusedIndex, setFocusedIndex] = useState(-1);

  const charsRef = useRef(chars);
  charsRef.current = chars;

  const refs = useRef<(HTMLInputElement | null)[]>([]);

  const changed = useRef(onChange);
  changed.current = onChange;
  const completed = useRef(onComplete);
  completed.current = onComplete;

  useEffect(() => {
    setChars((prev) =>
      prev.length === length
        ? prev
        : Array.from({ length }, (_, i) => prev[i] ?? ""),
    );
    refs.current.length = length;
  }, [length]);

  const commit = useCallback((next: string[]) => {
    charsRef.current = next;
    setChars(next);
    const value = next.join("");
    changed.current?.(value);
    if (next.length > 0 && next.every((c) => c !== "")) completed.current?.(value);
  }, []);

  const focusAt = useCallback(
    (index: number) => {
      const el = refs.current[Math.max(0, Math.min(length - 1, index))];
      if (!el) return;
      el.focus();
      el.select();
    },
    [length],
  );

  const fillFrom = useCallback(
    (index: number, text: string) => {
      const incoming = keep(text);
      if (incoming.length === 0) return;
      const next = [...charsRef.current];
      let cursor = index;
      for (const c of incoming) {
        if (cursor >= length) break;
        next[cursor] = c;
        cursor += 1;
      }
      commit(next);
      focusAt(cursor);
    },
    [commit, focusAt, keep, length],
  );

  const clear = useCallback(() => {
    commit(Array.from({ length }, () => ""));
    focusAt(0);
  }, [commit, focusAt, length]);

  const getCellProps = useCallback(
    (index: number): OtpCellProps => ({
      ref: (el) => {
        refs.current[index] = el;
      },
      value: chars[index] ?? "",
      disabled,
      type: "text",
      inputMode: mode === "numeric" ? "numeric" : "text",
      autoComplete: index === 0 ? "one-time-code" : "off",
      autoCorrect: "off",
      autoCapitalize: "off",
      spellCheck: false,
      onChange: (e) => {
        const previous = charsRef.current[index] ?? "";
        const raw = e.currentTarget.value;
        const trimmed =
          raw.length > 1 && previous && raw.startsWith(previous)
            ? raw.slice(previous.length)
            : raw;
        const incoming = keep(trimmed);

        if (incoming.length === 0) {
          if (raw.length === 0 && previous) {
            const next = [...charsRef.current];
            next[index] = "";
            commit(next);
          }
          e.currentTarget.value = charsRef.current[index] ?? "";
          return;
        }

        if (incoming.length === 1) {
          const next = [...charsRef.current];
          next[index] = incoming;
          e.currentTarget.value = incoming;
          commit(next);
          if (index < length - 1) focusAt(index + 1);
          return;
        }

        fillFrom(index, incoming);
      },
      onKeyDown: (e) => {
        if (e.key === "Backspace") {
          e.preventDefault();
          const current = charsRef.current;
          const next = [...current];
          if (current[index]) {
            next[index] = "";
            commit(next);
            return;
          }
          if (index > 0) {
            next[index - 1] = "";
            commit(next);
            focusAt(index - 1);
          }
          return;
        }
        if (e.key === "Delete") {
          e.preventDefault();
          const next = [...charsRef.current];
          next[index] = "";
          commit(next);
          return;
        }
        if (e.key === "ArrowLeft") {
          e.preventDefault();
          focusAt(index - 1);
          return;
        }
        if (e.key === "ArrowRight") {
          e.preventDefault();
          focusAt(index + 1);
          return;
        }
        if (e.key === "Home") {
          e.preventDefault();
          focusAt(0);
          return;
        }
        if (e.key === "End") {
          e.preventDefault();
          focusAt(length - 1);
        }
      },
      onPaste: (e) => {
        e.preventDefault();
        const text = keep(e.clipboardData.getData("text"));
        fillFrom(text.length >= length ? 0 : index, text);
      },
      onFocus: (e) => {
        e.currentTarget.select();
        const firstEmpty = charsRef.current.findIndex((c) => c === "");
        if (firstEmpty !== -1 && firstEmpty < index) {
          focusAt(firstEmpty);
          return;
        }
        setFocusedIndex(index);
      },
      onBlur: (e) => {
        const to = e.relatedTarget as HTMLInputElement | null;
        if (to && refs.current.includes(to)) return;
        setFocusedIndex(-1);
      },
    }),
    [chars, commit, disabled, fillFrom, focusAt, keep, length, mode],
  );

  const value = chars.join("");

  return {
    chars,
    value,
    length,
    complete: chars.length > 0 && chars.every((c) => c !== ""),
    focusedIndex,
    getCellProps,
    focusAt,
    clear,
  };
}

export type OtpStatus = "idle" | "error" | "success";

export type OtpInputHandle = {
  clear: () => void;
  focus: () => void;
};

export type OtpInputProps = {
  length?: number;
  mode?: OtpMode;
  defaultValue?: string;
  onChange?: (value: string) => void;
  onComplete?: (value: string) => void;
  status?: OtpStatus;
  errorMessage?: string;
  successMessage?: string;
  hint?: string;
  label?: string;
  groupEvery?: number;
  disabled?: boolean;
  autoFocus?: boolean;
  focusOnError?: boolean;
  className?: string;
  ref?: React.Ref<OtpInputHandle>;
};

export function OtpInput({
  length = 6,
  mode = "numeric",
  defaultValue = "",
  onChange,
  onComplete,
  status = "idle",
  errorMessage = "",
  successMessage = "",
  hint = "",
  label = "Verification code",
  groupEvery = 3,
  disabled = false,
  autoFocus = false,
  focusOnError = true,
  className = "",
  ref,
}: OtpInputProps) {
  const reduced = useReducedMotion();
  const statusId = useId();

  const { chars, focusedIndex, getCellProps, focusAt, clear } = useOtpInput({
    length,
    mode,
    defaultValue,
    disabled,
    onChange,
    onComplete,
  });

  const wasError = useRef(false);
  const error = status === "error";
  const success = status === "success";

  useImperativeHandle(
    ref,
    () => ({
      clear: () => {
        clear();
        focusAt(0);
      },
      focus: () => focusAt(0),
    }),
    [clear, focusAt],
  );

  useEffect(() => {
    if (error && !wasError.current && focusOnError && !disabled) focusAt(0);
    wasError.current = error;
  }, [error, focusOnError, disabled, focusAt]);

  useEffect(() => {
    if (autoFocus && !disabled) focusAt(0);
  }, [autoFocus, disabled, focusAt]);

  const enter = reduced ? { duration: 0 } : { duration: 0.22, ease: EASE };
  const swap = reduced ? { duration: 0 } : CROSSFADE;
  const hasStatus =
    hint.length > 0 || errorMessage.length > 0 || successMessage.length > 0;

  const message = error ? errorMessage : success ? successMessage : hint;
  const messageTone = error
    ? "text-red-600 dark:text-red-400"
    : success
      ? "text-emerald-600 dark:text-emerald-400"
      : "text-stone-500 dark:text-stone-400";

  return (
    <div className={`inline-flex flex-col ${className}`}>
      <motion.div
        role="group"
        aria-label={label}
        className="relative flex gap-2"
        initial={false}
        variants={{ idle: { x: 0 }, wrong: { x: [0, -5, 4, -3, 0] } }}
        animate={error && !reduced ? "wrong" : "idle"}
        transition={{ duration: 0.32, ease: EASE }}
      >
        {Array.from({ length }, (_, i) => {
          const char = chars[i] ?? "";
          const active = focusedIndex === i;
          const gap = groupEvery > 0 && i > 0 && i % groupEvery === 0;

          return (
            <div
              key={i}
              className={`relative h-12 w-10 ${gap ? "ml-3" : ""}`}
            >
              <input
                {...getCellProps(i)}
                aria-label={`${label}, character ${i + 1} of ${length}`}
                aria-invalid={error || undefined}
                aria-describedby={hasStatus ? statusId : undefined}
                className={`h-12 w-10 rounded-[10px] border-2 text-center text-[15px] text-transparent caret-transparent outline-none transition-[background-color,border-color,box-shadow] duration-150 selection:bg-transparent focus-visible:outline-none disabled:opacity-50 ${
                  error
                    ? "border-red-500 bg-white dark:border-red-400 dark:bg-[#252522]"
                    : success
                      ? "border-emerald-500 bg-white dark:border-emerald-400 dark:bg-[#252522]"
                      : active
                        ? "border-[#4568FF] bg-white dark:border-[#93B0FF] dark:bg-[#252522]"
                        : char
                          ? "border-stone-300 bg-white dark:border-white/20 dark:bg-[#252522]"
                          : "border-stone-200 bg-stone-100/70 shadow-[inset_0_1px_2px_rgba(28,25,23,0.07)] dark:border-white/[0.08] dark:bg-[#1D1D1A] dark:shadow-[inset_0_1px_2px_rgba(0,0,0,0.45)]"
                }`}
              />

              <span
                aria-hidden
                className="pointer-events-none absolute inset-0 grid place-items-center"
              >
                <AnimatePresence initial={false} mode="popLayout">
                  {char ? (
                    <motion.span
                      key={char}
                      initial={
                        reduced
                          ? false
                          : { opacity: 0, scale: 0.97, y: 10, filter: "blur(6px)" }
                      }
                      animate={{ opacity: 1, scale: 1, y: 0, filter: "blur(0px)" }}
                      exit={
                        reduced
                          ? { opacity: 0 }
                          : { opacity: 0, scale: 0.98, y: -6, filter: "blur(3px)" }
                      }
                      transition={enter}
                      className="col-start-1 row-start-1 font-mono text-[15px] tabular-nums text-stone-700 dark:text-stone-200"
                    >
                      {char}
                    </motion.span>
                  ) : null}
                </AnimatePresence>

                {active && !char && !disabled ? (
                  <motion.span
                    className="col-start-1 row-start-1 block h-[17px] w-[1.5px] rounded-[1px] bg-stone-700 dark:bg-stone-200"
                    initial={{ opacity: 1 }}
                    animate={reduced ? { opacity: 1 } : { opacity: [1, 1, 0, 0] }}
                    transition={
                      reduced
                        ? { duration: 0 }
                        : {
                            duration: 1.06,
                            times: [0, 0.5, 0.5, 1],
                            repeat: Infinity,
                            ease: "linear",
                          }
                    }
                  />
                ) : null}
              </span>
            </div>
          );
        })}
      </motion.div>

      {hasStatus && (
        <>
          <div aria-hidden className="mt-2 grid h-4 text-[11.5px] leading-[16px]">
            <AnimatePresence initial={false} mode="wait">
              <motion.span
                key={status}
                initial={reduced ? { opacity: 0 } : { opacity: 0, y: 3 }}
                animate={{ opacity: 1, y: 0 }}
                exit={reduced ? { opacity: 0 } : { opacity: 0, y: -3 }}
                transition={swap}
                className={`col-start-1 row-start-1 ${messageTone}`}
              >
                {message}
              </motion.span>
            </AnimatePresence>
          </div>
          <span id={statusId} role="status" className="sr-only">
            {message}
          </span>
        </>
      )}
    </div>
  );
}
```

---

## Tag Input · Input

Enter adds, backspace highlights then removes.

Docs: https://yugo.click/docs/tag-input
Install: `bun add motion`, then copy the source below into `components/yugo/tag-input.tsx` · or `bunx shadcn@latest add https://yugo.click/r/tag-input.json`.

Guarantees:
- Backspace on an empty field highlights the last tag before it removes anything, and a held Backspace is dropped until the key is released, so key repeat cannot chain-delete a list a user only meant to trim by one.
- Enter is ignored while an IME composition is open, so confirming a Japanese or Korean candidate commits the word to the field instead of committing a half-typed tag to the list.
- Pasted text is split on the configured separators plus newlines and tabs, so a copied comma list arrives as six tags rather than one tag six words long.
- A refused duplicate lights the tag that already holds the value instead of only printing an error, and the hint and the error share one grid cell, so nothing below the field moves when a message appears.
- The idle and highlighted labels are two layers in the same grid cell, so arming a tag never re-measures it; removals leave on opacity and x while the remaining tags close the gap with layout position, and the row is capped in height and scrolls rather than growing without bound.
- Assistive technology gets one polite announcement per event: added, selected, removed, each with the running count: not a stream, and every path is reachable from the keyboard: arrow keys walk the tags, Delete removes the armed one, Escape only disarms so a surrounding dialog still closes.


### Usage

```tsx
"use client";

import { useState } from "react";
import { TagInput } from "@/components/yugo/tag-input";

export function SegmentForm() {
  const [topics, setTopics] = useState<string[]>(["motion"]);

  return (
    <form
      onSubmit={(e) => {
        e.preventDefault();
        void fetch("/api/segments", {
          method: "POST",
          body: JSON.stringify({ topics }),
        });
      }}
    >
      <TagInput
        label="Topics"
        value={topics}
        onChange={setTopics}
        max={8}
        separators={[",", ";"]}
        validate={(candidate) => candidate.length <= 24}
        hint="Enter adds · Backspace highlights, then removes"
      />

      <button
        type="submit"
        disabled={topics.length === 0}
        className="mt-3 h-9 rounded-[9px] border border-stone-200 px-3 text-[13px] font-medium text-stone-700 disabled:opacity-50 dark:border-white/[0.16] dark:text-stone-200"
      >
        Save segment
      </button>
    </form>
  );
}
```

### Source (`components/yugo/tag-input.tsx`)

```tsx
"use client";

import { useCallback, useEffect, useId, useMemo, useRef, useState } from "react";
import { AnimatePresence, motion, useReducedMotion } from "motion/react";

const LEAVE = [0.4, 0, 1, 1] as const;
const CROSSFADE = { type: "spring", stiffness: 260, damping: 34, mass: 0.8 } as const;
const CHIP = { type: "spring", stiffness: 700, damping: 46, mass: 0.5 } as const;
const EXIT = { duration: 0.18, ease: LEAVE } as const;
const INSTANT = { duration: 0 } as const;

const clean = (raw: string) => raw.trim().replace(/\s+/g, " ");

const splitter = (separators: string[]) =>
  new RegExp(`[${separators.map((s) => s.replace(/[\\\]^-]/g, "\\$&")).join("")}\\n\\r\\t]+`);

export type TagRejection = "duplicate" | "limit" | "invalid";

export type UseTagInputOptions = {
  value?: string[];
  defaultValue?: string[];
  onChange?: (tags: string[]) => void;
  max?: number;
  separators?: string[];
  allowDuplicates?: boolean;
  validate?: (candidate: string, tags: string[]) => boolean;
};

type Rejection = { reason: TagRejection; tag: string; visible: boolean };

export function useTagInput({
  value,
  defaultValue,
  onChange,
  max,
  separators = [","],
  allowDuplicates = false,
  validate,
}: UseTagInputOptions = {}) {
  const [internal, setInternal] = useState<string[]>(() => defaultValue ?? []);
  const [draft, setDraft] = useState("");
  const [armed, setArmed] = useState(-1);
  const [rejection, setRejection] = useState<Rejection | null>(null);
  const [flashed, setFlashed] = useState<string | null>(null);
  const [announcement, setAnnouncement] = useState("");

  const controlled = value !== undefined;
  const tags = value ?? internal;
  const armedIndex = armed >= tags.length ? -1 : armed;

  const emit = useRef(onChange);
  emit.current = onChange;
  const check = useRef(validate);
  check.current = validate;

  const rejectTimer = useRef<ReturnType<typeof setTimeout> | null>(null);
  const flashTimer = useRef<ReturnType<typeof setTimeout> | null>(null);

  useEffect(
    () => () => {
      if (rejectTimer.current) clearTimeout(rejectTimer.current);
      if (flashTimer.current) clearTimeout(flashTimer.current);
    },
    [],
  );

  const dismiss = useCallback(() => {
    if (rejectTimer.current) clearTimeout(rejectTimer.current);
    rejectTimer.current = null;
    setRejection((prev) => (prev && prev.visible ? { ...prev, visible: false } : prev));
  }, []);

  const refuse = useCallback(
    (reason: TagRejection, tag: string) => {
      if (rejectTimer.current) clearTimeout(rejectTimer.current);
      setRejection({ reason, tag, visible: true });
      rejectTimer.current = setTimeout(() => {
        setRejection((prev) => (prev ? { ...prev, visible: false } : prev));
      }, 2400);

      setAnnouncement(
        reason === "duplicate"
          ? `${tag} is already in the list.`
          : reason === "limit"
            ? `That is the limit of ${max} tags.`
            : `${tag} is not allowed here.`,
      );

      if (reason !== "duplicate") return;
      if (flashTimer.current) clearTimeout(flashTimer.current);
      setFlashed(tag);
      flashTimer.current = setTimeout(() => setFlashed(null), 460);
    },
    [max],
  );

  const apply = useCallback(
    (next: string[]) => {
      if (!controlled) setInternal(next);
      emit.current?.(next);
    },
    [controlled],
  );

  const add = useCallback(
    (raws: string[]) => {
      const next = [...tags];
      let added = 0;
      let failure: { reason: TagRejection; tag: string } | null = null;

      for (const raw of raws) {
        const candidate = clean(raw);
        if (!candidate) continue;

        if (max !== undefined && next.length >= max) {
          failure = { reason: "limit", tag: candidate };
          break;
        }

        if (!allowDuplicates) {
          const twin = next.find((t) => t.toLowerCase() === candidate.toLowerCase());
          if (twin) {
            failure = { reason: "duplicate", tag: twin };
            continue;
          }
        }

        if (check.current && !check.current(candidate, next)) {
          failure = { reason: "invalid", tag: candidate };
          continue;
        }

        next.push(candidate);
        added += 1;
      }

      if (added > 0) {
        apply(next);
        setDraft("");
        setArmed(-1);
        dismiss();
        setAnnouncement(
          `${added === 1 ? next[next.length - 1] : `${added} tags`} added, ${next.length} total.`,
        );
      }

      if (failure) refuse(failure.reason, failure.tag);
      return added > 0;
    },
    [tags, max, allowDuplicates, apply, dismiss, refuse],
  );

  const removeAt = useCallback(
    (index: number) => {
      if (index < 0 || index >= tags.length) return;
      const gone = tags[index];
      const next = tags.filter((_, i) => i !== index);
      apply(next);
      setArmed(-1);
      dismiss();
      setAnnouncement(`${gone} removed, ${next.length} left.`);
    },
    [tags, apply, dismiss],
  );

  const arm = useCallback(
    (index: number) => {
      setArmed(index);
      setAnnouncement(`${tags[index]} selected, press Backspace again to remove it.`);
    },
    [tags],
  );

  const inputProps = {
    value: draft,
    onChange: (e: React.ChangeEvent<HTMLInputElement>) => {
      setDraft(e.target.value);
      setArmed(-1);
      dismiss();
    },
    onKeyDown: (e: React.KeyboardEvent<HTMLInputElement>) => {
      if (e.nativeEvent.isComposing) return;

      if (e.key === "Enter" || separators.includes(e.key)) {
        e.preventDefault();
        add([draft]);
        return;
      }

      if (e.key === "Backspace" && draft === "") {
        e.preventDefault();
        if (e.repeat) return;
        if (armedIndex >= 0) removeAt(armedIndex);
        else if (tags.length > 0) arm(tags.length - 1);
        return;
      }

      if (e.key === "Delete" && armedIndex >= 0) {
        e.preventDefault();
        if (e.repeat) return;
        removeAt(armedIndex);
        return;
      }

      if (e.key === "ArrowLeft") {
        const start = e.currentTarget.selectionStart;
        const end = e.currentTarget.selectionEnd;
        if (start !== 0 || end !== 0 || tags.length === 0) return;
        e.preventDefault();
        arm(armedIndex < 0 ? tags.length - 1 : Math.max(0, armedIndex - 1));
        return;
      }

      if (e.key === "ArrowRight" && armedIndex >= 0) {
        e.preventDefault();
        if (armedIndex >= tags.length - 1) setArmed(-1);
        else arm(armedIndex + 1);
        return;
      }

      if (e.key === "Escape" && armedIndex >= 0) {
        e.preventDefault();
        setArmed(-1);
      }
    },
    onPaste: (e: React.ClipboardEvent<HTMLInputElement>) => {
      const text = e.clipboardData.getData("text");
      const pattern = splitter(separators);
      if (!pattern.test(text)) return;
      e.preventDefault();
      add(text.split(pattern));
    },
    onBlur: () => setArmed(-1),
  };

  return {
    tags,
    draft,
    setDraft,
    armedIndex,
    flashed,
    rejection,
    announcement,
    inputProps,
    add,
    removeAt,
    max,
  };
}

export type TagInputProps = UseTagInputOptions & {
  label?: string;
  placeholder?: string;
  hint?: string;
  className?: string;
};

function CloseGlyph() {
  return (
    <svg
      viewBox="0 0 10 10"
      aria-hidden
      className="size-[9px]"
      fill="none"
      stroke="currentColor"
      strokeWidth={1.6}
      strokeLinecap="round"
    >
      <path d="M2.6 2.6 7.4 7.4M7.4 2.6 2.6 7.4" />
    </svg>
  );
}

export function TagInput({
  label,
  placeholder = "Add a tag",
  hint = "Enter adds · Backspace removes",
  className = "",
  ...options
}: TagInputProps) {
  const { tags, draft, armedIndex, flashed, rejection, announcement, inputProps, removeAt, max } =
    useTagInput(options);

  const reduced = useReducedMotion();
  const inputRef = useRef<HTMLInputElement>(null);
  const uid = useId();
  const inputId = `${uid}-tag-input`;
  const hintId = `${uid}-tag-hint`;

  const rows = useMemo(() => {
    const seen = new Map<string, number>();
    return tags.map((tag) => {
      const n = seen.get(tag) ?? 0;
      seen.set(tag, n + 1);
      return { tag, key: n === 0 ? tag : `${tag}#${n}` };
    });
  }, [tags]);

  const message = !rejection
    ? ""
    : rejection.reason === "duplicate"
      ? `${rejection.tag} is already in the list`
      : rejection.reason === "limit"
        ? `That is the limit of ${max} tags`
        : `${rejection.tag} is not allowed here`;

  const showMessage = rejection?.visible === true;

  return (
    <div className={`w-full ${className}`}>
      {label ? (
        <label
          htmlFor={inputId}
          className="mb-1.5 block text-[12.5px] font-medium text-stone-700 dark:text-stone-200"
        >
          {label}
        </label>
      ) : null}

      <ul
        onPointerDown={(e) => {
          if (e.target !== e.currentTarget) return;
          e.preventDefault();
          inputRef.current?.focus();
        }}
        className="relative flex max-h-[116px] min-h-10 list-none flex-wrap items-center gap-1.5 overflow-y-auto overscroll-contain rounded-[10px] border-2 border-stone-200 bg-stone-100/70 p-[4px] shadow-[inset_0_1px_2px_rgba(28,25,23,0.07)] transition-[background-color,border-color,box-shadow] duration-150 focus-within:border-[#4568FF] focus-within:bg-white focus-within:shadow-none dark:border-white/[0.08] dark:bg-[#1D1D1A] dark:shadow-[inset_0_1px_2px_rgba(0,0,0,0.45)] dark:focus-within:border-[#93B0FF] dark:focus-within:bg-[#252522]"
      >
        <AnimatePresence initial={false} mode="popLayout">
          {rows.map(({ tag, key }, index) => {
            const lit = armedIndex === index || flashed === tag;
            return (
              <motion.li
                key={key}
                role="listitem"
                layout="position"
                initial={reduced ? false : { opacity: 0, scale: 0.9 }}
                animate={{ opacity: 1, scale: 1 }}
                exit={
                  reduced
                    ? { opacity: 0, transition: INSTANT }
                    : { opacity: 0, scale: 0.9, transition: EXIT }
                }
                transition={reduced ? INSTANT : { default: CHIP, layout: CHIP }}
                className={`flex h-6 max-w-full shrink-0 select-none items-center gap-1 rounded-[6px] border pl-2 pr-1.5 text-[12.5px] transition-[background-color,border-color,box-shadow,color] duration-150 ${
                  lit
                    ? "border-stone-800 bg-stone-800 text-white shadow-[0_1px_2px_rgba(28,25,23,0.18)] dark:border-stone-100 dark:bg-stone-100 dark:text-stone-900 dark:shadow-[0_1px_2px_rgba(0,0,0,0.4)]"
                    : "border-stone-200 bg-white text-stone-800 shadow-[inset_0_1.5px_0_rgba(255,255,255,0.95),inset_0_-1px_0_rgba(28,25,23,0.06),0_1px_2px_rgba(28,25,23,0.08)] dark:border-white/[0.16] dark:bg-[#2A2A27] dark:text-stone-200 dark:shadow-[inset_0_1px_0_rgba(255,255,255,0.07),0_1px_2px_rgba(0,0,0,0.4)]"
                }`}
              >
                <span className="truncate">{tag}</span>
                <button
                  type="button"
                  tabIndex={-1}
                  aria-label={`Remove ${tag}`}
                  onMouseDown={(e) => e.preventDefault()}
                  onClick={() => {
                    removeAt(index);
                    inputRef.current?.focus();
                  }}
                  className={`-mr-0.5 grid size-[14px] shrink-0 place-items-center rounded-[5px] transition-colors duration-150 ${
                    lit
                      ? "text-white/70 hover:text-white dark:text-stone-900/60 dark:hover:text-stone-900"
                      : "text-stone-500 hover:text-stone-900 dark:text-stone-400 dark:hover:text-stone-100"
                  }`}
                >
                  <CloseGlyph />
                </button>
              </motion.li>
            );
          })}
        </AnimatePresence>

        <motion.li
          layout={reduced ? false : "position"}
          transition={reduced ? INSTANT : CHIP}
          className="relative flex h-6 flex-1"
        >
          <span
            aria-hidden
            className="pointer-events-none invisible max-w-56 overflow-hidden whitespace-pre px-1 text-[12.5px]"
          >
            {draft || placeholder}
          </span>
          <input
            {...inputProps}
            ref={inputRef}
            id={inputId}
            type="text"
            aria-describedby={hintId}
            aria-label={label ? undefined : "Tags"}
            placeholder={placeholder}
            autoComplete="off"
            autoCapitalize="off"
            autoCorrect="off"
            spellCheck={false}
            enterKeyHint="done"
            className="absolute inset-0 h-full w-full bg-transparent px-1 text-[12.5px] text-stone-700 outline-none placeholder:text-stone-400 dark:text-stone-200 dark:placeholder:text-stone-500"
          />
        </motion.li>
      </ul>

      <div className="mt-1.5 flex items-baseline justify-between gap-3">
        <div className="grid min-w-0 flex-1">
          <motion.p
            id={hintId}
            initial={false}
            animate={{ opacity: showMessage ? 0 : 1 }}
            transition={reduced ? INSTANT : CROSSFADE}
            className="col-start-1 row-start-1 truncate text-[11.5px] text-stone-500 dark:text-stone-400"
          >
            {hint}
          </motion.p>
          <motion.p
            aria-hidden
            initial={false}
            animate={{ opacity: showMessage ? 1 : 0 }}
            transition={reduced ? INSTANT : CROSSFADE}
            className="col-start-1 row-start-1 truncate text-[11.5px] text-stone-700 dark:text-stone-200"
          >
            {message}
          </motion.p>
        </div>

        {max === undefined ? null : (
          <p className="shrink-0 text-[11.5px] tabular-nums text-stone-500 dark:text-stone-400">
            <span className="inline-grid justify-items-end">
              <span aria-hidden className="invisible col-start-1 row-start-1">
                {max}
              </span>
              <span className="col-start-1 row-start-1">{tags.length}</span>
            </span>
            <span> / {max}</span>
          </p>
        )}
      </div>

      <span role="status" aria-live="polite" aria-atomic="true" className="sr-only">
        {announcement}
      </span>
    </div>
  );
}
```

---

## Expanding Search · Input

Icon to field with focus handled.

Docs: https://yugo.click/docs/expanding-search
Install: `bun add motion`, then copy the source below into `components/yugo/expanding-search.tsx` · or `bunx shadcn@latest add https://yugo.click/r/expanding-search.json`.

Guarantees:
- The track reserves the expanded width before anything opens, so the row beside the field never reflows; neighbouring actions fade where they stand instead of being shoved sideways.
- Focus moves to the input synchronously inside the click handler rather than on animation-complete, so the iOS keyboard is not suppressed and a screen reader is never left pointing at a trigger that has already gone.
- Blur collapses the field only when it is empty, and a blur caused by switching browser tabs is ignored, so a typed query is never destroyed by clicking somewhere else.
- Escape clears a non-empty query and collapses an empty one, returning focus to the trigger instead of the document body, and the event is consumed so a dialog behind the field does not close along with it.
- Keystrokes are debounced before onSearch fires and Enter flushes the pending call, so the search runs once per intent; the polite live region announces only the settled result count, not one message per character.
- The input holds its expanded width at all times and is clipped by the shell, so the text inside never re-wraps mid-spring, and prefers-reduced-motion drops the transitions to zero without hiding either state.


### Usage

```tsx
"use client";

import { useState } from "react";
import { ExpandingSearch } from "@/components/yugo/expanding-search";

export function LibraryToolbar({ items }: { items: string[] }) {
  const [query, setQuery] = useState("");
  const [searching, setSearching] = useState(false);

  const hits = items.filter((name) =>
    name.toLowerCase().includes(query.trim().toLowerCase()),
  );

  return (
    <div className="relative flex h-9 items-center px-2">
      <h2 className="text-[13px] font-medium">Library</h2>

      <div
        aria-hidden={searching}
        style={{ opacity: searching ? 0 : 1 }}
        className="ml-auto flex items-center gap-1.5 transition-opacity"
      >
        <button type="button">Sort</button>
        <button type="button">New</button>
      </div>

      <div className="absolute inset-y-0 right-2 w-[240px]">
        <ExpandingSearch
          placeholder="Search library"
          resultCount={hits.length}
          debounce={200}
          onSearch={setQuery}
          onOpenChange={setSearching}
          onSubmit={(value) => console.log("submit", value)}
        />
      </div>
    </div>
  );
}
```

### Source (`components/yugo/expanding-search.tsx`)

```tsx
"use client";

import {
  useCallback,
  useEffect,
  useId,
  useLayoutEffect,
  useRef,
  useState,
} from "react";
import { motion, useReducedMotion } from "motion/react";

const DISCLOSE = { type: "spring", stiffness: 380, damping: 38, mass: 0.7 } as const;
const CROSSFADE = { type: "spring", stiffness: 260, damping: 34, mass: 0.8 } as const;
const CELL = { type: "spring", stiffness: 520, damping: 34, mass: 0.45 } as const;
const INSTANT = { duration: 0 } as const;

const COLLAPSED = 40;
const TEXT_LEFT = 34;
const CLEAR_SLOT = 35;
const COUNT_SLOT = 38;
const ANNOUNCE_DELAY = 500;

const useIsomorphicLayoutEffect =
  typeof window === "undefined" ? useEffect : useLayoutEffect;

export type UseExpandingSearchOptions = {
  value?: string;
  defaultValue?: string;
  onChange?: (value: string) => void;
  onSearch?: (value: string) => void;
  onSubmit?: (value: string) => void;
  open?: boolean;
  defaultOpen?: boolean;
  onOpenChange?: (open: boolean) => void;
  debounce?: number;
  collapseOnBlur?: boolean;
  disabled?: boolean;
};

export type UseExpandingSearchReturn = {
  open: boolean;
  focused: boolean;
  query: string;
  expand: () => void;
  collapse: (returnFocus?: boolean) => void;
  toggle: () => void;
  clear: () => void;
  inputRef: React.RefObject<HTMLInputElement | null>;
  triggerRef: React.RefObject<HTMLButtonElement | null>;
  rootProps: {
    onFocus: (event: React.FocusEvent<HTMLElement>) => void;
    onBlur: (event: React.FocusEvent<HTMLElement>) => void;
  };
  triggerProps: {
    ref: React.RefObject<HTMLButtonElement | null>;
    type: "button";
    disabled: boolean;
    tabIndex: number;
    "aria-expanded": boolean;
    onClick: () => void;
  };
  inputProps: {
    ref: React.RefObject<HTMLInputElement | null>;
    value: string;
    disabled: boolean;
    tabIndex: number;
    onChange: (event: React.ChangeEvent<HTMLInputElement>) => void;
    onKeyDown: (event: React.KeyboardEvent<HTMLInputElement>) => void;
    onFocus: () => void;
  };
};

export function useExpandingSearch({
  value,
  defaultValue = "",
  onChange,
  onSearch,
  onSubmit,
  open,
  defaultOpen = false,
  onOpenChange,
  debounce = 220,
  collapseOnBlur = true,
  disabled = false,
}: UseExpandingSearchOptions = {}): UseExpandingSearchReturn {
  const [ownValue, setOwnValue] = useState(defaultValue);
  const [ownOpen, setOwnOpen] = useState(defaultOpen);
  const [focused, setFocused] = useState(false);

  const query = value ?? ownValue;
  const isOpen = open ?? ownOpen;

  const inputRef = useRef<HTMLInputElement | null>(null);
  const triggerRef = useRef<HTMLButtonElement | null>(null);
  const timer = useRef<ReturnType<typeof setTimeout> | null>(null);
  const openRef = useRef(isOpen);

  const latest = useRef({ query, onChange, onSearch, onSubmit, onOpenChange });
  latest.current = { query, onChange, onSearch, onSubmit, onOpenChange };

  useEffect(() => {
    openRef.current = isOpen;
  }, [isOpen]);

  useEffect(
    () => () => {
      if (timer.current) clearTimeout(timer.current);
    },
    [],
  );

  const setOpen = useCallback((next: boolean) => {
    if (openRef.current === next) return;
    openRef.current = next;
    setOwnOpen(next);
    latest.current.onOpenChange?.(next);
  }, []);

  const commit = useCallback(
    (next: string) => {
      setOwnValue(next);
      latest.current.onChange?.(next);
      if (timer.current) clearTimeout(timer.current);
      timer.current = setTimeout(() => {
        timer.current = null;
        latest.current.onSearch?.(next);
      }, debounce);
    },
    [debounce],
  );

  const flush = useCallback(() => {
    if (!timer.current) return;
    clearTimeout(timer.current);
    timer.current = null;
    latest.current.onSearch?.(latest.current.query);
  }, []);

  const expand = useCallback(() => {
    if (disabled) return;
    setOpen(true);
    inputRef.current?.focus();
  }, [disabled, setOpen]);

  const collapse = useCallback(
    (returnFocus = false) => {
      setOpen(false);
      if (returnFocus) triggerRef.current?.focus();
    },
    [setOpen],
  );

  const toggle = useCallback(() => {
    if (openRef.current) collapse(true);
    else expand();
  }, [collapse, expand]);

  const clear = useCallback(() => {
    commit("");
    inputRef.current?.focus();
  }, [commit]);

  const onRootFocus = useCallback(() => setFocused(true), []);

  const onRootBlur = useCallback(
    (event: React.FocusEvent<HTMLElement>) => {
      const next = event.relatedTarget as Node | null;
      if (next && event.currentTarget.contains(next)) return;
      setFocused(false);
      if (!collapseOnBlur) return;
      if (!document.hasFocus()) return;
      if (latest.current.query.length > 0) return;
      setOpen(false);
    },
    [collapseOnBlur, setOpen],
  );

  const onInputKeyDown = useCallback(
    (event: React.KeyboardEvent<HTMLInputElement>) => {
      if (event.key === "Escape") {
        event.preventDefault();
        event.stopPropagation();
        if (latest.current.query.length > 0) {
          commit("");
          return;
        }
        collapse(true);
        return;
      }
      if (event.key === "Enter") {
        event.preventDefault();
        flush();
        latest.current.onSubmit?.(latest.current.query);
      }
    },
    [collapse, commit, flush],
  );

  const onInputFocus = useCallback(() => setOpen(true), [setOpen]);

  const onInputChange = useCallback(
    (event: React.ChangeEvent<HTMLInputElement>) => commit(event.currentTarget.value),
    [commit],
  );

  return {
    open: isOpen,
    focused,
    query,
    expand,
    collapse,
    toggle,
    clear,
    inputRef,
    triggerRef,
    rootProps: { onFocus: onRootFocus, onBlur: onRootBlur },
    triggerProps: {
      ref: triggerRef,
      type: "button",
      disabled,
      tabIndex: isOpen ? -1 : 0,
      "aria-expanded": isOpen,
      onClick: expand,
    },
    inputProps: {
      ref: inputRef,
      value: query,
      disabled,
      tabIndex: isOpen ? 0 : -1,
      onChange: onInputChange,
      onKeyDown: onInputKeyDown,
      onFocus: onInputFocus,
    },
  };
}

export type ExpandingSearchProps = UseExpandingSearchOptions & {
  label?: string;
  placeholder?: string;
  resultCount?: number;
  align?: "left" | "right";
  className?: string;
};

export function ExpandingSearch({
  label = "Search",
  placeholder = "Search",
  resultCount,
  align = "right",
  className = "",
  ...options
}: ExpandingSearchProps) {
  const reduced = useReducedMotion();
  const auto = useId();
  const inputId = `${auto}-field`;

  const {
    open,
    focused,
    query,
    clear,
    inputRef,
    rootProps,
    triggerProps,
    inputProps,
  } = useExpandingSearch(options);

  const trackRef = useRef<HTMLDivElement | null>(null);
  const [track, setTrack] = useState(0);

  useIsomorphicLayoutEffect(() => {
    const el = trackRef.current;
    if (!el) return;
    const read = (w: number) =>
      setTrack((prev) => (Math.abs(prev - w) < 0.5 ? prev : w));
    read(el.getBoundingClientRect().width);
    const observer = new ResizeObserver((entries) => {
      const box = entries[0];
      if (box) read(box.contentRect.width);
    });
    observer.observe(el);
    return () => observer.disconnect();
  }, []);

  const [announced, setAnnounced] = useState("");
  useEffect(() => {
    const id = setTimeout(() => {
      if (!open || query.length === 0 || resultCount === undefined) {
        setAnnounced("");
        return;
      }
      setAnnounced(
        `${resultCount} ${resultCount === 1 ? "result" : "results"} for ${query}`,
      );
    }, ANNOUNCE_DELAY);
    return () => clearTimeout(id);
  }, [open, query, resultCount]);

  const expanded = Math.max(COLLAPSED, track);
  const rightInset = CLEAR_SLOT + (resultCount === undefined ? 0 : COUNT_SLOT);
  const inner = Math.max(0, expanded - TEXT_LEFT - rightInset);
  const filled = query.length > 0;
  const shellMotion = reduced ? INSTANT : DISCLOSE;
  const fadeMotion = reduced ? INSTANT : CROSSFADE;
  const cellMotion = reduced ? INSTANT : CELL;

  return (
    <div
      ref={trackRef}
      role="search"
      className={`relative h-10 w-full ${className}`}
      {...rootProps}
    >
      <motion.div
        initial={false}
        animate={{ width: open ? expanded : COLLAPSED }}
        transition={shellMotion}
        onMouseDown={(event) => {
          if (event.target !== event.currentTarget) return;
          event.preventDefault();
          if (open) inputRef.current?.focus();
        }}
        className={`absolute inset-y-0 ${
          align === "right" ? "right-0" : "left-0"
        } overflow-hidden rounded-[10px] border-2 transition-[background-color,border-color,box-shadow] duration-150 ${
          focused
            ? "border-[#4568FF] bg-white dark:border-[#93B0FF] dark:bg-[#252522]"
            : "border-stone-200 bg-stone-100/70 shadow-[inset_0_1px_2px_rgba(28,25,23,0.07)] dark:border-white/[0.08] dark:bg-[#1D1D1A] dark:shadow-[inset_0_1px_2px_rgba(0,0,0,0.45)]"
        }`}
      >
        <motion.input
          {...inputProps}
          id={inputId}
          type="search"
          placeholder={placeholder}
          aria-label={label}
          aria-describedby={`${auto}-live`}
          autoComplete="off"
          spellCheck={false}
          enterKeyHint="search"
          style={{ width: inner, left: TEXT_LEFT }}
          initial={false}
          animate={{ opacity: open ? 1 : 0 }}
          transition={
            reduced ? INSTANT : { ...CROSSFADE, delay: open ? 0.06 : 0 }
          }
          className="absolute inset-y-0 bg-transparent text-[13px] leading-9 text-stone-700 outline-none focus-visible:outline-none placeholder:text-stone-400 dark:text-stone-200 dark:placeholder:text-stone-500 [&::-webkit-search-cancel-button]:appearance-none [&::-webkit-search-decoration]:appearance-none"
        />

        <motion.div
          initial={false}
          animate={{ opacity: open ? 1 : 0 }}
          transition={fadeMotion}
          className="pointer-events-none absolute inset-y-0 right-[7px] flex items-center gap-1.5"
        >
          {resultCount === undefined ? null : (
            <span
              aria-hidden
              className="w-8 truncate text-right font-mono text-[9.5px] tabular-nums text-stone-500 dark:text-stone-400"
            >
              {filled ? resultCount : ""}
            </span>
          )}

          <motion.button
            type="button"
            onClick={clear}
            tabIndex={open && filled ? 0 : -1}
            aria-label="Clear search"
            aria-controls={inputId}
            initial={false}
            animate={{ opacity: filled ? 1 : 0, scale: filled ? 1 : 0.86 }}
            transition={cellMotion}
            className={`grid size-[22px] place-items-center rounded-[6px] text-stone-500 outline-none focus-visible:outline-2 focus-visible:-outline-offset-2 focus-visible:outline-[#4568FF] dark:text-stone-400 dark:focus-visible:outline-[#93B0FF] ${
              open && filled ? "pointer-events-auto" : ""
            }`}
          >
            <svg width="11" height="11" viewBox="0 0 11 11" fill="none" aria-hidden>
              <path
                d="M1.7 1.7 L9.3 9.3 M9.3 1.7 L1.7 9.3"
                stroke="currentColor"
                strokeWidth="1.5"
                strokeLinecap="round"
              />
            </svg>
          </motion.button>
        </motion.div>

      </motion.div>

      <motion.button
        {...triggerProps}
        aria-label={label}
        aria-controls={inputId}
        initial={false}
        animate={{
          x: align === "right" && open ? -(expanded - COLLAPSED) : 0,
        }}
        transition={shellMotion}
        className={`absolute inset-y-0 z-10 grid w-10 place-items-center rounded-[8px] text-stone-500 outline-none focus-visible:outline-2 focus-visible:-outline-offset-2 focus-visible:outline-[#4568FF] disabled:opacity-50 dark:text-stone-400 dark:focus-visible:outline-[#93B0FF] ${
          align === "right" ? "right-0" : "left-0"
        } ${open ? "pointer-events-none" : ""}`}
      >
        <svg width="15" height="15" viewBox="0 0 15 15" fill="none" aria-hidden>
          <circle cx="6.4" cy="6.4" r="4.5" stroke="currentColor" strokeWidth="1.4" />
          <path
            d="M9.8 9.8 L13.2 13.2"
            stroke="currentColor"
            strokeWidth="1.4"
            strokeLinecap="round"
          />
        </svg>
      </motion.button>

      <span id={`${auto}-live`} aria-live="polite" className="sr-only">
        {announced}
      </span>
    </div>
  );
}
```

---

## Exploding Input · Input

Every keystroke throws a particle off the field.

Docs: https://yugo.click/docs/exploding-input
Install: `bun add `, then copy the source below into `components/yugo/exploding-input.tsx` · or `bunx shadcn@latest add https://yugo.click/r/exploding-input.json`.

Guarantees:
- The file is unmodified from its source: the physics, the prop shape and the three-second default lifetime are all as authored.
- It mounts as a zero-by-zero container and finds the field by walking up to the nearest label and querying for an input, so it must be rendered inside the same label as the input it decorates.
- The spawn point is the measured width of the whole value, so particles leave the end of the text rather than the caret. Typing into the middle of a string throws from the right edge.
- Each particle with content mounts its own React root through a dynamic import of react-dom/client, and the root is never unmounted: the element is removed by a per-particle timeout when its life runs out.
- The animation frame loop runs for the life of the component whether or not any particles exist, and it does not check prefers-reduced-motion.
- Inspiration: Lochie on X, https://x.com/lochieaxon/status/1981323538322829516


### Usage

```tsx
"use client";

import { ExplodingInput } from "@/components/yugo/exploding-input";

export function Signup() {
  return (
    <label className="block">
      <input type="text" placeholder="try@yugo.click" className="h-10 w-72 border-b outline-none" />
      <ExplodingInput
        content={[
          <span key="1" className="text-4xl">🤩</span>,
          <span key="2" className="text-4xl">👾</span>,
          <span key="3" className="text-4xl">😺</span>,
        ]}
        direction={{ horizontal: "left", vertical: "top" }}
        gravity={0.5}
        duration={3}
        count={3}
      />
    </label>
  );
}
```

### Source (`components/yugo/exploding-input.tsx`)

```tsx
"use client";

import React, {
  useEffect,
  useRef,
  useCallback,
  type ReactNode,
  type CSSProperties,
} from "react";

type HorizontalDirection = "left" | "center" | "right";
type VerticalDirection = "top" | "center" | "bottom";

interface ExplodingInputProps {
  /** Content to render as particles (React nodes) */
  content?: ReactNode[];
  /** Number of particles to spawn per input event */
  count?: number;
  /** Direction of particle movement */
  direction?: {
    horizontal?: HorizontalDirection;
    vertical?: VerticalDirection;
  };
  /** Gravity value from -1 to 1 (negative = upward, positive = downward) */
  gravity?: number;
  /** Duration of particle animation in seconds */
  duration?: number;
  /** Scale configuration for particles */
  scale?: {
    value?: number;
    randomize?: boolean;
    randomVariation?: number;
  };
  /** Rotation configuration for particles */
  rotation?: {
    value?: number;
    animate?: boolean;
  };
  /** Custom styles for the container */
  style?: CSSProperties;
  /** Class name for the container */
  className?: string;
}

interface Particle {
  id: number;
  x: number;
  y: number;
  scale: number;
  rotate: number;
  opacity: number;
  vx: number;
  vy: number;
  gravity: number;
  birthTime: number;
  lifeMs: number;
  contentIdx: number;
  scaleStart: number;
  scaleEnd: number;
  rotateStart: number;
  rotateEnd: number;
  element: HTMLDivElement;
  isDead: boolean;
}

function mapLinear(
  value: number,
  inMin: number,
  inMax: number,
  outMin: number,
  outMax: number
): number {
  if (inMax === inMin) return outMin;
  const t = (value - inMin) / (inMax - inMin);
  return outMin + t * (outMax - outMin);
}

function createPRNG(seed: number): () => number {
  let s = seed;
  return function () {
    s |= 0;
    s = (s + 1831565813) | 0;
    let t = Math.imul(s ^ (s >>> 15), 1 | s);
    t = (t + Math.imul(t ^ (t >>> 7), 61 | t)) ^ t;
    return ((t ^ (t >>> 14)) >>> 0) / 4294967296;
  };
}

export function ExplodingInput({
  content = [],
  count = 1,
  direction = { horizontal: "center", vertical: "top" },
  gravity = 0.7,
  duration = 3,
  scale = { value: 1, randomize: false, randomVariation: 0 },
  rotation = { value: 0, animate: false },
  style,
  className,
}: ExplodingInputProps) {
  const particleIdCounter = useRef(0);
  const containerRef = useRef<HTMLDivElement>(null);
  const particleContainerRef = useRef<HTMLDivElement>(null);
  const particlesRef = useRef<Particle[]>([]);
  const randRef = useRef<() => number>(() => Math.random());
  const inputRef = useRef<HTMLInputElement | null>(null);
  const rafIdRef = useRef<number | null>(null);

  // Initialize PRNG and cleanup on unmount
  useEffect(() => {
    const timeBits = (Date.now() & 4294967295) >>> 0;
    const extra = Math.floor(Math.random() * 4294967295) >>> 0;
    const seed = (timeBits ^ extra) >>> 0;
    randRef.current = createPRNG(seed);

    return () => {
      particlesRef.current.forEach((p) => {
        if (p.element && p.element.parentNode) {
          p.element.parentNode.removeChild(p.element);
        }
      });
      particlesRef.current = [];
      if (rafIdRef.current !== null) {
        cancelAnimationFrame(rafIdRef.current);
      }
    };
  }, []);

  const getInputSpawnPosition = useCallback(
    (input: HTMLInputElement): { x: number; y: number } | null => {
      const container = containerRef.current;
      if (!container || !input) return null;

      const inputRect = input.getBoundingClientRect();
      const containerRect = container.getBoundingClientRect();
      const inputValue = input.value;

      const getTextWidth = (text: string, inp: HTMLInputElement): number => {
        const canvas = document.createElement("canvas");
        const context = canvas.getContext("2d");
        if (!context) return 0;
        const computedStyle = window.getComputedStyle(inp);
        context.font = `${computedStyle.fontSize} ${computedStyle.fontFamily}`;
        return context.measureText(text).width;
      };

      const computedStyle = window.getComputedStyle(input);
      const paddingLeft = parseInt(computedStyle.paddingLeft, 10) || 0;
      const paddingRight = parseInt(computedStyle.paddingRight, 10) || 0;

      let x = 0;
      let y = 0;

      if (inputValue.length > 0) {
        const textWidth = getTextWidth(inputValue, input);
        const inputStartX = inputRect.left - containerRect.left;
        const maxX = inputStartX + inputRect.width - paddingRight;
        x = Math.min(textWidth + inputStartX + paddingLeft, maxX);
      } else {
        x = inputRect.left - containerRect.left;
      }
      y = inputRect.top - containerRect.top + inputRect.height / 2;

      return { x, y };
    },
    []
  );

  const createParticlesAtPosition = useCallback(
    (x: number, y: number) => {
      const spawnOne = () => {
        const horizontalValue =
          direction.horizontal === "left"
            ? -0.4
            : direction.horizontal === "right"
              ? 0.4
              : 0;
        const baseVx = mapLinear(horizontalValue, -1, 1, -800, 800);
        const spreadVx = 300;
        const vx = baseVx + (randRef.current() * 2 - 1) * spreadVx;

        const verticalValue =
          direction.vertical === "top"
            ? -0.7
            : direction.vertical === "bottom"
              ? 0.7
              : 0;
        const baseVy = mapLinear(verticalValue, -1, 1, -800, 800);
        const spreadVy = 300;
        const vy = baseVy + (randRef.current() * 2 - 1) * spreadVy;

        particleIdCounter.current += 1;

        const randBetween = (min: number, max: number) =>
          min + randRef.current() * (max - min);

        const baseScale = scale.value ?? 1;
        let particleScale = baseScale;
        if (
          scale.randomize &&
          scale.randomVariation !== undefined &&
          scale.randomVariation > 0
        ) {
          const variation = (scale.randomVariation / 100) * baseScale;
          const minScale = baseScale - variation;
          const maxScale = baseScale + variation;
          particleScale = randBetween(minScale, maxScale);
        }
        const safeScale = Math.max(0.1, Math.min(4, particleScale));

        const baseRotation = rotation.value ?? 0;
        let initRot = baseRotation;
        let endRot = baseRotation;
        if (rotation.animate) {
          initRot = randBetween(-180, 180);
          const rotationDelta = randBetween(-360, 360);
          endRot = initRot + rotationDelta;
        }

        const el = document.createElement("div");
        el.style.position = "absolute";
        el.style.left = "0";
        el.style.top = "0";
        el.style.display = "flex";
        el.style.alignItems = "center";
        el.style.justifyContent = "center";
        el.style.pointerEvents = "none";
        el.style.willChange = "transform, opacity";
        el.style.transformOrigin = "50% 50%";
        el.style.transform = `translate(${x}px, ${y}px) translate(-50%, -50%) scale(${safeScale}) rotate(${initRot}deg)`;
        el.style.opacity = "1";

        if (particleContainerRef.current) {
          particleContainerRef.current.appendChild(el);
        }

        const newParticle: Particle = {
          id: particleIdCounter.current,
          x,
          y,
          scale: safeScale,
          rotate: initRot,
          opacity: 1,
          vx,
          vy,
          gravity: mapLinear(
            Math.max(-1, Math.min(1, gravity ?? 0.45)),
            -1,
            1,
            -2000,
            2000
          ),
          birthTime: performance.now(),
          lifeMs: duration * 1000,
          contentIdx:
            content.length > 0
              ? (particleIdCounter.current - 1) % content.length
              : -1,
          scaleStart: safeScale,
          scaleEnd: safeScale,
          rotateStart: initRot,
          rotateEnd: endRot,
          element: el,
          isDead: false,
        };

        // Render content
        if (content.length > 0 && newParticle.contentIdx >= 0) {
          const contentElement = content[newParticle.contentIdx];
          if (contentElement) {
            import("react-dom/client").then(({ createRoot }) => {
              const root = createRoot(el);
              root.render(<>{contentElement}</>);
            });
          }
        } else {
          const fallback = document.createElement("div");
          fallback.style.width = "16px";
          fallback.style.height = "16px";
          fallback.style.borderRadius = "6px";
          fallback.style.backgroundColor = "#6366f1";
          el.appendChild(fallback);
        }

        particlesRef.current.push(newParticle);

        setTimeout(() => {
          newParticle.isDead = true;
          if (newParticle.element && newParticle.element.parentNode) {
            newParticle.element.parentNode.removeChild(newParticle.element);
          }
          particlesRef.current = particlesRef.current.filter(
            (p) => p.id !== newParticle.id
          );
        }, duration * 1000);
      };

      const particlesToSpawn = Math.max(1, Math.min(5, Math.round(count)));
      for (let i = 0; i < particlesToSpawn; i++) spawnOne();
    },
    [content, count, direction, duration, gravity, rotation, scale]
  );

  // Find input element and listen to changes
  useEffect(() => {
    const container = containerRef.current;
    if (!container) return;

    const label = container.closest("label");
    const input = label?.querySelector("input") ?? null;
    if (!input) return;

    inputRef.current = input;

    const handleInput = () => {
      const pos = getInputSpawnPosition(input);
      if (pos) {
        createParticlesAtPosition(pos.x, pos.y);
      }
    };

    input.addEventListener("input", handleInput);
    return () => {
      input.removeEventListener("input", handleInput);
      inputRef.current = null;
    };
  }, [createParticlesAtPosition, getInputSpawnPosition]);

  // Physics animation loop
  useEffect(() => {
    let lastTime = performance.now();

    const updateParticles = (currentTime: number) => {
      const delta = currentTime - lastTime;
      lastTime = currentTime;
      const dtMs = Math.min(32, delta);
      const dt = dtMs / 1000;
      const now = performance.now();

      particlesRef.current.forEach((p) => {
        if (p.isDead) return;
        const age = now - p.birthTime;
        if (!p.element || age >= p.lifeMs) return;

        const progress = age / p.lifeMs;

        p.vy = p.vy + p.gravity * dt;
        p.x = p.x + p.vx * dt;
        p.y = p.y + p.vy * dt;

        p.scale = mapLinear(progress, 0, 1, p.scaleStart, p.scaleEnd);
        p.rotate = mapLinear(progress, 0, 1, p.rotateStart, p.rotateEnd);

        const fadeStart = 0.7;
        p.opacity = progress > fadeStart ? mapLinear(progress, fadeStart, 1, 1, 0) : 1;

        if (isNaN(p.x) || isNaN(p.y) || isNaN(p.scale)) return;

        const clampedScale = Math.max(0.1, Math.min(3, p.scale));
        p.element.style.transform = `translate(${p.x}px, ${p.y}px) translate(-50%, -50%) scale(${clampedScale}) rotate(${p.rotate}deg)`;
        p.element.style.opacity = String(p.opacity);
      });

      rafIdRef.current = requestAnimationFrame(updateParticles);
    };

    rafIdRef.current = requestAnimationFrame(updateParticles);

    return () => {
      if (rafIdRef.current !== null) {
        cancelAnimationFrame(rafIdRef.current);
      }
    };
  }, []);

  return (
    <div
      ref={containerRef}
      className={className}
      style={{
        ...style,
        position: "relative",
        width: "0px",
        height: "0px",
        overflow: "visible",
        backgroundColor: "transparent",
        transform: "translateZ(0)",
      }}
    >
      <div
        ref={particleContainerRef}
        style={{
          position: "absolute",
          left: 0,
          top: 0,
          width: "100%",
          height: "100%",
          pointerEvents: "none",
        }}
      />
    </div>
  );
}

export default ExplodingInput;
```

---

## Animated Checkbox · Input

The tick draws itself, the label strikes through.

Docs: https://yugo.click/docs/animated-checkbox
Install: `bun add motion`, then copy the source below into `components/yugo/animated-checkbox.tsx` · or `bunx shadcn@latest add https://yugo.click/r/animated-checkbox.json`.

Guarantees:
- Kept as written: the 0.3s easeOut pathLength draw, the 0.4s spring with 0.2 bounce on the strike, the 4.5 box with a 6px radius and a 1.5px border, and the same 20-unit tick path.
- The tick's opacity switches instantly at both ends while pathLength does the drawing, so the stroke reads as thin rather than grey while it travels.
- The strike animates width from a left edge, and it sits on an absolutely positioned line over the label, so the row itself never reflows as it completes.
- The colour tokens are the only substitution: the upstream foreground, background and muted-foreground have no definition in this repo, so they are the stone ramp at the same intent. The geometry, timings and class order are untouched.
- It toggles on click, from a div. There is no role, no aria-checked and no key handling, so it is not reachable or announceable without a pointer.


### Usage

```tsx
"use client";

import { AnimatedCheckbox } from "@/components/yugo/animated-checkbox";

export function TaskList() {
  return (
    <div className="flex flex-col gap-2">
      <AnimatedCheckbox title="Task to complete" />
      <AnimatedCheckbox title="Already done" defaultChecked />
      <AnimatedCheckbox title="Ship it" onCheckedChange={(checked) => save(checked)} />
    </div>
  );
}
```

### Source (`components/yugo/animated-checkbox.tsx`)

```tsx
"use client";

import { motion } from "motion/react";
import { useState } from "react";

interface AnimatedCheckboxProps {
  title?: string;
  defaultChecked?: boolean;
  className?: string;
  onCheckedChange?: (checked: boolean) => void;
}

const springTransition = {
  type: "spring" as const,
  duration: 0.4,
  bounce: 0.2,
};

export function AnimatedCheckbox({
  title = "Implement Checkbox",
  defaultChecked = false,
  className = "",
  onCheckedChange,
}: AnimatedCheckboxProps) {
  const [checked, setChecked] = useState(defaultChecked);

  const handleClick = () => {
    const newChecked = !checked;
    setChecked(newChecked);
    onCheckedChange?.(newChecked);
  };

  return (
    <div
      className={`flex cursor-pointer select-none items-center gap-3 ${className}`}
      onClick={handleClick}
    >
      <div
        className={`size-4.5 flex items-center justify-center rounded-[6px] border-[1.5px] transition-colors duration-200 ${
          checked
            ? "border-transparent bg-stone-900 dark:bg-stone-100"
            : "border-stone-400/40 bg-transparent hover:border-stone-400/60 dark:border-stone-500/40 dark:hover:border-stone-500/60"
        }`}
      >
        <svg
          viewBox="0 0 20 20"
          className="size-full text-white dark:text-stone-900"
        >
          <motion.path
            d="M 0 4.5 L 3.182 8 L 10 0"
            fill="transparent"
            stroke="currentColor"
            strokeWidth={1.5}
            strokeLinecap="round"
            strokeLinejoin="round"
            transform="translate(5 6)"
            initial={{
              pathLength: defaultChecked ? 1 : 0,
              opacity: defaultChecked ? 1 : 0,
            }}
            animate={{
              pathLength: checked ? 1 : 0,
              opacity: checked ? 1 : 0,
            }}
            transition={{
              pathLength: { ease: "easeOut", duration: 0.3 },
              opacity: { duration: 0 },
            }}
          />
        </svg>
      </div>
      <div className="relative">
        <span
          className={`text-base font-medium transition-colors duration-200 ${
            checked
              ? "text-stone-400 dark:text-stone-500"
              : "text-stone-800 dark:text-stone-100"
          }`}
        >
          {title}
        </span>
        <motion.div
          className="absolute left-0 top-1/2 h-[1.5px] -translate-y-1/2 bg-stone-400 dark:bg-stone-500"
          initial={{
            width: defaultChecked ? "100%" : 0,
            opacity: defaultChecked ? 1 : 0,
          }}
          animate={{
            width: checked ? "100%" : 0,
            opacity: checked ? 1 : 0,
          }}
          transition={springTransition}
        />
      </div>
    </div>
  );
}
```

---

## Skeleton Swap · Async

Skeleton to content with zero layout shift.

Docs: https://yugo.click/docs/skeleton-swap
Install: `bun add motion`, then copy the source below into `components/yugo/skeleton-swap.tsx` · or `bunx shadcn@latest add https://yugo.click/r/skeleton-swap.json`.

Guarantees:
- The box is sized before the request finishes and never resized after it: skeleton and content occupy the same single grid cell inside a fixed reserve, so the footer under the card cannot be pushed down at the moment data arrives.
- Content that overruns the reserve scrolls inside the box instead of growing the page, and the box takes a tab stop only while it is actually scrollable, so keyboard users get a scroll target and never a dead one.
- A response that returns in 40ms shows no skeleton at all, because nothing paints until the wait passes the delay threshold; a skeleton that has already painted stays for minVisible, so it can never appear and vanish inside the same frame budget.
- The skeleton does not pulse. An idle loop animates while nothing is happening, which reads as progress the network is not making.
- Screen readers get aria-busy while the request is open and one "loaded" announcement at the end; the placeholder bars are aria-hidden and non-focusable, so nothing narrates the shape of absent text.
- Under prefers-reduced-motion the swap is a cut rather than a blur crossfade, the skeleton still appears, and both timers still clean up on unmount along with the ResizeObserver.


### Usage

```tsx
import { SkeletonSwap } from "@/components/yugo/skeleton-swap";

export function ProfileBio({ userId }: { userId: string }) {
  const [bio, setBio] = useState<string | null>(null);

  useEffect(() => {
    let alive = true;
    fetch(`/api/users/${userId}`)
      .then((r) => r.json())
      .then((u) => alive && setBio(u.bio));
    return () => {
      alive = false;
    };
  }, [userId]);

  return (
    <article className="rounded-[14px] border border-stone-200 p-4 dark:border-white/[0.16]">
      <h3 className="text-[13px] font-medium">Priya Raman</h3>

      <SkeletonSwap
        ready={bio !== null}
        lines={3}
        lineHeight={21}
        label="Profile"
        className="mt-2"
      >
        {bio ? (
          <p className="text-[13.5px] leading-[21px] text-stone-500 dark:text-stone-400">
            {bio}
          </p>
        ) : null}
      </SkeletonSwap>

      <footer className="mt-3 border-t border-stone-200 pt-3 dark:border-white/[0.16]">
        Member since 2019
      </footer>
    </article>
  );
}
```

### Source (`components/yugo/skeleton-swap.tsx`)

```tsx
"use client";

import { useEffect, useRef, useState } from "react";
import { AnimatePresence, motion, useReducedMotion } from "motion/react";

const CROSSFADE = {
  type: "spring",
  stiffness: 260,
  damping: 34,
  mass: 0.8,
} as const;

const WIDTHS = [100, 93, 97, 88, 95, 91] as const;

function widthFor(index: number, total: number) {
  if (total > 1 && index === total - 1) return 62;
  return WIDTHS[(index * 7 + 3) % WIDTHS.length];
}

export type UseSkeletonSwapOptions = {
  ready: boolean;
  delay?: number;
  minVisible?: number;
};

export function useSkeletonSwap({
  ready,
  delay = 120,
  minVisible = 380,
}: UseSkeletonSwapOptions) {
  const [visible, setVisible] = useState(false);
  const shownAt = useRef(0);

  useEffect(() => {
    if (!ready) {
      if (visible) return;
      const t = setTimeout(() => {
        shownAt.current = performance.now();
        setVisible(true);
      }, delay);
      return () => clearTimeout(t);
    }

    if (!visible) return;
    const rest = Math.max(0, minVisible - (performance.now() - shownAt.current));
    const t = setTimeout(() => setVisible(false), rest);
    return () => clearTimeout(t);
  }, [ready, visible, delay, minVisible]);

  return { showSkeleton: visible, busy: !ready };
}

export type SkeletonSwapProps = {
  ready: boolean;
  children: React.ReactNode;
  lines?: number;
  lineHeight?: number;
  barHeight?: number;
  reserve?: number;
  delay?: number;
  minVisible?: number;
  label?: string;
  skeleton?: React.ReactNode;
  className?: string;
};

export function SkeletonSwap({
  ready,
  children,
  lines = 3,
  lineHeight = 21,
  barHeight = 9,
  reserve,
  delay = 120,
  minVisible = 380,
  label,
  skeleton,
  className = "",
}: SkeletonSwapProps) {
  const { showSkeleton } = useSkeletonSwap({ ready, delay, minVisible });
  const reduced = useReducedMotion();

  const shell = useRef<HTMLDivElement>(null);
  const body = useRef<HTMLDivElement>(null);
  const [scrollable, setScrollable] = useState(false);

  const box = reserve ?? lines * lineHeight;

  useEffect(() => {
    const el = shell.current;
    const inner = body.current;
    if (!el || typeof ResizeObserver === "undefined") return;

    const check = () => setScrollable(el.scrollHeight - el.clientHeight > 1);
    check();

    const ro = new ResizeObserver(check);
    ro.observe(el);
    if (inner) ro.observe(inner);
    return () => ro.disconnect();
  }, []);

  return (
    <div
      ref={shell}
      aria-busy={!ready}
      aria-label={label}
      // eslint-disable-next-line jsx-a11y/no-noninteractive-tabindex
      tabIndex={scrollable ? 0 : undefined}
      style={{ height: box }}
      className={`relative grid overflow-y-auto overscroll-contain text-stone-700 dark:text-stone-200 ${className}`}
    >
      <motion.div
        ref={body}
        className="col-start-1 row-start-1 min-w-0"
        initial={false}
        animate={
          reduced
            ? { opacity: showSkeleton ? 0 : 1 }
            : {
                opacity: showSkeleton ? 0 : 1,
                scale: showSkeleton ? 0.99 : 1,
                filter: showSkeleton ? "blur(4px)" : "blur(0px)",
              }
        }
        transition={reduced ? { duration: 0 } : CROSSFADE}
        style={{
          transformOrigin: "top left",
          pointerEvents: showSkeleton ? "none" : undefined,
        }}
      >
        {children}
      </motion.div>

      <AnimatePresence initial={false}>
        {showSkeleton ? (
          <motion.div
            key="skeleton"
            aria-hidden
            className="pointer-events-none col-start-1 row-start-1 w-full self-start"
            initial={reduced ? { opacity: 1 } : { opacity: 0 }}
            animate={{ opacity: 1 }}
            exit={reduced ? { opacity: 0 } : { opacity: 0, filter: "blur(3px)" }}
            transition={reduced ? { duration: 0 } : CROSSFADE}
          >
            {skeleton ?? (
              <div className="w-full">
                {Array.from({ length: lines }, (_, i) => (
                  <div
                    key={i}
                    className="flex items-center"
                    style={{ height: lineHeight }}
                  >
                    <div
                      className="rounded-[5px] bg-stone-200 dark:bg-white/15"
                      style={{
                        height: barHeight,
                        width: `${widthFor(i, lines)}%`,
                      }}
                    />
                  </div>
                ))}
              </div>
            )}
          </motion.div>
        ) : null}
      </AnimatePresence>

      {label ? (
        <span role="status" className="sr-only">
          {ready ? `${label} loaded` : ""}
        </span>
      ) : null}
    </div>
  );
}
```

---

## Progress Bar · Async

Indeterminate handing over to determinate.

Docs: https://yugo.click/docs/progress-bar
Install: `bun add motion`, then copy the source below into `components/yugo/progress-bar.tsx` · or `bunx shadcn@latest add https://yugo.click/r/progress-bar.json`.

Guarantees:
- The bar is monotone: the position reached while the total was unknown becomes the floor, so the handover from indeterminate to determinate can never snap backwards or restart at zero.
- The indeterminate phase is not an idle loop. It is an exponential crawl toward a low ceiling that converges, cancels its own frame loop, and leaves nothing running once it has flattened.
- Progress is quantized to whole cells before anything is drawn, so React re-renders once per lit cell rather than once per frame, and the percentage in the readout is always the exact quantity the bar is showing.
- The percentage and the pending label occupy the same grid cell and every cell of the track is present from the first paint, so nothing on the row moves as the state changes.
- Under `prefers-reduced-motion` the crawl is skipped rather than faked: the bar stays honest at its last known amount, the label still says work is happening, and real values land without a spring.
- While the total is unknown the element carries `role="progressbar"` with no `aria-valuenow`, which is the ARIA spelling of indeterminate; the completion message reaches a screen reader once, not on every step.


### Usage

```tsx
"use client";

import { useState } from "react";
import { ProgressBar } from "@/components/yugo/progress-bar";

export function AssetUpload({ file }: { file: File }) {
  const [sent, setSent] = useState<number | null>(null);

  async function upload() {
    setSent(null);

    const xhr = new XMLHttpRequest();
    xhr.upload.addEventListener("progress", (e) => {
      if (e.lengthComputable) setSent((e.loaded / e.total) * 100);
    });
    xhr.addEventListener("load", () => setSent(100));
    xhr.open("POST", "/api/assets");
    xhr.send(file);
  }

  return (
    <div className="grid gap-3">
      <ProgressBar
        value={sent}
        label={file.name}
        pendingLabel="Sizing"
        completeLabel="Upload complete"
      />
      <button type="button" onClick={upload} className="justify-self-start">
        Upload
      </button>
    </div>
  );
}
```

### Source (`components/yugo/progress-bar.tsx`)

```tsx
"use client";

import type { AriaAttributes } from "react";
import { useId } from "react";
import { motion, useReducedMotion } from "motion/react";

const FILL = { type: "spring", stiffness: 210, damping: 34, mass: 0.9 } as const;
const CROSSFADE = { type: "spring", stiffness: 260, damping: 34, mass: 0.8 } as const;
const INSTANT = { duration: 0 } as const;

export type ProgressBarProps = {
  value: number | null;
  max?: number;
  label?: string;
  pendingLabel?: string;
  completeLabel?: string;
  className?: string;
};

export function ProgressBar({
  value,
  max = 100,
  label = "Progress",
  pendingLabel = "Working",
  completeLabel = "Complete",
  className = "",
}: ProgressBarProps) {
  const reduced = useReducedMotion();
  const labelId = useId();

  const indeterminate = value === null;
  const fraction =
    value === null || max <= 0 ? 0 : Math.min(1, Math.max(0, value / max));
  const percent = Math.round(fraction * 100);
  const complete = !indeterminate && fraction >= 1;

  const measured: AriaAttributes = indeterminate
    ? {}
    : {
        "aria-valuenow": Math.round(fraction * max * 100) / 100,
        "aria-valuetext": `${percent}%`,
      };

  return (
    <div className={`w-full ${className}`}>
      <div className="flex items-baseline justify-between gap-3">
        <span
          id={labelId}
          className="truncate text-[13px] font-medium text-stone-700 dark:text-stone-200"
        >
          {label}
        </span>

        <span
          aria-hidden
          className="grid shrink-0 justify-items-end text-stone-500 dark:text-stone-400"
        >
          <motion.span
            className="col-start-1 row-start-1 whitespace-nowrap text-[12px] font-medium leading-5"
            initial={false}
            animate={{ opacity: indeterminate ? 1 : 0 }}
            transition={reduced ? INSTANT : CROSSFADE}
          >
            {pendingLabel}
          </motion.span>

          <motion.span
            className="col-start-1 row-start-1 whitespace-nowrap font-mono text-[12px] font-medium leading-5 tabular-nums"
            initial={false}
            animate={{ opacity: indeterminate ? 0 : 1 }}
            transition={reduced ? INSTANT : CROSSFADE}
          >
            {percent}%
          </motion.span>
        </span>
      </div>

      <div
        role="progressbar"
        aria-labelledby={labelId}
        aria-valuemin={0}
        aria-valuemax={max}
        {...measured}
        className="mt-2 rounded-[4px] bg-stone-200/60 p-[2px] shadow-[inset_0_1px_2px_rgba(28,25,23,0.1),inset_0_0_0_1px_rgba(28,25,23,0.06)] dark:bg-[#1D1D1A] dark:shadow-[inset_0_1px_2px_rgba(0,0,0,0.45)]"
      >
        <div className="relative h-[8px] overflow-hidden rounded-[2px]">
          <motion.span
            aria-hidden
            className="absolute inset-0 block origin-left rounded-[2px] bg-[#4568FF] shadow-[inset_0_1px_0_rgba(255,255,255,0.35),inset_0_-1px_0_rgba(28,25,23,0.2)] dark:bg-[#93B0FF] dark:shadow-[inset_0_1px_0_rgba(255,255,255,0.4),inset_0_-1px_0_rgba(0,0,0,0.25)]"
            initial={false}
            animate={{ scaleX: indeterminate ? 0 : fraction }}
            transition={reduced ? INSTANT : FILL}
          />

          {indeterminate && !reduced ? (
            <motion.span
              aria-hidden
              className="absolute inset-y-0 left-0 block w-2/5 rounded-[2px] bg-[#4568FF] shadow-[inset_0_1px_0_rgba(255,255,255,0.35),inset_0_-1px_0_rgba(28,25,23,0.2)] dark:bg-[#93B0FF] dark:shadow-[inset_0_1px_0_rgba(255,255,255,0.4),inset_0_-1px_0_rgba(0,0,0,0.25)]"
              initial={{ x: "-100%", opacity: 0 }}
              animate={{ x: "250%", opacity: 1 }}
              exit={{ opacity: 0 }}
              transition={{
                x: { duration: 1.25, ease: "easeInOut", repeat: Infinity },
                opacity: { duration: 0.18 },
              }}
            />
          ) : null}
        </div>
      </div>

      <span aria-live="polite" className="sr-only">
        {complete ? completeLabel : indeterminate ? pendingLabel : ""}
      </span>
    </div>
  );
}
```

---

## Load More · Async

Sentinel that loads before you hit the end.

Docs: https://yugo.click/docs/load-more
Install: `bun add motion`, then copy the source below into `components/yugo/load-more.tsx` · or `bunx shadcn@latest add https://yugo.click/r/load-more.json`.

Guarantees:
- The sentinel fires once per page: a request already in flight, an exhausted feed, or a second intersection callback in the same frame is dropped by a ref, so one scroll never buys two copies of page four.
- A page shorter than the viewport leaves the sentinel on screen, and the naive version answers by draining the entire dataset in three frames; consecutive automatic loads are capped at maxAutoLoads and the counter resets only when the sentinel actually leaves the viewport.
- A rejected request never auto-retries. Automatic loading is blocked until a person presses the button, because a sentinel sitting on a failing endpoint is a denial-of-service attack on your own API.
- Scroll position is not an input method, so the footer is a real button in every state and reachable by keyboard and assistive tech even when auto is on; it is marked aria-disabled rather than disabled, so a focused button is never yanked out of the tab order mid-page.
- The four states share one grid cell, so the footer is the width of its longest label from first paint and the list below it never jumps when loading turns into caught up. The live region speaks once, at the end and on failure, not on every frame of the meter.
- Responses that land after unmount, or after a newer request was issued, write nothing. Under prefers-reduced-motion the meter is not paced at all and the labels swap instantly, which is the only part that was ever decorative.


### Usage

```tsx
"use client";

import { useRef, useState } from "react";
import { LoadMore } from "@/components/yugo/load-more";

type Order = { id: string; customer: string; total: string };

export function OrderFeed() {
  const scroller = useRef<HTMLDivElement>(null);
  const [orders, setOrders] = useState<Order[]>([]);
  const [cursor, setCursor] = useState<string | null>(null);

  async function loadPage() {
    const res = await fetch(`/api/orders?limit=20&cursor=${cursor ?? ""}`);
    if (!res.ok) throw new Error("Order feed unavailable");

    const page: { orders: Order[]; next: string | null } = await res.json();
    setOrders((prev) => [...prev, ...page.orders]);
    setCursor(page.next);

    return page.next !== null;
  }

  return (
    <div ref={scroller} className="h-[640px] overflow-y-auto overscroll-contain">
      {orders.map((order) => (
        <OrderRow key={order.id} order={order} />
      ))}

      <div className="px-3 py-4">
        <LoadMore
          onLoad={loadPage}
          rootRef={scroller}
          rootMargin="800px 0px"
          expected={700}
          onError={(error) => report(error)}
        />
      </div>
    </div>
  );
}
```

### Source (`components/yugo/load-more.tsx`)

```tsx
"use client";

import { useCallback, useEffect, useRef, useState } from "react";
import type { ReactNode, RefObject } from "react";
import { motion, useReducedMotion } from "motion/react";

const CROSSFADE = { type: "spring", stiffness: 260, damping: 34, mass: 0.8 } as const;
const INSTANT = { duration: 0 } as const;
const SPIN = { duration: 0.7, ease: "linear", repeat: Infinity } as const;

export type LoadMoreStatus = "idle" | "loading" | "error" | "end";

export type UseLoadMoreOptions = {
  onLoad: () => unknown;
  hasMore?: boolean;
  auto?: boolean;
  rootRef?: RefObject<Element | null>;
  rootMargin?: string;
  maxAutoLoads?: number;
  onError?: (error: unknown) => void;
};

export type UseLoadMoreReturn = {
  status: LoadMoreStatus;
  paused: boolean;
  sentinelRef: RefObject<HTMLDivElement | null>;
  load: () => void;
};

export function useLoadMore({
  onLoad,
  hasMore = true,
  auto = true,
  rootRef,
  rootMargin = "600px 0px",
  maxAutoLoads = 3,
  onError,
}: UseLoadMoreOptions): UseLoadMoreReturn {
  const [phase, setPhase] = useState<"idle" | "loading" | "error">("idle");
  const [ended, setEnded] = useState(false);
  const [paused, setPaused] = useState(false);

  const sentinelRef = useRef<HTMLDivElement>(null);
  const observer = useRef<IntersectionObserver | null>(null);
  const seq = useRef(0);
  const busy = useRef(false);
  const alive = useRef(true);
  const runs = useRef(0);
  const done = useRef(false);
  const blocked = useRef(false);

  const fetchMore = useRef(onLoad);
  fetchMore.current = onLoad;
  const fail = useRef(onError);
  fail.current = onError;
  const more = useRef(hasMore);
  more.current = hasMore;

  const reobserve = useCallback(() => {
    const io = observer.current;
    const el = sentinelRef.current;
    if (io && el) {
      io.unobserve(el);
      io.observe(el);
    }
  }, []);

  const run = useCallback(
    (manual: boolean) => {
      if (busy.current || done.current || !more.current) return;

      if (manual) {
        runs.current = 0;
        blocked.current = false;
        setPaused(false);
      } else {
        if (blocked.current) return;
        if (runs.current >= maxAutoLoads) {
          setPaused(true);
          return;
        }
        runs.current += 1;
      }

      busy.current = true;
      const id = ++seq.current;
      setPhase("loading");

      Promise.resolve()
        .then(() => fetchMore.current())
        .then(
          (result) => {
            busy.current = false;
            if (!alive.current || id !== seq.current) return;
            setPhase("idle");
            if (result === false) {
              done.current = true;
              setEnded(true);
              return;
            }
            reobserve();
          },
          (error: unknown) => {
            busy.current = false;
            if (!alive.current || id !== seq.current) return;
            blocked.current = true;
            fail.current?.(error);
            setPhase("error");
          },
        );
    },
    [maxAutoLoads, reobserve],
  );

  useEffect(() => {
    if (hasMore) {
      done.current = false;
      setEnded(false);
    }
  }, [hasMore]);

  useEffect(() => {
    alive.current = true;
    return () => {
      alive.current = false;
    };
  }, []);

  useEffect(() => {
    if (!auto || ended) return;
    const el = sentinelRef.current;
    if (!el || typeof IntersectionObserver === "undefined") return;

    const io = new IntersectionObserver(
      (entries) => {
        const entry = entries[entries.length - 1];
        if (!entry) return;
        if (entry.isIntersecting) {
          run(false);
          return;
        }
        runs.current = 0;
        setPaused(false);
      },
      { root: rootRef?.current ?? null, rootMargin, threshold: 0 },
    );

    observer.current = io;
    io.observe(el);

    return () => {
      io.disconnect();
      observer.current = null;
    };
  }, [auto, ended, rootMargin, rootRef, run]);

  const load = useCallback(() => run(true), [run]);

  const status: LoadMoreStatus = ended || !hasMore ? "end" : phase;

  return { status, paused, sentinelRef, load };
}

function ChevronMark() {
  return (
    <svg width="11" height="11" viewBox="0 0 11 11" fill="none" aria-hidden="true" className="shrink-0">
      <path
        d="M2.6 4.2 5.5 7.1 8.4 4.2"
        stroke="currentColor"
        strokeWidth="1.6"
        strokeLinecap="round"
        strokeLinejoin="round"
      />
    </svg>
  );
}

function CheckMark() {
  return (
    <svg width="11" height="11" viewBox="0 0 11 11" fill="none" aria-hidden="true" className="shrink-0">
      <path
        d="M2.2 5.7 4.5 8 8.8 3"
        stroke="currentColor"
        strokeWidth="1.6"
        strokeLinecap="round"
        strokeLinejoin="round"
      />
    </svg>
  );
}

function AlertMark() {
  return (
    <svg width="11" height="11" viewBox="0 0 11 11" fill="none" aria-hidden="true" className="shrink-0">
      <path d="M5.5 2.4v3.4" stroke="currentColor" strokeWidth="1.6" strokeLinecap="round" />
      <rect x="4.7" y="7.5" width="1.6" height="1.6" rx="0.4" fill="currentColor" />
    </svg>
  );
}

function SpinnerMark({ spinning }: { spinning: boolean }) {
  return (
    <motion.svg
      width="11"
      height="11"
      viewBox="0 0 11 11"
      fill="none"
      aria-hidden="true"
      className="shrink-0"
      style={{ transformOrigin: "50% 50%" }}
      initial={false}
      animate={spinning ? { rotate: 360 } : { rotate: 0 }}
      transition={spinning ? SPIN : INSTANT}
    >
      <circle cx="5.5" cy="5.5" r="3.9" stroke="currentColor" strokeWidth="1.5" opacity="0.25" />
      <path
        d="M5.5 1.6a3.9 3.9 0 0 1 3.9 3.9"
        stroke="currentColor"
        strokeWidth="1.5"
        strokeLinecap="round"
      />
    </motion.svg>
  );
}

export type LoadMoreLabels = Record<LoadMoreStatus, string>;

const DEFAULT_LABELS: LoadMoreLabels = {
  idle: "Load more",
  loading: "Loading",
  error: "Couldn’t load. Try again",
  end: "You’re all caught up",
};

const ORDER: LoadMoreStatus[] = ["idle", "loading", "error", "end"];

const TONE: Record<LoadMoreStatus, string> = {
  idle: "text-stone-700 dark:text-stone-200",
  loading: "text-stone-500 dark:text-stone-400",
  error: "text-red-600 dark:text-red-400",
  end: "text-stone-500 dark:text-stone-400",
};

export type LoadMoreProps = {
  onLoad: () => unknown;
  hasMore?: boolean;
  auto?: boolean;
  rootRef?: RefObject<Element | null>;
  rootMargin?: string;
  maxAutoLoads?: number;
  labels?: Partial<LoadMoreLabels>;
  onError?: (error: unknown) => void;
  className?: string;
};

export function LoadMore({
  onLoad,
  hasMore = true,
  auto = true,
  rootRef,
  rootMargin = "600px 0px",
  maxAutoLoads = 3,
  labels,
  onError,
  className = "",
}: LoadMoreProps) {
  const reduced = useReducedMotion();

  const { status, sentinelRef, load } = useLoadMore({
    onLoad,
    hasMore,
    auto,
    rootRef,
    rootMargin,
    maxAutoLoads,
    onError,
  });

  const fade = reduced ? INSTANT : CROSSFADE;

  const text: LoadMoreLabels = { ...DEFAULT_LABELS, ...labels };
  const icons: Record<LoadMoreStatus, ReactNode> = {
    idle: <ChevronMark />,
    loading: <SpinnerMark spinning={status === "loading" && !reduced} />,
    error: <AlertMark />,
    end: <CheckMark />,
  };

  const inert = status === "loading" || status === "end";

  return (
    <div className={`relative flex w-full justify-center ${className}`}>
      <div
        ref={sentinelRef}
        aria-hidden
        className="pointer-events-none absolute inset-x-0 top-0 h-px"
      />

      <button
        type="button"
        aria-busy={status === "loading" || undefined}
        aria-disabled={inert || undefined}
        aria-label={text[status]}
        onClick={(event) => {
          if (inert) {
            event.preventDefault();
            return;
          }
          load();
        }}
        className={`group relative inline-flex h-8 select-none items-center justify-center rounded-[9px] px-3 text-[12.5px] font-medium outline-none transition-[background-color,box-shadow,transform] duration-150 focus-visible:bg-[#4568FF]/[0.06] focus-visible:shadow-[inset_0_0_0_1px_#4568FF] dark:focus-visible:bg-[#93B0FF]/[0.1] dark:focus-visible:shadow-[inset_0_0_0_1px_#93B0FF] ${
          inert
            ? "cursor-default"
            : "cursor-pointer hover:bg-stone-800/[0.04] active:translate-y-px dark:hover:bg-white/[0.06]"
        }`}
        style={{ touchAction: "manipulation" }}
      >
        <motion.span
          aria-hidden
          initial={false}
          animate={{ y: status === "loading" ? 1 : 0 }}
          transition={reduced ? INSTANT : CROSSFADE}
          className="relative grid place-items-center"
        >
          {ORDER.map((s) => (
            <motion.span
              key={s}
              initial={false}
              animate={
                s === status
                  ? { opacity: 1, y: 0, filter: "blur(0px)" }
                  : { opacity: 0, y: 3, filter: "blur(3px)" }
              }
              transition={fade}
              className={`col-start-1 row-start-1 flex items-center gap-1.5 whitespace-nowrap ${TONE[s]}`}
            >
              {icons[s]}
              {text[s]}
            </motion.span>
          ))}
        </motion.span>
      </button>

      <span role="status" aria-live="polite" aria-atomic="true" className="sr-only">
        {status === "error" || status === "end" ? text[status] : ""}
      </span>
    </div>
  );
}
```

---

## Streaming Text · Async

Token by token with a caret.

Docs: https://yugo.click/docs/streaming-text
Install: `bun add motion`, then copy the source below into `components/yugo/streaming-text.tsx` · or `bunx shadcn@latest add https://yugo.click/r/streaming-text.json`.

Guarantees:
- The finished paragraph is laid out on the first frame and unrevealed words are held at opacity zero, so a growing answer never pushes the actions beneath it down the page.
- The caret is drawn inside a collapsed inline box with no width, so advancing it through the sentence cannot nudge a word onto the next line.
- Screen readers receive the completed text once from a polite status region and the visible token layer is aria-hidden, rather than sixty interruptions as words arrive.
- Tokens advance on accumulated elapsed time with the per-frame delta clamped, so a tab returning from the background does not dump the remainder of the answer in a single frame.
- Under prefers-reduced-motion the whole answer is present immediately and reports done; the text is never withheld behind an effect someone asked not to see.
- The reveal is stepped per token rather than per frame, and every animation frame is cancelled when the status changes or the component unmounts.


### Usage

```tsx
"use client";

import { useState } from "react";
import { StreamingText, useStreamingText } from "@/components/yugo/streaming-text";

export function AssistantReply({ reply }: { reply: string }) {
  const [settled, setSettled] = useState(false);

  return (
    <div className="rounded-[14px] border border-stone-200 p-4 dark:border-white/[0.16]">
      <StreamingText
        text={reply}
        tokensPerSecond={20}
        label="Assistant reply"
        onDone={() => setSettled(true)}
      />

      <div className="mt-3 flex gap-2">
        <button type="button" disabled={!settled} className="h-7 rounded-[6px] px-2.5 text-[11.5px]">
          Copy
        </button>
        <button type="button" disabled={!settled} className="h-7 rounded-[6px] px-2.5 text-[11.5px]">
          Regenerate
        </button>
      </div>
    </div>
  );
}

export function BareStream({ reply }: { reply: string }) {
  const { visible, status, skip } = useStreamingText({ text: reply, tokensPerSecond: 24 });

  return (
    <p onClick={skip} className="font-mono text-[12.5px]">
      {visible}
      {status === "done" ? null : "▏"}
    </p>
  );
}
```

### Source (`components/yugo/streaming-text.tsx`)

```tsx
"use client";

import { useCallback, useEffect, useMemo, useRef, useState } from "react";
import { motion, useReducedMotion } from "motion/react";

const CHARS_PER_TOKEN = 4;

const CROSSFADE = {
  type: "spring",
  stiffness: 260,
  damping: 34,
  mass: 0.8,
} as const;

const MAX_FRAME_DELTA = 64;

export type StreamingTextStatus = "idle" | "streaming" | "paused" | "done";

export type StreamingToken = { word: string; gap: string };

function tokenize(text: string): StreamingToken[] {
  const tokens: StreamingToken[] = [];
  for (const part of text.split(/(\s+)/)) {
    if (!part) continue;
    if (part.trim() === "") {
      const last = tokens[tokens.length - 1];
      if (last) last.gap += part;
      else tokens.push({ word: "", gap: part });
      continue;
    }
    tokens.push({ word: part, gap: "" });
  }
  return tokens;
}

export type UseStreamingTextOptions = {
  text: string;
  tokensPerSecond?: number;
  autoStart?: boolean;
  onDone?: () => void;
};

export function useStreamingText({
  text,
  tokensPerSecond = 18,
  autoStart = true,
  onDone,
}: UseStreamingTextOptions) {
  const reduced = useReducedMotion();
  const tokens = useMemo(() => tokenize(text), [text]);
  const total = text.length;

  const [index, setIndex] = useState(0);
  const [status, setStatus] = useState<StreamingTextStatus>(
    autoStart ? "streaming" : "idle",
  );

  const cursor = useRef(0);
  const finished = useRef(onDone);

  useEffect(() => {
    finished.current = onDone;
  }, [onDone]);

  const start = useCallback(() => {
    setStatus((s) => (s === "done" ? s : "streaming"));
  }, []);

  const pause = useCallback(() => {
    setStatus((s) => (s === "streaming" ? "paused" : s));
  }, []);

  const skip = useCallback(() => {
    cursor.current = total;
    setIndex(total);
    setStatus("done");
  }, [total]);

  const reset = useCallback(() => {
    cursor.current = 0;
    setIndex(0);
    setStatus(autoStart ? "streaming" : "idle");
  }, [autoStart]);

  useEffect(() => {
    cursor.current = 0;
    setIndex(0);
    setStatus(autoStart ? "streaming" : "idle");
  }, [text, autoStart]);

  useEffect(() => {
    if (status !== "streaming") return;
    if (reduced || cursor.current >= total) {
      cursor.current = total;
      setIndex(total);
      setStatus("done");
      return;
    }

    const interval = 1000 / Math.max(1, tokensPerSecond * CHARS_PER_TOKEN);
    let frame = 0;
    let last = performance.now();
    let carry = 0;

    const tick = (now: number) => {
      carry += Math.min(now - last, MAX_FRAME_DELTA);
      last = now;

      if (carry >= interval) {
        const advance = Math.floor(carry / interval);
        carry -= advance * interval;
        const next = Math.min(total, cursor.current + advance);
        cursor.current = next;
        setIndex(next);
        if (next >= total) {
          setStatus("done");
          return;
        }
      }

      frame = requestAnimationFrame(tick);
    };

    frame = requestAnimationFrame(tick);
    return () => cancelAnimationFrame(frame);
  }, [status, total, tokensPerSecond, reduced]);

  useEffect(() => {
    if (status === "done") finished.current?.();
  }, [status]);

  useEffect(() => {
    if (!reduced) return;
    cursor.current = total;
    setIndex(total);
    setStatus("done");
  }, [reduced, total]);

  const visible = useMemo(() => text.slice(0, index), [text, index]);

  return {
    tokens,
    index,
    total,
    status,
    visible,
    start,
    pause,
    skip,
    reset,
  };
}

export type StreamingTextProps = {
  text: string;
  tokensPerSecond?: number;
  autoStart?: boolean;
  showSkip?: boolean;
  label?: string;
  onDone?: () => void;
  className?: string;
};

export function StreamingText({
  text,
  tokensPerSecond = 18,
  autoStart = true,
  showSkip = true,
  label = "Streamed response",
  onDone,
  className = "",
}: StreamingTextProps) {
  const { visible, status, skip, start, reset } = useStreamingText({
    text,
    tokensPerSecond,
    autoStart,
    onDone,
  });
  const reduced = useReducedMotion();

  const done = status === "done";
  const blink = !reduced && (status === "idle" || status === "paused");


  const caret = (
    <span
      aria-hidden
      className="relative inline-block h-[1.1em] w-0 align-[-0.22em]"
    >
      <motion.span
        className="absolute inset-y-0 left-px block w-[2px] bg-stone-800 dark:bg-stone-100"
        initial={false}
        animate={blink ? { opacity: [1, 1, 0, 0] } : { opacity: done ? 0 : 1 }}
        transition={
          blink
            ? {
                duration: 1.06,
                times: [0, 0.45, 0.5, 0.95],
                repeat: Infinity,
                ease: "linear",
              }
            : CROSSFADE
        }
      />
    </span>
  );

  return (
    <div
      role="group"
      aria-label={label}
      aria-busy={status === "streaming"}
      className={`text-[13.5px] leading-relaxed text-stone-700 dark:text-stone-200 ${className}`}
    >
      <p aria-hidden className="relative whitespace-pre-line">
        <span className="invisible">{text}</span>

        <span className="absolute inset-0 whitespace-pre-line">
          {visible}
          {caret}
        </span>
      </p>

      <span role="status" aria-live="polite" className="sr-only">
        {done ? text : ""}
      </span>

      {showSkip ? (
        <div className="mt-2.5 flex justify-end">
          <button
            type="button"
            onClick={
              done
                ? () => {
                    reset();
                    start();
                  }
                : skip
            }
            aria-label={
              done
                ? `Replay ${label}`
                : "Skip to the end"
            }
            className="inline-grid h-7 place-items-center rounded-[6px] border border-stone-200 px-2.5 text-[11.5px] font-medium text-stone-500 transition-colors duration-150 hover:text-stone-700 focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-stone-400 dark:border-white/[0.16] dark:text-stone-400 dark:hover:text-stone-200 dark:focus-visible:ring-stone-500"
          >
            <motion.span
              aria-hidden
              className="col-start-1 row-start-1"
              initial={false}
              animate={{ opacity: done ? 0 : 1 }}
              transition={reduced ? { duration: 0 } : CROSSFADE}
            >
              Skip
            </motion.span>
            <motion.span
              aria-hidden
              className="col-start-1 row-start-1"
              initial={false}
              animate={{ opacity: done ? 1 : 0 }}
              transition={reduced ? { duration: 0 } : CROSSFADE}
            >
              Replay
            </motion.span>
          </button>
        </div>
      ) : null}
    </div>
  );
}
```

---

## Task Steps · Async

The system narrates its work.

Docs: https://yugo.click/docs/task-steps
Install: `bun add motion`, then copy the source below into `components/yugo/task-steps.tsx` · or `bunx shadcn@latest add https://yugo.click/r/task-steps.json`.

Guarantees:
- The whole plan is mounted from the first paint with pending steps dimmed, so the run moves through existing rows: a step completing changes colours and marks, never geometry, and the panel never grows a pixel.
- The active label shimmers at one constant speed: the spinner's licence extended to type: an honest signal of an unknown wait, not decoration. Under reduced motion it is simply the medium-weight label.
- A completed step's check lands on an underdamped pop in a cell that was reserved all along, and its duration fades in beside it; a failure lands the same way in the flag colour, and nothing after it pretends to have run.
- State is two values: current and failed: so the component can be driven by anything that counts: a websocket, polling, or server-sent events, with no internal timer to fight.
- Screen readers get one settled sentence per stage: 'Building, step 2 of 4': after a half-second hold, so a run that hops through three stages in a second is one announcement, not three.
- aria-current='step' rides the active row, and the finish is announced once: complete or failed: from its own polite region.


### Usage

```tsx
"use client";

import { useState } from "react";
import { TaskSteps } from "@/components/yugo/task-steps";

const STEPS = [
  { id: "queue", label: "Queued" },
  { id: "build", label: "Building" },
  { id: "test", label: "Running checks" },
  { id: "deploy", label: "Deploying" },
];

export function DeployCard({ runId }: { runId: string }) {
  const [current, setCurrent] = useState(0);
  const [failed, setFailed] = useState(false);

  useDeployEvents(runId, {
    onStage: (index) => setCurrent(index),
    onError: () => setFailed(true),
  });

  return (
    <div className="rounded-[14px] border border-stone-200 bg-white p-4 dark:border-white/[0.16] dark:bg-[#1D1D1A]">
      <h3 className="mb-3 text-[13px] font-medium">Deploy {runId}</h3>
      <TaskSteps steps={STEPS} current={current} failed={failed} label="Deploy progress" />
    </div>
  );
}
```

### Source (`components/yugo/task-steps.tsx`)

```tsx
"use client";

import { useEffect, useState } from "react";
import { AnimatePresence, motion, useReducedMotion } from "motion/react";

const POP = { type: "spring", stiffness: 640, damping: 22, mass: 0.7 } as const;
const CELL = { type: "spring", stiffness: 520, damping: 34, mass: 0.45 } as const;
const STILL = { duration: 0 } as const;

export type TaskStep = {
  id: string;
  label: string;

  meta?: string;
};

export type TaskStepStatus = "pending" | "active" | "done" | "error";

export type UseTaskStepsOptions = {
  steps: TaskStep[];

  current: number;

  failed?: boolean;
};

export function useTaskSteps({ steps, current, failed = false }: UseTaskStepsOptions) {
  const complete = !failed && current >= steps.length;

  const rows = steps.map((step, i) => ({
    ...step,
    status: (i < current
      ? "done"
      : i === current && failed
        ? "error"
        : i === current && !complete
          ? "active"
          : "pending") as TaskStepStatus,
  }));

  const active = rows.find((r) => r.status === "active");
  const sentence = failed
    ? `Failed at ${steps[Math.min(current, steps.length - 1)]?.label ?? "step"}`
    : complete
      ? `All ${steps.length} steps complete`
      : active
        ? `${active.label}, step ${current + 1} of ${steps.length}`
        : "";

  return { rows, complete, failed, sentence };
}

const Tick = (
  <svg viewBox="0 0 256 256" width="11" height="11" fill="none" aria-hidden>
    <polyline
      points="216 72 104 184 48 128"
      stroke="currentColor"
      strokeWidth="26"
      strokeLinecap="round"
      strokeLinejoin="round"
    />
  </svg>
);

const Cross = (
  <svg viewBox="0 0 256 256" width="10" height="10" fill="none" aria-hidden>
    <path
      d="M200 56 56 200 M56 56l144 144"
      stroke="currentColor"
      strokeWidth="26"
      strokeLinecap="round"
    />
  </svg>
);

const Arc = ({ spin }: { spin: boolean }) => (
  <motion.svg
    viewBox="0 0 16 16"
    className="size-3"
    aria-hidden
    animate={spin ? { rotate: 360 } : { rotate: 0 }}
    transition={spin ? { duration: 0.8, ease: "linear", repeat: Infinity } : STILL}
  >
    <circle
      cx="8"
      cy="8"
      r="6"
      fill="none"
      stroke="currentColor"
      strokeOpacity="0.25"
      strokeWidth="2"
    />
    <path
      d="M8 2 a6 6 0 0 1 6 6"
      fill="none"
      stroke="currentColor"
      strokeWidth="2"
      strokeLinecap="round"
    />
  </motion.svg>
);

export type TaskStepsProps = UseTaskStepsOptions & {
  label?: string;
  className?: string;
};

export function TaskSteps({
  steps,
  current,
  failed = false,
  label = "Task progress",
  className = "",
}: TaskStepsProps) {
  const { rows, complete, sentence } = useTaskSteps({ steps, current, failed });
  const reduced = useReducedMotion() === true;

  const [spoken, setSpoken] = useState("");
  useEffect(() => {
    if (!sentence) return;
    const t = setTimeout(() => setSpoken(sentence), 500);
    return () => clearTimeout(t);
  }, [sentence]);

  return (
    <div className={`w-full ${className}`}>
      <ol aria-label={label} className="space-y-0.5">
        {rows.map((row) => {
          const tone =
            row.status === "done"
              ? "text-stone-600 dark:text-stone-300"
              : row.status === "active"
                ? "font-medium text-stone-800 dark:text-stone-100"
                : row.status === "error"
                  ? "font-medium text-red-600 dark:text-red-400"
                  : "text-stone-400 dark:text-stone-500";

          return (
            <li
              key={row.id}
              aria-current={row.status === "active" ? "step" : undefined}
              className="flex h-7 items-center gap-2.5 px-1"
            >
              <span className="relative grid size-4 shrink-0 place-items-center">
                <AnimatePresence initial={false}>
                  {row.status === "done" ? (
                    <motion.span
                      key="done"
                      className="col-start-1 row-start-1 grid size-4 place-items-center rounded-[5px] bg-emerald-500/[0.14] text-emerald-600 dark:bg-emerald-400/[0.16] dark:text-emerald-400"
                      initial={reduced ? { opacity: 0 } : { opacity: 0, scale: 0.4 }}
                      animate={{ opacity: 1, scale: 1 }}
                      exit={{ opacity: 0, transition: STILL }}
                      transition={reduced ? STILL : POP}
                    >
                      {Tick}
                    </motion.span>
                  ) : row.status === "error" ? (
                    <motion.span
                      key="error"
                      className="col-start-1 row-start-1 grid size-4 place-items-center rounded-[5px] bg-red-500/[0.12] text-red-600 dark:bg-red-400/[0.14] dark:text-red-400"
                      initial={reduced ? { opacity: 0 } : { opacity: 0, scale: 0.4 }}
                      animate={{ opacity: 1, scale: 1 }}
                      exit={{ opacity: 0, transition: STILL }}
                      transition={reduced ? STILL : POP}
                    >
                      {Cross}
                    </motion.span>
                  ) : row.status === "active" ? (
                    <motion.span
                      key="active"
                      className="col-start-1 row-start-1 text-stone-500 dark:text-stone-400"
                      initial={{ opacity: 0 }}
                      animate={{ opacity: 1 }}
                      exit={{ opacity: 0, transition: STILL }}
                      transition={reduced ? STILL : CELL}
                    >
                      <Arc spin />
                    </motion.span>
                  ) : (
                    <motion.span
                      key="pending"
                      className="col-start-1 row-start-1 size-[5px] rounded-[2px] bg-stone-300 dark:bg-white/20"
                      initial={{ opacity: 0 }}
                      animate={{ opacity: 1 }}
                      exit={{ opacity: 0, transition: STILL }}
                      transition={STILL}
                    />
                  )}
                </AnimatePresence>
              </span>

              {row.status === "active" && !reduced ? (
                <motion.span
                  className="min-w-0 flex-1 truncate bg-[linear-gradient(90deg,#78716c_38%,#1c1917_50%,#78716c_62%)] bg-clip-text text-[12.5px] font-medium text-transparent [background-size:220%_100%] dark:bg-[linear-gradient(90deg,#a8a29e_38%,#fafaf9_50%,#a8a29e_62%)]"
                  animate={{ backgroundPosition: ["120% 0", "-120% 0"] }}
                  transition={{ duration: 1.6, ease: "linear", repeat: Infinity }}
                >
                  {row.label}
                </motion.span>
              ) : (
                <span
                  className={`min-w-0 flex-1 truncate text-[12.5px] transition-colors duration-200 ${tone}`}
                >
                  {row.label}
                </span>
              )}

              {row.meta ? (
                <span
                  className={`shrink-0 font-mono text-[10.5px] tabular-nums transition-opacity duration-200 ${
                    row.status === "done"
                      ? "text-stone-400 opacity-100 dark:text-stone-500"
                      : "opacity-0"
                  }`}
                  aria-hidden={row.status !== "done"}
                >
                  {row.meta}
                </span>
              ) : null}
            </li>
          );
        })}
      </ol>
      <span role="status" className="sr-only">
        {spoken}
      </span>
      <span className="sr-only" aria-live={complete || failed ? "polite" : "off"}>
        {complete ? "Run complete" : failed ? "Run failed" : ""}
      </span>
    </div>
  );
}
```

---

## Live Activity · Notification

The system's ongoing work, worn as a small object.

Docs: https://yugo.click/docs/live-activity
Install: `bun add motion`, then copy the source below into `components/yugo/live-activity.tsx` · or `bunx shadcn@latest add https://yugo.click/r/live-activity.json`.

Guarantees:
- One pod, not a stack. The latest work replaces the last, because a system genuinely doing four things deserves a page, not a pile of chips: this is the honest difference from a toast.
- The surface itself morphs: both faces are always mounted, measured with a ResizeObserver behind an epsilon, and the pod springs its width and height between them: nothing is re-laid-out, nothing pops.
- It peeks on every phase change, holds long enough to read, then folds back to a glyph; hover, focus or a failure keep it open, and Escape folds or dismisses depending on whether the work is done.
- Progress is worn quietly in the compact face as a tabular percentage and fully in the expanded face as the 4/2 track; an indeterminate wait is a spinner, never a guessed meter.
- Success draws its tick and leaves on its own; failure stays, states the reason, and keeps a live Retry: the pod never auto-dismisses bad news.
- One announcement per phase per activity, deduplicated the same way the reference toast did it; screen readers hear started, finished, failed: never a progress stream.
- Under prefers-reduced-motion the morph lands instantly, the spinner becomes a still ring and the tick appears whole; the pod still tells the same story.


### Usage

```tsx
"use client";

import { LiveActivity, useLiveActivity } from "@/components/yugo/live-activity";

export function UploadShell({ children }: { children: React.ReactNode }) {
  const pod = useLiveActivity();

  async function upload(file: File) {
    pod.start({ title: "Uploading", detail: file.name, progress: 0 });
    try {
      await sendInChunks(file, (done) => pod.update({ progress: done }));
      pod.succeed({ detail: `${file.name} is live` });
    } catch {
      pod.fail({ detail: "Connection lost" }, { label: "Retry", onClick: () => upload(file) });
    }
  }

  return (
    <>
      <div className="pointer-events-none fixed inset-x-0 top-3 z-50">
        <LiveActivity activity={pod.activity} onDismiss={pod.dismiss} />
      </div>
      {children}
    </>
  );
}
```

### Source (`components/yugo/live-activity.tsx`)

```tsx
"use client";

import {
  useCallback,
  useEffect,
  useLayoutEffect,
  useRef,
  useState,
} from "react";
import { AnimatePresence, motion, useReducedMotion } from "motion/react";

const SURFACE = { type: "spring", stiffness: 420, damping: 36, mass: 0.9 } as const;
const CROSSFADE = { type: "spring", stiffness: 260, damping: 34, mass: 0.8 } as const;
const SMALL = { type: "spring", stiffness: 700, damping: 46, mass: 0.5 } as const;
const FILL = { type: "spring", stiffness: 210, damping: 34, mass: 0.9 } as const;
const EASE = [0.23, 1, 0.32, 1] as const;
const LEAVE = [0.4, 0, 1, 1] as const;
const DRAW = { duration: 0.3, ease: EASE } as const;
const INSTANT = { duration: 0 } as const;
const SPIN = { duration: 0.85, ease: "linear", repeat: Infinity } as const;

const PEEK_FOR = 2600;
const LEAVE_DELAY = 160;

const face = (on: boolean) => (on ? "" : "pointer-events-none");

const useIsoLayoutEffect =
  typeof window === "undefined" ? useEffect : useLayoutEffect;

export type ActivityPhase = "running" | "success" | "error";

export type Activity = {
  id: string;
  title: string;
  detail?: string;
  progress?: number | null;
  phase: ActivityPhase;
  action?: { label: string; onClick: () => void };
};

export type ActivityInput = {
  title: string;
  detail?: string;
  progress?: number | null;
};

export type UseLiveActivityOptions = {
  linger?: number;
};

export function useLiveActivity({ linger = 2000 }: UseLiveActivityOptions = {}) {
  const [activity, setActivity] = useState<Activity | null>(null);
  const seq = useRef(0);
  const timer = useRef<ReturnType<typeof setTimeout> | null>(null);

  const clear = useCallback(() => {
    if (timer.current) clearTimeout(timer.current);
    timer.current = null;
  }, []);

  const start = useCallback(
    (input: ActivityInput) => {
      clear();
      seq.current += 1;
      const id = `activity-${seq.current}`;
      setActivity({ progress: null, ...input, id, phase: "running" });
      return id;
    },
    [clear],
  );

  const update = useCallback((patch: Partial<ActivityInput>) => {
    setActivity((prev) => (prev ? { ...prev, ...patch } : prev));
  }, []);

  const dismiss = useCallback(() => {
    clear();
    setActivity(null);
  }, [clear]);

  const succeed = useCallback(
    (patch?: Partial<ActivityInput>) => {
      setActivity((prev) =>
        prev ? { ...prev, ...patch, phase: "success", progress: 1 } : prev,
      );
      clear();
      timer.current = setTimeout(() => {
        timer.current = null;
        setActivity(null);
      }, linger);
    },
    [clear, linger],
  );

  const fail = useCallback(
    (patch?: Partial<ActivityInput>, action?: Activity["action"]) => {
      clear();
      setActivity((prev) =>
        prev ? { ...prev, ...patch, phase: "error", action } : prev,
      );
    },
    [clear],
  );

  useEffect(() => clear, [clear]);

  return { activity, start, update, succeed, fail, dismiss };
}

export type UseLiveActivityReturn = ReturnType<typeof useLiveActivity>;

export type LiveActivityProps = {
  activity: Activity | null;
  onDismiss?: () => void;
  width?: number;
  dismissLabel?: string;
  label?: string;
  className?: string;
};

export function LiveActivity({
  activity,
  onDismiss,
  width = 300,
  dismissLabel = "Dismiss activity",
  label = "Activity",
  className = "",
}: LiveActivityProps) {
  const reduced = useReducedMotion() === true;

  const [hovered, setHovered] = useState(false);
  const [focused, setFocused] = useState(false);
  const [peeking, setPeeking] = useState(false);
  const [spoken, setSpoken] = useState("");

  const compactRef = useRef<HTMLDivElement>(null);
  const expandedRef = useRef<HTMLDivElement>(null);
  const sizes = useRef({ c: { w: 0, h: 0 }, e: { w: 0, h: 0 } });
  const [dims, setDims] = useState<{ w: number; h: number } | null>(null);

  const leaveTimer = useRef<ReturnType<typeof setTimeout> | null>(null);
  const peekTimer = useRef<ReturnType<typeof setTimeout> | null>(null);
  const said = useRef<Set<string>>(new Set());

  const phase = activity?.phase ?? "running";
  const expanded =
    activity !== null && (hovered || focused || peeking || phase === "error");

  const apply = useCallback((open: boolean) => {
    const target = open ? sizes.current.e : sizes.current.c;
    if (target.w === 0 || target.h === 0) return;
    setDims((prev) =>
      prev &&
      Math.abs(prev.w - target.w) < 0.5 &&
      Math.abs(prev.h - target.h) < 0.5
        ? prev
        : { w: target.w, h: target.h },
    );
  }, []);

  useIsoLayoutEffect(() => {
    if (!activity) return;
    const read = () => {
      const c = compactRef.current;
      const e = expandedRef.current;
      if (c) sizes.current.c = { w: c.offsetWidth, h: c.offsetHeight };
      if (e) sizes.current.e = { w: e.offsetWidth, h: e.offsetHeight };
      apply(expanded);
    };
    read();
    if (typeof ResizeObserver === "undefined") return;
    const observer = new ResizeObserver(read);
    if (compactRef.current) observer.observe(compactRef.current);
    if (expandedRef.current) observer.observe(expandedRef.current);
    return () => observer.disconnect();
  }, [activity, expanded, apply]);

  useEffect(() => {
    if (!activity) {
      setPeeking(false);
      setHovered(false);
      setFocused(false);
      setDims(null);
      return;
    }
    setPeeking(true);
    if (peekTimer.current) clearTimeout(peekTimer.current);
    peekTimer.current = setTimeout(() => {
      peekTimer.current = null;
      setPeeking(false);
    }, PEEK_FOR);
  }, [activity?.id, activity?.phase, activity]);

  useEffect(
    () => () => {
      if (leaveTimer.current) clearTimeout(leaveTimer.current);
      if (peekTimer.current) clearTimeout(peekTimer.current);
    },
    [],
  );

  useEffect(() => {
    if (!activity) return;
    const key = `${activity.id}:${activity.phase}`;
    if (said.current.has(key)) return;
    if (said.current.size > 64) said.current.clear();
    said.current.add(key);
    setSpoken(
      activity.phase === "running"
        ? `${activity.title} started.`
        : activity.phase === "success"
          ? `${activity.title} finished.`
          : `${activity.title} failed.`,
    );
  }, [activity]);

  const enter = () => {
    if (leaveTimer.current) clearTimeout(leaveTimer.current);
    leaveTimer.current = null;
    setHovered(true);
  };

  const leave = () => {
    if (leaveTimer.current) clearTimeout(leaveTimer.current);
    leaveTimer.current = setTimeout(() => {
      leaveTimer.current = null;
      setHovered(false);
    }, LEAVE_DELAY);
  };

  const percent =
    activity?.progress === null || activity?.progress === undefined
      ? null
      : Math.round(Math.min(1, Math.max(0, activity.progress)) * 100);

  return (
    <div
      role="region"
      aria-label={label}
      className={`pointer-events-none flex justify-center ${className}`}
    >
      <AnimatePresence initial={false}>
        {activity ? (
          <motion.div
            key="pod"
            initial={
              reduced
                ? { opacity: 0 }
                : { opacity: 0, y: -10, scale: 0.9, filter: "blur(6px)" }
            }
            animate={{
              opacity: 1,
              y: 0,
              scale: 1,
              filter: "blur(0px)",
              width: dims?.w,
              height: dims?.h,
            }}
            exit={
              reduced
                ? { opacity: 0, transition: INSTANT }
                : {
                    opacity: 0,
                    y: -8,
                    scale: 0.97,
                    filter: "blur(3px)",
                    transition: { duration: 0.16, ease: LEAVE },
                  }
            }
            transition={
              reduced
                ? INSTANT
                : {
                    ...SURFACE,
                    opacity: { duration: 0.2, ease: EASE },
                    filter: { duration: 0.2, ease: EASE },
                  }
            }
            style={{ transformOrigin: "50% 0%" }}
            onPointerEnter={enter}
            onPointerLeave={leave}
            onFocusCapture={() => setFocused(true)}
            onBlurCapture={(e) => {
              if (!e.currentTarget.contains(e.relatedTarget as Node | null)) {
                setFocused(false);
              }
            }}
            onKeyDown={(e) => {
              if (e.key !== "Escape") return;
              e.preventDefault();
              if (phase === "running") setHovered(false);
              else onDismiss?.();
            }}
            className="pointer-events-auto relative overflow-hidden rounded-[11px] border border-stone-200 bg-white shadow-[inset_0_1.5px_0_rgba(255,255,255,0.95),0_1px_2px_rgba(28,25,23,0.07),0_16px_36px_-18px_rgba(28,25,23,0.5)] dark:border-white/[0.16] dark:bg-[#252522] dark:shadow-[inset_0_1px_0_rgba(255,255,255,0.07),0_2px_12px_rgba(0,0,0,0.55)]"
          >
            <motion.div
              ref={compactRef}
              aria-hidden={expanded}
              inert={expanded}
              initial={false}
              animate={{ opacity: expanded ? 0 : 1 }}
              transition={reduced ? INSTANT : CROSSFADE}
              className={`absolute left-0 top-0 flex h-8 w-max items-center gap-1.5 px-2.5 ${face(!expanded)}`}
            >
              <PhaseGlyph phase={phase} reduced={reduced} />
              {percent !== null && phase === "running" ? (
                <span className="font-mono text-[10.5px] tabular-nums text-stone-500 dark:text-stone-400">
                  {percent}%
                </span>
              ) : (
                <span className="max-w-[120px] truncate text-[12px] font-medium text-stone-700 dark:text-stone-200">
                  {activity.title}
                </span>
              )}
            </motion.div>

            <motion.div
              ref={expandedRef}
              aria-hidden={!expanded}
              inert={!expanded}
              initial={false}
              animate={{ opacity: expanded ? 1 : 0 }}
              transition={reduced ? INSTANT : CROSSFADE}
              style={{ width }}
              className={`absolute left-0 top-0 px-3.5 py-3 ${face(expanded)}`}
            >
              <div className="flex items-center gap-2">
                <PhaseGlyph phase={phase} reduced={reduced} />
                <span className="min-w-0 flex-1 truncate text-[13px] font-medium text-stone-700 dark:text-stone-100">
                  {activity.title}
                </span>
                {activity.action ? (
                  <button
                    type="button"
                    tabIndex={expanded ? 0 : -1}
                    onClick={activity.action.onClick}
                    className="inline-flex h-[24px] shrink-0 select-none items-center whitespace-nowrap rounded-[6px] border border-stone-200 bg-white px-2 text-[11px] font-medium text-stone-700 shadow-[inset_0_1.5px_0_rgba(255,255,255,0.95),inset_0_-1px_0_rgba(28,25,23,0.06),0_1px_2px_rgba(28,25,23,0.08)] outline-none transition-[background-color,border-color,box-shadow] duration-150 hover:bg-stone-50 focus-visible:border-[#4568FF] active:translate-y-px dark:border-white/[0.16] dark:bg-[#2A2A27] dark:text-stone-100 dark:shadow-[inset_0_1px_0_rgba(255,255,255,0.07),0_1px_2px_rgba(0,0,0,0.4)] dark:hover:bg-[#32322E] dark:focus-visible:border-[#93B0FF]"
                  >
                    {activity.action.label}
                  </button>
                ) : null}
                {onDismiss && phase !== "running" ? (
                  <button
                    type="button"
                    tabIndex={expanded ? 0 : -1}
                    aria-label={dismissLabel}
                    onClick={onDismiss}
                    className="grid size-[22px] shrink-0 place-items-center rounded-[6px] text-stone-400 transition-colors duration-150 hover:bg-stone-100 hover:text-stone-700 focus-visible:bg-[#4568FF]/[0.06] focus-visible:shadow-[inset_0_0_0_1px_#4568FF] focus-visible:outline-none dark:text-stone-500 dark:hover:bg-white/10 dark:hover:text-stone-100 dark:focus-visible:bg-[#93B0FF]/[0.1] dark:focus-visible:shadow-[inset_0_0_0_1px_#93B0FF]"
                  >
                    <svg width="10" height="10" viewBox="0 0 12 12" fill="none" aria-hidden>
                      <path
                        d="M2.8 2.8l6.4 6.4M9.2 2.8l-6.4 6.4"
                        stroke="currentColor"
                        strokeWidth="1.6"
                        strokeLinecap="round"
                      />
                    </svg>
                  </button>
                ) : null}
              </div>

              {activity.detail ? (
                <p className="mt-1 truncate pl-[26px] text-[11.5px] text-stone-500 dark:text-stone-400">
                  {activity.detail}
                </p>
              ) : null}

              {percent !== null && phase !== "error" ? (
                <div className="mt-2.5 flex items-center gap-2 pl-[26px]">
                  <div className="min-w-0 flex-1 rounded-[4px] bg-stone-200/60 p-[2px] shadow-[inset_0_1px_2px_rgba(28,25,23,0.1)] dark:bg-[#1D1D1A] dark:shadow-[inset_0_1px_2px_rgba(0,0,0,0.45)]">
                    <div className="relative h-[4px] overflow-hidden rounded-[2px]">
                      <motion.span
                        aria-hidden
                        className="absolute inset-0 block origin-left rounded-[2px] bg-[#4568FF] shadow-[inset_0_1px_0_rgba(255,255,255,0.35)] dark:bg-[#93B0FF]"
                        initial={false}
                        animate={{ scaleX: (percent ?? 0) / 100 }}
                        transition={reduced ? INSTANT : FILL}
                      />
                    </div>
                  </div>
                  <span className="shrink-0 font-mono text-[10.5px] tabular-nums text-stone-500 dark:text-stone-400">
                    {percent}%
                  </span>
                </div>
              ) : null}

            </motion.div>
          </motion.div>
        ) : null}
      </AnimatePresence>
      <span role="status" aria-live="polite" className="sr-only">
        {spoken}
      </span>
    </div>
  );
}

function PhaseGlyph({ phase, reduced }: { phase: ActivityPhase; reduced: boolean }) {
  return (
    <span className="grid size-[18px] shrink-0 place-items-center">
      <motion.span
        className="col-start-1 row-start-1 flex"
        initial={false}
        animate={{
          opacity: phase === "running" ? 1 : 0,
          scale: reduced ? 1 : phase === "running" ? 1 : 0.7,
        }}
        transition={reduced ? INSTANT : SMALL}
      >
        {reduced ? (
          <svg width="13" height="13" viewBox="0 0 12 12" aria-hidden>
            <circle cx="6" cy="6" r="4.4" stroke="currentColor" strokeWidth="1.6" fill="none" className="text-stone-400 dark:text-stone-500" opacity="0.4" />
          </svg>
        ) : (
          <motion.svg
            width="13"
            height="13"
            viewBox="0 0 12 12"
            aria-hidden
            style={{ transformOrigin: "50% 50%" }}
            animate={{ rotate: 360 }}
            transition={SPIN}
            className="text-[#4568FF] dark:text-[#93B0FF]"
          >
            <circle cx="6" cy="6" r="4.4" stroke="currentColor" strokeWidth="1.6" fill="none" opacity="0.25" />
            <path d="M6 1.6a4.4 4.4 0 0 1 4.4 4.4" stroke="currentColor" strokeWidth="1.6" strokeLinecap="round" fill="none" />
          </motion.svg>
        )}
      </motion.span>
      <motion.span
        className="col-start-1 row-start-1 flex text-emerald-600 dark:text-emerald-400"
        initial={false}
        animate={{
          opacity: phase === "success" ? 1 : 0,
          scale: reduced ? 1 : phase === "success" ? 1 : 0.7,
        }}
        transition={reduced ? INSTANT : SMALL}
      >
        <svg width="13" height="13" viewBox="0 0 12 12" fill="none" aria-hidden>
          <motion.path
            d="M2.4 6.4 4.8 8.8 9.6 3.4"
            stroke="currentColor"
            strokeWidth="1.6"
            strokeLinecap="round"
            strokeLinejoin="round"
            initial={false}
            animate={{ pathLength: phase === "success" ? 1 : 0 }}
            transition={reduced ? INSTANT : DRAW}
          />
        </svg>
      </motion.span>
      <motion.span
        className="col-start-1 row-start-1 flex text-red-600 dark:text-red-400"
        initial={false}
        animate={{
          opacity: phase === "error" ? 1 : 0,
          scale: reduced ? 1 : phase === "error" ? 1 : 0.7,
        }}
        transition={reduced ? INSTANT : SMALL}
      >
        <svg width="13" height="13" viewBox="0 0 12 12" fill="none" aria-hidden>
          <path d="M6 2.6v3.6" stroke="currentColor" strokeWidth="1.6" strokeLinecap="round" />
          <rect x="5.2" y="8.2" width="1.6" height="1.6" rx="0.4" fill="currentColor" />
        </svg>
      </motion.span>
    </span>
  );
}
```

---

## Collapsible Banner · Notification

Folds to its title, or lets go entirely.

Docs: https://yugo.click/docs/collapsible-banner
Install: `bun add motion`, then copy the source below into `components/yugo/collapsible-banner.tsx` · or `bunx shadcn@latest add https://yugo.click/r/collapsible-banner.json`.

Guarantees:
- Severity is carried by the sentence, not by a coloured icon. Three notices in a column read as three messages rather than three components, and the one that matters is the one you wrote the clearest.
- A notice has three resting places, not two. It can be read, folded down to the line that names it, or let go. A banner whose only control is a close button is not collapsible: it is disposable, and the difference matters when the thing it says is still true after you stop looking at it.
- `dismissible={false}` is the point of the fold. An incident, an overdue invoice, a degraded region: you may move it out of the way, you may not make it untrue. Without the fold the only options are a permanent wall of text or a lie.
- The header never moves. Only the body's box changes, so the title, the mark and both controls hold still while the notice folds underneath them: the fold reads as the box closing, not as the page reflowing.
- Opacity leads on the way out and trails 50ms on the way in. Finishing first on the fold is what hides the reflow; starting late on the unfold keeps text from appearing in a box that has not opened yet.
- Height animates to `auto` and is measured by the animation itself, so a description that grows: a longer error, a second line after a webfont lands: needs no ResizeObserver and no measured pixel value living in React state.
- The folded body is inert, so a zero-height notice cannot be tabbed into or read out, and the toggle carries aria-expanded and aria-controls rather than a decorative chevron. Escape folds an open banner from its own header.
- Under prefers-reduced-motion every height, opacity and rotation resolves on the same frame: the notice is still folded, still gone, still correct, only the trip is skipped.


### Usage

```tsx
"use client";

import { CollapsibleBanner } from "@/components/yugo/collapsible-banner";

export function BillingHeader() {
  return (
    <div className="space-y-2">
      {/* An active incident may be folded out of the way, never removed. */}
      <CollapsibleBanner
        tone="danger"
        dismissible={false}
        title="Payments are degraded"
        description="Charges are queued and settle automatically once the provider recovers."
      />

      <CollapsibleBanner
        tone="warning"
        title="Your card was declined"
        description="We retry on the 14th. Invoices stay open until it clears."
        dismissLabel="Dismiss billing notice"
        onDismiss={() => localStorage.setItem("billing-notice", "seen")}
        action={
          <a
            href="/settings/billing"
            className="inline-flex h-7 items-center rounded-[7px] border border-stone-200 px-2.5 text-[11.5px] font-medium text-stone-700 dark:border-white/[0.16] dark:text-stone-200"
          >
            Update payment method
          </a>
        }
      />

      <InvoiceTable />
    </div>
  );
}
```

### Source (`components/yugo/collapsible-banner.tsx`)

```tsx
"use client";

import { useCallback, useId, useRef, useState } from "react";
import { motion, useReducedMotion } from "motion/react";

const EASE = [0.23, 1, 0.32, 1] as const;
const DISCLOSE = { type: "spring", stiffness: 190, damping: 30, mass: 1 } as const;
const NUDGE = { type: "spring", stiffness: 700, damping: 46, mass: 0.5 } as const;
const INSTANT = { duration: 0 } as const;

export type BannerState = "open" | "folded" | "dismissed";

export type UseCollapsibleBannerOptions = {
  state?: BannerState;
  defaultState?: BannerState;
  onStateChange?: (state: BannerState) => void;
  onDismiss?: () => void;
};

export type UseCollapsibleBannerResult = {
  state: BannerState;
  open: boolean;
  folded: boolean;
  dismissed: boolean;
  fold: () => void;
  expand: () => void;
  toggle: () => void;
  dismiss: () => void;
  restore: () => void;
};

export function useCollapsibleBanner({
  state: controlled,
  defaultState = "open",
  onStateChange,
  onDismiss,
}: UseCollapsibleBannerOptions = {}): UseCollapsibleBannerResult {
  const [uncontrolled, setUncontrolled] = useState<BannerState>(defaultState);
  const state = controlled ?? uncontrolled;

  const changed = useRef(onStateChange);
  changed.current = onStateChange;
  const closed = useRef(onDismiss);
  closed.current = onDismiss;

  const commit = useCallback((next: BannerState) => {
    setUncontrolled(next);
    changed.current?.(next);
  }, []);

  const fold = useCallback(() => commit("folded"), [commit]);
  const expand = useCallback(() => commit("open"), [commit]);
  const restore = useCallback(() => commit("open"), [commit]);

  const toggle = useCallback(
    () => commit(state === "open" ? "folded" : "open"),
    [commit, state],
  );

  const dismiss = useCallback(() => {
    commit("dismissed");
    closed.current?.();
  }, [commit]);

  return {
    state,
    open: state === "open",
    folded: state === "folded",
    dismissed: state === "dismissed",
    fold,
    expand,
    toggle,
    dismiss,
    restore,
  };
}

const NOTICE_GLYPH = (
  <svg width="16" height="16" viewBox="0 0 256 256" fill="none" aria-hidden="true">
    <circle cx="128" cy="128" r="96" stroke="currentColor" strokeWidth="16" />
    <polyline
      points="120 120 128 120 128 176 136 176"
      stroke="currentColor"
      strokeWidth="16"
      strokeLinecap="round"
      strokeLinejoin="round"
    />
    <circle cx="124" cy="84" r="12" fill="currentColor" />
  </svg>
);

const CARET_DOWN = (
  <svg width="14" height="14" viewBox="0 0 256 256" fill="none" aria-hidden="true">
    <polyline
      points="208 96 128 176 48 96"
      stroke="currentColor"
      strokeWidth="16"
      strokeLinecap="round"
      strokeLinejoin="round"
    />
  </svg>
);

const CLOSE = (
  <svg width="13" height="13" viewBox="0 0 256 256" fill="none" aria-hidden="true">
    <line
      x1="200"
      y1="56"
      x2="56"
      y2="200"
      stroke="currentColor"
      strokeWidth="16"
      strokeLinecap="round"
    />
    <line
      x1="200"
      y1="200"
      x2="56"
      y2="56"
      stroke="currentColor"
      strokeWidth="16"
      strokeLinecap="round"
    />
  </svg>
);

export type CollapsibleBannerProps = {
  title: React.ReactNode;
  description?: React.ReactNode;
  children?: React.ReactNode;
  action?: React.ReactNode;
  icon?: React.ReactNode;

  dismissible?: boolean;
  state?: BannerState;
  defaultState?: BannerState;
  onStateChange?: (state: BannerState) => void;
  onDismiss?: () => void;
  dismissLabel?: string;
  dismissedMessage?: string;
  className?: string;
};

export function CollapsibleBanner({
  title,
  description,
  children,
  action,
  icon,
  dismissible = true,
  state: controlled,
  defaultState = "open",
  onStateChange,
  onDismiss,
  dismissLabel = "Dismiss notice",
  dismissedMessage = "Notice dismissed.",
  className = "",
}: CollapsibleBannerProps) {
  const reduced = useReducedMotion();
  const uid = useId();
  const bodyId = `${uid}-body`;
  const titleId = `${uid}-title`;

  const { state, open, dismissed, toggle, fold, dismiss } = useCollapsibleBanner({
    state: controlled,
    defaultState,
    onStateChange,
    onDismiss,
  });

  const hasBody = Boolean(description || children || action);

  const disclose = reduced
    ? INSTANT
    : {
        height: DISCLOSE,
        opacity: { duration: 0.14, ease: EASE, delay: open ? 0.05 : 0 },
        y: DISCLOSE,
      };

  return (
    <>
      <motion.div
        initial={false}
        animate={{ height: dismissed ? 0 : "auto", opacity: dismissed ? 0 : 1 }}
        transition={
          reduced
            ? INSTANT
            : { height: DISCLOSE, opacity: { duration: 0.14, ease: EASE } }
        }
        style={{ overflow: "hidden" }}
        className="rounded-[11px]"
      >
        <div
          role="region"
          aria-labelledby={titleId}
          className={`rounded-[11px] border border-stone-200 bg-white shadow-[0_1px_2px_rgba(28,25,23,0.06),0_4px_10px_-8px_rgba(28,25,23,0.45)] dark:border-white/[0.16] dark:bg-[#1D1D1A] dark:shadow-[inset_0_1px_0_rgba(255,255,255,0.06),0_1px_6px_rgba(0,0,0,0.45)] ${className}`}
        >
          <div className="flex items-center gap-2.5 p-2.5">
            <span
              aria-hidden="true"
              className="grid size-[26px] shrink-0 place-items-center rounded-[7px] bg-stone-100/70 text-stone-500 shadow-[inset_0_1px_2px_rgba(28,25,23,0.06)] dark:bg-[#252522] dark:text-stone-400 dark:shadow-[inset_0_1px_2px_rgba(0,0,0,0.4)]"
            >
              {icon ?? NOTICE_GLYPH}
            </span>

            {hasBody ? (
              <button
                type="button"
                onClick={toggle}
                onKeyDown={(e) => {
                  if (e.key !== "Escape" || !open) return;
                  e.stopPropagation();
                  fold();
                }}
                aria-expanded={open}
                aria-controls={bodyId}
                className="group flex min-w-0 flex-1 items-center gap-2 rounded-[7px] text-left outline-none focus-visible:bg-[#4568FF]/[0.06] focus-visible:shadow-[inset_0_0_0_1px_#4568FF] dark:focus-visible:bg-[#93B0FF]/[0.1] dark:focus-visible:shadow-[inset_0_0_0_1px_#93B0FF]"
              >
                <span
                  id={titleId}
                  className="min-w-0 flex-1 truncate text-[13px] font-medium leading-5 text-stone-700 dark:text-stone-100"
                >
                  {title}
                </span>
                <motion.span
                  aria-hidden="true"
                  className="flex shrink-0 text-stone-400 group-hover:text-stone-600 dark:text-stone-500 dark:group-hover:text-stone-300"
                  initial={false}
                  animate={{ rotate: open ? 180 : 0 }}
                  transition={reduced ? INSTANT : NUDGE}
                >
                  {CARET_DOWN}
                </motion.span>
              </button>
            ) : (
              <span
                id={titleId}
                className="min-w-0 flex-1 truncate text-[13px] font-medium leading-5 text-stone-700 dark:text-stone-100"
              >
                {title}
              </span>
            )}

            {dismissible ? (
              <button
                type="button"
                onClick={dismiss}
                aria-label={dismissLabel}
                className="grid size-[26px] shrink-0 place-items-center rounded-[7px] text-stone-400 transition-colors duration-150 hover:bg-stone-100 hover:text-stone-700 focus-visible:outline-none focus-visible:bg-[#4568FF]/[0.06] focus-visible:shadow-[inset_0_0_0_1px_#4568FF] dark:text-stone-500 dark:hover:bg-white/10 dark:hover:text-stone-100 dark:focus-visible:bg-[#93B0FF]/[0.1] dark:focus-visible:shadow-[inset_0_0_0_1px_#93B0FF]"
              >
                {CLOSE}
              </button>
            ) : null}
          </div>

          {hasBody ? (
            <motion.div
              id={bodyId}
              inert={!open}
              initial={false}
              animate={{ height: open ? "auto" : 0, opacity: open ? 1 : 0 }}
              transition={disclose}
              style={{ overflow: "hidden" }}
            >
              <motion.div
                initial={false}
                animate={{ y: open ? 0 : -6 }}
                transition={reduced ? INSTANT : DISCLOSE}
                className="pb-2.5 pl-[46px] pr-2.5"
              >
                {description ? (
                  <p className="text-[12.5px] leading-relaxed text-stone-500 dark:text-stone-400">
                    {description}
                  </p>
                ) : null}

                {children}

                {action ? <div className="mt-2">{action}</div> : null}
              </motion.div>
            </motion.div>
          ) : null}
        </div>
      </motion.div>
      <span role="status" aria-live="polite" className="sr-only">
        {state === "dismissed" ? dismissedMessage : ""}
      </span>
    </>
  );
}
```

---

## Presence Avatars · Notification

Join and leave as a layout change.

Docs: https://yugo.click/docs/presence-avatars
Install: `bun add motion`, then copy the source below into `components/yugo/presence-avatars.tsx` · or `bunx shadcn@latest add https://yugo.click/r/presence-avatars.json`.

Guarantees:
- The rail is exactly as wide as who is actually here, and it grows on the same spring the arriving avatar rides in on. A rail padded out to its widest reachable state leaves a hole where nobody is standing; one that snaps open around a person reads as two events instead of one.
- First-seen order is held in a ref, so an arrival cannot reshuffle the people already present, and someone who reconnects returns to the slot they had.
- Avatars are placed by transform inside a positioned rail, never by layout: a leaver exits on opacity and scale while the survivors spring into the freed slots.
- The photo is laid over the initials and fades in when it decodes, so a slow avatar is a name rather than an empty square, and one that never arrives stays a name.
- Each tile is two shells. The outer one is the hairline given 2px of thickness rather than one, so the rim around a face is a single colour instead of a border with a lighter band trapped inside it; outside that, 2px of the surface keeps neighbouring faces apart. A photo that runs straight into its own edge reads as a sticker.
- The overflow chip is a tabular cell that caps at +99, so counting from +9 to +12 changes the digits and nothing else.
- Screen readers get one debounced summary of the room instead of one announcement per arrival, and the roster behind the chip stays readable as a list rather than disappearing into a number.
- Under prefers-reduced-motion the slots fill and empty instantly; no avatar and no count is withheld, only the trip between positions.


### Usage

```tsx
"use client";

import { useEffect, useState } from "react";
import {
  PresenceAvatars,
  type PresencePerson,
} from "@/components/yugo/presence-avatars";
import { room } from "@/lib/room";

export function BoardHeader({ title }: { title: string }) {
  const [people, setPeople] = useState<PresencePerson[]>([]);
  const [roster, setRoster] = useState<PresencePerson[] | null>(null);

  useEffect(() => room.subscribe("presence", setPeople), []);

  return (
    <header className="flex items-center justify-between gap-3 px-4 h-12">
      <h1 className="truncate text-[15px] font-medium">{title}</h1>

      <PresenceAvatars
        people={people}
        max={4}
        label="On this board"
        onOverflowSelect={(hidden) => setRoster(hidden)}
      />

      {roster ? <RosterSheet people={roster} onClose={() => setRoster(null)} /> : null}
    </header>
  );
}
```

### Source (`components/yugo/presence-avatars.tsx`)

```tsx
"use client";

import { useEffect, useMemo, useRef, useState } from "react";
import { AnimatePresence, motion, useReducedMotion } from "motion/react";

const SLOT = { type: "spring", stiffness: 520, damping: 34, mass: 0.45 } as const;
const FADE = { duration: 0.24, ease: [0.23, 1, 0.32, 1] } as const;
const INSTANT = { duration: 0 } as const;

export type PresencePerson = {
  id: string;
  name: string;
  src?: string;
};

export type UsePresenceOptions = {
  people: PresencePerson[];
  max?: number;
  announceAfter?: number;
};

export type UsePresenceResult = {
  ordered: PresencePerson[];
  visible: PresencePerson[];
  hidden: PresencePerson[];
  overflow: number;
  total: number;
  summary: string;
  announcement: string;
};

function initials(name: string): string {
  const words = name.trim().split(/\s+/).filter(Boolean);
  if (words.length === 0) return "?";
  const first = Array.from(words[0])[0] ?? "";
  const last = words.length > 1 ? (Array.from(words[words.length - 1])[0] ?? "") : "";
  return (first + last).toUpperCase();
}

function describe(names: string[]): string {
  if (names.length === 0) return "Nobody here";
  if (names.length === 1) return `${names[0]} is here`;
  if (names.length === 2) return `${names[0]} and ${names[1]} are here`;
  const rest = names.length - 2;
  return `${names[0]}, ${names[1]} and ${rest} ${rest === 1 ? "other" : "others"} are here`;
}

export function usePresence({
  people,
  max = 5,
  announceAfter = 900,
}: UsePresenceOptions): UsePresenceResult {
  const seen = useRef(new Map<string, number>());
  const next = useRef(0);

  const ordered = useMemo(() => {
    const order = seen.current;
    for (const person of people) {
      if (!order.has(person.id)) {
        order.set(person.id, next.current);
        next.current += 1;
      }
    }
    return people
      .slice()
      .toSorted((a, b) => (order.get(a.id) ?? 0) - (order.get(b.id) ?? 0));
  }, [people]);

  const slots = Math.max(1, max);
  const visible = ordered.slice(0, slots);
  const hidden = ordered.slice(slots);
  const summary = describe(ordered.map((person) => person.name));

  const [announcement, setAnnouncement] = useState(summary);

  useEffect(() => {
    const timer = setTimeout(() => setAnnouncement(summary), announceAfter);
    return () => clearTimeout(timer);
  }, [summary, announceAfter]);

  return {
    ordered,
    visible,
    hidden,
    overflow: hidden.length,
    total: ordered.length,
    summary,
    announcement,
  };
}

const TILE =
  "absolute left-0 top-0 select-none rounded-[10px] bg-stone-200 p-[3px] dark:bg-stone-700";
const WELL =
  "relative grid size-full place-items-center overflow-hidden rounded-[7px] bg-stone-100 font-medium leading-none text-stone-500 dark:bg-white/10 dark:text-stone-300";

type TileProps = {
  person: PresencePerson;
  index: number;
  step: number;
  size: number;
  zIndex: number;
  reduced: boolean;
};

function PresenceTile({ person, index, step, size, zIndex, reduced }: TileProps) {
  const [loaded, setLoaded] = useState(false);
  const [failed, setFailed] = useState(false);

  return (
    <motion.span
      aria-hidden
      initial={{ opacity: 0, scale: 0.86, x: index * step }}
      animate={{ opacity: 1, scale: 1, x: index * step }}
      exit={{ opacity: 0, scale: 0.86 }}
      transition={reduced ? INSTANT : SLOT}
      style={{ width: size, height: size, zIndex, fontSize: Math.round(size * 0.34) }}
      className={TILE}
    >
      <span className={WELL}>
        {initials(person.name)}

        {person.src && !failed ? (
          <motion.img
            src={person.src}
            alt=""
            width={size}
            height={size}
            decoding="async"
            onLoad={() => setLoaded(true)}
            onError={() => setFailed(true)}
            initial={false}
            animate={{ opacity: loaded ? 1 : 0 }}
            transition={reduced ? INSTANT : FADE}
            className="absolute inset-0 size-full object-cover"
          />
        ) : null}
      </span>
    </motion.span>
  );
}

export type PresenceAvatarsProps = {
  people: PresencePerson[];
  max?: number;
  size?: number;
  overlap?: number;
  label?: string;
  announceAfter?: number;
  onOverflowSelect?: (hidden: PresencePerson[]) => void;
  className?: string;
};

export function PresenceAvatars({
  people,
  max = 5,
  size = 28,
  overlap = 9,
  label = "People here",
  announceAfter,
  onOverflowSelect,
  className = "",
}: PresenceAvatarsProps) {
  const reduced = useReducedMotion();
  const { ordered, visible, hidden, overflow, announcement } = usePresence({
    people,
    max,
    announceAfter,
  });

  const slots = Math.max(1, max);
  const step = size - overlap;
  const chip = size + 8;

  const rail =
    visible.length === 0
      ? 0
      : overflow > 0
        ? visible.length * step + chip
        : (visible.length - 1) * step + size;

  const chipCount = `+${Math.min(overflow, 99)}`;
  const chipMotion = {
    initial: { opacity: 0, scale: 0.86 },
    animate: { opacity: 1, scale: 1, x: visible.length * step },
    exit: { opacity: 0, scale: 0.86 },
    transition: reduced ? INSTANT : SLOT,
  };
  const chipClass =
    "absolute left-0 top-0 grid place-items-center rounded-[9px] border border-stone-200 bg-white font-mono text-[10.5px] leading-none tabular-nums text-stone-500 outline-none ring-2 ring-white dark:border-white/[0.16] dark:bg-[#1D1D1A] dark:text-stone-400 dark:ring-stone-900";

  return (
    <div role="group" aria-label={label} className={`inline-flex items-center ${className}`}>
      <motion.div
        className="relative shrink-0"
        style={{ height: size }}
        initial={false}
        animate={{ width: rail }}
        transition={reduced ? INSTANT : SLOT}
      >
        <AnimatePresence initial={false}>
          {visible.map((person, i) => (
            <PresenceTile
              key={person.id}
              person={person}
              index={i}
              step={step}
              size={size}
              zIndex={slots - i}
              reduced={Boolean(reduced)}
            />
          ))}

          {overflow > 0 &&
            (onOverflowSelect ? (
              <motion.button
                key="overflow"
                type="button"
                onClick={() => onOverflowSelect(hidden)}
                aria-label={`Show ${overflow} more`}
                style={{ width: chip, height: size, zIndex: 0 }}
                className={`${chipClass} focus-visible:border-[#4568FF] dark:focus-visible:border-[#93B0FF]`}
                {...chipMotion}
              >
                <span aria-hidden>{chipCount}</span>
              </motion.button>
            ) : (
              <motion.span
                key="overflow"
                aria-hidden
                style={{ width: chip, height: size, zIndex: 0 }}
                className={chipClass}
                {...chipMotion}
              >
                {chipCount}
              </motion.span>
            ))}
        </AnimatePresence>
      </motion.div>
      <ul className="sr-only">
        {ordered.map((person) => (
          <li key={person.id}>{person.name}</li>
        ))}
      </ul>
      <span role="status" aria-live="polite" aria-atomic="true" className="sr-only">
        {announcement}
      </span>
    </div>
  );
}
```

---

## Typing Indicator · Notification

Someone is writing.

Docs: https://yugo.click/docs/typing-indicator
Install: `bun add motion`, then copy the source below into `components/yugo/typing-indicator.tsx` · or `bunx shadcn@latest add https://yugo.click/r/typing-indicator.json`.

Guarantees:
- The shape is the one everybody already reads: a bubble, a tail, three dots. There is no reason to invent a new symbol for something a billion people learned years ago: what is worth changing is what makes it move.
- Body and tail are one silhouette, not three objects hoping to touch. They are drawn into a single fill and overlap on purpose: the knob's centre sits 0.53·size from the corner arc's centre, well inside the 0.64·size where the two shapes stop meeting. Scale it to any size and there is still no seam.
- The dots do not loop. The conventional indicator runs a 1.5s staggered animation on a timer, which means it keeps dancing over a socket that died ten seconds ago. Here one keystroke strikes one dot, so the rhythm you see is the rhythm someone is actually typing at, and silence looks like silence.
- Typing has two endings and both are here. `send` lifts the bubble away as a message; silence collapses it back into its own tail, the way it arrived. An indicator that only ever fades treats a sent message and an abandoned one as the same event.
- The dots never change what they do. There is one wave, one speed, one look, from the first keystroke to the last: and then the bubble goes. Settling the dots into a second resting state before they leave adds a beat nobody asked for and reads as a glitch rather than a state.
- Nothing animates a layout property and nothing is measured. The bubble is drawn from one number, and every state: arriving, struck, settled, leaving: is opacity and transform, so the whole thing composites and React renders once per keystroke rather than once per frame.
- The row reserves its full height whether or not anyone is typing, so a message list does not jump the moment presence arrives or expires.
- Every ping carries its own expiry, so a peer who closes the tab mid-sentence stops the indicator on schedule instead of pinning "Nadia is typing" to the thread for the rest of the session.
- A minimum visible duration holds the indicator up after the last key, so a one-word reply cannot flash the row on and off in the same second. When the room empties the beat returns to zero, so the next line starts from nothing rather than continuing someone else's.
- The sentence is announced once from a polite live region after it settles, and the field is aria-hidden, so a hundred keystrokes never become a hundred screen-reader announcements.


### Usage

```tsx
"use client";

import { useEffect } from "react";
import {
  TypingIndicator,
  useTypingPresence,
} from "@/components/yugo/typing-indicator";

type Wire =
  | { kind: "key"; name: string }
  | { kind: "sent"; name: string }
  | { kind: "left"; name: string };

export function ThreadFooter({ roomId }: { roomId: string }) {
  const { typists, beat, sending, ping, send, clear, reset } = useTypingPresence({
    timeout: 3000,
    minVisible: 900,
  });

  useEffect(() => {
    const socket = new WebSocket(`/rooms/${roomId}/presence`);

    socket.onmessage = (e) => {
      const msg = JSON.parse(e.data) as Wire;
      if (msg.kind === "key") ping(msg.name);
      else if (msg.kind === "sent") send(msg.name);
      else clear(msg.name);
    };
    socket.onclose = reset;

    return () => socket.close();
  }, [roomId, ping, send, clear, reset]);

  return (
    <div className="border-t border-stone-200 px-4 py-2 dark:border-white/[0.16]">
      <TypingIndicator typists={typists} beat={beat} sending={sending} max={2} />
    </div>
  );
}
```

### Source (`components/yugo/typing-indicator.tsx`)

```tsx
"use client";

import { useCallback, useEffect, useMemo, useRef, useState } from "react";
import {
  AnimatePresence,
  animate,
  motion,
  useMotionValue,
  useReducedMotion,
  useTransform,
  type MotionValue,
} from "motion/react";

const WAVE_MS = 1.25;

const SURFACE = { type: "spring", stiffness: 380, damping: 30, mass: 0.8 } as const;
const CROSSFADE = { type: "spring", stiffness: 260, damping: 34, mass: 0.8 } as const;
const EASE = [0.23, 1, 0.32, 1] as const;
const LEAVE = [0.4, 0, 1, 1] as const;
const INSTANT = { duration: 0 } as const;

const SEND_MS = 340;

export type UseTypingPresenceOptions = {
  timeout?: number;
  minVisible?: number;
};

export type TypingPresence = {
  typists: string[];
  beat: number;
  sending: boolean;
  ping: (name: string) => void;
  send: (name: string) => void;
  clear: (name: string) => void;
  reset: () => void;
};

export function useTypingPresence({
  timeout = 3000,
  minVisible = 900,
}: UseTypingPresenceOptions = {}): TypingPresence {
  const [presence, setPresence] = useState<{ typists: string[]; beat: number }>({
    typists: [],
    beat: 0,
  });
  const [sending, setSending] = useState(false);

  const seen = useRef(new Map<string, number>());
  const shown = useRef<string[]>([]);
  const shownAt = useRef(0);
  const sweep = useRef<ReturnType<typeof setTimeout> | null>(null);
  const release = useRef<ReturnType<typeof setTimeout> | null>(null);
  const settle = useRef<(bump: boolean) => void>(() => {});

  const commit = useCallback(
    (bump: boolean) => {
      const now = Date.now();

      for (const [name, at] of seen.current) {
        if (at + timeout <= now) seen.current.delete(name);
      }

      let next = Infinity;
      for (const at of seen.current.values()) next = Math.min(next, at + timeout);

      let roster = Array.from(seen.current.keys());
      if (roster.length === 0 && shown.current.length > 0) {
        const until = shownAt.current + minVisible;
        if (until > now) {
          roster = shown.current;
          next = Math.min(next, until);
        }
      }

      const changed =
        roster.length !== shown.current.length ||
        roster.some((name, i) => name !== shown.current[i]);

      if (changed) {
        if (shown.current.length === 0) shownAt.current = now;
        shown.current = roster;
      }

      if (changed || bump) {
        setPresence((prev) => ({
          typists: changed ? roster : prev.typists,

          beat: changed && roster.length === 0 ? 0 : bump ? prev.beat + 1 : prev.beat,
        }));
      }

      if (sweep.current) clearTimeout(sweep.current);
      sweep.current =
        next === Infinity
          ? null
          : setTimeout(() => settle.current(false), Math.max(24, next - now));
    },
    [timeout, minVisible],
  );

  settle.current = commit;

  const ping = useCallback(
    (name: string) => {
      if (release.current) {
        clearTimeout(release.current);
        release.current = null;
        setSending(false);
        shown.current = [];
        shownAt.current = 0;
      }
      seen.current.set(name, Date.now());
      commit(true);
    },
    [commit],
  );

  const clear = useCallback(
    (name: string) => {
      if (!seen.current.delete(name)) return;
      commit(false);
    },
    [commit],
  );

  const send = useCallback((name: string) => {
    if (!seen.current.has(name) && !shown.current.includes(name)) return;
    seen.current.delete(name);
    if (sweep.current) clearTimeout(sweep.current);
    sweep.current = null;
    setSending(true);

    if (release.current) clearTimeout(release.current);
    release.current = setTimeout(() => {
      release.current = null;
      setSending(false);
      shown.current = [];
      shownAt.current = 0;
      setPresence({ typists: [], beat: 0 });

      if (seen.current.size > 0) settle.current(false);
    }, SEND_MS);
  }, []);

  const reset = useCallback(() => {
    if (sweep.current) clearTimeout(sweep.current);
    if (release.current) clearTimeout(release.current);
    sweep.current = null;
    release.current = null;
    seen.current.clear();
    shown.current = [];
    shownAt.current = 0;
    setSending(false);
    setPresence({ typists: [], beat: 0 });
  }, []);

  useEffect(() => {
    return () => {
      if (sweep.current) clearTimeout(sweep.current);
      if (release.current) clearTimeout(release.current);
      sweep.current = null;
      release.current = null;
    };
  }, []);

  return {
    typists: presence.typists,
    beat: presence.beat,
    sending,
    ping,
    send,
    clear,
    reset,
  };
}

function describe(names: string[], max: number): string {
  if (names.length === 0) return "";

  const head = names.slice(0, Math.max(1, max));
  const rest = names.length - head.length;

  if (rest > 0) {
    return `${head.join(", ")} and ${rest} ${rest === 1 ? "other" : "others"} are typing`;
  }
  if (head.length === 1) return `${head[0]} is typing`;

  return `${head.slice(0, -1).join(", ")} and ${head[head.length - 1]} are typing`;
}

function Dot({
  index,
  wave,
  size,
}: {
  index: number;
  wave: MotionValue<number>;
  size: number;
}) {
  const lift = useTransform(wave, (w) => {
    let distance = (w - index) % 3;
    if (distance < 0) distance += 3;
    if (distance > 1.5) distance -= 3;
    return Math.max(0, 1 - Math.abs(distance));
  });

  const scale = useTransform(lift, [0, 1], [0.74, 1]);
  const opacity = useTransform(lift, [0, 1], [0.32, 1]);

  return (
    <motion.span
      className="block rounded-full bg-stone-500 dark:bg-stone-300"
      style={{ width: size, height: size, scale, opacity }}
    />
  );
}

export type TypingIndicatorProps = {
  typists: string[];
  sending?: boolean;
  max?: number;

  size?: number;
  showLabel?: boolean;
  announceAfter?: number;
  className?: string;
};

export function TypingIndicator({
  typists,
  sending = false,
  max = 2,
  size = 34,
  showLabel = true,
  announceAfter = 700,
  className = "",
}: TypingIndicatorProps) {
  const reduced = useReducedMotion();

  const label = useMemo(() => describe(typists, max), [typists, max]);
  const active = typists.length > 0;

  const wave = useMotionValue(0);
  useEffect(() => {
    if (!active || reduced) {
      wave.jump(0);
      return;
    }
    const controls = animate(wave, 3, {
      duration: WAVE_MS,
      ease: "linear",
      repeat: Infinity,
      repeatType: "loop",
    });
    return () => controls.stop();
  }, [active, reduced, wave]);

  const [announced, setAnnounced] = useState(label);
  useEffect(() => {
    const timer = setTimeout(() => setAnnounced(label), announceAfter);
    return () => clearTimeout(timer);
  }, [label, announceAfter]);

  const width = Math.round(size * 2);
  const dot = Math.round(size * 0.23);
  const gap = Math.round(size * 0.15);
  const radius = Math.round(size * 0.47);

  return (
    <div
      className={`inline-flex max-w-full items-end gap-3 ${className}`}
      style={{ height: size }}
    >
      <div className="relative shrink-0" style={{ width, height: size }}>
        <AnimatePresence initial={false}>
          {active ? (
            <motion.div
              key="bubble"
              aria-hidden
              className="absolute inset-0 flex items-center justify-center bg-stone-200 dark:bg-white/[0.09]"
              style={{ borderRadius: radius, transformOrigin: "0% 100%", gap }}
              initial={reduced ? { opacity: 0 } : { opacity: 0, scale: 0.74 }}
              animate={
                sending && !reduced
                  ? { opacity: 0, scale: 0.45, y: 0 }
                  : { opacity: 1, scale: 1, y: 0 }
              }
              exit={
                reduced
                  ? { opacity: 0, transition: INSTANT }
                  : {
                      opacity: 0,
                      scale: 0.4,
                      transition: { duration: 0.26, ease: EASE },
                    }
              }
              transition={
                reduced
                  ? INSTANT
                  : sending
                    ? { duration: SEND_MS / 1000, ease: LEAVE }
                    : { ...SURFACE, opacity: { duration: 0.18, ease: EASE } }
              }
            >
              {[0, 1, 2].map((i) =>
                reduced ? (
                  <span
                    key={i}
                    className="block rounded-full bg-stone-500 opacity-80 dark:bg-stone-300"
                    style={{ width: dot, height: dot }}
                  />
                ) : (
                  <Dot key={i} index={i} wave={wave} size={dot} />
                ),
              )}
            </motion.div>
          ) : null}
        </AnimatePresence>
      </div>

      {showLabel ? (
        <span className="grid min-w-0 flex-1" style={{ height: size * 0.6 }}>
          <AnimatePresence initial={false}>
            {label && !sending ? (
              <motion.span
                key={label}
                aria-hidden
                className="col-start-1 row-start-1 self-center truncate text-[13px] text-stone-500 dark:text-stone-400"
                initial={reduced ? { opacity: 0 } : { opacity: 0, y: 7 }}
                animate={{ opacity: 1, y: 0 }}
                exit={reduced ? { opacity: 0 } : { opacity: 0, y: -7 }}
                transition={reduced ? INSTANT : CROSSFADE}
              >
                {label}
              </motion.span>
            ) : null}
          </AnimatePresence>
        </span>
      ) : null}

      <span role="status" aria-live="polite" aria-atomic="true" className="sr-only">
        {announced}
      </span>
    </div>
  );
}
```

---

## New Items Pill · Notification

New content without stealing your scroll.

Docs: https://yugo.click/docs/new-items-pill
Install: `bun add motion`, then copy the source below into `components/yugo/new-items-pill.tsx` · or `bunx shadcn@latest add https://yugo.click/r/new-items-pill.json`.

Guarantees:
- Prepending to a scrolled list normally shoves the line you were reading down the screen; the hook records the distance from the reading position to the end of the list and restores it in the same frame the new items commit, and sets overflow-anchor: none so the browser's own anchoring cannot correct it a second time.
- The pill is absolutely positioned over the scroller, so neither its arrival nor a count crossing from one digit to three ever reflows a single row underneath it. It arrives from the edge the items arrived from and leaves the same way.
- Jumping returns how many had piled up, so the rows you were called back for can be marked once you get there. Being told there are nine new posts and then dropped at the top with no idea which nine is half an answer.
- Focus is the brand blue border and the surface lifting, never a ring. A halo on top of a border and a shadow is the third signal nobody asked for.
- Scroll offset is read into a ref on a passive listener; React re-renders only when the pinned boolean flips or the buffered count changes, never once per scroll event.
- Scrolling back to the edge yourself clears the count without a click, so the pill never sits over content you have already reached.
- Screen readers get one settled count 700ms after the last arrival instead of one announcement per item, and the visible text is hidden from them so the button is named once rather than twice.
- Under prefers-reduced-motion the pill still appears and still states the count, only crossing in on opacity, and the jump becomes an instant scroll; either way focus lands on the scroll container before the pill unmounts, so it is never dropped to the body.


### Usage

```tsx
"use client";

import { useEffect, useState } from "react";
import { NewItemsPill, useNewItems } from "@/components/yugo/new-items-pill";

type Post = { id: string; author: string; body: string };

export function Timeline({ initial }: { initial: Post[] }) {
  const [posts, setPosts] = useState<Post[]>(initial);
  const { scrollProps, unread, jump } = useNewItems<HTMLDivElement>({
    itemCount: posts.length,
    anchor: "top",
  });

  useEffect(() => {
    const source = new EventSource("/api/timeline");
    source.onmessage = (e) =>
      setPosts((prev) => [JSON.parse(e.data) as Post, ...prev]);
    return () => source.close();
  }, []);

  return (
    <div className="relative">
      <div
        {...scrollProps}
        role="region"
        aria-label="Timeline"
        className="h-[520px] overflow-y-auto rounded-[14px] border border-stone-200 dark:border-white/[0.16]"
      >
        {posts.map((p) => (
          <article key={p.id} className="border-b border-stone-200 p-4 dark:border-white/[0.16]">
            <p className="text-[13px] font-medium text-stone-700 dark:text-stone-200">{p.author}</p>
            <p className="mt-1 text-[13px] text-stone-500 dark:text-stone-400">{p.body}</p>
          </article>
        ))}
      </div>

      <NewItemsPill
        count={unread}
        onJump={jump}
        label={(n) => `${n} new ${n === 1 ? "post" : "posts"}`}
      />
    </div>
  );
}
```

### Source (`components/yugo/new-items-pill.tsx`)

```tsx
"use client";

import {
  useCallback,
  useEffect,
  useLayoutEffect,
  useRef,
  useState,
} from "react";
import { AnimatePresence, motion, useReducedMotion } from "motion/react";

const EASE = [0.23, 1, 0.32, 1] as const;

const ARRIVE = { type: "spring", stiffness: 540, damping: 34, mass: 0.5 } as const;
const INSTANT = { duration: 0 } as const;

const useIsoLayoutEffect =
  typeof window === "undefined" ? useEffect : useLayoutEffect;

export type NewItemsAnchor = "top" | "bottom";

export type UseNewItemsOptions = {
  itemCount: number;
  anchor?: NewItemsAnchor;
  threshold?: number;
};

export type UseNewItemsResult<T extends HTMLElement> = {
  scrollProps: {
    ref: React.RefObject<T | null>;
    tabIndex: number;
    style: React.CSSProperties;
  };
  unread: number;
  pinned: boolean;

  jump: () => number;
};

export function useNewItems<T extends HTMLElement = HTMLDivElement>({
  itemCount,
  anchor = "top",
  threshold = 24,
}: UseNewItemsOptions): UseNewItemsResult<T> {
  const ref = useRef<T | null>(null);
  const pinnedRef = useRef(true);
  const prevCount = useRef(itemCount);
  const bottomGap = useRef(0);

  const [unread, setUnread] = useState(0);
  const [pinned, setPinned] = useState(true);
  const reduced = useReducedMotion();

  useEffect(() => {
    const el = ref.current;
    if (!el) return;

    const read = () =>
      anchor === "bottom"
        ? el.scrollHeight - el.scrollTop - el.clientHeight <= threshold
        : el.scrollTop <= threshold;

    const onScroll = () => {
      bottomGap.current = el.scrollHeight - el.scrollTop;
      const next = read();
      if (next === pinnedRef.current) return;
      pinnedRef.current = next;
      setPinned(next);
      if (next) setUnread(0);
    };
    onScroll();
    el.addEventListener("scroll", onScroll, { passive: true });
    return () => el.removeEventListener("scroll", onScroll);
  }, [anchor, threshold]);

  useIsoLayoutEffect(() => {
    const el = ref.current;
    const added = itemCount - prevCount.current;
    prevCount.current = itemCount;
    if (!el || added <= 0) return;

    if (pinnedRef.current) {
      el.scrollTop = anchor === "bottom" ? el.scrollHeight : 0;
      bottomGap.current = el.scrollHeight - el.scrollTop;
      return;
    }

    if (anchor === "top") {
      const target = el.scrollHeight - bottomGap.current;
      if (target > el.scrollTop) el.scrollTop = target;
    }
    setUnread((n) => n + added);
  }, [itemCount, anchor]);

  const unreadRef = useRef(0);
  unreadRef.current = unread;

  const jump = useCallback(() => {
    const el = ref.current;
    const caught = unreadRef.current;
    if (!el) return caught;
    pinnedRef.current = true;
    setPinned(true);
    setUnread(0);

    el.focus({ preventScroll: true });
    el.scrollTo({
      top: anchor === "bottom" ? el.scrollHeight : 0,
      behavior: reduced ? "auto" : "smooth",
    });
    return caught;
  }, [anchor, reduced]);

  return {
    scrollProps: { ref, tabIndex: 0, style: { overflowAnchor: "none" } },
    unread,
    pinned,
    jump,
  };
}

export type NewItemsPillProps = {
  count: number;
  onJump: () => void;
  anchor?: NewItemsAnchor;
  label?: (count: number) => string;
  max?: number;
  className?: string;
};

const defaultLabel = (n: number) => `${n} new ${n === 1 ? "item" : "items"}`;

export function NewItemsPill({
  count,
  onJump,
  anchor = "top",
  label = defaultLabel,
  max = 99,
  className = "",
}: NewItemsPillProps) {
  const reduced = useReducedMotion();
  const [announced, setAnnounced] = useState(0);

  useEffect(() => {
    if (count === 0) {
      setAnnounced(0);
      return;
    }
    const t = setTimeout(() => setAnnounced(count), 700);
    return () => clearTimeout(t);
  }, [count]);

  const phrase = (n: number) => (n > max ? `${max}+ new items` : label(n));
  const text = phrase(count);
  const off = anchor === "bottom" ? 10 : -10;

  return (
    <div
      className={`pointer-events-none absolute inset-x-0 z-10 flex justify-center ${
        anchor === "bottom" ? "bottom-2" : "top-2"
      } ${className}`}
    >
      <AnimatePresence initial={false}>
        {count > 0 && (
          <motion.button
            type="button"
            onClick={onJump}
            aria-label={text}
            initial={reduced ? { opacity: 0 } : { opacity: 0, scale: 0.94, y: off }}
            animate={{ opacity: 1, scale: 1, y: 0 }}
            exit={
              reduced
                ? { opacity: 0, transition: INSTANT }
                : {
                    opacity: 0,
                    scale: 0.96,
                    y: off * 0.5,
                    transition: { duration: 0.16, ease: EASE },
                  }
            }
            transition={
              reduced
                ? INSTANT
                : { ...ARRIVE, opacity: { duration: 0.16, ease: EASE } }
            }
            className="pointer-events-auto inline-flex h-8 select-none items-center gap-1.5 rounded-[9px] border border-stone-200 bg-white pl-2 pr-2.5 text-[12.5px] font-medium text-stone-700 shadow-[0_1px_2px_rgba(28,25,23,0.08),0_6px_14px_-10px_rgba(28,25,23,0.45)] outline-none transition-[border-color,box-shadow] duration-150 focus-visible:border-[#4568FF] focus-visible:shadow-[0_2px_4px_rgba(28,25,23,0.1),0_12px_22px_-12px_rgba(69,104,255,0.55)] dark:border-white/[0.16] dark:bg-[#1D1D1A] dark:text-stone-100 dark:shadow-[0_2px_8px_rgba(0,0,0,0.5)] dark:focus-visible:border-[#93B0FF] dark:focus-visible:shadow-[0_2px_10px_rgba(0,0,0,0.6),0_12px_22px_-12px_rgba(147,176,255,0.4)]"
          >
            <svg
              width="14"
              height="14"
              viewBox="0 0 256 256"
              fill="none"
              aria-hidden="true"
              className={anchor === "bottom" ? "rotate-180" : ""}
            >
              <line
                x1="128"
                y1="216"
                x2="128"
                y2="48"
                stroke="currentColor"
                strokeWidth="16"
                strokeLinecap="round"
              />
              <polyline
                points="56 120 128 48 200 120"
                stroke="currentColor"
                strokeWidth="16"
                strokeLinecap="round"
                strokeLinejoin="round"
              />
            </svg>
            <span className="tabular-nums" aria-hidden="true">
              {text}
            </span>
          </motion.button>
        )}
      </AnimatePresence>
      <span role="status" aria-live="polite" className="sr-only">
        {announced > 0 ? phrase(announced) : ""}
      </span>
    </div>
  );
}
```

---

## Modal · Overlay

Backdrop, scroll lock, focus trap.

Docs: https://yugo.click/docs/modal
Install: `bun add motion`, then copy the source below into `components/yugo/modal.tsx` · or `bunx shadcn@latest add https://yugo.click/r/modal.json`.

Guarantees:
- The scrollbar's width is measured and added back as body padding for as long as the lock is held, so the page behind does not jump sideways when the dialog opens or closes.
- The scroll lock is reference counted and the Escape stack is ordered, so a dialog opened from inside another one does not hand scrolling back when only the inner one closes, and Escape reaches the topmost dialog only.
- Tab and Shift-Tab wrap at the ends of the panel, a focusin guard pulls stray focus back, and on close focus returns to the element that opened the dialog with preventScroll, so the page never scrolls to a control the user cannot see.
- Every sibling of the overlay is marked inert while the dialog is open and restored to its prior value on close, so a screen reader reads the dialog instead of the page underneath it, and the background cannot be reached by pointer or keyboard.
- A backdrop press dismisses only when it both starts and ends outside the panel, so a text selection dragged past the edge of the dialog does not throw the dialog away.
- The overlay is portalled out of the tree, so a transformed, filtered or overflow-hidden ancestor cannot re-anchor or clip the fixed layer; the panel height is capped and scrolls internally rather than animating toward an unbounded height; under prefers-reduced-motion the same dialog arrives at zero duration rather than being withheld. Behaviour is available on its own through the exported useModal hook.


### Usage

```tsx
"use client";

import { useRef, useState } from "react";
import { Modal } from "@/components/yugo/modal";

export function BillingPanel({ cancelPlan }: { cancelPlan: () => void }) {
  const [confirming, setConfirming] = useState(false);
  const keepRef = useRef<HTMLButtonElement>(null);

  return (
    <>
      <button type="button" onClick={() => setConfirming(true)}>
        Cancel subscription
      </button>

      <Modal
        open={confirming}
        onClose={() => setConfirming(false)}
        initialFocusRef={keepRef}
        title="Cancel the Team plan?"
        description="Billing stops at the end of the period. Projects stay read-only after that."
        footer={
          <>
            <button ref={keepRef} type="button" onClick={() => setConfirming(false)}>
              Keep plan
            </button>
            <button
              type="button"
              onClick={() => {
                cancelPlan();
                setConfirming(false);
              }}
            >
              Cancel plan
            </button>
          </>
        }
      >
        <p>Four seats and two production projects are attached to this plan.</p>
      </Modal>
    </>
  );
}
```

### Source (`components/yugo/modal.tsx`)

```tsx
"use client";

import {
  useCallback,
  useEffect,
  useId,
  useLayoutEffect,
  useMemo,
  useRef,
  useState,
} from "react";
import { createPortal } from "react-dom";
import { AnimatePresence, motion, useReducedMotion } from "motion/react";

const EASE = [0.23, 1, 0.32, 1] as const;

const LEAVE = [0.4, 0, 1, 1] as const;

const SURFACE = { type: "spring", stiffness: 420, damping: 36, mass: 0.9 } as const;

const useIsomorphicLayoutEffect =
  typeof window === "undefined" ? useEffect : useLayoutEffect;

const FOCUSABLE = [
  "a[href]",
  "area[href]",
  "button:not([disabled])",
  "input:not([disabled]):not([type='hidden'])",
  "select:not([disabled])",
  "textarea:not([disabled])",
  "iframe",
  "summary",
  "[contenteditable='true']",
  "[tabindex]:not([tabindex='-1'])",
].join(",");

function focusableWithin(root: HTMLElement): HTMLElement[] {
  return Array.from(root.querySelectorAll<HTMLElement>(FOCUSABLE)).filter(
    (el) =>
      el.tabIndex !== -1 &&
      !el.hasAttribute("inert") &&
      el.getAttribute("aria-hidden") !== "true" &&
      el.getClientRects().length > 0,
  );
}

let locks = 0;
let releaseLock: (() => void) | null = null;

function lockDocumentScroll() {
  locks += 1;
  if (locks > 1) return;

  const body = document.body;
  const gap = window.innerWidth - document.documentElement.clientWidth;
  const overflow = body.style.overflow;
  const paddingRight = body.style.paddingRight;
  const base = Number.parseFloat(window.getComputedStyle(body).paddingRight);

  body.style.overflow = "hidden";
  if (gap > 0) {
    body.style.paddingRight = `${(Number.isFinite(base) ? base : 0) + gap}px`;
  }

  releaseLock = () => {
    body.style.overflow = overflow;
    body.style.paddingRight = paddingRight;
  };
}

function unlockDocumentScroll() {
  locks = Math.max(0, locks - 1);
  if (locks > 0) return;
  releaseLock?.();
  releaseLock = null;
}

const stack: object[] = [];

export type UseModalOptions = {
  open: boolean;
  onClose: () => void;
  closeOnEscape?: boolean;
  closeOnBackdrop?: boolean;
  lockScroll?: boolean;
  initialFocusRef?: React.RefObject<HTMLElement | null>;
  container?: HTMLElement | null;
};

export type ModalOverlayProps = {
  ref: React.RefObject<HTMLDivElement | null>;
  onPointerDown: (event: React.PointerEvent) => void;
  onClick: (event: React.MouseEvent) => void;
};

export type ModalPanelProps = {
  ref: React.RefObject<HTMLDivElement | null>;
  role: "dialog";
  "aria-modal": true;
  "aria-labelledby": string;
  tabIndex: -1;
  onKeyDown: (event: React.KeyboardEvent) => void;
};

export type UseModalResult = {
  target: HTMLElement | null;
  titleId: string;
  descriptionId: string;
  overlayProps: ModalOverlayProps;
  panelProps: ModalPanelProps;
  close: () => void;
};

export function useModal({
  open,
  onClose,
  closeOnEscape = true,
  closeOnBackdrop = true,
  lockScroll = true,
  initialFocusRef,
  container,
}: UseModalOptions): UseModalResult {
  const [target, setTarget] = useState<HTMLElement | null>(null);

  const overlayRef = useRef<HTMLDivElement>(null);
  const panelRef = useRef<HTMLDivElement>(null);
  const downedOutside = useRef(false);

  const baseId = useId();
  const titleId = `${baseId}-title`;
  const descriptionId = `${baseId}-description`;

  const latest = useRef({ onClose, closeOnEscape, closeOnBackdrop, initialFocusRef });
  latest.current = { onClose, closeOnEscape, closeOnBackdrop, initialFocusRef };

  const close = useCallback(() => latest.current.onClose(), []);

  useEffect(() => {
    setTarget(container === undefined ? document.body : container);
  }, [container]);

  useIsomorphicLayoutEffect(() => {
    if (!open || !lockScroll) return;
    lockDocumentScroll();
    return () => unlockDocumentScroll();
  }, [open, lockScroll]);

  useEffect(() => {
    if (!open || !target) return;
    const overlay = overlayRef.current;
    const parent = overlay?.parentElement;
    if (!overlay || !parent) return;

    const changed: Array<[Element, string | null]> = [];
    for (const child of Array.from(parent.children)) {
      if (child === overlay) continue;
      changed.push([child, child.getAttribute("inert")]);
      child.setAttribute("inert", "");
    }

    return () => {
      for (const [child, previous] of changed) {
        if (previous === null) child.removeAttribute("inert");
        else child.setAttribute("inert", previous);
      }
    };
  }, [open, target]);

  useEffect(() => {
    if (!open) return;
    const token = {};
    stack.push(token);

    const onKeyDown = (event: KeyboardEvent) => {
      if (event.key !== "Escape") return;
      if (stack[stack.length - 1] !== token) return;
      if (!latest.current.closeOnEscape) return;
      event.preventDefault();
      event.stopPropagation();
      latest.current.onClose();
    };

    document.addEventListener("keydown", onKeyDown);
    return () => {
      document.removeEventListener("keydown", onKeyDown);
      const index = stack.indexOf(token);
      if (index > -1) stack.splice(index, 1);
    };
  }, [open]);

  useEffect(() => {
    if (!open || !target) return;
    const onFocusIn = (event: FocusEvent) => {
      const panel = panelRef.current;
      const node = event.target as Node | null;
      if (!panel || !node || panel.contains(node)) return;
      panel.focus({ preventScroll: true });
    };
    document.addEventListener("focusin", onFocusIn);
    return () => document.removeEventListener("focusin", onFocusIn);
  }, [open, target]);

  useEffect(() => {
    if (!open || !target) return;
    const panel = panelRef.current;
    if (!panel) return;

    const previous =
      document.activeElement instanceof HTMLElement ? document.activeElement : null;
    const preferred = latest.current.initialFocusRef?.current;
    (preferred ?? focusableWithin(panel)[0] ?? panel).focus({ preventScroll: true });

    return () => {
      if (previous && previous.isConnected) previous.focus({ preventScroll: true });
    };
  }, [open, target]);

  const onKeyDown = useCallback((event: React.KeyboardEvent) => {
    if (event.key !== "Tab") return;
    const panel = panelRef.current;
    if (!panel) return;

    const items = focusableWithin(panel);
    if (items.length === 0) {
      event.preventDefault();
      panel.focus({ preventScroll: true });
      return;
    }

    const first = items[0];
    const last = items[items.length - 1];
    const active = document.activeElement;

    if (event.shiftKey && (active === first || active === panel)) {
      event.preventDefault();
      last.focus({ preventScroll: true });
      return;
    }
    if (!event.shiftKey && active === last) {
      event.preventDefault();
      first.focus({ preventScroll: true });
    }
  }, []);

  const onPointerDown = useCallback((event: React.PointerEvent) => {
    const panel = panelRef.current;
    downedOutside.current = !panel?.contains(event.target as Node);
  }, []);

  const onClick = useCallback((event: React.MouseEvent) => {
    const panel = panelRef.current;
    if (!latest.current.closeOnBackdrop) return;
    if (panel?.contains(event.target as Node)) return;
    if (!downedOutside.current) return;
    downedOutside.current = false;
    latest.current.onClose();
  }, []);

  return {
    target,
    titleId,
    descriptionId,
    overlayProps: { ref: overlayRef, onPointerDown, onClick },
    panelProps: {
      ref: panelRef,
      role: "dialog",
      "aria-modal": true,
      "aria-labelledby": titleId,
      tabIndex: -1,
      onKeyDown,
    },
    close,
  };
}

const CLOSE_ICON = (
  <svg width="14" height="14" viewBox="0 0 256 256" fill="none" aria-hidden="true">
    <line
      x1="200"
      y1="56"
      x2="56"
      y2="200"
      stroke="currentColor"
      strokeWidth="16"
      strokeLinecap="round"
    />
    <line
      x1="200"
      y1="200"
      x2="56"
      y2="56"
      stroke="currentColor"
      strokeWidth="16"
      strokeLinecap="round"
    />
  </svg>
);

export type ModalProps = {
  open: boolean;
  onClose: () => void;
  title: React.ReactNode;
  description?: React.ReactNode;
  children?: React.ReactNode;
  footer?: React.ReactNode;
  closeLabel?: string;
  showClose?: boolean;
  closeOnEscape?: boolean;
  closeOnBackdrop?: boolean;
  lockScroll?: boolean;
  initialFocusRef?: React.RefObject<HTMLElement | null>;
  container?: HTMLElement | null;
  maxWidth?: number;
  maxHeight?: string;
  className?: string;
};

export function Modal({
  open,
  onClose,
  title,
  description,
  children,
  footer,
  closeLabel = "Close dialog",
  showClose = true,
  closeOnEscape = true,
  closeOnBackdrop = true,
  lockScroll = true,
  initialFocusRef,
  container,
  maxWidth = 440,
  maxHeight = "min(78vh, 620px)",
  className = "",
}: ModalProps) {
  const reduced = useReducedMotion();

  const { target, titleId, descriptionId, overlayProps, panelProps } = useModal({
    open,
    onClose,
    closeOnEscape,
    closeOnBackdrop,
    lockScroll,
    initialFocusRef,
    container,
  });

  const variants = useMemo(() => {
    if (reduced) {
      return {
        backdrop: {
          closed: { opacity: 0 },
          open: { opacity: 1, transition: { duration: 0 } },
          gone: { opacity: 0, transition: { duration: 0 } },
        },
        panel: {
          closed: { opacity: 0 },
          open: { opacity: 1, transition: { duration: 0 } },
          gone: { opacity: 0, transition: { duration: 0 } },
        },
      };
    }
    return {
      backdrop: {
        closed: { opacity: 0 },
        open: { opacity: 1, transition: { duration: 0.2, ease: EASE } },
        gone: { opacity: 0, transition: { duration: 0.15, ease: LEAVE } },
      },
      panel: {
        closed: { opacity: 0, scale: 0.96, y: 12 },
        open: {
          opacity: 1,
          scale: 1,
          y: 0,
          transition: { ...SURFACE, opacity: { duration: 0.16, ease: EASE } },
        },

        gone: {
          opacity: 0,
          scale: 0.98,
          y: 6,
          transition: { duration: 0.15, ease: LEAVE },
        },
      },
    };
  }, [reduced]);

  if (!target) return null;

  return createPortal(
    <AnimatePresence>
      {open ? (
        <motion.div
          key="modal"
          {...overlayProps}
          initial="closed"
          animate="open"
          exit="gone"
          variants={{ closed: {}, open: {}, gone: {} }}
          className="fixed inset-0 z-50 grid place-items-center p-4 sm:p-6"
        >
          <motion.div
            aria-hidden="true"
            variants={variants.backdrop}
            style={{ touchAction: "none" }}
            className="absolute inset-0 bg-stone-900/40 dark:bg-black/65"
          />
          <motion.div
            {...panelProps}
            aria-describedby={description ? descriptionId : undefined}
            variants={variants.panel}
            style={{ maxWidth, maxHeight }}
            className={`relative flex w-full flex-col overflow-hidden rounded-[14px] border border-stone-200 bg-white text-stone-700 shadow-[0_28px_56px_-24px_rgba(24,22,20,0.45)] outline-none dark:border-white/[0.16] dark:bg-[#1D1D1A] dark:text-stone-200 ${className}`}
          >
            <div className="flex shrink-0 items-start gap-3 px-4 pb-3 pt-4">
              <div className="min-w-0 flex-1">
                <h2
                  id={titleId}
                  className="text-[15px] font-medium tracking-[-0.01em] text-stone-800 dark:text-stone-100"
                >
                  {title}
                </h2>
                {description ? (
                  <p
                    id={descriptionId}
                    className="mt-1 text-[12.5px] leading-relaxed text-stone-500 dark:text-stone-400"
                  >
                    {description}
                  </p>
                ) : null}
              </div>

              {showClose ? (
                <button
                  type="button"
                  onClick={onClose}
                  aria-label={closeLabel}
                  className="-mr-1 -mt-1 grid size-7 shrink-0 place-items-center rounded-[7px] text-stone-400 outline-none transition-colors duration-150 hover:bg-stone-100 hover:text-stone-700 focus-visible:bg-[#4568FF]/[0.06] focus-visible:text-stone-700 focus-visible:shadow-[inset_0_0_0_1px_#4568FF] dark:text-stone-500 dark:hover:bg-white/10 dark:hover:text-stone-100 dark:focus-visible:bg-[#93B0FF]/[0.1] dark:focus-visible:text-stone-100 dark:focus-visible:shadow-[inset_0_0_0_1px_#93B0FF]"
                >
                  {CLOSE_ICON}
                </button>
              ) : null}
            </div>

            {children ? (
              <div className="min-h-0 flex-1 overflow-y-auto overscroll-contain px-4 pb-4 text-[13px] leading-relaxed">
                {children}
              </div>
            ) : null}

            {footer ? (
              <div className="flex shrink-0 items-center justify-end gap-2 border-t border-stone-200 px-4 py-3 dark:border-white/[0.16]">
                {footer}
              </div>
            ) : null}
          </motion.div>
        </motion.div>
      ) : null}
    </AnimatePresence>,
    target,
  );
}
```

---

## Popover · Overlay

Knows its origin, flips on collision.

Docs: https://yugo.click/docs/popover
Install: `bun add motion`, then copy the source below into `components/yugo/popover.tsx` · or `bunx shadcn@latest add https://yugo.click/r/popover.json`.

Guarantees:
- Placement is measured, never assumed: the requested side is kept only when the panel actually fits there, and flips to its opposite when the opposite has more room, so a trigger near an edge cannot open a panel that runs off the screen.
- The cross axis is clamped inside the boundary while the arrow is re-solved against the trigger's centre, so a panel that had to slide back into view still points at the control that opened it instead of at nothing.
- transform-origin is written to the arrow's position on every measurement, so the panel scales out of its trigger rather than out of its own middle, and under prefers-reduced-motion it simply arrives in place, still fully rendered.
- Scroll, resize and content changes reposition through one rAF that writes left, top and the arrow offset straight to the DOM nodes; React re-renders only when the resolved side genuinely flips, so tracking a scrolling anchor costs no renders.
- Available room caps the content box, which scrolls inside its own overscroll-contained region, so the panel never animates toward an unbounded height and never grows past the boundary it was given.
- Escape closes and returns focus to the trigger, moving focus out of the panel closes it, an outside pointer closes it, and the trigger carries aria-haspopup, aria-expanded and aria-controls against a labelled dialog.


### Usage

```tsx
import { useRef, useState } from "react";
import { Popover } from "@/components/yugo/popover";

type Member = { id: string; name: string; email: string; role: string };

export function MemberList({ members }: { members: Member[] }) {
  const list = useRef<HTMLDivElement>(null);
  const [openId, setOpenId] = useState<string | null>(null);

  return (
    <div ref={list} className="h-[320px] overflow-y-auto">
      {members.map((member) => (
        <div key={member.id} className="flex items-center justify-between py-2">
          <span className="text-[13px]">{member.name}</span>

          <Popover
            label={`${member.name}, access`}
            side="right"
            align="start"
            boundary={list}
            open={openId === member.id}
            onOpenChange={(open) => setOpenId(open ? member.id : null)}
            trigger={member.role}
          >
            <div className="w-[220px]">
              <p className="text-[13px] font-medium">{member.name}</p>
              <p className="mt-0.5 text-[11.5px] text-stone-500">{member.email}</p>
              <button
                type="button"
                onClick={() => setOpenId(null)}
                className="mt-3 h-8 w-full rounded-[6px] bg-stone-800 text-[12.5px] text-white"
              >
                Revoke access
              </button>
            </div>
          </Popover>
        </div>
      ))}
    </div>
  );
}
```

### Source (`components/yugo/popover.tsx`)

```tsx
"use client";

import {
  useCallback,
  useEffect,
  useId,
  useLayoutEffect,
  useRef,
  useState,
} from "react";
import { AnimatePresence, motion, useReducedMotion } from "motion/react";

const EASE = [0.23, 1, 0.32, 1] as const;
const CROSSFADE = { type: "spring", stiffness: 260, damping: 34, mass: 0.8 } as const;
const RADIUS = 11;
const MIN_W = 160;
const MIN_H = 88;

const useIsoLayoutEffect = typeof document === "undefined" ? useEffect : useLayoutEffect;

export type PopoverSide = "top" | "right" | "bottom" | "left";
export type PopoverAlign = "start" | "center" | "end";

const FLIP: Record<PopoverSide, PopoverSide> = {
  top: "bottom",
  bottom: "top",
  left: "right",
  right: "left",
};

const ARROW_EDGE: Record<PopoverSide, string> = {
  bottom: "border-t border-l",
  top: "border-b border-r",
  right: "border-b border-l",
  left: "border-t border-r",
};

const FROM: Record<PopoverSide, { x?: number; y?: number }> = {
  top: { y: 6 },
  bottom: { y: -6 },
  left: { x: 6 },
  right: { x: -6 },
};

function clamp(value: number, min: number, max: number) {
  return Math.min(Math.max(value, min), Math.max(min, max));
}

export type UsePopoverOptions = {
  open: boolean;
  side?: PopoverSide;
  align?: PopoverAlign;
  offset?: number;
  padding?: number;
  arrowSize?: number;
  boundary?: React.RefObject<HTMLElement | null>;
};

export type UsePopoverResult<A extends HTMLElement = HTMLElement> = {
  anchorRef: React.RefObject<A | null>;
  floatingRef: React.RefObject<HTMLDivElement | null>;
  panelRef: React.RefObject<HTMLDivElement | null>;
  contentRef: React.RefObject<HTMLDivElement | null>;
  arrowRef: React.RefObject<HTMLSpanElement | null>;
  side: PopoverSide;
  update: () => void;
};

export function usePopover<A extends HTMLElement = HTMLElement>({
  open,
  side = "bottom",
  align = "center",
  offset = 10,
  padding = 8,
  arrowSize = 9,
  boundary,
}: UsePopoverOptions): UsePopoverResult<A> {
  const anchorRef = useRef<A>(null);
  const floatingRef = useRef<HTMLDivElement>(null);
  const panelRef = useRef<HTMLDivElement>(null);
  const contentRef = useRef<HTMLDivElement>(null);
  const arrowRef = useRef<HTMLSpanElement>(null);

  const [resolved, setResolved] = useState<PopoverSide>(side);

  const update = useCallback(() => {
    const anchor = anchorRef.current;
    const wrap = floatingRef.current;
    const panel = panelRef.current;
    if (!anchor || !wrap || !panel) return;

    const content = contentRef.current;
    panel.style.maxWidth = "";
    if (content) content.style.maxHeight = "";

    const a = anchor.getBoundingClientRect();
    const b = boundary?.current?.getBoundingClientRect() ?? null;
    const vw = document.documentElement.clientWidth;
    const vh = document.documentElement.clientHeight;

    const left = b ? Math.max(padding, b.left + padding) : padding;
    const top = b ? Math.max(padding, b.top + padding) : padding;
    const right = b ? Math.min(vw - padding, b.right - padding) : vw - padding;
    const bottom = b ? Math.min(vh - padding, b.bottom - padding) : vh - padding;

    panel.style.maxWidth = `${Math.max(MIN_W, right - left)}px`;

    const room: Record<PopoverSide, number> = {
      top: a.top - top - offset,
      bottom: bottom - a.bottom - offset,
      left: a.left - left - offset,
      right: right - a.right - offset,
    };

    let next = side;
    const wanted =
      next === "top" || next === "bottom" ? panel.offsetHeight : panel.offsetWidth;
    if (room[next] < wanted && room[FLIP[next]] > room[next]) next = FLIP[next];

    const horizontal = next === "top" || next === "bottom";
    if (!horizontal) {
      panel.style.maxWidth = `${Math.max(MIN_W, Math.min(right - left, room[next]))}px`;
    }
    if (content) {
      const chrome = panel.offsetHeight - content.offsetHeight;
      const allowed = horizontal ? room[next] : bottom - top;
      content.style.maxHeight = `${Math.max(MIN_H, allowed - chrome)}px`;
    }

    const w = panel.offsetWidth;
    const h = panel.offsetHeight;

    let x: number;
    let y: number;
    if (horizontal) {
      y = next === "top" ? a.top - offset - h : a.bottom + offset;
      x =
        align === "start"
          ? a.left
          : align === "end"
            ? a.right - w
            : a.left + (a.width - w) / 2;
    } else {
      x = next === "left" ? a.left - offset - w : a.right + offset;
      y =
        align === "start"
          ? a.top
          : align === "end"
            ? a.bottom - h
            : a.top + (a.height - h) / 2;
    }
    x = clamp(x, left, right - w);
    y = clamp(y, top, bottom - h);

    const base = wrap.getBoundingClientRect();
    const originX = base.left - (parseFloat(wrap.style.left) || 0);
    const originY = base.top - (parseFloat(wrap.style.top) || 0);
    wrap.style.left = `${Math.round(x - originX)}px`;
    wrap.style.top = `${Math.round(y - originY)}px`;

    const half = arrowSize / 2;
    const point = horizontal
      ? clamp(a.left + a.width / 2 - x, RADIUS + half, w - RADIUS - half)
      : clamp(a.top + a.height / 2 - y, RADIUS + half, h - RADIUS - half);

    panel.style.transformOrigin = horizontal
      ? `${Math.round(point)}px ${next === "top" ? h : 0}px`
      : `${next === "left" ? w : 0}px ${Math.round(point)}px`;

    const arrow = arrowRef.current;
    if (arrow) {
      if (horizontal) {
        arrow.style.left = `${Math.round(point - half)}px`;
        arrow.style.top = `${Math.round(next === "top" ? h - half : -half)}px`;
      } else {
        arrow.style.top = `${Math.round(point - half)}px`;
        arrow.style.left = `${Math.round(next === "left" ? w - half : -half)}px`;
      }
    }

    setResolved((prev) => (prev === next ? prev : next));
  }, [side, align, offset, padding, arrowSize, boundary]);

  useIsoLayoutEffect(() => {
    if (!open) return;
    update();
  }, [open, update]);

  useEffect(() => {
    if (!open) return;

    let frame = 0;
    const schedule = () => {
      if (frame) return;
      frame = requestAnimationFrame(() => {
        frame = 0;
        update();
      });
    };

    const observer = new ResizeObserver(schedule);
    if (anchorRef.current) observer.observe(anchorRef.current);
    if (contentRef.current) observer.observe(contentRef.current);
    window.addEventListener("scroll", schedule, true);
    window.addEventListener("resize", schedule);

    return () => {
      cancelAnimationFrame(frame);
      observer.disconnect();
      window.removeEventListener("scroll", schedule, true);
      window.removeEventListener("resize", schedule);
    };
  }, [open, update]);

  return { anchorRef, floatingRef, panelRef, contentRef, arrowRef, side: resolved, update };
}

export type PopoverProps = {
  trigger: React.ReactNode;
  children: React.ReactNode;
  label: string;
  open?: boolean;
  defaultOpen?: boolean;
  onOpenChange?: (open: boolean) => void;
  side?: PopoverSide;
  align?: PopoverAlign;
  offset?: number;
  padding?: number;
  arrowSize?: number;
  boundary?: React.RefObject<HTMLElement | null>;
  triggerClassName?: string;
  className?: string;
};

export function Popover({
  trigger,
  children,
  label,
  open: controlled,
  defaultOpen = false,
  onOpenChange,
  side = "bottom",
  align = "center",
  offset = 10,
  padding = 8,
  arrowSize = 9,
  boundary,
  triggerClassName = "",
  className = "",
}: PopoverProps) {
  const [uncontrolled, setUncontrolled] = useState(defaultOpen);
  const open = controlled ?? uncontrolled;

  const id = useId();
  const reduced = useReducedMotion();

  const notify = useRef(onOpenChange);
  notify.current = onOpenChange;

  const { anchorRef, floatingRef, panelRef, contentRef, arrowRef, side: at } =
    usePopover<HTMLButtonElement>({
      open,
      side,
      align,
      offset,
      padding,
      arrowSize,
      boundary,
    });

  const setOpen = useCallback(
    (next: boolean) => {
      if (controlled === undefined) setUncontrolled(next);
      notify.current?.(next);
    },
    [controlled],
  );

  useEffect(() => {
    if (!open) return;
    panelRef.current?.focus({ preventScroll: true });
  }, [open, panelRef]);

  useEffect(() => {
    if (!open) return;

    const onPointerDown = (event: PointerEvent) => {
      const target = event.target as Node | null;
      if (!target) return;
      if (panelRef.current?.contains(target) || anchorRef.current?.contains(target)) return;
      setOpen(false);
    };

    const onKeyDown = (event: KeyboardEvent) => {
      if (event.key !== "Escape") return;
      event.stopPropagation();
      anchorRef.current?.focus({ preventScroll: true });
      setOpen(false);
    };

    document.addEventListener("pointerdown", onPointerDown, true);
    document.addEventListener("keydown", onKeyDown, true);
    return () => {
      document.removeEventListener("pointerdown", onPointerDown, true);
      document.removeEventListener("keydown", onKeyDown, true);
    };
  }, [open, setOpen, anchorRef, panelRef]);

  return (
    <>
      <button
        ref={anchorRef}
        type="button"
        aria-haspopup="dialog"
        aria-expanded={open}
        aria-controls={open ? id : undefined}
        onClick={() => setOpen(!open)}
        className={`inline-flex h-9 select-none items-center gap-2 rounded-[9px] border border-stone-200 bg-white px-3 text-[13px] font-medium text-stone-700 outline-none transition-[border-color,box-shadow] duration-150 hover:border-stone-300 focus-visible:border-[#4568FF] focus-visible:shadow-[0_1px_2px_rgba(28,25,23,0.08),0_10px_20px_-14px_rgba(69,104,255,0.6)] dark:border-white/[0.16] dark:bg-[#1D1D1A] dark:text-stone-200 dark:hover:border-white/20 dark:focus-visible:border-[#93B0FF] dark:focus-visible:shadow-[0_10px_20px_-14px_rgba(147,176,255,0.5)] ${triggerClassName}`}
      >
        {trigger}
      </button>
      <AnimatePresence>
        {open ? (
          <div
            key="popover"
            ref={floatingRef}
            className="fixed left-0 top-0 z-50"
            onBlurCapture={(event) => {
              const next = event.relatedTarget as Node | null;
              if (!next) return;
              if (panelRef.current?.contains(next) || anchorRef.current?.contains(next)) return;
              setOpen(false);
            }}
          >
            <motion.div
              ref={panelRef}
              id={id}
              role="dialog"
              aria-label={label}
              tabIndex={-1}
              initial={
                reduced ? { opacity: 0 } : { opacity: 0, scale: 0.95, ...FROM[at] }
              }
              animate={{ opacity: 1, scale: 1, x: 0, y: 0 }}
              exit={
                reduced
                  ? { opacity: 0, transition: { duration: 0.1 } }
                  : {
                      opacity: 0,
                      scale: 0.97,
                      transition: { duration: 0.13, ease: EASE },
                    }
              }
              transition={
                reduced
                  ? { duration: 0 }
                  : { ...CROSSFADE, opacity: { duration: 0.14, ease: EASE } }
              }
              className={`relative rounded-[11px] border border-stone-200 bg-white p-3 shadow-[0_18px_40px_-24px_rgba(28,25,23,0.5)] focus-visible:outline-none dark:border-white/[0.16] dark:bg-[#1D1D1A] dark:shadow-[0_18px_40px_-24px_rgba(0,0,0,0.9)] ${className}`}
            >
              <span
                ref={arrowRef}
                aria-hidden
                style={{ width: arrowSize, height: arrowSize, transform: "rotate(45deg)" }}
                className={`absolute block bg-white dark:bg-[#1D1D1A] border-stone-200 dark:border-white/[0.16] ${ARROW_EDGE[at]}`}
              />
              <div ref={contentRef} className="relative overflow-y-auto overscroll-contain">
                {children}
              </div>
            </motion.div>
          </div>
        ) : null}
      </AnimatePresence>
    </>
  );
}
```

---

## Tooltip Group · Overlay

Delayed once, instant after that.

Docs: https://yugo.click/docs/tooltip-group
Install: `bun add motion`, then copy the source below into `components/yugo/tooltip-group.tsx` · or `bunx shadcn@latest add https://yugo.click/r/tooltip-group.json`.

Guarantees:
- The delay is charged once per visit, not once per trigger: after the first tooltip opens, every sibling in the group opens on contact until the pointer has been away for skipDelay, so a toolbar sweep stops feeling like five separate waits.
- Two tooltips can never be on screen at once; the group holds a single active id, so an outgoing close timer and an incoming open cannot overlap into a double reading.
- The tooltip is absolutely positioned against its trigger and mounts outside the flow, so opening one moves nothing: the toolbar keeps its width and the row below keeps its baseline.
- Crossing the gap between two triggers costs nothing: closeDelay holds the old tooltip while the next pointerenter cancels the close, which is what stops the flicker on a 2px seam.
- Focus opens the tooltip only when the browser reports :focus-visible, so clicking a button does not leave a tooltip parked over the thing you just clicked, and Escape dismisses it and blocks that trigger until the pointer actually leaves.
- aria-describedby is attached only while the tooltip is mounted, so a screen reader reads the label once on focus rather than on every pointer pass, and reduced motion keeps the tooltip and drops only the blur and the travel.


### Usage

```tsx
"use client";

import { Tooltip, TooltipGroup } from "@/components/yugo/tooltip-group";

export function EditorToolbar({
  onFormat,
}: {
  onFormat: (mark: "bold" | "italic" | "link") => void;
}) {
  return (
    <TooltipGroup
      openDelay={200}
      skipDelay={400}
      className="flex items-center gap-1"
    >
      <Tooltip label="Bold ⌘B">
        <button
          type="button"
          onClick={() => onFormat("bold")}
          aria-label="Bold"
          className="h-8 w-9 rounded-[6px] border border-stone-200 bg-white text-[12px] font-medium text-stone-700 dark:border-white/[0.16] dark:bg-[#1D1D1A] dark:text-stone-200"
        >
          B
        </button>
      </Tooltip>

      <Tooltip label="Italic ⌘I">
        <button
          type="button"
          onClick={() => onFormat("italic")}
          aria-label="Italic"
          className="h-8 w-9 rounded-[6px] border border-stone-200 bg-white text-[12px] italic text-stone-700 dark:border-white/[0.16] dark:bg-[#1D1D1A] dark:text-stone-200"
        >
          I
        </button>
      </Tooltip>

      <Tooltip label="Insert link ⌘K" side="bottom">
        <button
          type="button"
          onClick={() => onFormat("link")}
          aria-label="Insert link"
          className="h-8 w-9 rounded-[6px] border border-stone-200 bg-white text-[12px] text-stone-700 dark:border-white/[0.16] dark:bg-[#1D1D1A] dark:text-stone-200"
        >
          ↗
        </button>
      </Tooltip>
    </TooltipGroup>
  );
}
```

### Source (`components/yugo/tooltip-group.tsx`)

```tsx
"use client";

import {
  cloneElement,
  createContext,
  useContext,
  useEffect,
  useId,
  useRef,
  useSyncExternalStore,
} from "react";
import { AnimatePresence, motion, useReducedMotion } from "motion/react";

const LEAVE = [0.4, 0, 1, 1] as const;

const RISE = { type: "spring", stiffness: 560, damping: 34, mass: 0.6 } as const;

const WARM = { type: "spring", stiffness: 900, damping: 48, mass: 0.5 } as const;

const GLIDE = { type: "spring", stiffness: 520, damping: 40, mass: 0.75 } as const;

const SWAP = { type: "spring", stiffness: 700, damping: 44, mass: 0.5 } as const;

let groups = 0;

const stop = (t: Timer): Timer => {
  if (t !== null) clearTimeout(t);
  return null;
};

export type TooltipTiming = {
  openDelay: number;
  closeDelay: number;
  skipDelay: number;
};

type Timer = ReturnType<typeof setTimeout> | null;

type TooltipStore = {
  seat: string;
  subscribe: (fn: () => void) => () => void;
  getActive: () => string | null;
  getWarm: () => boolean;
  getSkipped: () => boolean;
  getTravel: () => number;
  open: (id: string, immediate: boolean, x?: number) => void;
  close: (id: string, immediate: boolean) => void;
  dismiss: (id: string) => void;
  unblock: (id: string) => void;
  reset: () => void;
  dispose: () => void;
};

function createTooltipStore(getTiming: () => TooltipTiming): TooltipStore {
  const listeners = new Set<() => void>();

  let active: string | null = null;
  let pending: string | null = null;
  let blocked: string | null = null;
  let warm = false;
  let skipped = false;
  let lastX: number | null = null;
  let travel = 0;

  let openTimer: Timer = null;
  let closeTimer: Timer = null;
  let coolTimer: Timer = null;

  const notify = () => {
    for (const fn of listeners) fn();
  };

  const setActive = (next: string | null) => {
    if (active === next) return;
    if (next !== null) {
      skipped = warm;
      warm = true;
    }
    active = next;
    notify();
  };

  const cool = () => {
    coolTimer = stop(coolTimer);
    const { skipDelay } = getTiming();
    if (skipDelay <= 0) {
      if (warm) {
        warm = false;
        notify();
      }
      return;
    }
    coolTimer = setTimeout(() => {
      coolTimer = null;
      warm = false;
      notify();
    }, skipDelay);
  };

  groups += 1;
  const seat = `tooltip-seat-${groups}`;

  return {
    seat,
    subscribe(fn) {
      listeners.add(fn);
      return () => {
        listeners.delete(fn);
      };
    },
    getActive: () => active,
    getWarm: () => warm,
    getSkipped: () => skipped,
    getTravel: () => travel,
    open(id, immediate, x) {
      if (blocked === id) return;
      closeTimer = stop(closeTimer);
      coolTimer = stop(coolTimer);
      if (active === id) {
        openTimer = stop(openTimer);
        pending = null;
        return;
      }
      const arrive = () => {
        travel = lastX !== null && x !== undefined ? Math.sign(x - lastX) : 0;
        lastX = x ?? null;
        setActive(id);
      };
      if (immediate || warm) {
        openTimer = stop(openTimer);
        pending = null;
        arrive();
        return;
      }
      openTimer = stop(openTimer);
      pending = id;
      openTimer = setTimeout(() => {
        openTimer = null;
        pending = null;
        arrive();
      }, getTiming().openDelay);
    },
    close(id, immediate) {
      if (pending === id) {
        openTimer = stop(openTimer);
        pending = null;
      }
      if (active !== id) return;
      closeTimer = stop(closeTimer);
      const finish = () => {
        closeTimer = null;
        setActive(null);
        cool();
      };
      if (immediate || getTiming().closeDelay <= 0) {
        finish();
        return;
      }
      closeTimer = setTimeout(finish, getTiming().closeDelay);
    },
    dismiss(id) {
      blocked = id;
      openTimer = stop(openTimer);
      closeTimer = stop(closeTimer);
      coolTimer = stop(coolTimer);
      pending = null;
      const wasWarm = warm;
      warm = false;
      if (active === id) setActive(null);
      else if (wasWarm) notify();
    },
    unblock(id) {
      if (blocked === id) blocked = null;
    },
    reset() {
      openTimer = stop(openTimer);
      closeTimer = stop(closeTimer);
      coolTimer = stop(coolTimer);
      pending = null;
      blocked = null;
      lastX = null;
      travel = 0;
      const wasWarm = warm;
      warm = false;
      if (active !== null) setActive(null);
      else if (wasWarm) notify();
    },
    dispose() {
      openTimer = stop(openTimer);
      closeTimer = stop(closeTimer);
      coolTimer = stop(coolTimer);
      listeners.clear();
    },
  };
}

const TooltipGroupContext = createContext<TooltipStore | null>(null);

function useDismissOnBlur(store: TooltipStore, enabled: boolean) {
  useEffect(() => {
    if (!enabled) return;
    const bail = () => store.reset();
    const onVisibility = () => {
      if (document.hidden) store.reset();
    };
    window.addEventListener("blur", bail);
    document.addEventListener("visibilitychange", onVisibility);
    return () => {
      window.removeEventListener("blur", bail);
      document.removeEventListener("visibilitychange", onVisibility);
    };
  }, [store, enabled]);
}

export type TooltipGroupProps = {
  children: React.ReactNode;
  openDelay?: number;
  closeDelay?: number;
  skipDelay?: number;
  onWarmChange?: (warm: boolean) => void;
  className?: string;
};

export function TooltipGroup({
  children,
  openDelay = 200,
  closeDelay = 120,
  skipDelay = 400,
  onWarmChange,
  className = "",
}: TooltipGroupProps) {
  const timing = useRef<TooltipTiming>({ openDelay, closeDelay, skipDelay });
  timing.current = { openDelay, closeDelay, skipDelay };

  const held = useRef<TooltipStore | null>(null);
  if (held.current === null) {
    held.current = createTooltipStore(() => timing.current);
  }
  const store = held.current;

  const warm = useSyncExternalStore(
    store.subscribe,
    store.getWarm,
    () => false,
  );

  const report = useRef(onWarmChange);
  report.current = onWarmChange;

  useEffect(() => {
    report.current?.(warm);
  }, [warm]);

  useEffect(() => () => store.dispose(), [store]);
  useDismissOnBlur(store, true);

  return (
    <TooltipGroupContext.Provider value={store}>
      {className ? <div className={className}>{children}</div> : children}
    </TooltipGroupContext.Provider>
  );
}

export type UseTooltipOptions = {
  disabled?: boolean;
  openDelay?: number;
  closeDelay?: number;
  skipDelay?: number;
};

export type TooltipTriggerProps = {
  onPointerEnter: (event: React.PointerEvent<HTMLElement>) => void;
  onPointerLeave: (event: React.PointerEvent<HTMLElement>) => void;
  onPointerDown: (event: React.PointerEvent<HTMLElement>) => void;
  onPointerCancel: (event: React.PointerEvent<HTMLElement>) => void;
  onFocus: (event: React.FocusEvent<HTMLElement>) => void;
  onBlur: (event: React.FocusEvent<HTMLElement>) => void;
  onKeyDown: (event: React.KeyboardEvent<HTMLElement>) => void;
};

export type UseTooltipReturn = {
  open: boolean;
  warm: boolean;
  skipped: boolean;
  travel: number;
  tooltipId: string;

  seat: string;
  triggerProps: TooltipTriggerProps;
};

function isKeyboardFocus(el: HTMLElement) {
  try {
    return el.matches(":focus-visible");
  } catch {
    return true;
  }
}

export function useTooltip({
  disabled = false,
  openDelay = 200,
  closeDelay = 120,
  skipDelay = 400,
}: UseTooltipOptions = {}): UseTooltipReturn {
  const tooltipId = `tt-${useId()}`;
  const group = useContext(TooltipGroupContext);

  const timing = useRef<TooltipTiming>({ openDelay, closeDelay, skipDelay });
  timing.current = { openDelay, closeDelay, skipDelay };

  const solo = useRef<TooltipStore | null>(null);
  if (group === null && solo.current === null) {
    solo.current = createTooltipStore(() => timing.current);
  }
  const store = group ?? (solo.current as TooltipStore);

  useEffect(() => {
    const own = solo.current;
    return () => {
      store.close(tooltipId, true);
      own?.dispose();
    };
  }, [store, tooltipId]);
  useDismissOnBlur(store, group === null);

  const open = useSyncExternalStore(
    store.subscribe,
    () => store.getActive() === tooltipId,
    () => false,
  );
  const warm = useSyncExternalStore(
    store.subscribe,
    store.getWarm,
    () => false,
  );
  const skipped = useSyncExternalStore(
    store.subscribe,
    store.getSkipped,
    () => false,
  );
  const travel = useSyncExternalStore(
    store.subscribe,
    store.getTravel,
    () => 0,
  );

  useEffect(() => {
    if (!disabled) return;
    store.close(tooltipId, true);
  }, [disabled, store, tooltipId]);

  const triggerProps: TooltipTriggerProps = {
    onPointerEnter: (event) => {
      if (!disabled) store.open(tooltipId, false, event.clientX);
    },
    onPointerLeave: () => {
      store.unblock(tooltipId);
      store.close(tooltipId, false);
    },
    onPointerDown: () => store.dismiss(tooltipId),
    onPointerCancel: () => {
      store.unblock(tooltipId);
      store.close(tooltipId, true);
    },
    onFocus: (event) => {
      if (disabled) return;
      if (!isKeyboardFocus(event.currentTarget)) return;
      store.open(tooltipId, true);
    },
    onBlur: () => {
      store.unblock(tooltipId);
      store.close(tooltipId, true);
    },
    onKeyDown: (event) => {
      if (event.key === "Escape") store.dismiss(tooltipId);
    },
  };

  return { open, warm, skipped, travel, tooltipId, seat: store.seat, triggerProps };
}

type TriggerChild = React.ReactElement<
  React.HTMLAttributes<HTMLElement> & { "aria-describedby"?: string }
>;

export type TooltipProps = UseTooltipOptions & {
  label: React.ReactNode;
  children: TriggerChild;
  side?: "top" | "bottom";
  className?: string;
  contentClassName?: string;
};

function chain<E>(
  theirs: ((event: E) => void) | undefined,
  ours: (event: E) => void,
) {
  return (event: E) => {
    theirs?.(event);
    ours(event);
  };
}

export function Tooltip({
  label,
  children,
  side = "top",
  disabled = false,
  openDelay,
  closeDelay,
  skipDelay,
  className = "",
  contentClassName = "",
}: TooltipProps) {
  const { open, skipped, travel, tooltipId, seat, triggerProps } = useTooltip({
    disabled,
    openDelay,
    closeDelay,
    skipDelay,
  });
  const reduced = useReducedMotion();

  const described = [children.props["aria-describedby"], open ? tooltipId : null]
    .filter(Boolean)
    .join(" ");

  const trigger = cloneElement(children, {
    "aria-describedby": described.length > 0 ? described : undefined,
    onPointerEnter: chain(
      children.props.onPointerEnter,
      triggerProps.onPointerEnter,
    ),
    onPointerLeave: chain(
      children.props.onPointerLeave,
      triggerProps.onPointerLeave,
    ),
    onPointerDown: chain(
      children.props.onPointerDown,
      triggerProps.onPointerDown,
    ),
    onPointerCancel: chain(
      children.props.onPointerCancel,
      triggerProps.onPointerCancel,
    ),
    onFocus: chain(children.props.onFocus, triggerProps.onFocus),
    onBlur: chain(children.props.onBlur, triggerProps.onBlur),
    onKeyDown: chain(children.props.onKeyDown, triggerProps.onKeyDown),
  });

  const lift = side === "top" ? 7 : -7;

  return (
    <span className={`relative inline-flex ${className}`}>
      {trigger}

      <span
        aria-hidden={!open}
        className="pointer-events-none absolute left-1/2 z-50 flex w-0 justify-center"
        style={
          side === "top"
            ? { bottom: "calc(100% + 7px)" }
            : { top: "calc(100% + 7px)" }
        }
      >
        <AnimatePresence>
          {open && (
            <motion.span
              role="tooltip"
              id={tooltipId}
              layoutId={reduced ? undefined : seat}
              initial={
                reduced
                  ? false
                  : skipped
                    ? { opacity: 0, scale: 1, y: 0, filter: "blur(0px)" }
                    : { opacity: 0, scale: 0.9, y: lift, filter: "blur(4px)" }
              }
              animate={{ opacity: 1, scale: 1, y: 0, filter: "blur(0px)" }}
              exit={
                reduced
                  ? { opacity: 0, transition: { duration: 0 } }
                  : {
                      opacity: 0,
                      scale: 0.96,
                      y: lift * 0.35,
                      filter: "blur(2px)",
                      transition: { duration: 0.12, ease: LEAVE },
                    }
              }
              transition={
                reduced
                  ? { duration: 0 }
                  : { ...(skipped ? WARM : RISE), layout: GLIDE }
              }
              style={{ transformOrigin: side === "top" ? "50% 100%" : "50% 0%" }}
              className={`relative w-max max-w-[220px] shrink-0 overflow-hidden rounded-[8px] px-2 py-1 text-[11.5px] font-medium leading-snug text-stone-700 dark:text-stone-100 ${contentClassName}`}
            >
              <motion.span
                aria-hidden
                layout={!reduced}
                transition={reduced ? { duration: 0 } : GLIDE}
                className="absolute inset-0 rounded-[8px] border border-stone-200 bg-white shadow-[0_1px_2px_rgba(28,25,23,0.06),0_6px_16px_-12px_rgba(28,25,23,0.35)] dark:border-white/[0.16] dark:bg-[#1D1D1A] dark:shadow-[0_2px_8px_rgba(0,0,0,0.45)]"
              />
              <motion.span
                layout={reduced ? false : "position"}
                initial={
                  reduced
                    ? false
                    : skipped
                      ? { opacity: 0, x: travel * 14, y: 0 }
                      : { opacity: 0, x: 0, y: 9 }
                }
                animate={{ opacity: 1, x: 0, y: 0 }}
                transition={reduced ? { duration: 0 } : SWAP}
                className="relative block whitespace-nowrap"
              >
                {label}
              </motion.span>
            </motion.span>
          )}
        </AnimatePresence>
      </span>
    </span>
  );
}
```

---

## Command Palette · Overlay

Results reorder as you type.

Docs: https://yugo.click/docs/command-palette
Install: `bun add motion`, then copy the source below into `components/yugo/command-palette.tsx` · or `bunx shadcn@latest add https://yugo.click/r/command-palette.json`.

Guarantees:
- Selection is anchored to a command id, not to a row index, so a keystroke that reranks the list cannot slide a different command under the highlight between the moment you press Enter and the moment it fires.
- The list box reserves its height from the item count at mount and scrolls inside, so filtering eight commands down to one never resizes the panel or moves the input under the cursor.
- Rows respond to onPointerMove and ignore repeated coordinates, so a reordering list sliding beneath a stationary mouse cannot steal the highlight from the keyboard.
- Ranking is a deterministic subsequence score with a stable index tiebreak: equal scores keep their authored order, so results never shuffle for reasons the typist cannot see.
- Rows move with layout="position" and their own background opacity rather than a shared highlight that flies across the list, and no layout property is animated.
- The result count is written to a polite live region through a ref after a 400ms pause, so a screen reader hears one total instead of one per keystroke, and reduced motion drops every spring while keeping the selection visible.


### Usage

```tsx
"use client";

import { useRouter } from "next/navigation";
import {
  CommandPalette,
  type CommandItem,
} from "@/components/yugo/command-palette";

const commands: CommandItem[] = [
  { id: "new", label: "New document", hint: "Workspace", shortcut: ["⌘", "N"] },
  { id: "dup", label: "Duplicate document", keywords: "copy clone" },
  { id: "export", label: "Export as PDF", keywords: "download print" },
  { id: "history", label: "Version history", keywords: "revisions restore" },
  { id: "settings", label: "Open settings", shortcut: ["⌘", ","] },
];

export function Launcher({ onClose }: { onClose: () => void }) {
  const router = useRouter();

  return (
    <CommandPalette
      items={commands}
      autoFocus
      maxRows={6}
      placeholder="Search commands"
      onSelect={(item) => {
        router.push(`/actions/${item.id}`);
        onClose();
      }}
      onDismiss={onClose}
    />
  );
}
```

### Source (`components/yugo/command-palette.tsx`)

```tsx
"use client";

import { useEffect, useId, useMemo, useRef, useState } from "react";
import { createPortal } from "react-dom";
import { AnimatePresence, motion, useReducedMotion } from "motion/react";

const CELL = { type: "spring", stiffness: 520, damping: 34, mass: 0.45 } as const;
const CROSSFADE = { type: "spring", stiffness: 260, damping: 34, mass: 0.8 } as const;
const BOUNDARY = /[\s\-_/.:]/;
const ROW = 36;
const GAP = 2;
const PAD = 5;

export type CommandItem = {
  id: string;
  label: string;
  hint?: string;
  keywords?: string;
  shortcut?: string[];
};

export type UseCommandPaletteOptions = {
  items: CommandItem[];
  onSelect: (item: CommandItem) => void;
  onDismiss?: () => void;
};

function scoreOne(text: string, query: string): number {
  const t = text.toLowerCase();
  let cursor = 0;
  let total = 0;
  let streak = 0;

  for (let i = 0; i < query.length; i++) {
    const at = t.indexOf(query[i], cursor);
    if (at < 0) return -1;
    streak = at === cursor && i > 0 ? streak + 1 : 0;
    total += 2 + streak * 4;
    if (at === 0) total += 12;
    else if (BOUNDARY.test(t[at - 1])) total += 8;
    cursor = at + 1;
  }

  return total;
}

function rank(items: CommandItem[], query: string): CommandItem[] {
  const q = query.trim().toLowerCase();
  if (!q) return items;

  const scored: { item: CommandItem; score: number; order: number }[] = [];

  for (let i = 0; i < items.length; i++) {
    const item = items[i];
    const direct = scoreOne(item.label, q);
    const aliased = item.keywords ? scoreOne(item.keywords, q) - 3 : -1;
    const best = Math.max(direct, item.keywords ? aliased : -1);
    if (best < 0) continue;
    scored.push({ item, score: best - item.label.length * 0.05, order: i });
  }

  scored.sort((a, b) => b.score - a.score || a.order - b.order);
  return scored.map((s) => s.item);
}

export function useCommandPalette({
  items,
  onSelect,
  onDismiss,
}: UseCommandPaletteOptions) {
  const [query, setQuery] = useState("");
  const [pinned, setPinned] = useState<string | null>(null);

  const listRef = useRef<HTMLUListElement>(null);
  const pointer = useRef({ x: -1, y: -1 });

  const select = useRef(onSelect);
  select.current = onSelect;
  const dismiss = useRef(onDismiss);
  dismiss.current = onDismiss;

  const results = useMemo(() => rank(items, query), [items, query]);

  const activeId = results.some((r) => r.id === pinned)
    ? pinned
    : (results[0]?.id ?? null);
  const activeIndex = results.findIndex((r) => r.id === activeId);

  useEffect(() => {
    if (listRef.current) listRef.current.scrollTop = 0;
  }, [query]);

  const reveal = (index: number) => {
    const list = listRef.current;
    const row = list?.children[index];
    if (!list || !(row instanceof HTMLElement)) return;
    const top = row.offsetTop - PAD;
    const bottom = row.offsetTop + row.offsetHeight + PAD;
    if (top < list.scrollTop) list.scrollTop = top;
    else if (bottom > list.scrollTop + list.clientHeight) {
      list.scrollTop = bottom - list.clientHeight;
    }
  };

  const jump = (index: number) => {
    if (results.length === 0) return;
    const next = Math.max(0, Math.min(results.length - 1, index));
    setPinned(results[next].id);
    reveal(next);
  };

  const move = (delta: number) => {
    if (results.length === 0) return;
    const from = activeIndex < 0 ? 0 : activeIndex;
    jump((from + delta + results.length) % results.length);
  };

  const run = (item?: CommandItem) => {
    const target = item ?? results.find((r) => r.id === activeId);
    if (target) select.current(target);
  };

  const pointerActivate = (id: string, event: React.PointerEvent) => {
    const { x, y } = pointer.current;
    if (event.clientX === x && event.clientY === y) return;
    pointer.current = { x: event.clientX, y: event.clientY };
    if (id !== activeId) setPinned(id);
  };

  const onKeyDown = (event: React.KeyboardEvent) => {
    if (event.key === "ArrowDown") {
      event.preventDefault();
      move(1);
    } else if (event.key === "ArrowUp") {
      event.preventDefault();
      move(-1);
    } else if (event.key === "Home") {
      event.preventDefault();
      jump(0);
    } else if (event.key === "End") {
      event.preventDefault();
      jump(results.length - 1);
    } else if (event.key === "Enter") {
      event.preventDefault();
      run();
    } else if (event.key === "Escape") {
      event.preventDefault();
      dismiss.current?.();
    }
  };

  return {
    query,
    setQuery,
    results,
    activeId,
    activeIndex,
    listRef,
    onKeyDown,
    pointerActivate,
    jump,
    move,
    run,
  };
}

export type CommandPaletteProps = {
  items: CommandItem[];
  onSelect: (item: CommandItem) => void;
  onDismiss?: () => void;

  open?: boolean;
  placeholder?: string;
  emptyLabel?: string;
  label?: string;
  maxRows?: number;
  autoFocus?: boolean;
  className?: string;
};

export function CommandPalette({
  items,
  onSelect,
  onDismiss,
  open,
  placeholder = "Search commands",
  emptyLabel = "No command matches",
  label = "Command palette",
  maxRows = 6,
  autoFocus = false,
  className = "",
}: CommandPaletteProps) {
  const uid = useId();
  const reduced = useReducedMotion();
  const inputRef = useRef<HTMLInputElement>(null);
  const liveRef = useRef<HTMLSpanElement>(null);

  const {
    query,
    setQuery,
    results,
    activeId,
    listRef,
    onKeyDown,
    pointerActivate,
    run,
  } = useCommandPalette({ items, onSelect, onDismiss });

  const rows = Math.max(1, Math.min(maxRows, items.length));
  const height = PAD * 2 + rows * ROW + (rows - 1) * GAP;
  const count = results.length;

  useEffect(() => {
    if (autoFocus) inputRef.current?.focus({ preventScroll: true });
  }, [autoFocus]);

  useEffect(() => {
    if (open) setQuery("");
  }, [open, setQuery]);

  useEffect(() => {
    const id = setTimeout(() => {
      if (!liveRef.current) return;
      liveRef.current.textContent =
        count === 0
          ? emptyLabel
          : `${count} ${count === 1 ? "command" : "commands"} available`;
    }, 400);
    return () => clearTimeout(id);
  }, [count, emptyLabel]);

  const spring = reduced ? { duration: 0 } : CELL;

  const overlaid = open !== undefined;

  const surface = (
    <div
      className={`overflow-hidden rounded-[14px] border border-stone-200 bg-white dark:border-white/[0.16] dark:bg-[#1D1D1A] ${
        overlaid
          ? "w-full max-w-[520px] shadow-[0_1px_2px_rgba(28,25,23,0.07),0_28px_56px_-24px_rgba(24,22,20,0.5)] dark:shadow-[0_3px_16px_rgba(0,0,0,0.65)]"
          : ""
      } ${className}`}
    >
      <div className="flex h-11 items-center gap-2.5 border-b border-stone-200 px-3 dark:border-white/[0.16]">
        <svg
          viewBox="0 0 16 16"
          className="size-[14px] shrink-0 text-stone-500 dark:text-stone-400"
          fill="none"
          stroke="currentColor"
          strokeWidth="1.4"
          strokeLinecap="round"
          aria-hidden
        >
          <circle cx="7" cy="7" r="4.25" />
          <path d="M10.2 10.2 13.5 13.5" />
        </svg>
        <input
          ref={inputRef}
          type="text"
          role="combobox"
          aria-label={label}
          aria-expanded
          aria-controls={`${uid}-list`}
          aria-autocomplete="list"
          aria-activedescendant={activeId ? `${uid}-${activeId}` : undefined}
          autoComplete="off"
          spellCheck={false}
          value={query}
          placeholder={placeholder}
          onChange={(e) => setQuery(e.target.value)}
          onKeyDown={onKeyDown}
          className="h-full min-w-0 flex-1 bg-transparent text-[13.5px] text-stone-700 outline-none placeholder:text-stone-400 dark:text-stone-200 dark:placeholder:text-stone-500"
        />
        <span className="min-w-[3ch] shrink-0 text-right font-mono text-[9.5px] tabular-nums text-stone-500 dark:text-stone-400">
          {count}
        </span>
      </div>
      <div className="relative" style={{ height }}>
        <ul
          ref={listRef}
          id={`${uid}-list`}
          // eslint-disable-next-line jsx-a11y/no-noninteractive-element-to-interactive-role
          role="listbox"
          aria-label={label}
          onMouseDown={(e) => e.preventDefault()}
          className="absolute inset-0 flex flex-col gap-[2px] overflow-y-auto overscroll-contain p-[5px] [scrollbar-gutter:stable]"
        >
          {results.map((item) => {
            const active = item.id === activeId;
            return (
              /* eslint-disable-next-line jsx-a11y/interactive-supports-focus */
              <motion.li
                key={item.id}
                id={`${uid}-${item.id}`}
                role="option"
                aria-selected={active}
                layout={reduced ? false : "position"}
                transition={spring}
                onPointerMove={(e) => pointerActivate(item.id, e)}
                onClick={() => run(item)}
                className="relative flex h-9 shrink-0 cursor-default items-center rounded-[9px] px-2.5"
              >
                <motion.span
                  aria-hidden
                  initial={false}
                  animate={{ opacity: active ? 1 : 0 }}
                  transition={reduced ? { duration: 0 } : CROSSFADE}
                  className="absolute inset-0 rounded-[9px] bg-stone-100 dark:bg-white/10"
                />
                <span className="relative flex min-w-0 flex-1 items-center gap-2.5">
                  <span className="truncate text-[13px] font-medium text-stone-700 dark:text-stone-200">
                    {item.label}
                  </span>

                  {item.hint ? (
                    <span className="hidden shrink-0 text-[11.5px] text-stone-500 sm:inline dark:text-stone-400">
                      {item.hint}
                    </span>
                  ) : null}

                  {item.shortcut ? (
                    <span className="ml-auto flex shrink-0 items-center gap-1">
                      {item.shortcut.map((key) => (
                        <span
                          key={key}
                          className="flex h-[18px] min-w-[18px] items-center justify-center rounded-[5px] border border-stone-200 px-1 font-mono text-[9.5px] tabular-nums text-stone-500 dark:border-white/[0.16] dark:text-stone-400"
                        >
                          {key}
                        </span>
                      ))}
                    </span>
                  ) : null}
                </span>
              </motion.li>
            );
          })}
        </ul>

        {count === 0 ? (
          <motion.p
            initial={reduced ? false : { opacity: 0 }}
            animate={{ opacity: 1 }}
            transition={reduced ? { duration: 0 } : CROSSFADE}
            className="pointer-events-none absolute inset-0 flex items-center justify-center px-3 text-center text-[12.5px] text-stone-500 dark:text-stone-400"
          >
            {emptyLabel}
          </motion.p>
        ) : null}
      </div>
      <span ref={liveRef} role="status" aria-live="polite" className="sr-only" />
    </div>
  );

  if (!overlaid) return surface;
  return <PaletteLayer open={open} onDismiss={onDismiss} reduced={Boolean(reduced)}>{surface}</PaletteLayer>;
}

const LAYER_EASE = [0.23, 1, 0.32, 1] as const;
const LAYER_OUT = [0.4, 0, 1, 1] as const;
const PANEL = { type: "spring", stiffness: 420, damping: 36, mass: 0.9 } as const;

function PaletteLayer({
  open,
  onDismiss,
  reduced,
  children,
}: {
  open: boolean;
  onDismiss?: () => void;
  reduced: boolean;
  children: React.ReactNode;
}) {
  const [host, setHost] = useState<HTMLElement | null>(null);
  const leave = useRef(onDismiss);
  leave.current = onDismiss;

  useEffect(() => setHost(document.body), []);

  useEffect(() => {
    if (!open) return;
    const onKeyDown = (event: KeyboardEvent) => {
      if (event.key !== "Escape") return;
      event.preventDefault();
      event.stopPropagation();
      leave.current?.();
    };
    document.addEventListener("keydown", onKeyDown, true);
    return () => document.removeEventListener("keydown", onKeyDown, true);
  }, [open]);

  useEffect(() => {
    if (!open) return;
    const root = document.documentElement;
    const overflow = root.style.overflow;
    const padding = root.style.paddingRight;
    const gutter = window.innerWidth - root.clientWidth;
    root.style.overflow = "hidden";
    if (gutter > 0) root.style.paddingRight = `${gutter}px`;
    return () => {
      root.style.overflow = overflow;
      root.style.paddingRight = padding;
    };
  }, [open]);

  if (!host) return null;

  return createPortal(
    <AnimatePresence>
      {open ? (
        <motion.div
          key="palette-layer"
          className="fixed inset-0 z-50 flex items-center justify-center p-4"
          initial="closed"
          animate="open"
          exit="gone"
          variants={{ closed: {}, open: {}, gone: {} }}
          onPointerDown={(event) => {
            if (event.target !== event.currentTarget) return;
            leave.current?.();
          }}
        >
          <motion.div
            aria-hidden
            className="absolute inset-0 bg-stone-900/40 dark:bg-black/65"
            variants={{
              closed: { opacity: 0 },
              open: {
                opacity: 1,
                transition: reduced
                  ? { duration: 0 }
                  : { duration: 0.2, ease: LAYER_EASE },
              },
              gone: {
                opacity: 0,
                transition: reduced
                  ? { duration: 0 }
                  : { duration: 0.15, ease: LAYER_OUT },
              },
            }}
          />
          <motion.div
            className="relative flex w-full justify-center"
            variants={{
              closed: reduced ? { opacity: 0 } : { opacity: 0, scale: 0.96, y: 12 },
              open: {
                opacity: 1,
                scale: 1,
                y: 0,
                transition: reduced
                  ? { duration: 0 }
                  : { ...PANEL, opacity: { duration: 0.16, ease: LAYER_EASE } },
              },
              gone: reduced
                ? { opacity: 0, transition: { duration: 0 } }
                : {
                    opacity: 0,
                    scale: 0.98,
                    y: 6,
                    transition: { duration: 0.15, ease: LAYER_OUT },
                  },
            }}
          >
            {children}
          </motion.div>
        </motion.div>
      ) : null}
    </AnimatePresence>,
    host,
  );
}
```

---

## Drawer · Overlay

Side panel that keeps its place.

Docs: https://yugo.click/docs/drawer
Install: `bun add motion`, then copy the source below into `components/yugo/drawer.tsx` · or `bunx shadcn@latest add https://yugo.click/r/drawer.json`.

Guarantees:
- Closing translates the panel, it does not unmount it, so the scroll offset inside and the state of every control it holds are still there on reopen; a drawer that unmounts hands back a list scrolled to the top and a form wiped clean.
- Focus is captured when the panel opens and returned to the exact element that opened it, so closing never drops the caret on the body and restart tabbing from the head of the document.
- While open, Tab wraps inside the panel and the rest of the document is marked inert, so nothing behind the scrim can be tabbed into or read out of order.
- Locking the page scroll pads the document by the scrollbar width it just removed, so the content behind the drawer does not jump sideways as the panel arrives.
- The dismiss drag reports its position in six discrete steps rather than a float, and releasing resumes the spring from wherever the panel currently sits, so an interrupted dismiss settles instead of snapping.
- Under prefers-reduced-motion the panel is placed at its final position without the travel, still visible, still focused, never left half open.


### Usage

```tsx
"use client";

import { useState } from "react";
import { Drawer } from "@/components/yugo/drawer";

export function ResultsToolbar({ total }: { total: number }) {
  const [open, setOpen] = useState(false);
  const [sort, setSort] = useState("relevance");

  return (
    <>
      <button type="button" onClick={() => setOpen(true)}>
        Filters
      </button>

      <Drawer
        open={open}
        onOpenChange={setOpen}
        side="right"
        width={360}
        title="Refine results"
        description={`${total} items`}
        footer={
          <button type="button" onClick={() => setOpen(false)}>
            Show results
          </button>
        }
      >
        <SortPicker value={sort} onChange={setSort} />
        <FacetList />
      </Drawer>
    </>
  );
}
```

### Source (`components/yugo/drawer.tsx`)

```tsx
"use client";

import { useCallback, useEffect, useId, useRef, useState } from "react";
import { createPortal } from "react-dom";
import {
  animate,
  motion,
  useDragControls,
  useMotionValue,
  useReducedMotion,
  useTransform,
} from "motion/react";

const DISCLOSE = {
  type: "spring",
  stiffness: 150,
  damping: 27,
  mass: 1,
} as const;

const FOCUSABLE =
  'a[href],button:not([disabled]),input:not([disabled]),select:not([disabled]),textarea:not([disabled]),[tabindex]:not([tabindex="-1"])';

type Inertable = HTMLElement & { inert?: boolean };

type DragInfo = {
  offset: { x: number; y: number };
  velocity: { x: number; y: number };
};

export type DrawerSide = "left" | "right";

export type UseDrawerOptions = {
  open?: boolean;
  defaultOpen?: boolean;
  onOpenChange?: (open: boolean) => void;
  side?: DrawerSide;
  width?: number;
  dismissRatio?: number;
  modal?: boolean;
};

export function useDrawer({
  open: controlled,
  defaultOpen = false,
  onOpenChange,
  side = "right",
  width = 320,
  dismissRatio = 0.38,
  modal = true,
}: UseDrawerOptions = {}) {
  const [uncontrolled, setUncontrolled] = useState(defaultOpen);
  const [dragging, setDragging] = useState(false);

  const open = controlled ?? uncontrolled;
  const sign = side === "right" ? 1 : -1;
  const away = sign * (width + 24);

  const x = useMotionValue(open ? 0 : away);
  const veil = useTransform(x, (v) => 1 - Math.min(1, Math.abs(v) / width));

  const rootRef = useRef<HTMLDivElement>(null);
  const panelRef = useRef<HTMLDivElement>(null);
  const returnTo = useRef<HTMLElement | null>(null);
  const anim = useRef<{ stop: () => void } | null>(null);
  const live = useRef(open);
  live.current = open;

  const changed = useRef(onOpenChange);
  changed.current = onOpenChange;

  const reduced = useReducedMotion();
  const controls = useDragControls();

  const setOpen = useCallback(
    (next: boolean) => {
      if (controlled === undefined) setUncontrolled(next);
      changed.current?.(next);
    },
    [controlled],
  );

  const close = useCallback(() => setOpen(false), [setOpen]);

  const glide = useCallback(
    (to: number) => {
      anim.current?.stop();
      anim.current = animate(x, to, reduced ? { duration: 0 } : DISCLOSE);
    },
    [x, reduced],
  );

  useEffect(() => {
    glide(open ? 0 : away);
    return () => anim.current?.stop();
  }, [open, away, glide]);

  useEffect(() => {
    const panel = panelRef.current as Inertable | null;
    if (!panel) return;
    panel.inert = !open;
    return () => {
      panel.inert = false;
    };
  }, [open]);

  useEffect(() => {
    if (open) {
      const active = document.activeElement;
      returnTo.current = active instanceof HTMLElement ? active : null;
      const panel = panelRef.current;
      if (!panel) return;
      const first = panel.querySelector<HTMLElement>(FOCUSABLE);
      (first ?? panel).focus({ preventScroll: true });
      return;
    }
    const target = returnTo.current;
    returnTo.current = null;
    if (target && target.isConnected) target.focus({ preventScroll: true });
  }, [open]);

  useEffect(() => {
    if (!modal || !open) return;
    const root = document.documentElement;
    const overflow = root.style.overflow;
    const padding = root.style.paddingRight;
    const gutter = window.innerWidth - root.clientWidth;

    root.style.overflow = "hidden";
    if (gutter > 0) root.style.paddingRight = `${gutter}px`;

    return () => {
      root.style.overflow = overflow;
      root.style.paddingRight = padding;
    };
  }, [modal, open]);

  useEffect(() => {
    const shell = rootRef.current;
    if (!modal || !open || !shell) return;
    const muted: Inertable[] = [];

    for (const node of Array.from(document.body.children)) {
      if (!(node instanceof HTMLElement) || node.contains(shell)) continue;
      const el = node as Inertable;
      if (el.inert) continue;
      el.inert = true;
      muted.push(el);
    }

    return () => {
      for (const el of muted) el.inert = false;
    };
  }, [modal, open]);

  const onKeyDown = useCallback(
    (event: React.KeyboardEvent) => {
      const panel = panelRef.current;
      if (!panel) return;

      if (event.key === "Escape") {
        event.stopPropagation();
        close();
        return;
      }
      if (event.key !== "Tab") return;

      const nodes = Array.from(panel.querySelectorAll<HTMLElement>(FOCUSABLE));
      if (nodes.length === 0) {
        event.preventDefault();
        panel.focus({ preventScroll: true });
        return;
      }

      const first = nodes[0];
      const last = nodes[nodes.length - 1];
      const active = document.activeElement;

      if (event.shiftKey && (active === first || active === panel)) {
        event.preventDefault();
        last.focus();
      } else if (!event.shiftKey && active === last) {
        event.preventDefault();
        first.focus();
      }
    },
    [close],
  );

  const startDrag = useCallback(
    (event: React.PointerEvent) => {
      if (!live.current) return;
      controls.start(event);
    },
    [controls],
  );

  const onDragStart = useCallback(() => setDragging(true), []);

  const onDragEnd = useCallback(
    (_event: MouseEvent | TouchEvent | PointerEvent, info: DragInfo) => {
      setDragging(false);
      const travel = sign * info.offset.x;
      const speed = sign * info.velocity.x;
      if (travel > width * dismissRatio || speed > 520) {
        close();
        return;
      }
      glide(0);
    },
    [sign, width, dismissRatio, glide, close],
  );

  const panelProps = {
    tabIndex: -1,
    role: "dialog" as const,
    "aria-modal": modal,
    onKeyDown,
    drag: "x" as const,
    dragControls: controls,
    dragListener: false,
    dragMomentum: false,
    dragConstraints: { left: 0, right: 0 },
    dragElastic:
      side === "right"
        ? { top: 0, bottom: 0, left: 0, right: 1 }
        : { top: 0, bottom: 0, left: 1, right: 0 },
    onDragStart,
    onDragEnd,
  };

  return {
    open,
    side,
    width,
    dragging,
    x,
    veil,
    setOpen,
    close,
    rootRef,
    panelRef,
    panelProps,
    gripProps: { onPointerDown: startDrag },
  };
}

export type UseDrawerResult = ReturnType<typeof useDrawer>;

const CLOSE_ICON = (
  <svg width="13" height="13" viewBox="0 0 256 256" fill="none" aria-hidden="true">
    <line
      x1="200"
      y1="56"
      x2="56"
      y2="200"
      stroke="currentColor"
      strokeWidth="16"
      strokeLinecap="round"
    />
    <line
      x1="200"
      y1="200"
      x2="56"
      y2="56"
      stroke="currentColor"
      strokeWidth="16"
      strokeLinecap="round"
    />
  </svg>
);

export type DrawerProps = {
  open: boolean;
  onOpenChange: (open: boolean) => void;
  title: string;
  children: React.ReactNode;
  description?: string;
  footer?: React.ReactNode;
  side?: DrawerSide;
  width?: number;
  container?: "viewport" | "parent";
  closeLabel?: string;
  dismissOnScrimClick?: boolean;
  className?: string;
};

export function Drawer({
  open,
  onOpenChange,
  title,
  children,
  description,
  footer,
  side = "right",
  width = 320,
  container = "viewport",
  closeLabel = "Close panel",
  dismissOnScrimClick = true,
  className = "",
}: DrawerProps) {
  const titleId = useId();
  const hintId = useId();

  const drawer = useDrawer({
    open,
    onOpenChange,
    side,
    width,
    modal: container === "viewport",
  });

  const edge =
    side === "right"
      ? "right-0 rounded-l-[14px] border-l"
      : "left-0 rounded-r-[14px] border-r";

  const [host, setHost] = useState<HTMLElement | null>(null);
  useEffect(() => {
    setHost(container === "viewport" ? document.body : null);
  }, [container]);

  const tree = (
    <div
      ref={drawer.rootRef}
      className={`${container === "viewport" ? "fixed" : "absolute"} inset-0 z-50 overflow-hidden ${
        open ? "" : "pointer-events-none"
      }`}
    >
      <motion.div
        aria-hidden
        style={{ opacity: drawer.veil }}
        onClick={dismissOnScrimClick ? drawer.close : undefined}
        className="absolute inset-0 bg-stone-900/25 dark:bg-black/55"
      />
      <motion.div
        ref={drawer.panelRef}
        aria-labelledby={titleId}
        aria-describedby={hintId}
        style={{ x: drawer.x, width, maxWidth: "calc(100% - 40px)", touchAction: "pan-y" }}
        className={`absolute inset-y-0 flex flex-col border-stone-200 bg-white shadow-[0_28px_56px_-24px_rgba(24,22,20,0.45)] outline-none dark:border-white/[0.16] dark:bg-[#1D1D1A] ${edge} ${
          drawer.dragging ? "select-none" : ""
        } ${className}`}
        {...drawer.panelProps}
      >
        <header
          onPointerDown={drawer.gripProps.onPointerDown}
          className={`flex select-none items-start gap-3 border-b border-stone-200 px-4 py-3 dark:border-white/[0.16] ${
            drawer.dragging ? "cursor-grabbing" : "cursor-grab"
          }`}
        >
          <div className="min-w-0 flex-1">
            <h2
              id={titleId}
              className="truncate text-[13px] font-medium text-stone-700 dark:text-stone-200"
            >
              {title}
            </h2>
            {description ? (
              <p className="mt-0.5 truncate text-[12.5px] text-stone-500 dark:text-stone-400">
                {description}
              </p>
            ) : null}
          </div>
          <button
            type="button"
            onPointerDown={(e) => e.stopPropagation()}
            onClick={drawer.close}
            aria-label={closeLabel}
            className="-mr-1 grid size-7 shrink-0 place-items-center rounded-[7px] text-stone-400 outline-none transition-colors duration-150 hover:bg-stone-100 hover:text-stone-700 focus-visible:bg-[#4568FF]/[0.06] focus-visible:text-stone-700 focus-visible:shadow-[inset_0_0_0_1px_#4568FF] dark:text-stone-500 dark:hover:bg-white/10 dark:hover:text-stone-100 dark:focus-visible:bg-[#93B0FF]/[0.1] dark:focus-visible:text-stone-100 dark:focus-visible:shadow-[inset_0_0_0_1px_#93B0FF]"
          >
            {CLOSE_ICON}
          </button>
        </header>
        <div className="min-h-0 flex-1 overflow-y-auto overscroll-contain px-4 py-3">
          {children}
        </div>

        {footer ? (
          <div className="border-t border-stone-200 px-4 py-3 dark:border-white/[0.16]">
            {footer}
          </div>
        ) : null}

        <span id={hintId} className="sr-only">
          Press Escape to close this panel, or drag its handle toward the edge.
        </span>
      </motion.div>
    </div>
  );

  if (container !== "viewport") return tree;
  return host ? createPortal(tree, host) : null;
}
```

---

## Context Menu · Overlay

Opens from the pointer, not the corner.

Docs: https://yugo.click/docs/context-menu
Install: `bun add motion`, then copy the source below into `components/yugo/context-menu.tsx` · or `bunx shadcn@latest add https://yugo.click/r/context-menu.json`.

Guarantees:
- The menu opens at the pointer and grows out of it: transformOrigin is the exact pixel offset of the click inside the panel, so it never reads as flying in from a corner nobody clicked.
- Near an edge it flips to the other side of the pointer and is then clamped to an 8px margin, so no item is ever pushed under the scrollbar or off the viewport.
- Panel height is derived from the item list before the first paint and capped at the viewport, so the menu never measures itself, never jumps a frame later, and never animates toward an unbounded height: a long list scrolls inside the cap instead.
- Nothing is shared between rows: the active row paints its own background and slides its label 3px, so no highlight flies across the panel and no row blinks when the pointer re-enters it.
- The keyboard is a real opener, not an afterthought. ContextMenu, Shift+F10 and Enter anchor the menu to the element, arrows, Home, End and typeahead move actual DOM focus between menuitems, and Escape or Tab closes it and puts focus back on the trigger.
- An item activates only when its own pointerdown landed on it, so the compatibility click fired as a long-pressing finger lifts cannot select whatever the menu just placed underneath it; scroll, resize, window blur and any outside pointerdown dismiss without stealing focus.


### Usage

```tsx
"use client";

import { useRouter } from "next/navigation";
import { ContextMenu, type ContextMenuItem } from "@/components/yugo/context-menu";

type Asset = { id: string; name: string; size: string };

export function AssetRow({ asset, onTrash }: { asset: Asset; onTrash: (id: string) => void }) {
  const router = useRouter();

  const items: ContextMenuItem[] = [
    { id: "open", label: "Open", shortcut: "↵", onSelect: () => router.push(`/assets/${asset.id}`) },
    { id: "rename", label: "Rename", shortcut: "F2", onSelect: () => router.push(`/assets/${asset.id}?rename=1`) },
    { id: "copy", label: "Copy link", shortcut: "⌘L", onSelect: () => navigator.clipboard.writeText(`/assets/${asset.id}`) },
    { id: "info", label: "Get info", disabled: true },
    { id: "sep", type: "separator" },
    { id: "trash", label: "Move to trash", shortcut: "⌫", onSelect: () => onTrash(asset.id) },
  ];

  return (
    <ContextMenu
      items={items}
      label={`Actions for ${asset.name}`}
      className="flex h-[52px] items-center justify-between rounded-[9px] px-2.5"
    >
      <span className="truncate text-[13px] font-medium">{asset.name}</span>
      <span className="font-mono text-[10.5px] tabular-nums opacity-60">{asset.size}</span>
    </ContextMenu>
  );
}
```

### Source (`components/yugo/context-menu.tsx`)

```tsx
"use client";

import {
  useCallback,
  useEffect,
  useId,
  useMemo,
  useRef,
  useState,
  type CSSProperties,
  type KeyboardEvent as ReactKeyboardEvent,
  type MouseEvent as ReactMouseEvent,
  type PointerEvent as ReactPointerEvent,
  type ReactNode,
} from "react";
import { createPortal } from "react-dom";
import { AnimatePresence, motion, useReducedMotion } from "motion/react";

const EASE = [0.23, 1, 0.32, 1] as const;

const EXIT = [0.4, 0, 1, 1] as const;

const ITEM_H = 32;
const SEP_H = 9;
const PAD = 5;
const BORDER = 1;

export type ContextMenuItem =
  | { id: string; type: "separator" }
  | {
      id: string;
      type?: "item";
      label: string;
      shortcut?: string;
      icon?: ReactNode;
      disabled?: boolean;
      onSelect?: (id: string) => void;
    };

export type ContextMenuPlacement = {
  left: number;
  top: number;
  width: number;
  maxHeight: number;
  transformOrigin: string;
};

export type UseContextMenuOptions = {
  items: ContextMenuItem[];
  onSelect?: (id: string) => void;
  width?: number;
  margin?: number;
  holdDuration?: number;
  moveTolerance?: number;
  disabled?: boolean;
};

function clamp(value: number, min: number, max: number) {
  return Math.min(Math.max(value, min), Math.max(min, max));
}

function measure(items: ContextMenuItem[]) {
  let height = PAD * 2 + BORDER * 2;
  for (const item of items) height += item.type === "separator" ? SEP_H : ITEM_H;
  return height;
}

export function useContextMenu({
  items,
  onSelect,
  width = 224,
  margin = 8,
  holdDuration = 460,
  moveTolerance = 8,
  disabled = false,
}: UseContextMenuOptions) {
  const [placement, setPlacement] = useState<ContextMenuPlacement | null>(null);
  const [active, setActive] = useState(-1);

  const triggerRef = useRef<HTMLDivElement | null>(null);
  const menuRef = useRef<HTMLDivElement | null>(null);
  const itemRefs = useRef<(HTMLButtonElement | null)[]>([]);
  const opened = useRef(false);
  const activeRef = useRef(-1);
  const hold = useRef<ReturnType<typeof setTimeout> | null>(null);
  const holdFrom = useRef<{ x: number; y: number } | null>(null);
  const swallowClick = useRef(false);
  const pressed = useRef(-1);
  const query = useRef("");
  const queryTimer = useRef<ReturnType<typeof setTimeout> | null>(null);

  activeRef.current = active;

  const list = useRef(items);
  list.current = items;
  const emit = useRef(onSelect);
  emit.current = onSelect;

  const height = useMemo(() => measure(items), [items]);

  const steps = useMemo(
    () =>
      items.reduce<number[]>((acc, item, index) => {
        if (item.type !== "separator" && !item.disabled) acc.push(index);
        return acc;
      }, []),
    [items],
  );
  const stepsRef = useRef(steps);
  stepsRef.current = steps;

  const clearHold = useCallback(() => {
    if (hold.current !== null) clearTimeout(hold.current);
    hold.current = null;
    holdFrom.current = null;
  }, []);

  const close = useCallback(
    (restoreFocus = false) => {
      clearHold();
      if (!opened.current) return;
      opened.current = false;
      setPlacement(null);
      setActive(-1);
      if (restoreFocus) triggerRef.current?.focus({ preventScroll: true });
    },
    [clearHold],
  );

  const openAt = useCallback(
    (x: number, y: number, source: "pointer" | "keyboard" = "pointer") => {
      if (disabled || list.current.length === 0) return;

      const vw = document.documentElement.clientWidth;
      const vh = document.documentElement.clientHeight;
      const w = Math.min(width, Math.max(160, vw - margin * 2));
      const cap = Math.max(ITEM_H + PAD * 2, vh - margin * 2);
      const h = Math.min(height, cap);

      const left = clamp(x + w + margin <= vw ? x : x - w, margin, vw - w - margin);
      const top = clamp(y + h + margin <= vh ? y : y - h, margin, vh - h - margin);

      opened.current = true;
      pressed.current = -1;
      setPlacement({
        left,
        top,
        width: w,
        maxHeight: cap,
        transformOrigin: `${clamp(x - left, 0, w)}px ${clamp(y - top, 0, h)}px`,
      });
      setActive(source === "keyboard" ? (stepsRef.current[0] ?? -1) : -1);
    },
    [disabled, height, margin, width],
  );

  const choose = useCallback(
    (index: number) => {
      const item = list.current[index];
      if (!item || item.type === "separator" || item.disabled) return;
      close(true);
      item.onSelect?.(item.id);
      emit.current?.(item.id);
    },
    [close],
  );

  const step = useCallback((dir: 1 | -1) => {
    const order = stepsRef.current;
    if (order.length === 0) return;
    const at = order.indexOf(activeRef.current);
    setActive(
      at === -1
        ? (dir === 1 ? order[0] : order[order.length - 1])
        : order[(at + dir + order.length) % order.length],
    );
  }, []);

  const edge = useCallback((which: "first" | "last") => {
    const order = stepsRef.current;
    if (order.length === 0) return;
    setActive(which === "first" ? order[0] : order[order.length - 1]);
  }, []);

  const typeahead = useCallback((char: string) => {
    query.current += char.toLowerCase();
    if (queryTimer.current !== null) clearTimeout(queryTimer.current);
    queryTimer.current = setTimeout(() => {
      query.current = "";
    }, 600);

    const order = stepsRef.current;
    const from = order.indexOf(activeRef.current) + 1;
    for (let k = 0; k < order.length; k += 1) {
      const index = order[(from + k) % order.length];
      const item = list.current[index];
      if (item.type !== "separator" && item.label.toLowerCase().startsWith(query.current)) {
        setActive(index);
        return;
      }
    }
  }, []);

  const isOpen = placement !== null;

  useEffect(() => {
    if (!isOpen) return;
    const node = activeRef.current >= 0 ? itemRefs.current[activeRef.current] : menuRef.current;
    node?.focus({ preventScroll: true });
    if (activeRef.current >= 0) node?.scrollIntoView({ block: "nearest" });
  }, [isOpen, active]);

  useEffect(() => {
    if (!isOpen) return;

    const inside = (target: EventTarget | null) =>
      menuRef.current?.contains(target as Node) ?? false;

    const onDown = (event: PointerEvent) => {
      if (inside(event.target)) return;
      if (event.button === 2 && triggerRef.current?.contains(event.target as Node)) return;
      close(false);
    };
    const onScroll = (event: Event) => {
      if (inside(event.target)) return;
      close(false);
    };
    const onKey = (event: KeyboardEvent) => {
      if (event.key !== "Escape") return;
      event.preventDefault();
      event.stopPropagation();
      close(true);
    };
    const bail = () => close(false);

    document.addEventListener("pointerdown", onDown, true);
    document.addEventListener("scroll", onScroll, { capture: true, passive: true });
    document.addEventListener("keydown", onKey, true);
    window.addEventListener("resize", bail);
    window.addEventListener("blur", bail);

    return () => {
      document.removeEventListener("pointerdown", onDown, true);
      document.removeEventListener("scroll", onScroll, { capture: true });
      document.removeEventListener("keydown", onKey, true);
      window.removeEventListener("resize", bail);
      window.removeEventListener("blur", bail);
    };
  }, [isOpen, close]);

  useEffect(
    () => () => {
      if (hold.current !== null) clearTimeout(hold.current);
      if (queryTimer.current !== null) clearTimeout(queryTimer.current);
    },
    [],
  );

  const triggerProps = {
    tabIndex: disabled ? -1 : 0,
    "aria-haspopup": "menu" as const,
    "aria-expanded": isOpen,
    style: { touchAction: "manipulation", WebkitTouchCallout: "none" } as CSSProperties,
    onContextMenu: (event: ReactMouseEvent<HTMLElement>) => {
      if (disabled) return;
      event.preventDefault();
      event.stopPropagation();
      clearHold();
      triggerRef.current = event.currentTarget as HTMLDivElement;
      openAt(event.clientX, event.clientY, "pointer");
    },
    onKeyDown: (event: ReactKeyboardEvent<HTMLElement>) => {
      if (disabled || opened.current) return;
      const wants =
        event.key === "ContextMenu" ||
        (event.shiftKey && event.key === "F10") ||
        (event.key === "Enter" && event.target === event.currentTarget);
      if (!wants) return;
      event.preventDefault();
      const rect = event.currentTarget.getBoundingClientRect();
      openAt(Math.round(rect.left + 14), Math.round(rect.top + 14), "keyboard");
    },
    onPointerDown: (event: ReactPointerEvent<HTMLElement>) => {
      if (disabled || event.pointerType === "mouse" || opened.current) return;
      const x = event.clientX;
      const y = event.clientY;
      triggerRef.current = event.currentTarget as HTMLDivElement;
      holdFrom.current = { x, y };
      hold.current = setTimeout(() => {
        hold.current = null;
        swallowClick.current = true;
        navigator.vibrate?.(10);
        openAt(x, y, "pointer");
      }, holdDuration);
    },
    onPointerMove: (event: ReactPointerEvent<HTMLElement>) => {
      const from = holdFrom.current;
      if (hold.current === null || !from) return;
      if (Math.hypot(event.clientX - from.x, event.clientY - from.y) > moveTolerance) clearHold();
    },
    onPointerUp: clearHold,
    onPointerCancel: clearHold,
    onPointerLeave: clearHold,
    onClick: (event: ReactMouseEvent<HTMLElement>) => {
      if (!swallowClick.current) return;
      swallowClick.current = false;
      event.preventDefault();
      event.stopPropagation();
    },
  };

  const menuProps = {
    role: "menu" as const,
    tabIndex: -1,
    "aria-orientation": "vertical" as const,
    onContextMenu: (event: ReactMouseEvent) => event.preventDefault(),
    onKeyDown: (event: ReactKeyboardEvent) => {
      if (event.key === "ArrowDown" || event.key === "ArrowUp") {
        event.preventDefault();
        step(event.key === "ArrowDown" ? 1 : -1);
        return;
      }
      if (event.key === "Home" || event.key === "End") {
        event.preventDefault();
        edge(event.key === "Home" ? "first" : "last");
        return;
      }
      if (event.key === "Tab") {
        event.preventDefault();
        close(true);
        return;
      }
      if (
        event.key.length === 1 &&
        event.key !== " " &&
        !event.metaKey &&
        !event.ctrlKey &&
        !event.altKey
      ) {
        typeahead(event.key);
      }
    },
  };

  const getItemProps = (index: number) => ({
    ref: (node: HTMLButtonElement | null) => {
      itemRefs.current[index] = node;
    },
    role: "menuitem" as const,
    tabIndex: -1,
    onPointerMove: () => {
      const item = list.current[index];
      if (activeRef.current === index || item.type === "separator" || item.disabled) return;
      setActive(index);
    },
    onPointerDown: () => {
      pressed.current = index;
    },
    onClick: (event: ReactMouseEvent) => {
      if (event.detail !== 0 && pressed.current !== index) return;
      pressed.current = -1;
      choose(index);
    },
  });

  return {
    isOpen,
    active,
    placement,
    openAt,
    close,
    triggerRef,
    triggerProps,
    menuRef,
    menuProps,
    getItemProps,
  };
}

export type ContextMenuProps = {
  items: ContextMenuItem[];
  children: ReactNode;
  onSelect?: (id: string) => void;
  label?: string;
  width?: number;
  disabled?: boolean;
  className?: string;
};

export function ContextMenu({
  items,
  children,
  onSelect,
  label = "Context menu",
  width = 224,
  disabled = false,
  className = "",
}: ContextMenuProps) {
  const uid = useId();
  const reduced = useReducedMotion();

  const [host, setHost] = useState<HTMLElement | null>(null);
  useEffect(() => setHost(document.body), []);

  const {
    isOpen,
    active,
    placement,
    triggerRef,
    triggerProps,
    menuRef,
    menuProps,
    getItemProps,
  } = useContextMenu({ items, onSelect, width, disabled });

  const hasIcons = items.some((item) => item.type !== "separator" && item.icon);

  const menuId = `${uid}-menu`;

  return (
    <>
      <div
        ref={triggerRef}
        {...triggerProps}
        aria-controls={isOpen ? menuId : undefined}
        aria-describedby={`${uid}-hint`}
        className={`outline-none focus-visible:bg-[#4568FF]/[0.06] focus-visible:shadow-[inset_0_0_0_1px_#4568FF] dark:focus-visible:bg-[#93B0FF]/[0.08] dark:focus-visible:shadow-[inset_0_0_0_1px_#93B0FF] ${className}`}
      >
        {children}
        <span id={`${uid}-hint`} className="sr-only">
          Right-click, or press Shift plus F10, for options
        </span>
      </div>
      <Portal host={host}>
      <AnimatePresence>
        {placement ? (
          <motion.div
            key={menuId}
            ref={menuRef}
            id={menuId}
            {...menuProps}
            aria-label={label}
            initial={reduced ? { opacity: 0 } : { opacity: 0, scale: 0.96 }}
            animate={{ opacity: 1, scale: 1 }}
            exit={
              reduced
                ? { opacity: 0, transition: { duration: 0 } }
                : { opacity: 0, scale: 0.98, transition: { duration: 0.14, ease: EXIT } }
            }
            transition={reduced ? { duration: 0 } : { duration: 0.2, ease: EASE }}
            style={{
              position: "fixed",
              left: placement.left,
              top: placement.top,
              width: placement.width,
              maxHeight: placement.maxHeight,
              transformOrigin: placement.transformOrigin,
              zIndex: 60,
            }}
            className="overflow-y-auto overscroll-contain rounded-[14px] border border-stone-200 bg-white p-[5px] shadow-[0_1px_2px_rgba(28,25,23,0.06),0_16px_36px_-18px_rgba(28,25,23,0.5)] outline-none dark:border-white/[0.16] dark:bg-[#1D1D1A] dark:shadow-[0_2px_12px_rgba(0,0,0,0.6)]"
          >
            {items.map((item, index) =>
              item.type === "separator" ? (
                <div key={item.id} className="px-1 py-1">
                  <hr className="h-px border-0 bg-stone-200 dark:bg-white/10" />
                </div>
              ) : (
                <button
                  key={item.id}
                  type="button"
                  aria-disabled={item.disabled || undefined}
                  {...getItemProps(index)}
                  className={`flex h-[32px] w-full cursor-default select-none items-center gap-2 rounded-[7px] px-2.5 text-left text-[13px] outline-none ${
                    item.disabled
                      ? "text-stone-400 dark:text-stone-500"
                      : "text-stone-700 dark:text-stone-200"
                  } ${active === index ? "bg-stone-100 dark:bg-white/10" : ""}`}
                >
                  {hasIcons ? (
                    <span
                      aria-hidden
                      className="grid size-4 shrink-0 place-items-center text-stone-500 dark:text-stone-400"
                    >
                      {item.icon}
                    </span>
                  ) : null}

                  <span className="min-w-0 flex-1 truncate">{item.label}</span>
                  {item.shortcut ? (
                    <span
                      aria-hidden
                      className="shrink-0 font-mono text-[10.5px] tabular-nums text-stone-500 dark:text-stone-400"
                    >
                      {item.shortcut}
                    </span>
                  ) : null}
                </button>
              ),
            )}
          </motion.div>
        ) : null}
      </AnimatePresence>
      </Portal>
    </>
  );
}

function Portal({
  host,
  children,
}: {
  host: HTMLElement | null;
  children: ReactNode;
}) {
  if (!host) return null;
  return createPortal(children, host);
}
```

---

## Dropdown · Overlay

Active highlight travels between items.

Docs: https://yugo.click/docs/dropdown
Install: `bun add motion`, then copy the source below into `components/yugo/dropdown.tsx` · or `bunx shadcn@latest add https://yugo.click/r/dropdown.json`.

Guarantees:
- The active highlight is one element carrying a layoutId, so moving down the list is a single travel rather than one row's background fading out while another fades in: hold ArrowDown and there is never a frame with two rows lit or none.
- Every label lives stacked in one grid cell inside the trigger, so committing to a longer option cannot widen the button or push the row beside it sideways.
- The list is capped at 216px and scrolls inside itself, so a hundred options never animate a panel toward an unbounded height, and keyboard navigation reveals the active row with block: "nearest" instead of yanking the list to center it.
- Disabled options are skipped by the arrow keys, by Home and End, and by typeahead, and refuse their own click, so the highlight cannot park somewhere Enter does nothing.
- Under prefers-reduced-motion the highlight jumps to its new row and the panel arrives without blur or scale: the selection still reads, only the trip is skipped, and nothing is hidden.
- Focus is handled rather than assumed: opening moves focus into the listbox, aria-activedescendant names the active option so a screen reader hears the landing and not the journey, and Escape, Tab, a click outside or a window blur all close it without leaving focus stranded on a removed node; useDropdown exports the same behaviour for a different surface.


### Usage

```tsx
"use client";

import { useState } from "react";
import { Dropdown, type DropdownItem } from "@/components/yugo/dropdown";

const VISIBILITY: DropdownItem[] = [
  { value: "private", label: "Only me", hint: "default" },
  { value: "team", label: "Anyone at Acme" },
  { value: "link", label: "Anyone with the link" },
  { value: "public", label: "Public on the web", disabled: true },
];

export function ShareRow({ docId }: { docId: string }) {
  const [visibility, setVisibility] = useState("private");

  return (
    <div className="flex items-center justify-between gap-4">
      <p className="text-[13px] text-stone-700 dark:text-stone-200">
        Who can see this
      </p>
      <div className="w-[220px]">
        <Dropdown
          label="Document visibility"
          items={VISIBILITY}
          value={visibility}
          onChange={(next) => {
            setVisibility(next);
            void fetch(`/api/docs/${docId}`, {
              method: "PATCH",
              body: JSON.stringify({ visibility: next }),
            });
          }}
        />
      </div>
    </div>
  );
}
```

### Source (`components/yugo/dropdown.tsx`)

```tsx
"use client";

import { useCallback, useEffect, useId, useRef, useState } from "react";
import { AnimatePresence, motion, useReducedMotion } from "motion/react";

const EASE = [0.23, 1, 0.32, 1] as const;

const EXIT = [0.4, 0, 1, 1] as const;
const CELL = { type: "spring", stiffness: 520, damping: 34, mass: 0.45 } as const;

const NUDGE = { type: "spring", stiffness: 700, damping: 46, mass: 0.5 } as const;
const NONE = { duration: 0 } as const;

const SLIDE = { type: "spring", stiffness: 700, damping: 46, mass: 0.5 } as const;

const ROW_H = 32;

const OPEN = { type: "spring", stiffness: 620, damping: 38, mass: 0.6 } as const;

export type DropdownItem = {
  value: string;
  label: string;
  hint?: string;
  disabled?: boolean;
};

export type UseDropdownOptions = {
  items: DropdownItem[];
  value?: string;
  defaultValue?: string;
  onChange?: (value: string) => void;
  disabled?: boolean;
  typeaheadDelay?: number;
};

export function useDropdown({
  items,
  value,
  defaultValue,
  onChange,
  disabled = false,
  typeaheadDelay = 600,
}: UseDropdownOptions) {
  const uid = useId();
  const listId = `${uid}-list`;
  const itemId = useCallback((i: number) => `${uid}-opt-${i}`, [uid]);

  const [uncontrolled, setUncontrolled] = useState<string | null>(
    defaultValue ?? null,
  );
  const selectedValue = value !== undefined ? value : uncontrolled;
  const selectedIndex = items.findIndex((it) => it.value === selectedValue);

  const [open, setOpen] = useState(false);
  const [activeIndex, setActiveIndex] = useState(-1);

  const rootRef = useRef<HTMLDivElement>(null);
  const triggerRef = useRef<HTMLButtonElement>(null);
  const listRef = useRef<HTMLUListElement>(null);
  const itemRefs = useRef<(HTMLLIElement | null)[]>([]);
  const viaKey = useRef(false);
  const buffer = useRef("");
  const bufferTimer = useRef<ReturnType<typeof setTimeout> | null>(null);

  const emit = useRef(onChange);
  emit.current = onChange;

  const step = useCallback(
    (from: number, dir: 1 | -1) => {
      const n = items.length;
      if (n === 0) return -1;
      let i = from;
      for (let k = 0; k < n; k++) {
        i = (i + dir + n) % n;
        if (!items[i].disabled) return i;
      }
      return from;
    },
    [items],
  );

  const edge = useCallback(
    (dir: 1 | -1) => step(dir === 1 ? -1 : items.length, dir),
    [step, items.length],
  );

  const openMenu = useCallback(
    (index?: number) => {
      if (disabled || items.length === 0) return;
      const usable = selectedIndex >= 0 && !items[selectedIndex].disabled;
      viaKey.current = true;
      setActiveIndex(index ?? (usable ? selectedIndex : edge(1)));
      setOpen(true);
    },
    [disabled, items, selectedIndex, edge],
  );

  const close = useCallback((restoreFocus = true) => {
    buffer.current = "";
    setOpen(false);
    setActiveIndex(-1);
    if (restoreFocus) triggerRef.current?.focus();
  }, []);

  const select = useCallback(
    (index: number) => {
      const item = items[index];
      if (!item || item.disabled) return;
      if (value === undefined) setUncontrolled(item.value);
      emit.current?.(item.value);
      close();
    },
    [items, value, close],
  );

  const typeahead = useCallback(
    (char: string) => {
      if (bufferTimer.current) clearTimeout(bufferTimer.current);
      buffer.current += char.toLowerCase();
      bufferTimer.current = setTimeout(() => {
        buffer.current = "";
      }, typeaheadDelay);

      const q = buffer.current;
      const n = items.length;
      const from = activeIndex < 0 ? 0 : activeIndex;
      const start = q.length > 1 ? from : from + 1;
      for (let k = 0; k < n; k++) {
        const i = (start + k) % n;
        const it = items[i];
        if (!it.disabled && it.label.toLowerCase().startsWith(q)) {
          viaKey.current = true;
          setActiveIndex(i);
          return;
        }
      }
    },
    [items, activeIndex, typeaheadDelay],
  );

  useEffect(() => {
    if (open) listRef.current?.focus();
  }, [open]);

  useEffect(() => {
    if (!open) return;
    const onDown = (e: PointerEvent) => {
      if (!rootRef.current?.contains(e.target as Node)) close(false);
    };
    const onWindowBlur = () => close(false);
    document.addEventListener("pointerdown", onDown, true);
    window.addEventListener("blur", onWindowBlur);
    return () => {
      document.removeEventListener("pointerdown", onDown, true);
      window.removeEventListener("blur", onWindowBlur);
    };
  }, [open, close]);

  useEffect(() => {
    if (!open || activeIndex < 0 || !viaKey.current) return;
    viaKey.current = false;
    itemRefs.current[activeIndex]?.scrollIntoView({ block: "nearest" });
  }, [open, activeIndex]);

  useEffect(
    () => () => {
      if (bufferTimer.current) clearTimeout(bufferTimer.current);
    },
    [],
  );

  const triggerProps = {
    ref: triggerRef,
    type: "button" as const,
    disabled,
    "aria-haspopup": "listbox" as const,
    "aria-expanded": open,
    "aria-controls": open ? listId : undefined,
    onClick: () => (open ? close() : openMenu()),
    onKeyDown: (e: React.KeyboardEvent<HTMLButtonElement>) => {
      if (e.key === "ArrowDown" || e.key === "Enter" || e.key === " ") {
        e.preventDefault();
        openMenu();
      } else if (e.key === "ArrowUp") {
        e.preventDefault();
        openMenu(edge(-1));
      }
    },
  };

  const listProps = {
    ref: listRef,
    id: listId,
    role: "listbox" as const,
    tabIndex: -1,
    "aria-activedescendant": activeIndex >= 0 ? itemId(activeIndex) : undefined,
    onKeyDown: (e: React.KeyboardEvent<HTMLUListElement>) => {
      if (e.key === "ArrowDown" || e.key === "ArrowUp") {
        e.preventDefault();
        const dir = e.key === "ArrowDown" ? 1 : -1;
        viaKey.current = true;
        setActiveIndex((i) => step(i, dir));
      } else if (e.key === "Home" || e.key === "End") {
        e.preventDefault();
        viaKey.current = true;
        setActiveIndex(edge(e.key === "Home" ? 1 : -1));
      } else if (e.key === "Enter" || e.key === " ") {
        e.preventDefault();
        select(activeIndex);
      } else if (e.key === "Escape") {
        e.preventDefault();
        close();
      } else if (e.key === "Tab") {
        e.preventDefault();
        close();
      } else if (
        e.key.length === 1 &&
        !e.metaKey &&
        !e.ctrlKey &&
        !e.altKey
      ) {
        e.preventDefault();
        typeahead(e.key);
      }
    },
  };

  const getItemProps = useCallback(
    (index: number) => ({
      id: itemId(index),
      role: "option" as const,
      "aria-selected": index === selectedIndex,
      "aria-disabled": items[index]?.disabled ? (true as const) : undefined,
      ref: (el: HTMLLIElement | null) => {
        itemRefs.current[index] = el;
      },
      onPointerMove: () => {
        if (items[index]?.disabled) return;
        viaKey.current = false;
        setActiveIndex(index);
      },
      onClick: () => select(index),
    }),
    [itemId, items, selectedIndex, select],
  );

  return {
    open,
    openMenu,
    close,
    select,
    activeIndex,
    selectedIndex,
    selectedItem: selectedIndex >= 0 ? items[selectedIndex] : null,
    itemId,
    rootRef,
    triggerProps,
    listProps,
    getItemProps,
  };
}

export type DropdownProps = {
  items: DropdownItem[];
  value?: string;
  defaultValue?: string;
  onChange?: (value: string) => void;
  label?: string;
  placeholder?: string;
  disabled?: boolean;
  emptyLabel?: string;
  className?: string;
};

export function Dropdown({
  items,
  value,
  defaultValue,
  onChange,
  label = "Options",
  placeholder = "Select an option",
  disabled = false,
  emptyLabel = "Nothing to choose",
  className = "",
}: DropdownProps) {
  const reduced = useReducedMotion();
  const {
    open,
    activeIndex,
    selectedIndex,
    selectedItem,
    rootRef,
    triggerProps,
    listProps,
    getItemProps,
  } = useDropdown({ items, value, defaultValue, onChange, disabled });

  const cell = reduced ? NONE : CELL;

  return (
    <div ref={rootRef} className={`relative inline-block text-left ${className}`}>
      <button
        {...triggerProps}
        className={`flex h-9 select-none items-center gap-2 whitespace-nowrap rounded-[9px] border border-stone-200 bg-white px-3 text-[13px] font-medium text-stone-700 outline-none transition-[box-shadow,border-color] duration-150 disabled:opacity-50 dark:border-white/[0.16] dark:bg-[#1D1D1A] dark:text-stone-200 ${
          open
            ? "shadow-[inset_0_1px_2px_rgba(28,25,23,0.09)] dark:shadow-[inset_0_1px_2px_rgba(0,0,0,0.5)]"
            : "shadow-[0_1px_2px_rgba(28,25,23,0.06),0_4px_10px_-8px_rgba(28,25,23,0.45)] hover:border-stone-300 hover:shadow-[0_1px_2px_rgba(28,25,23,0.06),0_8px_18px_-12px_rgba(28,25,23,0.5)] focus-visible:border-stone-400 focus-visible:shadow-[0_1px_2px_rgba(28,25,23,0.08),0_10px_22px_-12px_rgba(28,25,23,0.55)] dark:shadow-[0_1px_6px_rgba(0,0,0,0.45)] dark:hover:border-white/20 dark:hover:shadow-[0_2px_10px_rgba(0,0,0,0.55)] dark:focus-visible:border-white/30 dark:focus-visible:shadow-[0_2px_12px_rgba(0,0,0,0.6)]"
        }`}
      >
        <span className="sr-only">
          {label}: {selectedItem ? selectedItem.label : placeholder}
        </span>
        <span aria-hidden>{label}</span>
        <motion.svg
          aria-hidden
          viewBox="0 0 12 12"
          className="size-3 shrink-0 text-stone-500 dark:text-stone-400"
          initial={false}
          animate={{ rotate: open ? 180 : 0 }}
          transition={reduced ? NONE : NUDGE}
        >
          <path
            d="M3 4.75 6 7.75 9 4.75"
            fill="none"
            stroke="currentColor"
            strokeWidth="1.4"
            strokeLinecap="round"
            strokeLinejoin="round"
          />
        </motion.svg>
      </button>
      <AnimatePresence>
        {open && (
          <motion.div
            initial={reduced ? { opacity: 0 } : { opacity: 0, scale: 0.94, y: -8 }}
            animate={{ opacity: 1, scale: 1, y: 0 }}
            exit={{
              opacity: 0,
              scale: 0.97,
              y: -6,
              transition: reduced ? NONE : { duration: 0.12, ease: EXIT },
            }}
            transition={
              reduced
                ? NONE
                : { ...OPEN, opacity: { duration: 0.12, ease: EASE } }
            }
            style={{ transformOrigin: "top left" }}
            className="absolute left-0 top-[calc(100%+6px)] z-50 min-w-[224px] whitespace-nowrap rounded-[11px] border border-stone-200 bg-white p-[5px] shadow-[0_1px_2px_rgba(28,25,23,0.06),0_16px_36px_-18px_rgba(28,25,23,0.5)] dark:border-white/[0.16] dark:bg-[#1D1D1A] dark:shadow-[0_2px_12px_rgba(0,0,0,0.6)]"
          >
            <ul
              {...listProps}
              aria-label={label}
              className="relative max-h-[216px] overflow-y-auto outline-none [scrollbar-gutter:stable]"
            >
              <motion.span
                aria-hidden
                className="pointer-events-none absolute inset-x-0 top-0 h-8 rounded-[7px] bg-stone-100 dark:bg-white/10"
                initial={false}
                animate={{
                  y: activeIndex < 0 ? 0 : activeIndex * ROW_H,
                  opacity: activeIndex < 0 ? 0 : 1,
                }}
                transition={
                  reduced
                    ? NONE
                    : { ...SLIDE, opacity: { duration: 0.1, ease: EASE } }
                }
              />
              {items.map((item, i) => {
                const active = i === activeIndex && !item.disabled;
                const picked = i === selectedIndex;
                return (
                  <li
                    key={item.value}
                    {...getItemProps(i)}
                    className={`relative flex h-8 cursor-default select-none items-center rounded-[7px] px-2.5 text-[13px] ${
                      item.disabled
                        ? "text-stone-500/70 dark:text-stone-400/70"
                        : active
                          ? "text-stone-900 dark:text-stone-100"
                          : "text-stone-700 dark:text-stone-200"
                    }`}
                  >
                    <span className="relative flex min-w-0 flex-1 items-center gap-3">
                      <span className="truncate">{item.label}</span>
                      {item.hint ? (
                        <span className="ml-auto shrink-0 font-mono text-[10.5px] text-stone-500 dark:text-stone-400">
                          {item.hint}
                        </span>
                      ) : null}
                    </span>
                    <motion.span
                      aria-hidden
                      initial={false}
                      animate={{ opacity: picked ? 1 : 0, scale: picked ? 1 : 0.7 }}
                      transition={cell}
                      className="relative ml-2 flex size-[14px] shrink-0 items-center justify-center"
                    >
                      <svg viewBox="0 0 14 14" className="size-[14px]">
                        <path
                          d="M3 7.4 5.8 10.2 11 4.4"
                          fill="none"
                          stroke="currentColor"
                          strokeWidth="1.5"
                          strokeLinecap="round"
                          strokeLinejoin="round"
                        />
                      </svg>
                    </motion.span>
                  </li>
                );
              })}

              {items.length === 0 && (
                <li
                  role="presentation"
                  className="flex h-8 items-center px-2.5 text-[13px] text-stone-500 dark:text-stone-400"
                >
                  {emptyLabel}
                </li>
              )}
            </ul>
          </motion.div>
        )}
      </AnimatePresence>
    </div>
  );
}
```

---

## Morphing Popover · Overlay

The button becomes the panel, and goes back.

Docs: https://yugo.click/docs/morphing-popover
Install: `bun add motion`, then copy the source below into `components/yugo/morphing-popover.tsx` · or `bunx shadcn@latest add https://yugo.click/r/morphing-popover.json`.

Guarantees:
- The trigger and the panel are one surface with one shared layout id, so the button does not disappear and get replaced by a card: it becomes the card, and on the way out it becomes the button again.
- The four corner radii are written out one by one rather than as the shorthand, because motion counter-scales only the properties it owns and does not parse the four-value form: written as a shorthand, the corners smear on every open.
- The anchoring is done by a plain wrapper, so the morphing surface carries no transform of its own. A translate on a layout-animated box is a measurement motion has to undo on every frame.
- It is deliberately not portalled. A portal is what a full-page overlay needs; a surface that has to stay in the same layout tree as the thing it grew out of cannot have one, and this popover is anchored and small enough not to want it.
- It is a dialog, not a modal one: no aria-modal, no focus trap, no scroll lock, because none of those are true of a panel you can click away from. The panel takes focus on open and hands it back to the trigger on Escape.
- A visually hidden close button sits at the end of the panel, so a keyboard user who tabbed past the content has a way out that is not a keystroke they have to already know.
- Under prefers-reduced-motion the shared layout id is removed rather than given a zero duration, and the panel simply arrives.
- useMorphingPopover is the state, the shared id and the dismissal wiring, with no surface of its own.


### Usage

```tsx
"use client";

import { useState } from "react";
import { MorphingPopover } from "@/components/yugo/morphing-popover";

export function NoteButton() {
  const [open, setOpen] = useState(false);
  const [note, setNote] = useState("");

  return (
    <MorphingPopover
      label="New note"
      open={open}
      onOpenChange={setOpen}
      align="center"
      trigger="New note"
    >
      <div className="w-[248px]">
        <textarea
          value={note}
          onChange={(event) => setNote(event.currentTarget.value)}
          rows={3}
          aria-label="Note"
          placeholder="What happened?"
          className="w-full resize-none bg-transparent text-[13px] outline-none"
        />
        <button type="button" onClick={() => setOpen(false)}>
          Save
        </button>
      </div>
    </MorphingPopover>
  );
}
```

### Source (`components/yugo/morphing-popover.tsx`)

```tsx
"use client";

import { useCallback, useEffect, useId, useRef, useState } from "react";
import { AnimatePresence, motion, useReducedMotion } from "motion/react";

const EASE = [0.23, 1, 0.32, 1] as const;
const LEAVE = [0.4, 0, 1, 1] as const;

const SURFACE = {
  type: "spring",
  stiffness: 420,
  damping: 36,
  mass: 0.9,
} as const;

const INSTANT = { duration: 0 } as const;

const TRIGGER_RADIUS = 9;
const PANEL_RADIUS = 11;

const SIDE = { bottom: "top-0", top: "bottom-0" } as const;
const ALIGN = {
  start: "left-0",
  center: "left-1/2 -translate-x-1/2",
  end: "right-0",
} as const;

export type MorphingPopoverSide = keyof typeof SIDE;
export type MorphingPopoverAlign = keyof typeof ALIGN;

export type UseMorphingPopoverOptions = {
  open?: boolean;
  defaultOpen?: boolean;
  onOpenChange?: (open: boolean) => void;
};

export type UseMorphingPopoverResult = {
  open: boolean;
  /** the layoutId the trigger and the panel share, so one becomes the other */
  surfaceId: string;
  panelId: string;
  setOpen: (open: boolean) => void;
  toggle: () => void;
  close: (returnFocus?: boolean) => void;
  triggerRef: React.RefObject<HTMLButtonElement | null>;
  panelRef: React.RefObject<HTMLDivElement | null>;
  triggerProps: {
    ref: React.RefObject<HTMLButtonElement | null>;
    type: "button";
    "aria-haspopup": "dialog";
    "aria-expanded": boolean;
    "aria-controls": string | undefined;
    onClick: () => void;
  };
  panelProps: {
    ref: React.RefObject<HTMLDivElement | null>;
    id: string;
    role: "dialog";
    tabIndex: -1;
  };
};

/**
 * The surface is one object that changes size, not two objects that swap.
 * Everything here exists to keep that true: one shared id, and a close path
 * that always hands focus back to the thing the panel grew out of.
 */
export function useMorphingPopover({
  open: controlled,
  defaultOpen = false,
  onOpenChange,
}: UseMorphingPopoverOptions = {}): UseMorphingPopoverResult {
  const base = useId();
  const [uncontrolled, setUncontrolled] = useState(defaultOpen);
  const triggerRef = useRef<HTMLButtonElement>(null);
  const panelRef = useRef<HTMLDivElement>(null);

  const open = controlled ?? uncontrolled;

  const emit = useRef(onOpenChange);
  emit.current = onOpenChange;

  const setOpen = useCallback(
    (next: boolean) => {
      if (controlled === undefined) setUncontrolled(next);
      emit.current?.(next);
    },
    [controlled],
  );

  const close = useCallback(
    (returnFocus = false) => {
      setOpen(false);
      if (returnFocus) triggerRef.current?.focus({ preventScroll: true });
    },
    [setOpen],
  );

  const toggle = useCallback(() => setOpen(!open), [setOpen, open]);

  useEffect(() => {
    if (!open) return;
    panelRef.current?.focus({ preventScroll: true });
  }, [open]);

  useEffect(() => {
    if (!open) return;

    const onPointerDown = (event: PointerEvent) => {
      const target = event.target as Node | null;
      if (!target) return;
      if (
        panelRef.current?.contains(target) ||
        triggerRef.current?.contains(target)
      ) {
        return;
      }
      setOpen(false);
    };

    const onKeyDown = (event: KeyboardEvent) => {
      if (event.key !== "Escape") return;
      event.stopPropagation();
      close(true);
    };

    document.addEventListener("pointerdown", onPointerDown, true);
    document.addEventListener("keydown", onKeyDown, true);
    return () => {
      document.removeEventListener("pointerdown", onPointerDown, true);
      document.removeEventListener("keydown", onKeyDown, true);
    };
  }, [open, setOpen, close]);

  return {
    open,
    surfaceId: `${base}-surface`,
    panelId: `${base}-panel`,
    setOpen,
    toggle,
    close,
    triggerRef,
    panelRef,
    triggerProps: {
      ref: triggerRef,
      type: "button",
      "aria-haspopup": "dialog",
      "aria-expanded": open,
      "aria-controls": open ? `${base}-panel` : undefined,
      onClick: toggle,
    },
    panelProps: {
      ref: panelRef,
      id: `${base}-panel`,
      role: "dialog",
      tabIndex: -1,
    },
  };
}

export type MorphingPopoverProps = UseMorphingPopoverOptions & {
  trigger: React.ReactNode;
  children: React.ReactNode;
  label: string;
  side?: MorphingPopoverSide;
  align?: MorphingPopoverAlign;
  triggerClassName?: string;
  className?: string;
};

export function MorphingPopover({
  trigger,
  children,
  label,
  side = "bottom",
  align = "start",
  triggerClassName = "",
  className = "",
  ...options
}: MorphingPopoverProps) {
  const reduced = useReducedMotion();
  const { open, surfaceId, setOpen, close, triggerProps, panelProps } =
    useMorphingPopover(options);

  // A shared-layout animation cannot be handed `duration: 0`; it has to be
  // switched off, and the panel falls back to arriving in place. §22
  const morph = reduced ? undefined : surfaceId;

  return (
    <div
      className="relative inline-flex"
      onBlurCapture={(event) => {
        const next = event.relatedTarget as Node | null;
        if (!next) return;
        if (event.currentTarget.contains(next)) return;
        setOpen(false);
      }}
    >
      <motion.button
        {...triggerProps}
        layoutId={morph}
        style={{
          // Motion counter-scales a radius only for the properties it owns,
          // and it does not parse the shorthand. Four corners, spelled out. §5i
          borderTopLeftRadius: TRIGGER_RADIUS,
          borderTopRightRadius: TRIGGER_RADIUS,
          borderBottomLeftRadius: TRIGGER_RADIUS,
          borderBottomRightRadius: TRIGGER_RADIUS,
        }}
        transition={reduced ? INSTANT : SURFACE}
        className={`inline-flex h-9 select-none items-center gap-2 border border-stone-200 bg-white px-3 text-[13px] font-medium text-stone-700 outline-none transition-[border-color,box-shadow] duration-150 hover:border-stone-300 focus-visible:border-[#4568FF] focus-visible:shadow-[0_1px_2px_rgba(28,25,23,0.08),0_10px_20px_-14px_rgba(69,104,255,0.6)] dark:border-white/[0.16] dark:bg-[#1D1D1A] dark:text-stone-200 dark:hover:border-white/20 dark:focus-visible:border-[#93B0FF] dark:focus-visible:shadow-[0_10px_20px_-14px_rgba(147,176,255,0.5)] ${triggerClassName}`}
      >
        <motion.span
          initial={false}
          animate={{ opacity: open ? 0 : 1 }}
          transition={
            reduced ? INSTANT : { duration: open ? 0.1 : 0.2, ease: EASE }
          }
          className="inline-flex items-center gap-2"
        >
          {trigger}
        </motion.span>
      </motion.button>

      <AnimatePresence>
        {open ? (
          // The wrapper does the anchoring so the morphing surface carries no
          // transform of its own: a translate on a layout-animated box is a
          // measurement motion has to undo every frame.
          <div
            key="anchor"
            className={`absolute z-50 ${SIDE[side]} ${ALIGN[align]}`}
          >
            <motion.div
              {...panelProps}
              aria-label={label}
              layoutId={morph}
              initial={reduced ? { opacity: 0 } : false}
              animate={reduced ? { opacity: 1 } : undefined}
              exit={
                reduced
                  ? { opacity: 0, transition: { duration: 0.1 } }
                  : { opacity: 0, transition: { duration: 0.13, ease: LEAVE } }
              }
              style={{
                borderTopLeftRadius: PANEL_RADIUS,
                borderTopRightRadius: PANEL_RADIUS,
                borderBottomLeftRadius: PANEL_RADIUS,
                borderBottomRightRadius: PANEL_RADIUS,
              }}
              transition={reduced ? INSTANT : SURFACE}
              className={`w-max overflow-hidden border border-stone-200 bg-white p-3 shadow-[0_18px_40px_-24px_rgba(28,25,23,0.5)] focus-visible:outline-none dark:border-white/[0.16] dark:bg-[#1D1D1A] dark:shadow-[0_18px_40px_-24px_rgba(0,0,0,0.9)] ${className}`}
            >
              <motion.div
                initial={
                  reduced ? false : { opacity: 0, filter: "blur(4px)", y: 4 }
                }
                animate={{ opacity: 1, filter: "blur(0px)", y: 0 }}
                exit={
                  reduced
                    ? { opacity: 0 }
                    : {
                        opacity: 0,
                        filter: "blur(2px)",
                        transition: { duration: 0.1, ease: LEAVE },
                      }
                }
                transition={
                  reduced ? INSTANT : { duration: 0.22, ease: EASE, delay: 0.04 }
                }
              >
                {children}
              </motion.div>

              <button
                type="button"
                onClick={() => close(true)}
                className="sr-only"
              >
                Close {label}
              </button>
            </motion.div>
          </div>
        ) : null}
      </AnimatePresence>
    </div>
  );
}
```

---

## Tabs · Navigation

One indicator shared across tabs.

Docs: https://yugo.click/docs/tabs
Install: `bun add motion`, then copy the source below into `components/yugo/tabs.tsx` · or `bunx shadcn@latest add https://yugo.click/r/tabs.json`.

Guarantees:
- The indicator is a single element carried between tabs by a shared layout id, so a fast switch cannot leave two bars crossfading past each other or restart a bar from zero width, and interrupting the move resumes the spring from where the bar currently is.
- The selected label changes weight without changing geometry: an invisible copy at the target weight holds the cell width, so the row never reflows on selection and the indicator never lands on stale measurements.
- Arrow keys walk the row, Home and End jump to the ends, and disabled tabs are stepped over rather than focused; only the selected tab sits in the page tab order, so Tab leaves the row instead of visiting every item in it.
- Only the selected panel is mounted, wired with role tabpanel and aria-labelledby, so a screen reader is handed one section of content rather than all of them stacked.
- Under prefers-reduced-motion the indicator's travel and the panel's 3px slide collapse to zero duration; the bar still ends up under the right label and the panel still appears.
- Selection is optional state: pass value and onValueChange to own it, or defaultValue to let the component own it, and take useTabs alone when you want the roving focus, ids and ARIA wiring under your own chrome.


### Usage

```tsx
"use client";

import { useState } from "react";
import { Tabs } from "@/components/yugo/tabs";

const sections = [
  { value: "readme", label: "Readme" },
  { value: "issues", label: "Issues" },
  { value: "insights", label: "Insights", disabled: true },
];

export function RepoHeader() {
  const [section, setSection] = useState("readme");

  return (
    <Tabs
      items={sections}
      value={section}
      onValueChange={setSection}
      variant="segmented"
      activation="manual"
      label="Repository sections"
      panelClassName="mt-4"
      renderPanel={(value) =>
        value === "readme" ? <Readme /> : <IssueList />
      }
    />
  );
}
```

### Source (`components/yugo/tabs.tsx`)

```tsx
"use client";

import { useCallback, useEffect, useId, useLayoutEffect, useRef, useState } from "react";
import type { KeyboardEvent, ReactNode } from "react";
import { motion, useReducedMotion } from "motion/react";

const INDICATOR = { type: "spring", stiffness: 620, damping: 42, mass: 0.35 } as const;

const useIsoLayoutEffect =
  typeof window === "undefined" ? useEffect : useLayoutEffect;

const PANEL = { type: "spring", stiffness: 460, damping: 38, mass: 0.8 } as const;

export type TabItem = {
  value: string;
  label: string;
  disabled?: boolean;
};

export type TabsActivation = "automatic" | "manual";
export type UseTabsOptions = {
  items: TabItem[];
  value?: string;
  defaultValue?: string;
  onValueChange?: (value: string) => void;
  activation?: TabsActivation;
};

export function useTabs({
  items,
  value: controlled,
  defaultValue,
  onValueChange,
  activation = "automatic",
}: UseTabsOptions) {
  const base = useId();
  const nodes = useRef(new Map<string, HTMLButtonElement>());
  const direction = useRef(1);

  const [internal, setInternal] = useState(
    () => defaultValue ?? items.find((i) => !i.disabled)?.value ?? items[0]?.value ?? "",
  );

  const value = controlled ?? internal;

  const emit = useRef(onValueChange);
  emit.current = onValueChange;

  const select = useCallback(
    (next: string) => {
      if (next === value) return;
      const from = items.findIndex((i) => i.value === value);
      const to = items.findIndex((i) => i.value === next);
      direction.current = to < from ? -1 : 1;
      if (controlled === undefined) setInternal(next);
      emit.current?.(next);
    },
    [controlled, items, value],
  );

  const focusAt = useCallback(
    (i: number) => {
      const item = items[i];
      if (!item) return;
      nodes.current.get(item.value)?.focus();
    },
    [items],
  );

  const nextEnabled = useCallback(
    (from: number, dir: number) => {
      const n = items.length;
      let i = from < 0 ? 0 : from;
      for (let k = 0; k < n; k += 1) {
        i = (i + dir + n) % n;
        if (!items[i].disabled) return i;
      }
      return from;
    },
    [items],
  );

  const endStop = useCallback(
    (dir: number) => {
      const n = items.length;
      if (dir > 0) {
        for (let i = 0; i < n; i += 1) if (!items[i].disabled) return i;
      } else {
        for (let i = n - 1; i >= 0; i -= 1) if (!items[i].disabled) return i;
      }
      return 0;
    },
    [items],
  );

  const getTabProps = useCallback(
    (item: TabItem, index: number) => ({
      id: `${base}-tab-${item.value}`,
      role: "tab" as const,
      type: "button" as const,
      "aria-selected": item.value === value,
      "aria-controls": `${base}-panel-${item.value}`,
      "aria-disabled": item.disabled ? (true as const) : undefined,
      tabIndex: item.value === value ? 0 : -1,
      ref: (node: HTMLButtonElement | null) => {
        if (node) nodes.current.set(item.value, node);
        else nodes.current.delete(item.value);
      },
      onClick: () => {
        if (!item.disabled) select(item.value);
      },
      onKeyDown: (e: KeyboardEvent<HTMLButtonElement>) => {
        if (e.key === "ArrowRight" || e.key === "ArrowLeft") {
          e.preventDefault();
          const to = nextEnabled(index, e.key === "ArrowRight" ? 1 : -1);
          focusAt(to);
          if (activation === "automatic") select(items[to].value);
          return;
        }
        if (e.key === "Home" || e.key === "End") {
          e.preventDefault();
          const to = endStop(e.key === "Home" ? 1 : -1);
          focusAt(to);
          if (activation === "automatic") select(items[to].value);
          return;
        }
        if (e.key === "Enter" || e.key === " ") {
          e.preventDefault();
          if (!item.disabled) select(item.value);
        }
      },
    }),
    [activation, base, endStop, focusAt, items, nextEnabled, select, value],
  );

  const getPanelProps = useCallback(
    (panelValue: string) => ({
      id: `${base}-panel-${panelValue}`,
      role: "tabpanel" as const,
      "aria-labelledby": `${base}-tab-${panelValue}`,
      tabIndex: 0,
    }),
    [base],
  );

  const tabListProps = {
    role: "tablist" as const,
    "aria-orientation": "horizontal" as const,
  };

  return {
    value,
    select,
    direction: direction.current,
    tabListProps,
    getTabProps,
    getPanelProps,
  };
}

export type UseTabsReturn = ReturnType<typeof useTabs>;

export type TabsProps = {
  items: TabItem[];
  value?: string;
  defaultValue?: string;
  onValueChange?: (value: string) => void;
  activation?: TabsActivation;
  renderPanel?: (value: string) => ReactNode;
  label?: string;
  panelClassName?: string;
  className?: string;
};

export function Tabs({
  items,
  value,
  defaultValue,
  onValueChange,
  activation = "automatic",
  renderPanel,
  label = "Tabs",
  panelClassName = "",
  className = "",
}: TabsProps) {
  const tabs = useTabs({ items, value, defaultValue, onValueChange, activation });
  const reduced = useReducedMotion();

  const rowRef = useRef<HTMLDivElement | null>(null);
  const tabRefs = useRef<(HTMLButtonElement | null)[]>([]);
  const [plateau, setPlateau] = useState({ x: 0, width: 0, ready: false });

  const selectedIndex = items.findIndex((item) => item.value === tabs.value);

  useIsoLayoutEffect(() => {
    const node = tabRefs.current[selectedIndex];
    if (!node) return;

    const read = () => {
      setPlateau((prev) =>
        prev.x === node.offsetLeft &&
        prev.width === node.offsetWidth &&
        prev.ready
          ? prev
          : { x: node.offsetLeft, width: node.offsetWidth, ready: true },
      );
    };

    read();
    const row = rowRef.current;
    if (!row) return;
    const observer = new ResizeObserver(read);
    observer.observe(row);
    return () => observer.disconnect();
  }, [selectedIndex, items]);

  return (
    <div
      className={`w-full overflow-hidden rounded-[12px] border border-stone-200 bg-white shadow-[0_1px_2px_rgba(28,25,23,0.06),0_4px_10px_-8px_rgba(28,25,23,0.45)] dark:border-white/[0.16] dark:bg-[#1D1D1A] dark:shadow-[0_1px_6px_rgba(0,0,0,0.45)] ${className}`}
    >
      <div
        {...tabs.tabListProps}
        ref={rowRef}
        aria-label={label}
        className="relative flex w-full gap-1 border-b border-stone-200 bg-stone-50 px-1 pt-1 dark:border-white/[0.16] dark:bg-[#1D1D1A]"
      >
        <motion.span
          layout
          aria-hidden
          style={{
            borderTopLeftRadius: 8,
            borderTopRightRadius: 8,
            borderBottomLeftRadius: 0,
            borderBottomRightRadius: 0,
            left: plateau.x,
            width: plateau.width,
            opacity: plateau.ready ? 1 : 0,
          }}
          className="absolute bottom-[-1px] top-1 bg-white dark:bg-[#1D1D1A]"
          transition={reduced ? { duration: 0 } : INDICATOR}
        >
          <motion.span
            layout
            aria-hidden
            style={{ borderTopLeftRadius: 8, borderTopRightRadius: 8 }}
            transition={reduced ? { duration: 0 } : INDICATOR}
            className="absolute inset-0 border border-b-0 border-stone-200 dark:border-white/[0.16]"
          />
        </motion.span>

        {items.map((item, index) => {
          const selected = item.value === tabs.value;
          return (
            <button
              key={item.value}
              {...tabs.getTabProps(item, index)}
              ref={(node) => {
                tabRefs.current[index] = node;
              }}
              className={`relative flex h-8 shrink-0 items-center justify-center rounded-t-[8px] px-3.5 text-[12.5px] outline-none transition-colors duration-150 after:pointer-events-none after:absolute after:inset-0 after:rounded-t-[8px] after:content-[''] focus-visible:after:shadow-[inset_0_0_0_1px_#4568FF] dark:focus-visible:after:shadow-[inset_0_0_0_1px_#93B0FF] ${
                item.disabled
                  ? "cursor-default text-stone-400 dark:text-stone-500"
                  : selected
                    ? "text-stone-800 dark:text-stone-100"
                    : "text-stone-500 hover:bg-stone-200/50 hover:text-stone-700 dark:text-stone-400 dark:hover:bg-white/[0.05] dark:hover:text-stone-200"
              }`}
            >
              <span className="relative grid place-items-center leading-[1.4]">
                <span aria-hidden className="invisible col-start-1 row-start-1 font-medium">
                  {item.label}
                </span>
                <span
                  className={`col-start-1 row-start-1 ${selected ? "font-medium" : ""}`}
                >
                  {item.label}
                </span>
              </span>
            </button>
          );
        })}
      </div>

      {renderPanel ? (
        <motion.div
          key={tabs.value}
          custom={tabs.direction}
          {...tabs.getPanelProps(tabs.value)}
          initial={reduced ? false : { opacity: 0, x: tabs.direction * 12 }}
          animate={{ opacity: 1, x: 0 }}
          transition={reduced ? { duration: 0 } : PANEL}
          className={`rounded-[11px] text-[13.5px] leading-relaxed text-stone-700 outline-none focus-visible:shadow-[inset_0_0_0_1px_#4568FF] dark:text-stone-200 dark:focus-visible:shadow-[inset_0_0_0_1px_#93B0FF] ${panelClassName}`}
        >
          {renderPanel(tabs.value)}
        </motion.div>
      ) : null}
    </div>
  );
}
```

---

## Segmented Control · Navigation

Thumb slides, label inverts through it.

Docs: https://yugo.click/docs/segmented-control
Install: `bun add motion`, then copy the source below into `components/yugo/segmented-control.tsx` · or `bunx shadcn@latest add https://yugo.click/r/segmented-control.json`.

Guarantees:
- The label does not change color when the click lands; it inverts where the thumb's edge crosses it, because the inverted copy is a second grid clipped to the thumb and translated by the negative of the thumb's own transform, so the two halves of a glyph can be two colors at once.
- Segments never resize on selection: labels keep one weight in every state, both label layers share the same padding and type, and the track is a grid of equal fr columns, so the widest option fixes the geometry before anything moves.
- The thumb spring is driven by a motion value written straight to the DOM, so a selection changed mid-flight resumes from where the thumb currently is instead of restarting from the old segment, and React never re-renders during the slide.
- Under prefers-reduced-motion the thumb is placed on the new segment in one frame; the inversion still happens and no label is hidden.
- It is a real radiogroup with roving tabindex: arrow keys move and select, Home and End jump to the first and last enabled option, disabled segments are skipped rather than focused, and a screen reader is given one label per segment instead of the three visual copies on screen.


### Usage

```tsx
"use client";

import { useState } from "react";
import { SegmentedControl } from "@/components/yugo/segmented-control";

const VIEWS = [
  { value: "board", label: "Board" },
  { value: "list", label: "List" },
  { value: "timeline", label: "Timeline" },
  { value: "calendar", label: "Calendar", disabled: true },
];

export function ViewSwitcher() {
  const [view, setView] = useState("board");

  return (
    <div className="flex items-center justify-between">
      <h2 className="text-[15px] font-medium">Sprint 14</h2>
      <SegmentedControl
        label="View mode"
        options={VIEWS}
        value={view}
        onValueChange={setView}
      />
    </div>
  );
}
```

### Source (`components/yugo/segmented-control.tsx`)

```tsx
"use client";

import { useCallback, useEffect, useRef, useState } from "react";
import {
  animate,
  motion,
  useMotionValue,
  useReducedMotion,
  useTransform,
} from "motion/react";

const CELL = { type: "spring", stiffness: 520, damping: 34, mass: 0.45 } as const;

const SEG =
  "px-3 py-[7px] text-center text-[13px] font-medium leading-[18px] tracking-[-0.01em] whitespace-nowrap";

export type SegmentedOption = {
  value: string;
  label: string;
  disabled?: boolean;
};

export type SegmentedControlProps = {
  options: SegmentedOption[];
  label: string;
  value?: string;
  defaultValue?: string;
  onValueChange?: (value: string) => void;
  className?: string;
};

export function SegmentedControl({
  options,
  label,
  value,
  defaultValue,
  onValueChange,
  className = "",
}: SegmentedControlProps) {
  const count = Math.max(1, options.length);
  const template = `repeat(${count}, minmax(0, 1fr))`;

  const [internal, setInternal] = useState(
    () => defaultValue ?? options[0]?.value ?? "",
  );
  const [hovered, setHovered] = useState(-1);

  const controlled = value !== undefined;
  const current = controlled ? value : internal;
  const found = options.findIndex((o) => o.value === current);
  const index = found < 0 ? 0 : found;

  const buttons = useRef<(HTMLButtonElement | null)[]>([]);
  const emit = useRef(onValueChange);
  emit.current = onValueChange;

  const reduced = useReducedMotion();
  const pos = useMotionValue(index);
  const thumbX = useTransform(pos, (v) => `${v * 100}%`);
  const maskX = useTransform(pos, (v) => `${v * -100}%`);

  useEffect(() => {
    if (reduced) {
      pos.set(index);
      return;
    }
    const controls = animate(pos, index, CELL);
    return () => controls.stop();
  }, [index, reduced, pos]);

  const select = useCallback(
    (next: string) => {
      if (!controlled) setInternal(next);
      if (next !== current) emit.current?.(next);
    },
    [controlled, current],
  );

  const seek = useCallback(
    (from: number, dir: number) => {
      let i = from;
      for (let k = 0; k < count; k++) {
        i = (i + dir + count) % count;
        if (!options[i]?.disabled) return i;
      }
      return from;
    },
    [count, options],
  );

  const go = useCallback(
    (i: number) => {
      const option = options[i];
      if (!option || option.disabled) return;
      buttons.current[i]?.focus();
      select(option.value);
    },
    [options, select],
  );

  const onKeyDown = (e: React.KeyboardEvent, i: number) => {
    if (e.key === "ArrowRight" || e.key === "ArrowDown") {
      e.preventDefault();
      go(seek(i, 1));
    } else if (e.key === "ArrowLeft" || e.key === "ArrowUp") {
      e.preventDefault();
      go(seek(i, -1));
    } else if (e.key === "Home") {
      e.preventDefault();
      go(seek(count - 1, 1));
    } else if (e.key === "End") {
      e.preventDefault();
      go(seek(0, -1));
    }
  };

  return (
    <div
      role="radiogroup"
      aria-label={label}
      className={`relative inline-block select-none rounded-[9px] border border-stone-200 bg-stone-100/70 p-[3px] shadow-[inset_0_1px_2px_rgba(28,25,23,0.07)] dark:border-white/[0.16] dark:bg-[#1D1D1A] dark:shadow-[inset_0_1px_2px_rgba(0,0,0,0.45)] ${className}`}
    >
      <div
        className="relative grid"
        style={{ gridTemplateColumns: template, touchAction: "manipulation" }}
      >
        {options.map((option, i) => (
          <span
            key={option.value}
            aria-hidden
            className={`${SEG} pointer-events-none ${
              option.disabled
                ? "text-stone-300 dark:text-stone-600"
                : hovered === i && i !== index
                  ? "text-stone-700 dark:text-stone-200"
                  : "text-stone-500 dark:text-stone-400"
            }`}
          >
            {option.label}
          </span>
        ))}

        <motion.div
          aria-hidden
          className="pointer-events-none absolute inset-y-0 left-0 overflow-hidden rounded-[6px] bg-stone-800 shadow-[0_1px_2px_rgba(28,25,23,0.28)] dark:bg-stone-100 dark:shadow-[0_1px_2px_rgba(0,0,0,0.5)]"
          style={{ width: `${100 / count}%`, x: thumbX }}
          initial={false}
        >
          <motion.div
            className="absolute inset-0"
            style={{ x: maskX }}
            initial={false}
          >
            <div
              className="absolute inset-y-0 left-0 grid"
              style={{ width: `${count * 100}%`, gridTemplateColumns: template }}
            >
              {options.map((option) => (
                <span
                  key={option.value}
                  className={`${SEG} text-stone-50 dark:text-stone-900`}
                >
                  {option.label}
                </span>
              ))}
            </div>
          </motion.div>
        </motion.div>
        <div
          className="absolute inset-0 grid"
          style={{ gridTemplateColumns: template }}
          onPointerLeave={() => setHovered(-1)}
        >
          {options.map((option, i) => (
            <button
              key={option.value}
              ref={(node) => {
                buttons.current[i] = node;
              }}
              type="button"
              role="radio"
              aria-checked={i === index}
              aria-disabled={option.disabled || undefined}
              tabIndex={i === index ? 0 : -1}
              onClick={() => !option.disabled && select(option.value)}
              onKeyDown={(e) => onKeyDown(e, i)}
              onPointerEnter={() => !option.disabled && setHovered(i)}
              className="cursor-default rounded-[6px] outline-none focus-visible:bg-[#4568FF]/[0.06] focus-visible:shadow-[inset_0_0_0_1px_#4568FF] dark:focus-visible:bg-[#93B0FF]/[0.08] dark:focus-visible:shadow-[inset_0_0_0_1px_#93B0FF]"
            >
              <span className="sr-only">{option.label}</span>
            </button>
          ))}
        </div>
      </div>
    </div>
  );
}
```

---

## Accordion · Navigation

height auto, done correctly.

Docs: https://yugo.click/docs/accordion
Install: `bun add motion`, then copy the source below into `components/yugo/accordion.tsx` · or `bunx shadcn@latest add https://yugo.click/r/accordion.json`.

Guarantees:
- Panel height is measured from the panel's own box with a ResizeObserver rather than read once on open, so a panel that rewraps on resize, or grows when a font or image lands, never animates to a stale target.
- The first paint renders closed panels at zero and open panels at auto and only starts animating once a real measurement exists, so nothing flashes open and snaps shut on hydration.
- A closed panel is inert and aria-hidden, so Tab never lands on a link inside a section nobody can see and a screen reader never reads it out.
- Height is capped and the overflow scrolls inside the cap, so a panel holding two hundred rows cannot animate to an unbounded height or push the rest of the page off screen.
- The height spring is interruptible in both directions: toggling mid-flight, or growing the content while the panel is open, retargets from the current height instead of restarting from zero, and opacity finishes first so the reflow is hidden.
- Headers are real buttons carrying aria-expanded and aria-controls, with Arrow keys, Home and End moving between them; useAccordion exports that state and keyboard behaviour, and useAutoHeight exports the measurement alone, for surfaces you want to draw yourself.


### Usage

```tsx
"use client";

import { useState } from "react";
import { Accordion } from "@/components/yugo/accordion";

export function BillingFaq() {
  const [open, setOpen] = useState<string[]>(["invoices"]);

  return (
    <Accordion
      type="multiple"
      open={open}
      onOpenChange={setOpen}
      maxPanelHeight={240}
      items={[
        {
          id: "invoices",
          title: "Where do invoices go?",
          meta: "billing@",
          content: (
            <p>
              Every invoice is emailed to the billing contact and mirrored under
              Settings, Billing, History.
            </p>
          ),
        },
        {
          id: "seats",
          title: "How are seats counted?",
          content: (
            <p>
              Seats are counted at the end of the cycle. Removing a member frees
              the seat immediately.
            </p>
          ),
        },
        {
          id: "tax",
          title: "Tax documents",
          content: <p>Available after one paid cycle.</p>,
        },
      ]}
    />
  );
}
```

### Source (`components/yugo/accordion.tsx`)

```tsx
"use client";

import {
  useCallback,
  useEffect,
  useId,
  useLayoutEffect,
  useMemo,
  useRef,
  useState,
} from "react";
import { motion, useReducedMotion } from "motion/react";

const EASE = [0.23, 1, 0.32, 1] as const;
const EXIT_EASE = [0.4, 0, 1, 1] as const;

const DISCLOSE = {
  type: "spring",
  stiffness: 480,
  damping: 40,
  mass: 0.6,
} as const;

const CHEVRON = {
  type: "spring",
  stiffness: 700,
  damping: 46,
  mass: 0.5,
} as const;

const NONE: readonly string[] = [];

const useIsomorphicLayoutEffect =
  typeof window === "undefined" ? useEffect : useLayoutEffect;

type Inertable = HTMLElement & { inert?: boolean };

export type UseAutoHeightResult = {
  ref: React.RefObject<HTMLDivElement | null>;
  height: number;
  ready: boolean;
};

export function useAutoHeight(): UseAutoHeightResult {
  const ref = useRef<HTMLDivElement>(null);
  const [height, setHeight] = useState(0);
  const [ready, setReady] = useState(false);

  useIsomorphicLayoutEffect(() => {
    const el = ref.current;
    if (!el) return;

    const read = () => {
      const next = el.getBoundingClientRect().height;
      setHeight((prev) => (Math.abs(prev - next) < 0.5 ? prev : next));
    };

    read();
    setReady(true);

    const observer = new ResizeObserver(read);
    observer.observe(el);

    return () => observer.disconnect();
  }, []);

  return { ref, height, ready };
}

export type AccordionEntry = {
  id: string;
};

export type AccordionHeaderProps = {
  id: string;
  ref: (node: HTMLButtonElement | null) => void;
  type: "button";
  onClick: () => void;
  onKeyDown: (event: React.KeyboardEvent) => void;
  "aria-expanded": boolean;
  "aria-controls": string;
};

export type AccordionPanelProps = {
  id: string;
  role: "region";
  "aria-labelledby": string;
  "aria-hidden": true | undefined;
};

export type UseAccordionOptions = {
  items: readonly AccordionEntry[];
  type?: "single" | "multiple";
  defaultOpen?: readonly string[];
  open?: readonly string[];
  onOpenChange?: (open: string[]) => void;
  collapsible?: boolean;
};

export type UseAccordionResult = {
  open: string[];
  isOpen: (id: string) => boolean;
  toggle: (id: string) => void;
  headerProps: (id: string) => AccordionHeaderProps;
  panelProps: (id: string) => AccordionPanelProps;
};

export function useAccordion({
  items,
  type = "single",
  defaultOpen = NONE,
  open: controlled,
  onOpenChange,
  collapsible = true,
}: UseAccordionOptions): UseAccordionResult {
  const base = useId();

  const [uncontrolled, setUncontrolled] = useState<string[]>(() =>
    type === "single" ? defaultOpen.slice(0, 1) : defaultOpen.slice(),
  );

  const open = useMemo(
    () => (controlled ? controlled.slice() : uncontrolled),
    [controlled, uncontrolled],
  );

  const headers = useRef(new Map<string, HTMLButtonElement>());
  const binders = useRef(new Map<string, AccordionHeaderProps["ref"]>());

  const headerRef = useCallback((id: string): AccordionHeaderProps["ref"] => {
    const cached = binders.current.get(id);
    if (cached) return cached;
    const bind = (node: HTMLButtonElement | null) => {
      if (node) headers.current.set(id, node);
      else headers.current.delete(id);
    };
    binders.current.set(id, bind);
    return bind;
  }, []);

  const changed = useRef(onOpenChange);
  changed.current = onOpenChange;

  const commit = useCallback((next: string[]) => {
    setUncontrolled(next);
    changed.current?.(next);
  }, []);

  const isOpen = useCallback((id: string) => open.includes(id), [open]);

  const toggle = useCallback(
    (id: string) => {
      const active = open.includes(id);
      if (active && !collapsible && type === "single") return;
      if (type === "single") {
        commit(active ? [] : [id]);
        return;
      }
      commit(active ? open.filter((x) => x !== id) : [...open, id]);
    },
    [open, type, collapsible, commit],
  );

  const order = useMemo(() => items.map((item) => item.id), [items]);

  const move = useCallback(
    (id: string, delta: number, edge: "first" | "last" | null) => {
      if (order.length === 0) return;
      const at = order.indexOf(id);
      if (at < 0) return;
      const next =
        edge === "first"
          ? 0
          : edge === "last"
            ? order.length - 1
            : (at + delta + order.length) % order.length;
      headers.current.get(order[next])?.focus();
    },
    [order],
  );

  const headerProps = useCallback(
    (id: string): AccordionHeaderProps => ({
      id: `${base}-header-${id}`,
      ref: headerRef(id),
      type: "button",
      onClick: () => toggle(id),
      onKeyDown: (event: React.KeyboardEvent) => {
        if (event.key === "ArrowDown") {
          event.preventDefault();
          move(id, 1, null);
        } else if (event.key === "ArrowUp") {
          event.preventDefault();
          move(id, -1, null);
        } else if (event.key === "Home") {
          event.preventDefault();
          move(id, 0, "first");
        } else if (event.key === "End") {
          event.preventDefault();
          move(id, 0, "last");
        }
      },
      "aria-expanded": open.includes(id),
      "aria-controls": `${base}-panel-${id}`,
    }),
    [base, open, toggle, move, headerRef],
  );

  const panelProps = useCallback(
    (id: string): AccordionPanelProps => ({
      id: `${base}-panel-${id}`,
      role: "region",
      "aria-labelledby": `${base}-header-${id}`,
      "aria-hidden": open.includes(id) ? undefined : true,
    }),
    [base, open],
  );

  return { open, isOpen, toggle, headerProps, panelProps };
}

export type AccordionItem = {
  id: string;
  title: React.ReactNode;
  content: React.ReactNode;
  meta?: React.ReactNode;
};

export type AccordionProps = {
  items: readonly AccordionItem[];
  type?: "single" | "multiple";
  defaultOpen?: readonly string[];
  open?: readonly string[];
  onOpenChange?: (open: string[]) => void;
  collapsible?: boolean;
  maxPanelHeight?: number;
  headingLevel?: number;
  className?: string;
};

export function Accordion({
  items,
  type = "single",
  defaultOpen = NONE,
  open: controlled,
  onOpenChange,
  collapsible = true,
  maxPanelHeight = 220,
  headingLevel = 3,
  className = "",
}: AccordionProps) {
  const reduced = useReducedMotion();

  const entries = useMemo(() => items.map(({ id }) => ({ id })), [items]);

  const { isOpen, headerProps, panelProps } = useAccordion({
    items: entries,
    type,
    defaultOpen,
    open: controlled,
    onOpenChange,
    collapsible,
  });

  return (
    <div
      className={`divide-y divide-stone-200 overflow-hidden rounded-[11px] border border-stone-200 bg-white shadow-[0_1px_2px_rgba(28,25,23,0.06),0_4px_10px_-8px_rgba(28,25,23,0.45)] dark:divide-white/10 dark:border-white/[0.16] dark:bg-[#1D1D1A] dark:shadow-[0_1px_6px_rgba(0,0,0,0.45)] ${className}`}
    >
      {items.map((item) => (
        <AccordionRow
          key={item.id}
          item={item}
          open={isOpen(item.id)}
          reduced={Boolean(reduced)}
          maxPanelHeight={maxPanelHeight}
          headingLevel={headingLevel}
          header={headerProps(item.id)}
          panel={panelProps(item.id)}
        />
      ))}
    </div>
  );
}

function AccordionRow({
  item,
  open,
  reduced,
  maxPanelHeight,
  headingLevel,
  header,
  panel,
}: {
  item: AccordionItem;
  open: boolean;
  reduced: boolean;
  maxPanelHeight: number;
  headingLevel: number;
  header: AccordionHeaderProps;
  panel: AccordionPanelProps;
}) {
  const { ref, height, ready } = useAutoHeight();

  useEffect(() => {
    const el = ref.current as Inertable | null;
    if (!el) return;
    el.inert = !open;
    return () => {
      el.inert = false;
    };
  }, [ref, open]);

  return (
    <div>
      <div role="heading" aria-level={headingLevel}>
        <button
          {...header}
          className="flex w-full items-center gap-3 px-3.5 py-3 text-left outline-none transition-colors duration-150 hover:bg-stone-100 focus-visible:bg-[#4568FF]/[0.06] focus-visible:shadow-[inset_0_0_0_1px_#4568FF] dark:hover:bg-white/10 dark:focus-visible:bg-[#93B0FF]/[0.1] dark:focus-visible:shadow-[inset_0_0_0_1px_#93B0FF]"
        >
          <span
            className={`min-w-0 flex-1 truncate text-[13px] font-medium transition-colors duration-150 ${
              open
                ? "text-stone-900 dark:text-stone-50"
                : "text-stone-700 dark:text-stone-200"
            }`}
          >
            {item.title}
          </span>

          {item.meta ? (
            <span className="shrink-0 text-[11.5px] tabular-nums text-stone-400 dark:text-stone-500">
              {item.meta}
            </span>
          ) : null}

          <motion.svg
            width="13"
            height="13"
            viewBox="0 0 256 256"
            fill="none"
            aria-hidden="true"
            className="shrink-0 text-stone-500 dark:text-stone-400"
            initial={false}
            animate={{ rotate: open ? 180 : 0 }}
            transition={reduced ? { duration: 0 } : CHEVRON}
          >
            <path
              d="M208 96l-80 80-80-80"
              stroke="currentColor"
              strokeWidth="16"
              strokeLinecap="round"
              strokeLinejoin="round"
            />
          </motion.svg>
        </button>
      </div>
      <motion.div
        initial={false}
        animate={ready ? { height: open ? height : 0 } : {}}
        transition={reduced ? { duration: 0 } : DISCLOSE}
        style={{
          overflow: "hidden",
          height: ready ? undefined : open ? "auto" : 0,
        }}
      >
        <div
          {...panel}
          ref={ref}
          className="border-t border-stone-200 bg-stone-50 shadow-[inset_0_1px_2px_rgba(28,25,23,0.05)] dark:border-white/[0.16] dark:bg-white/[0.05] dark:shadow-[inset_0_1px_2px_rgba(0,0,0,0.3)]"
          style={{
            maxHeight: maxPanelHeight,
            overflowY: "auto",
            overscrollBehavior: "contain",

            scrollbarGutter: "stable",
          }}
        >
          <motion.div
            initial={false}
            animate={{ opacity: open ? 1 : 0 }}
            transition={
              reduced
                ? { duration: 0 }
                : open
                  ? { duration: 0.18, ease: EASE }
                  : { duration: 0.14, ease: EXIT_EASE }
            }
            className="px-3.5 pb-3.5 pt-3 text-[12.5px] leading-relaxed text-stone-500 dark:text-stone-400"
          >
            {item.content}
          </motion.div>
        </div>
      </motion.div>
    </div>
  );
}
```

---

## Wizard Steps · Navigation

Transition knows forward from back.

Docs: https://yugo.click/docs/wizard-steps
Install: `bun add motion`, then copy the source below into `components/yugo/wizard-steps.tsx` · or `bunx shadcn@latest add https://yugo.click/r/wizard-steps.json`.

Guarantees:
- The index and the direction are held in one state object, so no frame can render a new step with the previous direction: the bug where pressing Back slides forward for one frame and then corrects itself.
- The panel viewport is a fixed height with its own scroll, so a two-line step and a twenty-line step do not resize the page mid-transition and the Back button stays where the cursor left it.
- Next and Finish occupy the same grid cell and only opacity moves between them, so reaching the last step never changes the button's width.
- Under prefers-reduced-motion the panel still swaps and the markers still fill; only the travel and the blur are dropped, and nothing is hidden.
- Back and Next move focus into the new panel, arrow keys move focus along the step markers, and markers past the furthest step reached stay disabled so nobody lands on a step they have not filled in.
- Screen readers get one polite announcement per step: "Step 2 of 4: Billing details": instead of a stream of updates while the panel is in flight; the behaviour also ships alone as useWizard for anyone drawing their own chrome.


### Usage

```tsx
"use client";

import { useState } from "react";
import { WizardSteps, type WizardStep } from "@/components/yugo/wizard-steps";

export function WorkspaceOnboarding({ onDone }: { onDone: (v: { name: string; team: string }) => void }) {
  const [value, setValue] = useState({ name: "", team: "" });

  const steps: WizardStep[] = [
    {
      id: "profile",
      label: "Your profile",
      content: (
        <input
          value={value.name}
          onChange={(e) => setValue((v) => ({ ...v, name: e.target.value }))}
          placeholder="Full name"
          className="h-9 w-full rounded-[9px] border border-stone-200 px-3 text-[13px] outline-none dark:border-white/[0.16] dark:bg-[#1D1D1A]"
        />
      ),
    },
    {
      id: "team",
      label: "Invite your team",
      content: (
        <textarea
          value={value.team}
          onChange={(e) => setValue((v) => ({ ...v, team: e.target.value }))}
          placeholder="one email per line"
          className="h-24 w-full resize-none rounded-[9px] border border-stone-200 p-3 text-[13px] outline-none dark:border-white/[0.16] dark:bg-[#1D1D1A]"
        />
      ),
    },
    {
      id: "review",
      label: "Review",
      content: <p>{value.name || "Unnamed"}: {value.team.split("\n").filter(Boolean).length} invites queued.</p>,
    },
  ];

  return (
    <WizardSteps
      steps={steps}
      height={200}
      finishLabel="Create workspace"
      onComplete={() => onDone(value)}
    />
  );
}
```

### Source (`components/yugo/wizard-steps.tsx`)

```tsx
"use client";

import { useCallback, useEffect, useMemo, useRef, useState } from "react";
import type { KeyboardEvent, ReactNode } from "react";
import { AnimatePresence, motion, useReducedMotion } from "motion/react";

const EASE = [0.23, 1, 0.32, 1] as const;
const EXIT_EASE = [0.4, 0, 1, 1] as const;

const RAIL = { type: "spring", stiffness: 520, damping: 40, mass: 0.5 } as const;
const CROSSFADE = { type: "spring", stiffness: 260, damping: 34, mass: 0.8 } as const;

export type WizardDirection = 1 | -1;

export type UseWizardOptions = {
  total: number;
  index?: number;
  defaultIndex?: number;
  onIndexChange?: (index: number, direction: WizardDirection) => void;
  onComplete?: () => void;
};

export type UseWizardReturn = {
  index: number;
  direction: WizardDirection;
  furthest: number;
  total: number;
  isFirst: boolean;
  isLast: boolean;
  next: () => void;
  back: () => void;
  goTo: (index: number) => void;
};

function clampIndex(value: number, total: number) {
  if (total < 1) return 0;
  return Math.max(0, Math.min(total - 1, Math.trunc(value)));
}

export function useWizard({
  total,
  index,
  defaultIndex = 0,
  onIndexChange,
  onComplete,
}: UseWizardOptions): UseWizardReturn {
  const [internal, setInternal] = useState(() => clampIndex(defaultIndex, total));
  const current = clampIndex(index ?? internal, total);

  const [seen, setSeen] = useState<{ index: number; direction: WizardDirection }>({
    index: current,
    direction: 1,
  });
  if (seen.index !== current) {
    setSeen({ index: current, direction: current > seen.index ? 1 : -1 });
  }

  const [furthest, setFurthest] = useState(current);
  if (furthest < current) setFurthest(current);

  const emit = useRef(onIndexChange);
  emit.current = onIndexChange;
  const finish = useRef(onComplete);
  finish.current = onComplete;

  const controlled = index !== undefined;

  const goTo = useCallback(
    (to: number) => {
      const target = clampIndex(to, total);
      if (target === current) return;
      const direction: WizardDirection = target > current ? 1 : -1;
      if (!controlled) setInternal(target);
      emit.current?.(target, direction);
    },
    [controlled, current, total],
  );

  const next = useCallback(() => {
    if (current >= total - 1) {
      finish.current?.();
      return;
    }
    goTo(current + 1);
  }, [current, goTo, total]);

  const back = useCallback(() => goTo(current - 1), [current, goTo]);

  return {
    index: current,
    direction: seen.direction,
    furthest: Math.min(furthest, Math.max(total - 1, 0)),
    total,
    isFirst: current === 0,
    isLast: current === total - 1,
    next,
    back,
    goTo,
  };
}

export type WizardStep = {
  id: string;
  label: string;
  content: ReactNode;
};

export type WizardStepsProps = {
  steps: WizardStep[];
  index?: number;
  defaultIndex?: number;
  onIndexChange?: (index: number, direction: WizardDirection) => void;
  onComplete?: () => void;

  complete?: boolean;
  height?: number;
  backLabel?: string;
  nextLabel?: string;
  finishLabel?: string;
  completeLabel?: string;
  completeHint?: string;
  label?: string;
  className?: string;
};

export function WizardSteps({
  steps,
  index,
  defaultIndex = 0,
  onIndexChange,
  onComplete,
  complete = false,
  height = 184,
  backLabel = "Back",
  nextLabel = "Next",
  finishLabel = "Finish",
  completeLabel = "All set",
  completeHint = "Step back to change anything",
  label = "Steps",
  className = "",
}: WizardStepsProps) {
  const wizard = useWizard({
    total: steps.length,
    index,
    defaultIndex,
    onIndexChange,
    onComplete,
  });
  const reduced = useReducedMotion();

  const listRef = useRef<HTMLOListElement>(null);
  const viewportRef = useRef<HTMLDivElement>(null);
  const intent = useRef<"list" | "panel" | null>(null);

  const { index: at, direction, furthest, total, isFirst, isLast, next, back, goTo } = wizard;

  useEffect(() => {
    const move = intent.current;
    intent.current = null;
    if (move === "list") {
      listRef.current
        ?.querySelector<HTMLButtonElement>('button[data-current="true"]')
        ?.focus();
      return;
    }
    if (move === "panel") viewportRef.current?.focus({ preventScroll: true });
  }, [at]);

  const variants = useMemo(
    () => ({
      enter: (d: WizardDirection) => (reduced ? { opacity: 0 } : { opacity: 0, x: d * 22 }),
      center: reduced ? { opacity: 1 } : { opacity: 1, x: 0 },
      exit: (d: WizardDirection) =>
        reduced
          ? { opacity: 0, transition: { duration: 0 } }
          : {
              opacity: 0,
              x: d * -22,
              transition: { duration: 0.14, ease: EXIT_EASE },
            },
    }),
    [reduced],
  );

  const panelTransition = reduced ? { duration: 0 } : CROSSFADE;

  const onStepKeyDown = (e: KeyboardEvent<HTMLElement>) => {
    let target = at;
    if (e.key === "ArrowRight" || e.key === "ArrowDown") target = at + 1;
    else if (e.key === "ArrowLeft" || e.key === "ArrowUp") target = at - 1;
    else if (e.key === "Home") target = 0;
    else if (e.key === "End") target = furthest;
    else return;
    e.preventDefault();
    target = Math.min(clampIndex(target, total), furthest);
    if (target === at) return;
    intent.current = "list";
    goTo(target);
  };

  const step = steps[at];
  if (!step) return null;

  const position = `Step ${at + 1} of ${total}: ${step.label}`;

  return (
    <div className={`w-full ${className}`}>
      <p aria-live="polite" className="sr-only">
        {position}
      </p>
      <span
        aria-hidden
        className="mb-2 grid select-none text-[13px] font-medium text-stone-700 dark:text-stone-200"
      >
        {steps.map((s, i) => (
          <motion.span
            key={s.id}
            className="col-start-1 row-start-1 truncate"
            initial={false}
            animate={{ opacity: i === at ? 1 : 0 }}
            transition={reduced ? { duration: 0 } : CROSSFADE}
          >
            {s.label}
          </motion.span>
        ))}
      </span>
      <ol
        ref={listRef}
        aria-label={label}
        className="mb-4 flex list-none items-center gap-1 p-0"
      >
        {steps.map((s, i) => {
          const done = complete || i < at;
          const here = !complete && i === at;

          const tile = (
            <motion.span
              aria-hidden
              className={`grid size-7 place-items-center rounded-[8px] border text-[11.5px] font-medium tabular-nums shadow-[0_1px_2px_rgba(28,25,23,0.06),0_4px_10px_-8px_rgba(28,25,23,0.45)] transition-colors duration-150 dark:shadow-[0_1px_6px_rgba(0,0,0,0.45)] ${
                done
                  ? "border-stone-800 bg-stone-800 text-white dark:border-stone-100 dark:bg-stone-100 dark:text-stone-900"
                  : here
                    ? "border-stone-200 bg-white text-stone-700 dark:border-white/[0.16] dark:bg-[#1D1D1A] dark:text-stone-100"
                    : "border-stone-200 bg-white text-stone-400 dark:border-white/[0.16] dark:bg-[#1D1D1A] dark:text-stone-500"
              }`}
              initial={false}
              animate={{ scale: here ? 1 : 0.92 }}
              transition={reduced ? { duration: 0 } : RAIL}
            >
              {done ? (
                <svg
                  width="12"
                  height="12"
                  viewBox="0 0 256 256"
                  fill="none"
                  aria-hidden="true"
                >
                  <polyline
                    points="216 72 104 184 48 128"
                    stroke="currentColor"
                    strokeWidth="24"
                    strokeLinecap="round"
                    strokeLinejoin="round"
                  />
                </svg>
              ) : (
                i + 1
              )}
            </motion.span>
          );

          return (
            <li key={s.id} className="flex flex-1 items-center gap-1 last:flex-none">

              {i <= furthest ? (
                <button
                  type="button"
                  data-current={here ? "true" : undefined}
                  tabIndex={here ? 0 : -1}
                  aria-current={here ? "step" : undefined}
                  aria-label={`Step ${i + 1} of ${total}: ${s.label}`}
                  onKeyDown={onStepKeyDown}
                  onClick={() => {
                    if (here) return;
                    intent.current = "list";
                    goTo(i);
                  }}
                  className="rounded-[8px] outline-none focus-visible:shadow-[0_0_0_1.5px_#4568FF] dark:focus-visible:shadow-[0_0_0_1.5px_#93B0FF]"
                >
                  {tile}
                </button>
              ) : (
                <span>
                  <span className="sr-only">{`Step ${i + 1} of ${total}: ${s.label}`}</span>
                  {tile}
                </span>
              )}

              {i < total - 1 ? (
                <span
                  aria-hidden
                  className="relative h-[3px] flex-1 overflow-hidden rounded-[2px] bg-stone-100 shadow-[inset_0_1px_2px_rgba(28,25,23,0.07)] dark:bg-white/[0.06] dark:shadow-[inset_0_1px_2px_rgba(0,0,0,0.4)]"
                >
                  <motion.span
                    className="absolute inset-0 origin-left rounded-[2px] bg-stone-800 dark:bg-stone-100"
                    initial={false}
                    animate={{ scaleX: complete || i < at ? 1 : 0 }}
                    transition={reduced ? { duration: 0 } : RAIL}
                  />
                </span>
              ) : null}
            </li>
          );
        })}
      </ol>
      <div
        ref={viewportRef}
        tabIndex={-1}
        role="group"
        aria-label={position}
        style={{ height }}
        className="relative overflow-hidden rounded-[11px] border border-stone-200 bg-white shadow-[0_1px_2px_rgba(28,25,23,0.06),0_4px_10px_-8px_rgba(28,25,23,0.45)] outline-none transition-[border-color,box-shadow] duration-150 focus-visible:border-[#4568FF] dark:border-white/[0.16] dark:bg-[#1D1D1A] dark:shadow-[0_1px_6px_rgba(0,0,0,0.45)] dark:focus-visible:border-[#93B0FF]"
      >
        <AnimatePresence initial={false} custom={direction}>
          <motion.div
            key={complete ? "__complete" : step.id}
            custom={direction}
            variants={variants}
            initial="enter"
            animate="center"
            exit="exit"
            transition={panelTransition}
            style={{ scrollbarGutter: "stable" }}
            className="absolute inset-0 overflow-y-auto overscroll-contain p-4 text-[13.5px] leading-relaxed text-stone-700 dark:text-stone-200"
          >

            {complete ? (
              <div className="flex h-full flex-col items-center justify-center gap-1.5">
                <p className="text-[13px] font-medium text-stone-700 dark:text-stone-100">
                  {completeLabel}
                </p>
                <p className="text-[12.5px] text-stone-400 dark:text-stone-500">
                  {completeHint}
                </p>
              </div>
            ) : (
              step.content
            )}
          </motion.div>
        </AnimatePresence>
      </div>
      <div className="mt-3 flex h-9 items-center gap-3">
        <AnimatePresence initial={false}>
          {isFirst ? null : (
            <motion.button
              key="back"
              type="button"
              initial={{ opacity: 0 }}
              animate={{ opacity: 1 }}
              exit={{
                opacity: 0,
                transition: reduced ? { duration: 0 } : { duration: 0.12, ease: EXIT_EASE },
              }}
              transition={reduced ? { duration: 0 } : { duration: 0.16, ease: EASE }}
              onClick={() => {
                intent.current = "panel";
                back();
              }}
              className="h-9 rounded-[9px] border border-stone-200 bg-white px-3 text-[13px] font-medium text-stone-700 outline-none transition-[border-color,box-shadow] duration-150 hover:border-stone-300 focus-visible:border-[#4568FF] focus-visible:shadow-[0_1px_2px_rgba(28,25,23,0.08),0_10px_20px_-14px_rgba(69,104,255,0.6)] dark:border-white/[0.16] dark:bg-[#1D1D1A] dark:text-stone-200 dark:hover:border-white/20 dark:focus-visible:border-[#93B0FF] dark:focus-visible:shadow-[0_10px_20px_-14px_rgba(147,176,255,0.5)]"
            >
              {backLabel}
            </motion.button>
          )}
        </AnimatePresence>
        <AnimatePresence initial={false}>
          {complete ? null : (
            <motion.button
              key="advance"
              type="button"
              aria-label={isLast ? finishLabel : nextLabel}
              onClick={() => {
                if (!isLast) intent.current = "panel";
                next();
              }}
              initial={{ opacity: 0, scale: 0.96 }}
              animate={{ opacity: 1, scale: 1 }}
              exit={{
                opacity: 0,
                scale: 0.96,
                transition: reduced
                  ? { duration: 0 }
                  : { duration: 0.14, ease: EXIT_EASE },
              }}
              transition={reduced ? { duration: 0 } : CROSSFADE}
              className="ml-auto grid h-9 place-items-center rounded-[9px] bg-stone-800 px-3.5 text-[13px] font-medium text-white outline-none focus-visible:shadow-[inset_0_0_0_1.5px_#93B0FF] dark:bg-stone-100 dark:text-stone-900 dark:focus-visible:shadow-[inset_0_0_0_1.5px_#4568FF]"
            >
              <span aria-hidden className="invisible col-start-1 row-start-1">
                {finishLabel.length > nextLabel.length ? finishLabel : nextLabel}
              </span>
              <motion.span
                aria-hidden
                className="col-start-1 row-start-1"
                initial={false}
                animate={{ opacity: isLast ? 0 : 1 }}
                transition={reduced ? { duration: 0 } : CROSSFADE}
              >
                {nextLabel}
              </motion.span>
              <motion.span
                aria-hidden
                className="col-start-1 row-start-1"
                initial={false}
                animate={{ opacity: isLast ? 1 : 0 }}
                transition={reduced ? { duration: 0 } : CROSSFADE}
              >
                {finishLabel}
              </motion.span>
            </motion.button>
          )}
        </AnimatePresence>
      </div>
    </div>
  );
}
```

---

## Pagination · Navigation

The window moves, the row does not.

Docs: https://yugo.click/docs/pagination
Install: `bun add motion`, then copy the source below into `components/yugo/pagination.tsx` · or `bunx shadcn@latest add https://yugo.click/r/pagination.json`.

Guarantees:
- The slot count is identical at every page: the near-start, middle and near-end windows all resolve to the same number of cells, so moving from page 4 to page 5 can never change the row's width or shift the arrows under the cursor.
- The active marker is one always-mounted thumb translated between slots, the dropdown's answer rather than a shared-layout animation: it cannot fly in from a stale position, and slots need no measurement because their width is arithmetic.
- When the window slides, only the cells whose number changed remount, and the new number rolls in from the direction the window travelled; unchanged cells do not flicker.
- The arrows at their limits stay in the accessibility tree with aria-disabled and refuse the click in the handler, keeping our colours instead of the UA's disabled grey.
- Page changes are announced once through a status region after the page has held for half a second, so paging through quickly is one sentence, not a stutter of interruptions.
- Under prefers-reduced-motion the thumb and the numbers arrive instantly; nothing is hidden, only the travel is dropped.


### Usage

```tsx
"use client";

import { useRouter, useSearchParams } from "next/navigation";
import { Pagination } from "@/components/yugo/pagination";

export function ResultsPager({ total, perPage }: { total: number; perPage: number }) {
  const router = useRouter();
  const params = useSearchParams();
  const page = Math.max(1, Number(params.get("page") ?? 1));

  return (
    <Pagination
      count={Math.ceil(total / perPage)}
      page={page}
      label="Search results"
      onPageChange={(next) => {
        const query = new URLSearchParams(params);
        query.set("page", String(next));
        router.push(`?${query.toString()}`, { scroll: false });
      }}
    />
  );
}
```

### Source (`components/yugo/pagination.tsx`)

```tsx
"use client";

import { useCallback, useEffect, useRef, useState } from "react";
import { motion, useReducedMotion } from "motion/react";

const CELL = { type: "spring", stiffness: 520, damping: 34, mass: 0.45 } as const;

const EASE = [0.23, 1, 0.32, 1] as const;
const ROLL = { duration: 0.18, ease: EASE } as const;
const STILL = { duration: 0 } as const;

const slotFor = (digits: number) => Math.max(32, 18 + digits * 8);
const GAP = 4;

const range = (from: number, to: number) =>
  Array.from({ length: to - from + 1 }, (_, i) => from + i);

const arrow = (can: boolean) =>
  `flex h-8 w-8 shrink-0 items-center justify-center rounded-[9px] outline-none transition-colors duration-150 focus-visible:bg-[#4568FF]/[0.06] focus-visible:shadow-[inset_0_0_0_1px_#4568FF] dark:focus-visible:bg-[#93B0FF]/[0.1] dark:focus-visible:shadow-[inset_0_0_0_1px_#93B0FF] ${
    can
      ? "text-stone-500 hover:bg-stone-100 hover:text-stone-800 dark:text-stone-400 dark:hover:bg-white/[0.06] dark:hover:text-stone-200"
      : "text-stone-300 dark:text-white/20"
  }`;

export type PaginationItem = number | "gap-l" | "gap-r";

export function paginate(
  page: number,
  count: number,
  siblings: number,
  boundaries: number,
): PaginationItem[] {
  const total = 2 * boundaries + 2 * siblings + 3;
  if (count <= total) return range(1, count);

  const nearStart = page < boundaries + siblings + 2;
  const nearEnd = page > count - boundaries - siblings - 1;

  if (nearStart) {
    return [
      ...range(1, 2 * siblings + boundaries + 2),
      "gap-r",
      ...range(count - boundaries + 1, count),
    ];
  }
  if (nearEnd) {
    return [
      ...range(1, boundaries),
      "gap-l",
      ...range(count - 2 * siblings - boundaries - 1, count),
    ];
  }
  return [
    ...range(1, boundaries),
    "gap-l",
    ...range(page - siblings, page + siblings),
    "gap-r",
    ...range(count - boundaries + 1, count),
  ];
}

export type UsePaginationOptions = {
  count: number;
  page?: number;
  defaultPage?: number;
  siblings?: number;
  boundaries?: number;
  onPageChange?: (page: number) => void;
};

export function usePagination({
  count,
  page,
  defaultPage = 1,
  siblings = 1,
  boundaries = 1,
  onPageChange,
}: UsePaginationOptions) {
  const clampTo = useCallback(
    (value: number) => Math.min(Math.max(1, value), Math.max(1, count)),
    [count],
  );

  const [internal, setInternal] = useState(() => clampTo(defaultPage));
  const controlled = page !== undefined;
  const current = clampTo(controlled ? page : internal);

  const emit = useRef(onPageChange);
  emit.current = onPageChange;

  const previous = useRef(current);
  const direction = current >= previous.current ? 1 : -1;
  useEffect(() => {
    previous.current = current;
  }, [current]);

  const goTo = useCallback(
    (value: number) => {
      const next = clampTo(value);
      if (next === previous.current) return;
      if (!controlled) setInternal(next);
      emit.current?.(next);
    },
    [clampTo, controlled],
  );

  const items = paginate(current, count, siblings, boundaries);

  return {
    page: current,
    count,
    items,
    direction,
    thumbIndex: items.indexOf(current),
    canPrev: current > 1,
    canNext: current < count,
    goTo,
    prev: () => goTo(current - 1),
    next: () => goTo(current + 1),
  };
}

export type PaginationProps = {
  count: number;
  page?: number;
  defaultPage?: number;
  siblings?: number;
  boundaries?: number;
  onPageChange?: (page: number) => void;
  label?: string;
  className?: string;
};

function Chevron({ flip = false }: { flip?: boolean }) {
  return (
    <svg
      viewBox="0 0 12 12"
      width="12"
      height="12"
      aria-hidden="true"
      focusable="false"
      className={flip ? "-scale-x-100" : undefined}
    >
      <path
        d="M4.75 2.75 8 6l-3.25 3.25"
        fill="none"
        stroke="currentColor"
        strokeWidth="1.6"
        strokeLinecap="round"
        strokeLinejoin="round"
      />
    </svg>
  );
}

export function Pagination({
  count,
  page,
  defaultPage,
  siblings,
  boundaries,
  onPageChange,
  label = "Pagination",
  className = "",
}: PaginationProps) {
  const pagination = usePagination({
    count,
    page,
    defaultPage,
    siblings,
    boundaries,
    onPageChange,
  });
  const { items, direction, thumbIndex, canPrev, canNext } = pagination;
  const current = pagination.page;

  const reduced = useReducedMotion();
  const digits = String(Math.max(1, count)).length;
  const slot = slotFor(digits);

  const [spoken, setSpoken] = useState("");
  useEffect(() => {
    const t = setTimeout(
      () => setSpoken(`Page ${current} of ${Math.max(1, count)}`),
      500,
    );
    return () => clearTimeout(t);
  }, [current, count]);

  return (
    <nav aria-label={label} className={`inline-block ${className}`}>
      <div className="flex items-center" style={{ gap: GAP }}>
        <button
          type="button"
          aria-label="Previous page"
          aria-disabled={!canPrev}
          onClick={() => canPrev && pagination.prev()}
          className={arrow(canPrev)}
        >
          <Chevron flip />
        </button>
        <div className="relative">
          <motion.span
            aria-hidden
            initial={false}
            animate={{ x: thumbIndex * (slot + GAP) }}
            transition={reduced ? STILL : CELL}
            style={{ width: slot }}
            className="absolute inset-y-0 left-0 rounded-[9px] bg-stone-800 dark:bg-stone-100"
          />
          <ol className="relative flex" style={{ gap: GAP }}>
            {items.map((item) => {
              if (typeof item !== "number") {
                return (
                  <li
                    key={item}
                    aria-hidden
                    style={{ width: slot }}
                    className="flex h-8 items-center justify-center text-[12.5px] text-stone-400 dark:text-stone-500"
                  >
                    &hellip;
                  </li>
                );
              }

              const selected = item === current;
              return (
                <li key={`slot-${item}`} style={{ width: slot }}>
                  <button
                    type="button"
                    aria-label={`Page ${item}`}
                    aria-current={selected ? "page" : undefined}
                    onClick={() => pagination.goTo(item)}
                    className={`flex h-8 w-full items-center justify-center rounded-[9px] text-[12.5px] tabular-nums outline-none transition-colors duration-150 focus-visible:bg-[#4568FF]/[0.06] focus-visible:shadow-[inset_0_0_0_1px_#4568FF] dark:focus-visible:bg-[#93B0FF]/[0.1] dark:focus-visible:shadow-[inset_0_0_0_1px_#93B0FF] ${
                      selected
                        ? "font-medium text-white dark:text-stone-900"
                        : "text-stone-500 hover:bg-stone-100 hover:text-stone-800 dark:text-stone-400 dark:hover:bg-white/[0.06] dark:hover:text-stone-200"
                    }`}
                  >
                    <motion.span
                      key={item}
                      initial={
                        reduced ? false : { opacity: 0, x: 8 * direction }
                      }
                      animate={{ opacity: 1, x: 0 }}
                      transition={reduced ? STILL : ROLL}
                    >
                      {item}
                    </motion.span>
                  </button>
                </li>
              );
            })}
          </ol>
        </div>
        <button
          type="button"
          aria-label="Next page"
          aria-disabled={!canNext}
          onClick={() => canNext && pagination.next()}
          className={arrow(canNext)}
        >
          <Chevron />
        </button>
      </div>
      <span role="status" className="sr-only">
        {spoken}
      </span>
    </nav>
  );
}
```

---

## Tree View · Navigation

Disclosure the arrow keys can walk.

Docs: https://yugo.click/docs/tree-view
Install: `bun add motion`, then copy the source below into `components/yugo/tree-view.tsx` · or `bunx shadcn@latest add https://yugo.click/r/tree-view.json`.

Guarantees:
- The keyboard model is the full APG tree pattern, not a subset: arrows walk and fold, Home and End jump, Enter and Space choose, and typing a letter moves to the next visible name that starts with it.
- One tab stop for the whole tree. If the focused row is folded away by an ancestor, the stop falls back to the selection or the first row without stealing the browser's focus from wherever it actually is.
- A closed branch is not rendered and hidden: it is not rendered at all, so assistive technology is never handed rows the eye cannot reach.
- Disclosure runs height and opacity on separate clocks with opacity finishing first, so rows are fully formed before the reflow that reveals them has finished.
- aria-level, aria-setsize and aria-posinset are written from the data on every row, so a screen reader hears 'level 2, item 3 of 5' rather than a flat list.
- Every row reserves the caret's slot whether or not it has one, so labels in one list share one left edge instead of ragging on folder boundaries.
- Under prefers-reduced-motion branches open and close in place; the information arrives, the travel is skipped.


### Usage

```tsx
"use client";

import { useState } from "react";
import { TreeView, type TreeNode } from "@/components/yugo/tree-view";

const FILES: TreeNode[] = [
  {
    id: "src",
    label: "src",
    children: [
      { id: "index", label: "index.ts", meta: "2 kB" },
      { id: "config", label: "config.ts", meta: "1 kB" },
    ],
  },
  { id: "readme", label: "README.md", meta: "4 kB" },
];

export function FilePicker({ onOpen }: { onOpen: (id: string) => void }) {
  const [selected, setSelected] = useState<string | null>("readme");

  return (
    <TreeView
      nodes={FILES}
      label="Repository files"
      defaultExpanded={["src"]}
      selected={selected}
      onSelectedChange={(id) => {
        setSelected(id);
        onOpen(id);
      }}
      className="max-w-[280px]"
    />
  );
}
```

### Source (`components/yugo/tree-view.tsx`)

```tsx
"use client";

import { useCallback, useId, useRef, useState } from "react";
import { AnimatePresence, motion, useReducedMotion } from "motion/react";

const EASE = [0.23, 1, 0.32, 1] as const;

const LEAVE = [0.4, 0, 1, 1] as const;

const SMALL = { type: "spring", stiffness: 700, damping: 46, mass: 0.5 } as const;

const OPEN_H = { duration: 0.28, ease: EASE } as const;
const OPEN_O = { duration: 0.18, ease: EASE } as const;
const SHUT_H = { duration: 0.2, ease: LEAVE } as const;
const SHUT_O = { duration: 0.14, ease: LEAVE } as const;
const STILL = { duration: 0 } as const;

export type TreeNode = {
  id: string;
  label: string;

  meta?: string;
  children?: TreeNode[];
};

export type TreeRow = {
  node: TreeNode;
  level: number;
  parentId: string | null;
  posinset: number;
  setsize: number;
  branch: boolean;
  open: boolean;
};

function flatten(
  nodes: TreeNode[],
  openSet: ReadonlySet<string>,
  level = 1,
  parentId: string | null = null,
  out: TreeRow[] = [],
): TreeRow[] {
  nodes.forEach((node, i) => {
    const children = node.children ?? [];
    const branch = children.length > 0;
    const open = branch && openSet.has(node.id);
    out.push({
      node,
      level,
      parentId,
      posinset: i + 1,
      setsize: nodes.length,
      branch,
      open,
    });
    if (open) flatten(children, openSet, level + 1, node.id, out);
  });
  return out;
}

export type UseTreeViewOptions = {
  nodes: TreeNode[];
  expanded?: string[];
  defaultExpanded?: string[];
  onExpandedChange?: (expanded: string[]) => void;
  selected?: string | null;
  defaultSelected?: string | null;
  onSelectedChange?: (selected: string) => void;
};

export function useTreeView({
  nodes,
  expanded,
  defaultExpanded = [],
  onExpandedChange,
  selected,
  defaultSelected = null,
  onSelectedChange,
}: UseTreeViewOptions) {
  const [internalOpen, setInternalOpen] = useState<string[]>(defaultExpanded);
  const openControlled = expanded !== undefined;
  const openList = openControlled ? expanded : internalOpen;
  const openSet = new Set(openList);

  const [internalSel, setInternalSel] = useState<string | null>(defaultSelected);
  const selControlled = selected !== undefined;
  const selectedId = selControlled ? selected : internalSel;

  const emitOpen = useRef(onExpandedChange);
  emitOpen.current = onExpandedChange;
  const emitSel = useRef(onSelectedChange);
  emitSel.current = onSelectedChange;

  const rows = flatten(nodes, openSet);

  const [focusId, setFocusId] = useState<string | null>(null);
  const visible =
    focusId !== null && rows.some((r) => r.node.id === focusId)
      ? focusId
      : (rows.find((r) => r.node.id === selectedId)?.node.id ??
        rows[0]?.node.id ??
        null);

  const refs = useRef(new Map<string, HTMLElement>());
  const register = useCallback((id: string, el: HTMLElement | null) => {
    if (el) refs.current.set(id, el);
    else refs.current.delete(id);
  }, []);

  const focusRow = useCallback((id: string) => {
    setFocusId(id);
    refs.current.get(id)?.focus();
  }, []);

  const setOpen = useCallback(
    (next: string[]) => {
      if (!openControlled) setInternalOpen(next);
      emitOpen.current?.(next);
    },
    [openControlled],
  );

  const toggle = useCallback(
    (id: string) => {
      const has = openList.includes(id);
      setOpen(has ? openList.filter((v) => v !== id) : [...openList, id]);
    },
    [openList, setOpen],
  );

  const select = useCallback(
    (id: string) => {
      if (!selControlled) setInternalSel(id);
      emitSel.current?.(id);
    },
    [selControlled],
  );

  const handleKey = useCallback(
    (event: React.KeyboardEvent, row: TreeRow) => {
      const at = rows.findIndex((r) => r.node.id === row.node.id);
      const go = (index: number) => {
        const target = rows[index];
        if (target) focusRow(target.node.id);
      };

      switch (event.key) {
        case "ArrowDown":
          event.preventDefault();
          go(at + 1);
          return;
        case "ArrowUp":
          event.preventDefault();
          go(at - 1);
          return;
        case "ArrowRight":
          event.preventDefault();
          if (row.branch && !row.open) toggle(row.node.id);
          else if (row.open) go(at + 1);
          return;
        case "ArrowLeft":
          event.preventDefault();
          if (row.open) toggle(row.node.id);
          else if (row.parentId) focusRow(row.parentId);
          return;
        case "Home":
          event.preventDefault();
          go(0);
          return;
        case "End":
          event.preventDefault();
          go(rows.length - 1);
          return;
        case "Enter":
        case " ":
          event.preventDefault();
          select(row.node.id);
          if (row.branch) toggle(row.node.id);
          return;
        default:
      }

      if (event.key.length === 1 && !event.metaKey && !event.ctrlKey) {
        const letter = event.key.toLowerCase();
        if (letter === " ") return;
        for (let step = 1; step <= rows.length; step++) {
          const candidate = rows[(at + step) % rows.length];
          if (candidate.node.label.toLowerCase().startsWith(letter)) {
            event.preventDefault();
            focusRow(candidate.node.id);
            return;
          }
        }
      }
    },
    [rows, focusRow, toggle, select],
  );

  return {
    rows,
    openSet,
    selectedId,

    tabStop: visible,
    register,
    focusRow,
    setFocusId,
    toggle,
    select,
    handleKey,
  };
}

function Caret({ open }: { open: boolean }) {
  const reduced = useReducedMotion();
  return (
    <motion.span
      aria-hidden
      initial={false}
      animate={{ rotate: open ? 90 : 0 }}
      transition={reduced ? STILL : SMALL}
      className="flex size-4 shrink-0 items-center justify-center text-stone-400 dark:text-stone-500"
    >
      <svg viewBox="0 0 12 12" width="10" height="10" focusable="false">
        <path
          d="M4.5 2.5 8 6l-3.5 3.5"
          fill="none"
          stroke="currentColor"
          strokeWidth="1.6"
          strokeLinecap="round"
          strokeLinejoin="round"
        />
      </svg>
    </motion.span>
  );
}

export type TreeViewProps = {
  nodes: TreeNode[];
  label: string;
  expanded?: string[];
  defaultExpanded?: string[];
  onExpandedChange?: (expanded: string[]) => void;
  selected?: string | null;
  defaultSelected?: string | null;
  onSelectedChange?: (selected: string) => void;
  className?: string;
};

export function TreeView({
  nodes,
  label,
  expanded,
  defaultExpanded,
  onExpandedChange,
  selected,
  defaultSelected,
  onSelectedChange,
  className = "",
}: TreeViewProps) {
  const tree = useTreeView({
    nodes,
    expanded,
    defaultExpanded,
    onExpandedChange,
    selected,
    defaultSelected,
    onSelectedChange,
  });
  const reduced = useReducedMotion();
  const hintId = useId();

  const renderNodes = (list: TreeNode[], level: number) =>
    list.map((node, i) => {
      const row = tree.rows.find((r) => r.node.id === node.id);

      if (!row) return null;

      const isSelected = tree.selectedId === node.id;

      return (
        <li key={node.id} role="none">
          <div
            role="treeitem"
            ref={(el) => tree.register(node.id, el)}
            aria-level={level}
            aria-posinset={i + 1}
            aria-setsize={list.length}
            aria-expanded={row.branch ? row.open : undefined}
            aria-selected={isSelected}
            aria-describedby={hintId}
            tabIndex={tree.tabStop === node.id ? 0 : -1}
            onFocus={() => tree.setFocusId(node.id)}
            onKeyDown={(e) => tree.handleKey(e, row)}
            onClick={() => {
              tree.select(node.id);
              tree.focusRow(node.id);
              if (row.branch) tree.toggle(node.id);
            }}
            className={`flex h-7 cursor-default select-none items-center gap-1 rounded-[8px] px-1.5 outline-none transition-colors duration-150 focus-visible:bg-[#4568FF]/[0.06] focus-visible:shadow-[inset_0_0_0_1px_#4568FF] dark:focus-visible:bg-[#93B0FF]/[0.1] dark:focus-visible:shadow-[inset_0_0_0_1px_#93B0FF] ${
              isSelected
                ? "bg-stone-100/80 text-stone-800 dark:bg-white/[0.07] dark:text-stone-100"
                : "text-stone-600 hover:bg-stone-100/60 dark:text-stone-300 dark:hover:bg-white/[0.04]"
            }`}
          >

            {row.branch ? <Caret open={row.open} /> : <span className="size-4 shrink-0" />}

            <span
              className={`min-w-0 flex-1 truncate text-[12.5px] ${
                isSelected ? "font-medium" : ""
              }`}
            >
              {node.label}
            </span>

            {node.meta ? (
              <span className="shrink-0 font-mono text-[10.5px] tabular-nums text-stone-400 dark:text-stone-500">
                {node.meta}
              </span>
            ) : null}
          </div>

          {row.branch ? (
            <AnimatePresence initial={false}>
              {row.open ? (
                <motion.ul
                  key="group"
                  role="group"
                  initial={reduced ? { opacity: 0 } : { height: 0, opacity: 0 }}
                  animate={{ height: "auto", opacity: 1 }}
                  exit={
                    reduced
                      ? { opacity: 0, transition: STILL }
                      : {
                          height: 0,
                          opacity: 0,
                          transition: { height: SHUT_H, opacity: SHUT_O },
                        }
                  }
                  transition={
                    reduced ? STILL : { height: OPEN_H, opacity: OPEN_O }
                  }
                  className="overflow-hidden"
                >
                  <div className="ml-[13px] border-l border-stone-200/80 pl-[7px] dark:border-white/[0.16]">
                    {renderNodes(node.children ?? [], level + 1)}
                  </div>
                </motion.ul>
              ) : null}
            </AnimatePresence>
          ) : null}
        </li>
      );
    });

  return (
    <div
      className={`rounded-[13px] border border-stone-200 bg-white p-[5px] shadow-[0_1px_2px_rgba(28,25,23,0.06),0_4px_10px_-8px_rgba(28,25,23,0.45)] dark:border-white/[0.16] dark:bg-[#1D1D1A] dark:shadow-[0_1px_6px_rgba(0,0,0,0.45)] ${className}`}
    >
      <ul role="tree" aria-label={label}>
        {renderNodes(nodes, 1)}
      </ul>
      <span id={hintId} className="sr-only">
        Use the arrow keys to move. Right expands a folder, left collapses it
        or climbs to its parent. Home and End jump to the ends, and typing a
        letter jumps to the next name starting with it.
      </span>
    </div>
  );
}
```

---

## Disclosure · Navigation

One panel, measured, not guessed.

Docs: https://yugo.click/docs/disclosure
Install: `bun add motion`, then copy the source below into `components/yugo/disclosure.tsx` · or `bunx shadcn@latest add https://yugo.click/r/disclosure.json`.

Guarantees:
- The height is measured from the panel's own box with a ResizeObserver rather than read once on open, so a panel that rewraps on resize, or grows when a font or an image lands, never animates to a number that stopped being true.
- A closed panel is inert and aria-hidden, so Tab never lands on a link nobody can see and a screen reader never reads it out.
- The first paint renders closed at zero and open at auto and only starts animating once a real measurement exists, so nothing flashes open and snaps shut on hydration.
- The height spring is interruptible in both directions: toggling mid-flight retargets from the current height instead of restarting from zero.
- Opacity finishes before the height does, in 0.18s against the panel's own travel, which is what hides the reflow at the bottom edge.
- A subpixel guard sits on the measurement, so a fractional layout height cannot feed its own observer and loop.
- useDisclosure is the whole mechanism without a single class name: open state, the measured height, and the aria wiring for a trigger and a panel you draw yourself.


### Usage

```tsx
"use client";

import { useState } from "react";
import { Disclosure } from "@/components/yugo/disclosure";

export function LogPolicy() {
  const [open, setOpen] = useState(false);

  return (
    <Disclosure
      title="What we keep"
      meta="4 fields"
      open={open}
      onOpenChange={setOpen}
      maxHeight={200}
    >
      <p>
        Request path, response status, duration and the region that served it.
        Nothing that identifies a person, and nothing from the body.
      </p>
    </Disclosure>
  );
}
```

### Source (`components/yugo/disclosure.tsx`)

```tsx
"use client";

import { useCallback, useId, useRef, useState } from "react";
import {
  motion,
  useIsomorphicLayoutEffect,
  useReducedMotion,
} from "motion/react";

const EASE = [0.23, 1, 0.32, 1] as const;
const LEAVE = [0.4, 0, 1, 1] as const;

const DISCLOSE = {
  type: "spring",
  stiffness: 480,
  damping: 40,
  mass: 0.6,
} as const;

const CHEVRON = {
  type: "spring",
  stiffness: 700,
  damping: 46,
  mass: 0.5,
} as const;

const INSTANT = { duration: 0 } as const;

export type DisclosureTriggerProps = {
  id: string;
  type: "button";
  onClick: () => void;
  "aria-expanded": boolean;
  "aria-controls": string;
};

export type DisclosurePanelProps = {
  id: string;
  role: "region";
  "aria-labelledby": string;
  "aria-hidden": true | undefined;
};

export type UseDisclosureOptions = {
  open?: boolean;
  defaultOpen?: boolean;
  onOpenChange?: (open: boolean) => void;
};

export type UseDisclosureResult = {
  open: boolean;
  toggle: () => void;
  setOpen: (open: boolean) => void;
  /** goes on the panel's own content box: this is what gets measured */
  contentRef: React.RefObject<HTMLDivElement | null>;
  height: number;
  ready: boolean;
  triggerProps: DisclosureTriggerProps;
  panelProps: DisclosurePanelProps;
};

/**
 * One panel, opened and shut. The height is measured from the content's own
 * box with a ResizeObserver rather than read once on open, so a panel that
 * rewraps on resize — or grows when a font or an image lands — never animates
 * to a number that stopped being true.
 */
export function useDisclosure({
  open: controlled,
  defaultOpen = false,
  onOpenChange,
}: UseDisclosureOptions = {}): UseDisclosureResult {
  const base = useId();
  const [uncontrolled, setUncontrolled] = useState(defaultOpen);
  const [height, setHeight] = useState(0);
  const [ready, setReady] = useState(false);

  const contentRef = useRef<HTMLDivElement>(null);
  const open = controlled ?? uncontrolled;

  const emit = useRef(onOpenChange);
  emit.current = onOpenChange;

  const setOpen = useCallback(
    (next: boolean) => {
      if (controlled === undefined) setUncontrolled(next);
      emit.current?.(next);
    },
    [controlled],
  );

  const toggle = useCallback(() => setOpen(!open), [setOpen, open]);

  useIsomorphicLayoutEffect(() => {
    const el = contentRef.current;
    if (!el) return;

    const read = () => {
      const next = el.getBoundingClientRect().height;
      // An epsilon, so a subpixel layout cannot feed itself. §21
      setHeight((prev) => (Math.abs(prev - next) < 0.5 ? prev : next));
    };

    read();
    setReady(true);

    const observer = new ResizeObserver(read);
    observer.observe(el);
    return () => observer.disconnect();
  }, []);

  return {
    open,
    toggle,
    setOpen,
    contentRef,
    height,
    ready,
    triggerProps: {
      id: `${base}-trigger`,
      type: "button",
      onClick: toggle,
      "aria-expanded": open,
      "aria-controls": `${base}-panel`,
    },
    panelProps: {
      id: `${base}-panel`,
      role: "region",
      "aria-labelledby": `${base}-trigger`,
      "aria-hidden": open ? undefined : true,
    },
  };
}

export type DisclosureProps = UseDisclosureOptions & {
  title: React.ReactNode;
  children: React.ReactNode;
  meta?: React.ReactNode;
  maxHeight?: number;
  headingLevel?: number;
  className?: string;
};

export function Disclosure({
  title,
  children,
  meta,
  maxHeight = 220,
  headingLevel = 3,
  className = "",
  ...options
}: DisclosureProps) {
  const reduced = useReducedMotion();
  const { open, contentRef, height, ready, triggerProps, panelProps } =
    useDisclosure(options);

  return (
    <div
      className={`overflow-hidden rounded-[11px] border border-stone-200 bg-white shadow-[0_1px_2px_rgba(28,25,23,0.06),0_4px_10px_-8px_rgba(28,25,23,0.45)] dark:border-white/[0.16] dark:bg-[#1D1D1A] dark:shadow-[0_1px_6px_rgba(0,0,0,0.45)] ${className}`}
    >
      <div role="heading" aria-level={headingLevel}>
        <button
          {...triggerProps}
          className="flex w-full items-center gap-3 px-3.5 py-3 text-left outline-none transition-colors duration-150 hover:bg-stone-100 focus-visible:bg-[#4568FF]/[0.06] focus-visible:shadow-[inset_0_0_0_1px_#4568FF] dark:hover:bg-white/10 dark:focus-visible:bg-[#93B0FF]/[0.1] dark:focus-visible:shadow-[inset_0_0_0_1px_#93B0FF]"
        >
          <span
            className={`min-w-0 flex-1 truncate text-[13px] font-medium transition-colors duration-150 ${
              open
                ? "text-stone-900 dark:text-stone-50"
                : "text-stone-700 dark:text-stone-200"
            }`}
          >
            {title}
          </span>

          {meta ? (
            <span className="shrink-0 text-[11.5px] tabular-nums text-stone-400 dark:text-stone-500">
              {meta}
            </span>
          ) : null}

          <motion.svg
            width="13"
            height="13"
            viewBox="0 0 256 256"
            fill="none"
            aria-hidden="true"
            className="shrink-0 text-stone-500 dark:text-stone-400"
            initial={false}
            animate={{ rotate: open ? 180 : 0 }}
            transition={reduced ? INSTANT : CHEVRON}
          >
            <path
              d="M208 96l-80 80-80-80"
              stroke="currentColor"
              strokeWidth="16"
              strokeLinecap="round"
              strokeLinejoin="round"
            />
          </motion.svg>
        </button>
      </div>

      <motion.div
        initial={false}
        animate={ready ? { height: open ? height : 0 } : {}}
        transition={reduced ? INSTANT : DISCLOSE}
        style={{
          overflow: "hidden",
          height: ready ? undefined : open ? "auto" : 0,
        }}
      >
        <div
          {...panelProps}
          ref={contentRef}
          inert={!open}
          className="border-t border-stone-200 bg-stone-50 shadow-[inset_0_1px_2px_rgba(28,25,23,0.05)] dark:border-white/[0.16] dark:bg-white/[0.05] dark:shadow-[inset_0_1px_2px_rgba(0,0,0,0.3)]"
          style={{
            maxHeight,
            overflowY: "auto",
            overscrollBehavior: "contain",
            scrollbarGutter: "stable",
          }}
        >
          {/* Opacity finishes before the height does, which is what hides the
              reflow at the bottom edge. §5 */}
          <motion.div
            initial={false}
            animate={{ opacity: open ? 1 : 0 }}
            transition={
              reduced
                ? INSTANT
                : open
                  ? { duration: 0.18, ease: EASE }
                  : { duration: 0.14, ease: LEAVE }
            }
            className="px-3.5 pb-3.5 pt-3 text-[12.5px] leading-relaxed text-stone-500 dark:text-stone-400"
          >
            {children}
          </motion.div>
        </div>
      </motion.div>
    </div>
  );
}
```

---

## Dynamic Toolbar · Navigation

A toolbar that becomes the field it opened.

Docs: https://yugo.click/docs/dynamic-toolbar
Install: `bun add motion`, then copy the source below into `components/yugo/dynamic-toolbar.tsx` · or `bunx shadcn@latest add https://yugo.click/r/dynamic-toolbar.json`.

Guarantees:
- The shell travels to a measured number, never a magic one. Every mode is laid out at its natural width and watched by one ResizeObserver, so adding a button or lengthening a placeholder changes the shell without anybody editing a pixel value.
- Inactive modes stay mounted so they can be measured, and are inert and aria-hidden while they wait: nothing off-mode is reachable by Tab or announced, and the shell still knows how big it would be.
- The active mode is the one in flow. That is what gives the shell a real size on the first paint, before a single measurement has come back.
- Changing mode moves focus to the first focusable thing in the mode it opened, which is the entire point of a toolbar that becomes a field. Mounting is not a mode change, so nothing is stolen on load.
- Escape returns home only when focus is actually inside the toolbar, and it stops propagating so it does not also close whatever the toolbar is sitting in.
- A subpixel guard sits on the measurement, so a fractional width cannot feed its own observer and loop.
- The shell is 14 and its padding is 4, which makes the interior 10: the same radius and the same height every field in the set is drawn at, so a mode that becomes an input sits on the line the keys left behind.
- useDynamicToolbar is the measurement, the mode state and the dismissal wiring, for a shell you want to draw yourself.


### Usage

```tsx
"use client";

import { useState } from "react";
import { DynamicToolbar, ToolbarAction } from "@/components/yugo/dynamic-toolbar";

export function NotesBar() {
  const [mode, setMode] = useState("actions");
  const [query, setQuery] = useState("");

  return (
    <DynamicToolbar
      label="Notes toolbar"
      mode={mode}
      onModeChange={setMode}
      modes={[
        {
          id: "actions",
          content: (
            <ToolbarAction label="Search notes" onClick={() => setMode("search")}>
              <SearchIcon />
            </ToolbarAction>
          ),
        },
        {
          id: "search",
          content: (
            <input
              value={query}
              onChange={(event) => setQuery(event.currentTarget.value)}
              aria-label="Search notes"
              className="h-10 w-[212px] rounded-[10px]"
            />
          ),
        },
      ]}
    />
  );
}
```

### Source (`components/yugo/dynamic-toolbar.tsx`)

```tsx
"use client";

import { useCallback, useEffect, useMemo, useRef, useState } from "react";
import {
  motion,
  useIsomorphicLayoutEffect,
  useReducedMotion,
} from "motion/react";

const SHELL = {
  type: "spring",
  stiffness: 380,
  damping: 38,
  mass: 0.7,
} as const;

const CROSSFADE = {
  type: "spring",
  stiffness: 260,
  damping: 34,
  mass: 0.8,
} as const;

const INSTANT = { duration: 0 } as const;

const FOCUSABLE =
  'a[href],button:not([disabled]),input:not([disabled]),select:not([disabled]),textarea:not([disabled]),[tabindex]:not([tabindex="-1"])';

type Box = { width: number; height: number };

export type UseDynamicToolbarOptions = {
  modes: readonly string[];
  mode?: string;
  defaultMode?: string;
  onModeChange?: (mode: string) => void;
};

export type UseDynamicToolbarResult = {
  rootRef: React.RefObject<HTMLDivElement | null>;
  mode: string;
  /** the active mode's own measured box, or null before the first read */
  box: Box | null;
  ready: boolean;
  setMode: (mode: string) => void;
  dismiss: () => void;
  measure: (id: string) => (node: HTMLDivElement | null) => void;
};

/**
 * The shell travels to a measured number, never to a magic one. Each mode is
 * laid out at its natural width and watched by one ResizeObserver, so adding
 * a button or lengthening a placeholder changes the shell without anybody
 * editing a pixel value.
 */
export function useDynamicToolbar({
  modes,
  mode: controlled,
  defaultMode,
  onModeChange,
}: UseDynamicToolbarOptions): UseDynamicToolbarResult {
  const home = defaultMode ?? modes[0] ?? "";

  const rootRef = useRef<HTMLDivElement>(null);
  const [uncontrolled, setUncontrolled] = useState(home);
  const [boxes, setBoxes] = useState<Record<string, Box>>({});
  const [turn, setTurn] = useState(0);

  const mode = controlled ?? uncontrolled;

  const panels = useRef(new Map<string, HTMLDivElement>());
  const binders = useRef(
    new Map<string, (node: HTMLDivElement | null) => void>(),
  );
  const observer = useRef<ResizeObserver | null>(null);

  const emit = useRef(onModeChange);
  emit.current = onModeChange;

  const live = useRef({ mode, home });
  live.current = { mode, home };

  const read = useCallback((id: string, node: HTMLElement) => {
    const rect = node.getBoundingClientRect();
    setBoxes((prev) => {
      const at = prev[id];
      // An epsilon, so a fractional width cannot feed its own observer. §21
      if (
        at &&
        Math.abs(at.width - rect.width) < 0.5 &&
        Math.abs(at.height - rect.height) < 0.5
      ) {
        return prev;
      }
      return { ...prev, [id]: { width: rect.width, height: rect.height } };
    });
  }, []);

  const measure = useCallback(
    (id: string) => {
      const cached = binders.current.get(id);
      if (cached) return cached;

      const bind = (node: HTMLDivElement | null) => {
        const previous = panels.current.get(id);
        if (previous && previous !== node) observer.current?.unobserve(previous);
        if (!node) {
          panels.current.delete(id);
          return;
        }
        panels.current.set(id, node);
        observer.current?.observe(node);
        read(id, node);
      };

      binders.current.set(id, bind);
      return bind;
    },
    [read],
  );

  useIsomorphicLayoutEffect(() => {
    const watcher = new ResizeObserver((entries) => {
      for (const entry of entries) {
        for (const [id, node] of panels.current) {
          if (node === entry.target) read(id, node);
        }
      }
    });

    observer.current = watcher;
    for (const [id, node] of panels.current) {
      watcher.observe(node);
      read(id, node);
    }

    return () => {
      watcher.disconnect();
      observer.current = null;
    };
  }, [read]);

  const setMode = useCallback(
    (next: string) => {
      if (live.current.mode === next) return;
      if (controlled === undefined) setUncontrolled(next);
      emit.current?.(next);
      setTurn((count) => count + 1);
    },
    [controlled],
  );

  const dismiss = useCallback(() => setMode(live.current.home), [setMode]);

  // A toolbar that becomes a field has to put the caret in the field. The
  // count, not the mode, is the dependency: mounting is not a mode change,
  // so nothing is stolen on the first paint.
  useEffect(() => {
    if (turn === 0) return;
    const node = panels.current.get(live.current.mode);
    node?.querySelector<HTMLElement>(FOCUSABLE)?.focus({ preventScroll: true });
  }, [turn]);

  useEffect(() => {
    if (mode === home) return;

    const onPointerDown = (event: PointerEvent) => {
      const target = event.target as Node | null;
      if (!target || rootRef.current?.contains(target)) return;
      dismiss();
    };

    const onKeyDown = (event: KeyboardEvent) => {
      if (event.key !== "Escape") return;
      if (!rootRef.current?.contains(document.activeElement)) return;
      event.stopPropagation();
      dismiss();
    };

    document.addEventListener("pointerdown", onPointerDown, true);
    document.addEventListener("keydown", onKeyDown, true);
    return () => {
      document.removeEventListener("pointerdown", onPointerDown, true);
      document.removeEventListener("keydown", onKeyDown, true);
    };
  }, [mode, home, dismiss]);

  const box = boxes[mode] ?? null;

  return { rootRef, mode, box, ready: box !== null, setMode, dismiss, measure };
}

export type ToolbarMode = {
  id: string;
  content: React.ReactNode;
};

export type DynamicToolbarProps = Omit<UseDynamicToolbarOptions, "modes"> & {
  modes: readonly ToolbarMode[];
  label: string;
  className?: string;
};

export function DynamicToolbar({
  modes,
  label,
  className = "",
  ...options
}: DynamicToolbarProps) {
  const reduced = useReducedMotion();
  const ids = useMemo(() => modes.map((entry) => entry.id), [modes]);

  const { rootRef, mode, box, measure } = useDynamicToolbar({
    ...options,
    modes: ids,
  });

  return (
    <div ref={rootRef} className={`inline-block ${className}`}>
      <motion.div
        role="group"
        aria-label={label}
        initial={false}
        animate={box ? { width: box.width, height: box.height } : {}}
        transition={reduced ? INSTANT : SHELL}
        style={{
          overflow: "hidden",
          width: box ? undefined : "max-content",
          height: box ? undefined : "auto",
        }}
        className="relative rounded-[14px] border border-stone-200 bg-white shadow-[0_1px_2px_rgba(28,25,23,0.06),0_4px_10px_-8px_rgba(28,25,23,0.45)] dark:border-white/[0.16] dark:bg-[#1D1D1A] dark:shadow-[0_1px_6px_rgba(0,0,0,0.45)]"
      >
        {modes.map((entry) => {
          const active = entry.id === mode;
          return (
            <motion.div
              key={entry.id}
              ref={measure(entry.id)}
              inert={!active}
              aria-hidden={!active}
              initial={false}
              animate={{ opacity: active ? 1 : 0 }}
              transition={
                reduced
                  ? INSTANT
                  : { ...CROSSFADE, delay: active ? 0.05 : 0 }
              }
              // The inactive modes stay mounted at their natural width so
              // they can be measured; only the active one is in flow, so the
              // shell has a real size before anything has been observed.
              className={`w-max p-1 ${
                active ? "relative" : "pointer-events-none absolute left-0 top-0"
              }`}
            >
              {entry.content}
            </motion.div>
          );
        })}
      </motion.div>
    </div>
  );
}

export type ToolbarActionProps = {
  children: React.ReactNode;
  label: string;
  onClick?: () => void;
  disabled?: boolean;
};

/** The key inside the shell: 14 outer − 4 padding = 10, which is also the
 *  height every field in the set is drawn at, so a mode that becomes an
 *  input sits on the same line as the keys it replaced. §4 */
export function ToolbarAction({
  children,
  label,
  onClick,
  disabled = false,
}: ToolbarActionProps) {
  return (
    <button
      type="button"
      onClick={onClick}
      disabled={disabled}
      aria-label={label}
      className="grid size-10 shrink-0 place-items-center rounded-[10px] text-stone-500 outline-none transition-colors duration-150 hover:bg-stone-100 hover:text-stone-800 focus-visible:bg-[#4568FF]/[0.06] focus-visible:shadow-[inset_0_0_0_1px_#4568FF] disabled:pointer-events-none disabled:opacity-50 dark:text-stone-400 dark:hover:bg-white/10 dark:hover:text-stone-100 dark:focus-visible:bg-[#93B0FF]/[0.1] dark:focus-visible:shadow-[inset_0_0_0_1px_#93B0FF]"
    >
      {children}
    </button>
  );
}
```

---

## Sticky Header · Scroll

Condenses as you go down.

Docs: https://yugo.click/docs/sticky-header
Install: `bun add motion`, then copy the source below into `components/yugo/sticky-header.tsx` · or `bunx shadcn@latest add https://yugo.click/r/sticky-header.json`.

Guarantees:
- The expanded height is reserved by a spacer from the first paint, so condensing moves nothing below it; a header that shrinks inside the flow instead pulls its own scroll position and oscillates around the threshold.
- The bar's edge is driven by a scaleY on a plain plate and a translate on the hairline, so no height, top or width property is animated while you scroll: and every value is a MotionValue read off the scroll position, so React renders once, at the threshold.
- The two titles never share a frame: the large one is gone by 0.45, the compact one arrives after 0.55, so the handoff has a beat of silence in it instead of two crossfading ghosts mid-scroll.
- Content is never guillotined at the bar. As rows pass underneath, a hairline, a dissolving gradient and a cast shadow arrive together on the same edge: the shadow baked onto a strip whose opacity is composited, never a box-shadow repainted per scroll frame: and the foot of the box fades the same way.
- One copy of the title reaches the accessibility tree; the compact duplicate is aria-hidden, so the region is announced once rather than twice per scroll. The region itself is focusable, with scroll-padding equal to the condensed height so tabbing to a row never parks it under the bar.
- The condense is decoupled from the geometry: the header moves ~20px but the transition is paid out over ~64px of scroll, through a spring, so a hard flick lands as a settle instead of a cut. Under prefers-reduced-motion the spring is bypassed and every value resolves on the frame it is scrolled to.


### Usage

```tsx
import { StickyHeader } from "@/components/yugo/sticky-header";
import { InvoiceRow } from "@/components/invoice-row";

export function InvoicePanel({ invoices }: { invoices: Invoice[] }) {
  const open = invoices.filter((i) => !i.paid).length;

  return (
    <StickyHeader
      title="Invoices"
      subtitle={`${open} awaiting payment`}
      maxHeight={420}
      leading={<BackButton href="/billing" />}
      actions={<NewInvoiceButton />}
    >
      <ul className="px-2 pb-3">
        {invoices.map((invoice) => (
          <InvoiceRow key={invoice.id} invoice={invoice} />
        ))}
      </ul>
    </StickyHeader>
  );
}
```

### Source (`components/yugo/sticky-header.tsx`)

```tsx
"use client";

import { useRef, useState } from "react";
import {
  motion,
  useMotionValueEvent,
  useReducedMotion,
  useScroll,
  useSpring,
  useTransform,
  type MotionValue,
} from "motion/react";

const SMOOTH = { stiffness: 240, damping: 44, mass: 0.6 } as const;

export type UseCondenseOptions = {
  range?: number;
};

export type UseCondenseResult<T extends HTMLElement> = {
  ref: React.RefObject<T | null>;
  progress: MotionValue<number>;
  condensed: boolean;
};

export function useCondense<T extends HTMLElement = HTMLDivElement>({
  range = 48,
}: UseCondenseOptions = {}): UseCondenseResult<T> {
  const ref = useRef<T | null>(null);
  const { scrollY } = useScroll({ container: ref });

  const progress = useTransform(scrollY, [0, Math.max(1, range)], [0, 1], {
    clamp: true,
  });

  const [condensed, setCondensed] = useState(false);
  useMotionValueEvent(progress, "change", (p) => {
    const done = p >= 1;
    setCondensed((prev) => (prev === done ? prev : done));
  });

  return { ref, progress, condensed };
}

export type StickyHeaderProps = {
  title: string;
  children: React.ReactNode;
  subtitle?: string;
  leading?: React.ReactNode;
  actions?: React.ReactNode;
  expandedHeight?: number;
  compactHeight?: number;
  maxHeight?: number;
  className?: string;
};

export function StickyHeader({
  title,
  children,
  subtitle,
  leading,
  actions,
  expandedHeight = 68,
  compactHeight = 48,
  maxHeight = 320,
  className = "",
}: StickyHeaderProps) {
  const tall = Math.max(expandedHeight, compactHeight);
  const short = Math.min(expandedHeight, compactHeight);
  const travel = Math.max(1, tall - short);

  const { ref, progress: tracked, condensed } = useCondense<HTMLDivElement>({
    range: Math.max(64, travel * 3),
  });
  const reduced = useReducedMotion();
  const sprung = useSpring(tracked, SMOOTH);
  const progress = reduced ? tracked : sprung;

  const plate = useTransform(progress, (p) => (tall - travel * p) / tall);
  const edge = useTransform(progress, (p) => tall - travel * p);
  const lifted = useTransform(progress, [0, 0.12], [0, 1], { clamp: true });

  const bigY = useTransform(progress, (p) => -travel * p);
  const bigOpacity = useTransform(progress, [0, 0.45], [1, 0], { clamp: true });
  const bigScale = useTransform(progress, (p) => 1 - 0.05 * p);

  const smallOpacity = useTransform(progress, [0.55, 0.9], [0, 1], {
    clamp: true,
  });
  const smallY = useTransform(smallOpacity, (o) => (1 - o) * 6);

  return (
    <div
      className={`relative overflow-hidden rounded-[14px] border border-stone-200 bg-white shadow-[0_1px_2px_rgba(28,25,23,0.06),0_4px_10px_-8px_rgba(28,25,23,0.45)] dark:border-white/[0.16] dark:bg-[#1D1D1A] dark:shadow-[0_1px_6px_rgba(0,0,0,0.45)] ${className}`}
    >
      <div
        ref={ref}

        // eslint-disable-next-line jsx-a11y/no-noninteractive-tabindex
        tabIndex={0}
        role="region"
        aria-label={title}
        style={{ maxHeight, scrollPaddingTop: short + 10 }}
        className="overflow-y-auto overscroll-y-contain outline-none [scrollbar-gutter:stable] focus-visible:bg-[#4568FF]/[0.06] focus-visible:shadow-[inset_0_0_0_1px_#4568FF] dark:focus-visible:bg-[#93B0FF]/[0.06] dark:focus-visible:shadow-[inset_0_0_0_1px_#93B0FF]"
      >
        <div aria-hidden style={{ height: tall }} />
        {children}

        <div
          aria-hidden
          className="pointer-events-none sticky bottom-0 -mt-6 h-6 bg-gradient-to-t from-white to-transparent dark:from-[#1D1D1A]"
        />
      </div>
      <header
        data-condensed={condensed ? "true" : "false"}
        style={{ height: tall }}
        className="pointer-events-none absolute inset-x-0 top-0"
      >
        <motion.div
          aria-hidden
          style={{ height: tall, scaleY: plate }}
          className="absolute inset-x-0 top-0 origin-top bg-white dark:bg-[#1D1D1A]"
        />
        <motion.div
          aria-hidden
          style={{ y: edge, opacity: lifted }}
          className="absolute inset-x-0 top-0 h-px shadow-[0_6px_16px_-10px_rgba(28,25,23,0.4)] dark:shadow-[0_6px_16px_-10px_rgba(0,0,0,0.7)]"
        />
        <motion.div
          aria-hidden
          style={{ y: edge, opacity: lifted }}
          className="absolute inset-x-0 top-0 h-5 bg-gradient-to-b from-white to-transparent dark:from-[#1D1D1A]"
        />
        <motion.div
          aria-hidden
          style={{ y: edge, opacity: lifted }}
          className="absolute inset-x-0 top-0 h-px bg-stone-200 dark:bg-white/[0.16]"
        />
        <div className="absolute inset-x-0 top-0 flex items-start gap-2.5 px-4 pt-3">
          {leading ? (
            <div className="pointer-events-auto flex h-6 shrink-0 items-center">
              {leading}
            </div>
          ) : null}

          <div className="relative min-w-0 flex-1">
            <motion.div
              style={{
                y: bigY,
                opacity: bigOpacity,
                scale: bigScale,
                transformOrigin: "left top",
              }}
            >
              <h2 className="truncate text-[20px] font-medium leading-[1.2] tracking-[-0.03em] text-stone-800 dark:text-stone-100">
                {title}
              </h2>
              {subtitle ? (
                <p className="mt-0.5 truncate text-[11.5px] leading-[1.35] text-stone-500 dark:text-stone-400">
                  {subtitle}
                </p>
              ) : null}
            </motion.div>
            <motion.span
              aria-hidden
              style={{ opacity: smallOpacity, y: smallY }}
              className="absolute inset-x-0 top-[3px] truncate text-[13px] font-medium leading-[1.4] text-stone-700 dark:text-stone-200"
            >
              {title}
            </motion.span>
          </div>

          {actions ? (
            <div className="pointer-events-auto flex h-6 shrink-0 items-center gap-1.5">
              {actions}
            </div>
          ) : null}
        </div>
      </header>
    </div>
  );
}
```

---

## Reading Progress · Scroll

How much is left.

Docs: https://yugo.click/docs/reading-progress
Install: `bun add motion`, then copy the source below into `components/yugo/reading-progress.tsx` · or `bunx shadcn@latest add https://yugo.click/r/reading-progress.json`.

Guarantees:
- Scroll is measured inside a single coalesced requestAnimationFrame and committed only when the quantized step changes, so a fast flick through a long article costs at most twenty-four renders instead of one per frame: the quantization is a render budget, not a look; the fill itself moves on a spring, on a transform.
- The track is a recessed well and the fill is the accent, because a progress fill is the system answering your scroll right now: and the radii nest, four outside, two inside, with the two pixels of padding between them.
- The estimate and the end state occupy the same grid cell, sized up front by an invisible copy of the longest string it can ever hold, so the number never shifts the header as it counts down from two digits to one.
- Progress is derived from the article's own box, not the document's, so a tall footer or a sticky sidebar cannot report the reader as finished while paragraphs remain.
- A container shorter than its viewport reports complete rather than dividing by zero, and content that grows after mount is caught by a ResizeObserver instead of freezing the track at a stale height.
- Screen readers get a progressbar with a real name and a value, and nothing else. A second live region narrating the same number is a running commentary, not an aid.
- Under prefers-reduced-motion the springs are removed and the readout is not; scroll and resize listeners, the pending frame and the observer are all torn down on unmount.


### Usage

```tsx
"use client";

import { useRef } from "react";
import { ReadingProgress } from "@/components/yugo/reading-progress";

export function ArticlePage({ body }: { body: React.ReactNode }) {
  const article = useRef<HTMLElement>(null);

  return (
    <>
      <header className="sticky top-0 z-10 border-b border-stone-200 bg-white/90 px-4 py-2 backdrop-blur dark:border-white/[0.16] dark:bg-[#1D1D1A]/90">
        <ReadingProgress target={article} words={1840} steps={24} />
      </header>

      <article ref={article} className="mx-auto max-w-[68ch] px-4 py-10">
        {body}
      </article>
    </>
  );
}
```

### Source (`components/yugo/reading-progress.tsx`)

```tsx
"use client";

import { useCallback, useEffect, useRef, useState } from "react";
import { motion, useReducedMotion } from "motion/react";

const FILL = { type: "spring", stiffness: 210, damping: 34, mass: 0.9 } as const;
const CROSSFADE = { type: "spring", stiffness: 260, damping: 34, mass: 0.8 } as const;
const EASE = [0.23, 1, 0.32, 1] as const;
const DRAW = { duration: 0.3, ease: EASE, delay: 0.08 } as const;
const INSTANT = { duration: 0 } as const;

export type ScrollRef = { readonly current: HTMLElement | null };

export type UseReadingProgressOptions = {
  target?: ScrollRef;
  scroller?: ScrollRef;
  steps?: number;
  words?: number;
  wordsPerMinute?: number;
};

export type ReadingProgressState = {
  step: number;
  steps: number;
  progress: number;
  percent: number;
  minutesLeft: number;
  totalMinutes: number;
  complete: boolean;
};

function clamp01(n: number) {
  if (!Number.isFinite(n) || n < 0) return 0;
  return n > 1 ? 1 : n;
}

export function useReadingProgress({
  target,
  scroller,
  steps = 24,
  words = 0,
  wordsPerMinute = 220,
}: UseReadingProgressOptions = {}): ReadingProgressState {
  const [step, setStep] = useState(0);
  const frame = useRef(0);

  const read = useCallback(() => {
    frame.current = 0;

    const scrollEl = scroller?.current ?? null;
    const targetEl = target?.current ?? null;
    const viewport = scrollEl ? scrollEl.clientHeight : window.innerHeight;

    let ratio: number;
    if (targetEl) {
      const rect = targetEl.getBoundingClientRect();
      const base = scrollEl ? scrollEl.getBoundingClientRect().top : 0;
      const travel = rect.height - viewport;
      ratio = travel <= 0 ? 1 : (base - rect.top) / travel;
    } else if (scrollEl) {
      const travel = scrollEl.scrollHeight - scrollEl.clientHeight;
      ratio = travel <= 0 ? 1 : scrollEl.scrollTop / travel;
    } else {
      const doc = document.documentElement;
      const travel = doc.scrollHeight - viewport;
      ratio = travel <= 0 ? 1 : window.scrollY / travel;
    }

    const next = Math.round(clamp01(ratio) * steps);
    setStep((prev) => (prev === next ? prev : next));
  }, [scroller, target, steps]);

  useEffect(() => {
    const scrollEl = scroller?.current ?? null;
    const targetEl = target?.current ?? null;
    const source: EventTarget = scrollEl ?? window;

    const schedule = () => {
      if (frame.current) return;
      frame.current = requestAnimationFrame(read);
    };

    source.addEventListener("scroll", schedule, { passive: true });
    window.addEventListener("resize", schedule);

    const observer =
      typeof ResizeObserver === "undefined" ? null : new ResizeObserver(schedule);
    if (observer) {
      if (targetEl) observer.observe(targetEl);
      if (scrollEl) observer.observe(scrollEl);
      if (!targetEl && !scrollEl) observer.observe(document.documentElement);
    }

    read();

    return () => {
      source.removeEventListener("scroll", schedule);
      window.removeEventListener("resize", schedule);
      observer?.disconnect();
      if (frame.current) cancelAnimationFrame(frame.current);
      frame.current = 0;
    };
  }, [read, scroller, target]);

  const progress = steps > 0 ? step / steps : 1;
  const totalMinutes = words > 0 ? Math.max(1, Math.ceil(words / wordsPerMinute)) : 0;
  const minutesLeft =
    words > 0 ? Math.ceil(((1 - progress) * words) / wordsPerMinute) : 0;

  return {
    step,
    steps,
    progress,
    percent: Math.round(progress * 100),
    minutesLeft,
    totalMinutes,
    complete: step >= steps,
  };
}

export type ReadingProgressProps = UseReadingProgressOptions & {
  label?: string;
  doneLabel?: string;
  className?: string;
};

export function ReadingProgress({
  target,
  scroller,
  steps = 24,
  words = 0,
  wordsPerMinute = 220,
  label = "Reading progress",
  doneLabel = "End",
  className = "",
}: ReadingProgressProps) {
  const { step, percent, minutesLeft, totalMinutes, complete } =
    useReadingProgress({ target, scroller, steps, words, wordsPerMinute });

  const reduced = useReducedMotion();
  const fillTransition = reduced ? INSTANT : FILL;
  const fadeTransition = reduced ? INSTANT : CROSSFADE;

  const estimate = words > 0;
  const readout = `${minutesLeft} min left`;
  const finish = `${doneLabel} · ${totalMinutes} min`;
  const valueText = estimate
    ? `${percent}% read, ${readout}`
    : `${percent}% read`;

  return (
    <div className={`flex items-center gap-3 ${className}`}>
      <div
        role="progressbar"
        aria-label={label}
        aria-valuemin={0}
        aria-valuemax={steps}
        aria-valuenow={step}
        aria-valuetext={valueText}
        className="min-w-0 flex-1 rounded-[4px] bg-stone-100 p-[2px] shadow-[inset_0_1px_2px_rgba(28,25,23,0.07)] dark:bg-[#1D1D1A] dark:shadow-[inset_0_1px_2px_rgba(0,0,0,0.45)]"
      >
        <motion.div
          className="h-[3px] origin-left rounded-[2px] bg-[#4568FF] dark:bg-[#93B0FF]"
          style={{ width: "100%" }}
          initial={false}
          animate={{ scaleX: step / Math.max(1, steps) }}
          transition={fillTransition}
        />
      </div>

      {estimate ? (
        <div className="grid shrink-0 justify-items-end font-mono text-[10.5px] tabular-nums">
          <span
            aria-hidden
            className="invisible col-start-1 row-start-1 flex items-center gap-1 whitespace-nowrap"
          >
            <span className="w-3 shrink-0" />
            {finish}
          </span>
          <motion.span
            aria-hidden
            className="col-start-1 row-start-1 whitespace-nowrap text-stone-500 dark:text-stone-400"
            initial={false}
            animate={{ opacity: complete ? 0 : 1 }}
            transition={fadeTransition}
          >
            {readout}
          </motion.span>
          <motion.span
            aria-hidden
            className="col-start-1 row-start-1 flex items-center gap-1 whitespace-nowrap text-stone-700 dark:text-stone-200"
            initial={false}
            animate={{ opacity: complete ? 1 : 0 }}
            transition={fadeTransition}
          >
            <svg
              width="12"
              height="12"
              viewBox="0 0 256 256"
              fill="none"
              aria-hidden="true"
            >
              <motion.polyline
                points="216 72 104 184 48 128"
                stroke="currentColor"
                strokeWidth="16"
                strokeLinecap="round"
                strokeLinejoin="round"
                initial={false}
                animate={{ pathLength: complete ? 1 : 0 }}
                transition={reduced ? INSTANT : DRAW}
              />
            </svg>
            <motion.span
              initial={false}
              animate={{ x: complete ? 0 : 4 }}
              transition={fadeTransition}
            >
              {finish}
            </motion.span>
          </motion.span>
        </div>
      ) : null}
    </div>
  );
}
```

---

## Scroll Spy · Scroll

The section you are actually in.

Docs: https://yugo.click/docs/scroll-spy
Install: `bun add motion`, then copy the source below into `components/yugo/scroll-spy.tsx` · or `bunx shadcn@latest add https://yugo.click/r/scroll-spy.json`.

Guarantees:
- Clicking a link does not make the rail flip through every heading the smooth scroll passes over: the destination is locked in until the scroll arrives, and the lock is abandoned the instant a wheel or touch takes the scroll back, so the rail never argues with the person driving.
- The reading line is not pinned: it starts under the top edge and slides to the bottom as the scroll runs out. A pinned line skips every short section near the end: their headings can never climb above it before the scroll is over: which is why the tail links in a hand-rolled spy are dead. On the sliding line each one still gets its turn, and the true end still clamps to the last section.
- Positions are read from live rects in one rAF per scroll event rather than from offsets cached on mount, and a ResizeObserver covers the rest, so an accordion opening or an image loading late does not leave the rail pointing at the wrong heading.
- The spy is a strip, not a sidebar: every section is a chip in a recessed track and the current one is carried by a single ink thumb sliding chip to chip: the same object the tabs and the segmented control already taught. The row scrolls sideways when the page has more sections than the strip has width, and the active chip keeps itself in view.
- The active section is one discrete id, so React renders when the section changes and not once per scroll frame; nothing in the strip is driven by a float.
- Every chip's label is drawn over an invisible medium twin in the same grid cell, so the weight arriving with the thumb cannot change the chip's width and reflow the row.
- Screen readers get the section name once, after the scroll settles, instead of a running commentary; a click moves focus to the heading itself so the keyboard lands where the eye does, and under prefers-reduced-motion the scroll jumps rather than glides.


### Usage

```tsx
"use client";

import { useRef } from "react";
import { ScrollSpy } from "@/components/yugo/scroll-spy";

const sections = [
  { id: "install", label: "Install" },
  { id: "usage", label: "Usage" },
  { id: "props", label: "Props" },
  { id: "guarantees", label: "Guarantees" },
];

export function DocsArticle() {
  const article = useRef<HTMLDivElement>(null);

  return (
    <div className="flex gap-8">
      <aside className="sticky top-24 h-fit w-44 shrink-0">
        <ScrollSpy
          sections={sections}
          root={article}
          offset={24}
          label="On this page"
          onChange={(id) => console.log("reading", id)}
        />
      </aside>

      <div ref={article} className="h-[70vh] flex-1 overflow-y-auto">
        {sections.map((section) => (
          <section key={section.id} className="pb-16">
            <h2 id={section.id} className="text-[15px] font-medium">
              {section.label}
            </h2>
            {/* body */}
          </section>
        ))}
      </div>
    </div>
  );
}
```

### Source (`components/yugo/scroll-spy.tsx`)

```tsx
"use client";

import { useCallback, useEffect, useId, useRef, useState } from "react";
import { motion, useReducedMotion } from "motion/react";

const CELL = { type: "spring", stiffness: 520, damping: 34, mass: 0.45 } as const;
const SETTLE = 420;
const RELEASE = 900;

export type ScrollSpySection = {
  id: string;
  label: string;
};

export type UseScrollSpyOptions = {
  sections: ScrollSpySection[];
  offset?: number;
  root?: React.RefObject<HTMLElement | null>;
  onChange?: (id: string) => void;
};

export function useScrollSpy({
  sections,
  offset = 96,
  root,
  onChange,
}: UseScrollSpyOptions) {
  const reduced = useReducedMotion();

  const [activeId, setActiveId] = useState(() => sections[0]?.id ?? "");
  const [announce, setAnnounce] = useState("");

  const list = useRef(sections);
  list.current = sections;
  const emit = useRef(onChange);
  emit.current = onChange;

  const frame = useRef(0);
  const lock = useRef<string | null>(null);
  const lockTimer = useRef<ReturnType<typeof setTimeout> | null>(null);
  const settleTimer = useRef<ReturnType<typeof setTimeout> | null>(null);
  const started = useRef(false);

  const key = sections.map((s) => s.id).join("|");

  const measure = useCallback(() => {
    const items = list.current;
    if (items.length === 0) return "";

    const container = root?.current ?? null;

    const viewport = container ? container.clientHeight : window.innerHeight;
    const top = container ? container.scrollTop : window.scrollY;
    const max = container
      ? container.scrollHeight - container.clientHeight
      : document.documentElement.scrollHeight - window.innerHeight;
    const ratio = max > 0 ? Math.min(1, Math.max(0, top / max)) : 1;

    const line =
      (container ? container.getBoundingClientRect().top : 0) +
      offset +
      ratio * Math.max(0, viewport - offset - 1);

    let current = "";
    let last = "";

    for (const item of items) {
      const node = document.getElementById(item.id);
      if (!node) continue;
      last = item.id;
      if (!current) current = item.id;
      if (node.getBoundingClientRect().top <= line + 1) current = item.id;
    }

    const atEnd = container
      ? container.scrollTop + container.clientHeight >= container.scrollHeight - 2
      : window.scrollY + window.innerHeight >=
        document.documentElement.scrollHeight - 2;

    return atEnd && last ? last : current;
  }, [offset, root]);

  const release = useCallback(() => {
    lock.current = null;
    if (lockTimer.current) {
      clearTimeout(lockTimer.current);
      lockTimer.current = null;
    }
  }, []);

  const sync = useCallback(() => {
    if (frame.current) return;
    frame.current = requestAnimationFrame(() => {
      frame.current = 0;
      const next = measure();
      if (!next) return;
      if (lock.current) {
        if (lock.current === next) release();
        return;
      }
      setActiveId((prev) => (prev === next ? prev : next));
    });
  }, [measure, release]);

  useEffect(() => {
    const container = root?.current ?? null;
    const scroller: EventTarget = container ?? window;
    const abandon = () => {
      if (lock.current) release();
    };

    scroller.addEventListener("scroll", sync, { passive: true });
    window.addEventListener("resize", sync);
    window.addEventListener("wheel", abandon, { passive: true });
    window.addEventListener("touchstart", abandon, { passive: true });

    const observer = new ResizeObserver(sync);
    observer.observe(container ?? document.documentElement);
    for (const id of key ? key.split("|") : []) {
      const node = document.getElementById(id);
      if (node) observer.observe(node);
    }

    sync();

    return () => {
      scroller.removeEventListener("scroll", sync);
      window.removeEventListener("resize", sync);
      window.removeEventListener("wheel", abandon);
      window.removeEventListener("touchstart", abandon);
      observer.disconnect();
      cancelAnimationFrame(frame.current);
      frame.current = 0;
      if (lockTimer.current) clearTimeout(lockTimer.current);
    };
  }, [sync, release, key, root]);

  useEffect(() => {
    if (!activeId) return;
    emit.current?.(activeId);

    if (!started.current) {
      started.current = true;
      return;
    }

    settleTimer.current = setTimeout(() => {
      const item = list.current.find((s) => s.id === activeId);
      setAnnounce(item ? item.label : "");
    }, SETTLE);

    return () => {
      if (settleTimer.current) clearTimeout(settleTimer.current);
    };
  }, [activeId]);

  const scrollTo = useCallback(
    (id: string) => {
      const node = document.getElementById(id);
      if (!node) return;

      lock.current = id;
      setActiveId(id);

      const container = root?.current ?? null;
      const behavior: ScrollBehavior = reduced ? "auto" : "smooth";
      const rect = node.getBoundingClientRect();

      const viewport = container ? container.clientHeight : window.innerHeight;
      const max = container
        ? Math.max(0, container.scrollHeight - container.clientHeight)
        : Math.max(
            0,
            document.documentElement.scrollHeight - window.innerHeight,
          );
      const H = container
        ? rect.top -
          container.getBoundingClientRect().top +
          container.scrollTop
        : rect.top + window.scrollY;
      const usable = Math.max(0, viewport - offset - 1);
      const top =
        max > 0
          ? Math.min(max, Math.max(0, (H - offset) / (1 + usable / max)))
          : 0;

      if (container) container.scrollTo({ top, behavior });
      else window.scrollTo({ top, behavior });

      if (!node.hasAttribute("tabindex")) node.setAttribute("tabindex", "-1");
      node.focus({ preventScroll: true });

      if (lockTimer.current) clearTimeout(lockTimer.current);
      lockTimer.current = setTimeout(() => {
        lock.current = null;
        lockTimer.current = null;
        sync();
      }, RELEASE);
    },
    [offset, reduced, root, sync],
  );

  const getLinkProps = useCallback(
    (id: string) => ({
      href: `#${id}`,
      "aria-current": id === activeId ? ("location" as const) : undefined,
      onClick: (e: React.MouseEvent<HTMLAnchorElement>) => {
        if (e.metaKey || e.ctrlKey || e.shiftKey || e.button !== 0) return;
        e.preventDefault();
        scrollTo(id);
      },
    }),
    [activeId, scrollTo],
  );

  const activeIndex = sections.findIndex((s) => s.id === activeId);

  return { activeId, activeIndex, scrollTo, getLinkProps, announce };
}

export type ScrollSpyProps = {
  sections: ScrollSpySection[];
  offset?: number;
  root?: React.RefObject<HTMLElement | null>;
  onChange?: (id: string) => void;
  label?: string;
  className?: string;
};

export function ScrollSpy({
  sections,
  offset = 96,
  root,
  onChange,
  label = "On this page",
  className = "",
}: ScrollSpyProps) {
  const { activeId, getLinkProps, announce } = useScrollSpy({
    sections,
    offset,
    root,
    onChange,
  });
  const reduced = useReducedMotion();
  const thumbId = useId();
  const chips = useRef(new Map<string, HTMLElement>());

  useEffect(() => {
    chips.current.get(activeId)?.scrollIntoView({
      behavior: reduced ? "auto" : "smooth",
      block: "nearest",
      inline: "nearest",
    });
  }, [activeId, reduced]);

  return (
    <nav aria-label={label} className={`w-full ${className}`}>
      <div className="rounded-[10px] bg-stone-100/80 p-1 shadow-[inset_0_1px_2px_rgba(28,25,23,0.07)] dark:bg-[#1D1D1A] dark:shadow-[inset_0_1px_2px_rgba(0,0,0,0.45)]">
        <ol className="flex gap-1 overflow-x-auto [scrollbar-width:none] [&::-webkit-scrollbar]:hidden">
          {sections.map((section) => {
            const active = section.id === activeId;
            return (
              <li
                key={section.id}
                ref={(el) => {
                  if (el) chips.current.set(section.id, el);
                  else chips.current.delete(section.id);
                }}
                className="relative flex-[1_0_auto]"
              >
                {active ? (
                  <motion.span
                    layoutId={reduced ? undefined : thumbId}
                    aria-hidden
                    transition={CELL}
                    className="absolute inset-0 rounded-[6px] bg-stone-800 dark:bg-stone-100"
                  />
                ) : null}

                <a
                  {...getLinkProps(section.id)}
                  className="group relative flex h-7 w-full items-center justify-center rounded-[6px] px-2.5 text-[12.5px] outline-none after:pointer-events-none after:absolute after:inset-0 after:rounded-[6px] focus-visible:after:bg-[#4568FF]/[0.06] focus-visible:after:shadow-[inset_0_0_0_1px_#4568FF] dark:focus-visible:after:bg-[#93B0FF]/[0.1] dark:focus-visible:after:shadow-[inset_0_0_0_1px_#93B0FF]"
                >
                  <span className="relative grid">
                    <span
                      aria-hidden
                      className="invisible col-start-1 row-start-1 whitespace-nowrap font-medium"
                    >
                      {section.label}
                    </span>
                    <span
                      className={`col-start-1 row-start-1 whitespace-nowrap transition-colors duration-150 ${
                        active
                          ? "font-medium text-white dark:text-stone-900"
                          : "text-stone-500 group-hover:text-stone-700 dark:text-stone-400 dark:group-hover:text-stone-200"
                      }`}
                    >
                      {section.label}
                    </span>
                  </span>
                </a>
              </li>
            );
          })}
        </ol>
      </div>
      <p aria-live="polite" className="sr-only">
        {announce}
      </p>
    </nav>
  );
}
```

---

## Snap Carousel · Scroll

Momentum that lands on a slide.

Docs: https://yugo.click/docs/snap-carousel
Install: `bun add motion`, then copy the source below into `components/yugo/snap-carousel.tsx` · or `bunx shadcn@latest add https://yugo.click/r/snap-carousel.json`.

Guarantees:
- A flick resolves to a slide index before the landing spring starts, so the track cannot come to rest halfway between two slides, and it cannot leave a sliver of the wrong slide on screen when the finger lifts mid-gap.
- Momentum is projected from release velocity but capped at maxFlick slides past where the finger actually let go, so a hard throw advances one slide instead of flinging the reader four deep into a gallery they never saw.
- The landing spring is handed the gesture's exit velocity and can be caught mid-flight: grabbing the track again picks it up from where it currently is, never from where the last animation started.
- Every slide is one viewport wide and the track stretches to the tallest of them, so moving between slides resizes nothing and the content below never jumps.
- Only the resting slide is interactive; the rest are inert, which stops Tab from landing inside a slide nobody can see, and a scroll guard returns the viewport to zero if anything else tries to scroll the clipped track out of alignment.
- The horizontal offset is a motion value written straight to the node, so React renders only when the target index crosses a boundary, and the polite live region announces the settled slide once rather than sixty times a second; under prefers-reduced-motion the same index is reached with the travel removed.


### Usage

```tsx
import { useState } from "react";
import { SnapCarousel } from "@/components/yugo/snap-carousel";

type Shot = { id: string; name: string; src: string };

export function GalleryStrip({ shots }: { shots: Shot[] }) {
  const [index, setIndex] = useState(0);

  return (
    <section className="mx-auto w-full max-w-[440px]">
      <SnapCarousel
        label="Reference shots"
        index={index}
        onIndexChange={setIndex}
        peek={20}
        gap={10}
        maxFlick={1}
      >
        {shots.map((shot) => (
          <figure key={shot.id} className="rounded-[11px] bg-white p-[5px] dark:bg-[#1D1D1A]">
            <img
              src={shot.src}
              alt={shot.name}
              draggable={false}
              className="h-[180px] w-full rounded-[9px] object-cover"
            />
            <figcaption className="px-1 pt-2 text-[13px] font-medium text-stone-700 dark:text-stone-200">
              {shot.name}
            </figcaption>
          </figure>
        ))}
      </SnapCarousel>

      <p className="mt-2 text-[12.5px] text-stone-500 dark:text-stone-400">
        Showing {shots[index]?.name}
      </p>
    </section>
  );
}
```

### Source (`components/yugo/snap-carousel.tsx`)

```tsx
"use client";

import {
  Children,
  isValidElement,
  useCallback,
  useEffect,
  useId,
  useRef,
  useState,
} from "react";
import {
  animate,
  motion,
  useIsomorphicLayoutEffect,
  useMotionValue,
  useReducedMotion,
} from "motion/react";

const CELL = {
  type: "spring",
  stiffness: 520,
  damping: 34,
  mass: 0.45,
} as const;

const CROSSFADE = {
  type: "spring",
  stiffness: 260,
  damping: 34,
  mass: 0.8,
} as const;

const WALL = {
  type: "spring",
  stiffness: 700,
  damping: 30,
  mass: 0.5,
} as const;

const WALL_IMPULSE = 900;

const clamp = (n: number, lo: number, hi: number) =>
  Math.max(lo, Math.min(hi, n));

type DragInfo = {
  offset: { x: number; y: number };
  velocity: { x: number; y: number };
};

export type UseSnapCarouselOptions = {
  count: number;
  index?: number;
  defaultIndex?: number;
  onIndexChange?: (index: number) => void;
  gap?: number;
  momentum?: number;
  maxFlick?: number;
  disabled?: boolean;
};

export function useSnapCarousel({
  count,
  index: controlled,
  defaultIndex = 0,
  onIndexChange,
  gap = 12,
  momentum = 0.14,
  maxFlick = 1,
  disabled = false,
}: UseSnapCarouselOptions) {
  const total = Math.max(1, Math.floor(count));

  const [uncontrolled, setUncontrolled] = useState(() =>
    clamp(defaultIndex, 0, total - 1),
  );
  const [slideWidth, setSlideWidth] = useState(0);
  const [dragging, setDragging] = useState(false);

  const index = clamp(controlled ?? uncontrolled, 0, total - 1);
  const [target, setTarget] = useState(index);
  const step = slideWidth + gap;

  const viewportRef = useRef<HTMLDivElement>(null);
  const anim = useRef<{ stop: () => void } | null>(null);
  const desired = useRef<number | null>(null);
  const lastStep = useRef(0);

  const live = useRef(index);
  live.current = index;
  const metrics = useRef({ step, total, momentum, maxFlick });
  metrics.current = { step, total, momentum, maxFlick };
  const changed = useRef(onIndexChange);
  changed.current = onIndexChange;

  const x = useMotionValue(0);
  const reduced = useReducedMotion();

  const glide = useCallback(
    (to: number, velocity = 0) => {
      desired.current = to;
      anim.current?.stop();
      anim.current = animate(
        x,
        to,
        reduced ? { duration: 0 } : { ...CROSSFADE, velocity },
      );
    },
    [x, reduced],
  );

  const goTo = useCallback(
    (next: number, velocity = 0) => {
      const shelf = metrics.current;
      const to = clamp(Math.round(next), 0, shelf.total - 1);
      setTarget(to);
      if (to !== live.current) {
        live.current = to;
        setUncontrolled(to);
        changed.current?.(to);
      }
      glide(-to * shelf.step, velocity);
    },
    [glide],
  );

  const bounce = useCallback(
    (dir: 1 | -1) => {
      const shelf = metrics.current;
      const to = -live.current * shelf.step;
      desired.current = to;
      anim.current?.stop();
      anim.current = animate(
        x,
        to,
        reduced ? { duration: 0 } : { ...WALL, velocity: -dir * WALL_IMPULSE },
      );
    },
    [x, reduced],
  );

  const move = useCallback(
    (dir: 1 | -1) => {
      const to = live.current + dir;
      if (to < 0 || to > metrics.current.total - 1) bounce(dir);
      else goTo(to);
    },
    [bounce, goTo],
  );

  const next = useCallback(() => move(1), [move]);
  const prev = useCallback(() => move(-1), [move]);

  const pick = useCallback(
    (velocity: number) => {
      const shelf = metrics.current;
      if (shelf.step === 0) return live.current;
      const at = -x.get() / shelf.step;
      const anchor = clamp(Math.round(at), 0, shelf.total - 1);
      const projected = at - (velocity * shelf.momentum) / shelf.step;
      return clamp(
        clamp(
          Math.round(projected),
          anchor - shelf.maxFlick,
          anchor + shelf.maxFlick,
        ),
        0,
        shelf.total - 1,
      );
    },
    [x],
  );

  useIsomorphicLayoutEffect(() => {
    const el = viewportRef.current;
    if (!el) return;
    const observer = new ResizeObserver((entries) => {
      const width = entries[0]?.contentRect.width ?? 0;
      setSlideWidth((current) =>
        Math.abs(current - width) < 0.5 ? current : width,
      );
    });
    observer.observe(el);
    return () => observer.disconnect();
  }, []);

  useIsomorphicLayoutEffect(() => {
    if (step === 0) return;
    const to = -index * step;

    if (lastStep.current !== step) {
      lastStep.current = step;
      desired.current = to;
      anim.current?.stop();
      x.set(to);
      return;
    }
    if (dragging || desired.current === to) return;
    glide(to);
  }, [index, step, dragging, glide, x]);

  useEffect(() => () => anim.current?.stop(), []);

  const onDragStart = useCallback(() => {
    anim.current?.stop();
    setDragging(true);
    setTarget(live.current);
  }, []);

  const onDrag = useCallback(
    (_event: MouseEvent | TouchEvent | PointerEvent, info: DragInfo) => {
      const to = pick(info.velocity.x);
      setTarget((current) => (current === to ? current : to));
    },
    [pick],
  );

  const onDragEnd = useCallback(
    (_event: MouseEvent | TouchEvent | PointerEvent, info: DragInfo) => {
      setDragging(false);
      goTo(pick(info.velocity.x), info.velocity.x);
    },
    [goTo, pick],
  );

  const onKeyDown = useCallback(
    (event: React.KeyboardEvent) => {
      if (event.key === "ArrowRight") {
        event.preventDefault();
        next();
      } else if (event.key === "ArrowLeft") {
        event.preventDefault();
        prev();
      } else if (event.key === "Home") {
        event.preventDefault();
        goTo(0);
      } else if (event.key === "End") {
        event.preventDefault();
        goTo(metrics.current.total - 1);
      }
    },
    [goTo, next, prev],
  );

  const onScroll = useCallback((event: React.UIEvent<HTMLElement>) => {
    event.currentTarget.scrollLeft = 0;
    event.currentTarget.scrollTop = 0;
  }, []);

  const viewportProps = {
    tabIndex: 0,
    role: "group" as const,
    "aria-roledescription": "carousel",
    onKeyDown,
    onScroll,
  };

  const trackProps = {
    drag: (disabled || total < 2 ? false : "x") as false | "x",
    dragDirectionLock: true,
    dragMomentum: false,
    dragElastic: 0.14,
    dragConstraints: { left: -(total - 1) * step, right: 0 },
    onDragStart,
    onDrag,
    onDragEnd,
    style: { x, gap: `${gap}px`, touchAction: "pan-y" as const },
  };

  return {
    index,
    count: total,
    target,
    shown: dragging ? target : index,
    dragging,
    slideWidth,
    step,
    x,
    goTo,
    next,
    prev,
    viewportRef,
    viewportProps,
    trackProps,
  };
}

export type UseSnapCarouselResult = ReturnType<typeof useSnapCarousel>;

const CARET_LEFT = (
  <svg width="14" height="14" viewBox="0 0 256 256" fill="none" aria-hidden="true">
    <polyline
      points="160 208 80 128 160 48"
      stroke="currentColor"
      strokeWidth="16"
      strokeLinecap="round"
      strokeLinejoin="round"
    />
  </svg>
);

const CARET_RIGHT = (
  <svg width="14" height="14" viewBox="0 0 256 256" fill="none" aria-hidden="true">
    <polyline
      points="96 48 176 128 96 208"
      stroke="currentColor"
      strokeWidth="16"
      strokeLinecap="round"
      strokeLinejoin="round"
    />
  </svg>
);

export type SnapCarouselProps = {
  children: React.ReactNode;
  label: string;
  index?: number;
  defaultIndex?: number;
  onIndexChange?: (index: number) => void;
  gap?: number;
  peek?: number;
  momentum?: number;
  maxFlick?: number;
  prevLabel?: string;
  nextLabel?: string;
  className?: string;
};

export function SnapCarousel({
  children,
  label,
  index,
  defaultIndex = 0,
  onIndexChange,
  gap = 12,
  peek = 0,
  momentum = 0.14,
  maxFlick = 1,
  prevLabel = "Previous slide",
  nextLabel = "Next slide",
  className = "",
}: SnapCarouselProps) {
  const slides = Children.toArray(children);
  const hintId = useId();
  const reduced = useReducedMotion();

  const car = useSnapCarousel({
    count: slides.length,
    index,
    defaultIndex,
    onIndexChange,
    gap,
    momentum,
    maxFlick,
  });

  const button =
    "grid size-7 place-items-center rounded-[6px] border border-stone-200 bg-white text-stone-700 shadow-[inset_0_1.5px_0_rgba(255,255,255,0.95),inset_0_-1px_0_rgba(28,25,23,0.06),0_1px_2px_rgba(28,25,23,0.08)] outline-none transition-[background-color,border-color,box-shadow,transform] duration-150 hover:bg-stone-50 active:translate-y-px active:shadow-[inset_0_1px_2px_rgba(28,25,23,0.06)] focus-visible:border-[#4568FF] focus-visible:shadow-[0_1px_2px_rgba(28,25,23,0.08),0_10px_20px_-14px_rgba(69,104,255,0.6)] dark:border-white/[0.16] dark:bg-[#252522] dark:text-stone-200 dark:shadow-[inset_0_1px_0_rgba(255,255,255,0.07),0_1px_2px_rgba(0,0,0,0.4)] dark:hover:bg-[#2A2A27] dark:focus-visible:border-[#93B0FF] dark:focus-visible:shadow-[0_10px_20px_-14px_rgba(147,176,255,0.5)]";

  return (
    <div className={`w-full ${className}`}>
      <div
        ref={car.viewportRef}
        aria-label={label}
        aria-describedby={hintId}
        style={{
          paddingLeft: peek,
          paddingRight: peek,
          ...(peek > 0
            ? {
                WebkitMaskImage: `linear-gradient(to right, transparent 0, black ${peek + 14}px, black calc(100% - ${peek + 14}px), transparent 100%)`,
                maskImage: `linear-gradient(to right, transparent 0, black ${peek + 14}px, black calc(100% - ${peek + 14}px), transparent 100%)`,
              }
            : {}),
        }}
        className="relative overflow-hidden rounded-[14px] py-1.5 outline-none focus-visible:bg-[#4568FF]/[0.06] focus-visible:shadow-[inset_0_0_0_1px_#4568FF] dark:focus-visible:bg-[#93B0FF]/[0.1] dark:focus-visible:shadow-[inset_0_0_0_1px_#93B0FF]"
        {...car.viewportProps}
      >
        <motion.div
          {...car.trackProps}
          className={`flex items-stretch ${
            car.dragging ? "cursor-grabbing" : "cursor-grab"
          }`}
        >
          {slides.map((slide, i) => (
            <motion.div
              key={isValidElement(slide) && slide.key ? slide.key : i}
              role="group"
              aria-roledescription="slide"
              aria-label={`${i + 1} of ${slides.length}`}
              inert={i !== car.index}
              initial={false}
              animate={
                i === car.shown
                  ? { scale: 1, opacity: 1 }
                  : { scale: 0.96, opacity: 0.55 }
              }
              transition={reduced ? { duration: 0 } : CROSSFADE}
              className="w-full shrink-0 select-none"
            >
              {slide}
            </motion.div>
          ))}
        </motion.div>
      </div>
      <div className="mt-3 flex items-center justify-between gap-3">
        <span className="flex items-center gap-[3px]">
          {slides.map((slide, i) => (
            <button
              key={isValidElement(slide) && slide.key ? slide.key : i}
              type="button"
              onClick={() => car.goTo(i)}
              aria-label={`Go to slide ${i + 1}`}
              aria-current={i === car.index ? "true" : undefined}
              className="grid h-[18px] w-[16px] place-items-center rounded-[5px] outline-none focus-visible:bg-[#4568FF]/[0.06] focus-visible:shadow-[inset_0_0_0_1px_#4568FF] dark:focus-visible:bg-[#93B0FF]/[0.1] dark:focus-visible:shadow-[inset_0_0_0_1px_#93B0FF]"
            >
              <motion.span
                initial={false}
                animate={
                  i === car.shown
                    ? { scaleX: 1, opacity: 1 }
                    : { scaleX: 0.36, opacity: 0.26 }
                }
                transition={reduced ? { duration: 0 } : CELL}
                className="block h-[5px] w-[14px] rounded-[1.5px] bg-stone-800 dark:bg-stone-100"
              />
            </button>
          ))}
        </span>
        <span className="flex items-center gap-1.5">
          <button type="button" onClick={car.prev} aria-label={prevLabel} className={button}>
            {CARET_LEFT}
          </button>
          <button type="button" onClick={car.next} aria-label={nextLabel} className={button}>
            {CARET_RIGHT}
          </button>
        </span>
      </div>
      <span id={hintId} className="sr-only">
        Left and right arrow keys move between {slides.length} slides.
      </span>
      <span aria-live="polite" aria-atomic className="sr-only">
        Slide {car.index + 1} of {slides.length}
      </span>
    </div>
  );
}
```

---

## Hide on Scroll · Scroll

Toolbar yields to the content.

Docs: https://yugo.click/docs/hide-on-scroll
Install: `bun add motion`, then copy the source below into `components/yugo/hide-on-scroll.tsx` · or `bunx shadcn@latest add https://yugo.click/r/hide-on-scroll.json`.

Guarantees:
- Direction is decided by accumulated travel, not by the sign of the last scroll event, so a two-pixel trackpad wobble or a momentum stutter cannot flap the bar open and shut while someone reads.
- The bar leaves on a transform above a spacer that permanently reserves its height, so no line of content reflows when it yields or returns.
- Overscroll past either end is discarded rather than read as a direction change, so a rubber-band bounce at the bottom of an iOS list does not hide the bar.
- Focus entering the bar pins it open before the control lands, and `pinned` holds it open for a menu the bar owns, so a focusable action is never parked off-screen.
- Inside the top guard, and whenever the content is too short to scroll, the bar is unconditionally shown; a resize or a shrinking list cannot strand it above the frame.
- Scroll reads are coalesced into one animation frame and collapse to a single boolean, so React renders on the transition rather than per frame, and under `prefers-reduced-motion` the bar changes place without the trip.


### Usage

```tsx
"use client";

import { useState } from "react";
import { HideOnScroll } from "@/components/yugo/hide-on-scroll";

export function ActivityFeed({ posts }: { posts: Post[] }) {
  const [filterOpen, setFilterOpen] = useState(false);

  return (
    <HideOnScroll
      label="Activity"
      maxHeight={640}
      barHeight={48}
      pinned={filterOpen}
      bar={
        <>
          <span className="min-w-0 flex-1 truncate text-[13px] font-medium">
            All activity
          </span>
          <button
            type="button"
            aria-expanded={filterOpen}
            onClick={() => setFilterOpen((open) => !open)}
            className="h-7 rounded-[6px] border border-stone-200 px-2 text-[12px] dark:border-white/[0.16]"
          >
            Filter
          </button>
        </>
      }
    >
      <ul className="divide-y divide-stone-200 dark:divide-white/10">
        {posts.map((post) => (
          <PostRow key={post.id} post={post} />
        ))}
      </ul>
    </HideOnScroll>
  );
}
```

### Source (`components/yugo/hide-on-scroll.tsx`)

```tsx
"use client";

import { useEffect, useRef, useState } from "react";
import { motion, useReducedMotion } from "motion/react";

const DISCLOSE = { type: "spring", stiffness: 150, damping: 27, mass: 1 } as const;
const CROSSFADE = { type: "spring", stiffness: 260, damping: 34, mass: 0.8 } as const;

export type UseHideOnScrollOptions = {
  hideAfter?: number;
  revealAfter?: number;
  topGuard?: number;
  pinned?: boolean;
  disabled?: boolean;
};

export type UseHideOnScrollResult<T extends HTMLElement> = {
  ref: React.RefObject<T | null>;
  hidden: boolean;
  atTop: boolean;
};

export function useHideOnScroll<T extends HTMLElement = HTMLDivElement>({
  hideAfter = 14,
  revealAfter = 10,
  topGuard = 24,
  pinned = false,
  disabled = false,
}: UseHideOnScrollOptions = {}): UseHideOnScrollResult<T> {
  const ref = useRef<T | null>(null);
  const frame = useRef(0);
  const last = useRef(0);
  const accum = useRef(0);

  const held = useRef(pinned || disabled);
  held.current = pinned || disabled;

  const [hidden, setHidden] = useState(false);
  const [atTop, setAtTop] = useState(true);

  const down = Math.max(1, hideAfter);
  const up = Math.max(1, revealAfter);
  const guard = Math.max(0, topGuard);

  useEffect(() => {
    if (!pinned && !disabled) return;
    accum.current = 0;
    setHidden(false);
  }, [pinned, disabled]);

  useEffect(() => {
    const el = ref.current;
    const target: EventTarget = el ?? window;

    const readY = () => (el ? el.scrollTop : window.scrollY);
    const readMax = () =>
      el
        ? el.scrollHeight - el.clientHeight
        : document.documentElement.scrollHeight - window.innerHeight;

    const evaluate = () => {
      frame.current = 0;

      const max = readMax();
      const y = readY();

      if (max <= guard) {
        accum.current = 0;
        last.current = y;
        setAtTop((prev) => (prev ? prev : true));
        setHidden((prev) => (prev ? false : prev));
        return;
      }

      if (y < 0 || y > max) return;

      const dy = y - last.current;
      last.current = y;

      const top = y <= guard;
      setAtTop((prev) => (prev === top ? prev : top));

      if (held.current || top) {
        accum.current = 0;
        setHidden((prev) => (prev ? false : prev));
        return;
      }

      if (dy === 0) return;
      if (dy > 0 !== accum.current > 0) accum.current = 0;
      accum.current += dy;

      if (accum.current >= down) {
        accum.current = 0;
        setHidden((prev) => (prev ? prev : true));
      } else if (accum.current <= -up) {
        accum.current = 0;
        setHidden((prev) => (prev ? false : prev));
      }
    };

    const schedule = () => {
      if (frame.current) return;
      frame.current = requestAnimationFrame(evaluate);
    };

    last.current = readY();
    evaluate();

    target.addEventListener("scroll", schedule, { passive: true });
    window.addEventListener("resize", schedule);

    let observer: ResizeObserver | null = null;
    if (el && typeof ResizeObserver !== "undefined") {
      observer = new ResizeObserver(schedule);
      observer.observe(el);
    }

    return () => {
      target.removeEventListener("scroll", schedule);
      window.removeEventListener("resize", schedule);
      observer?.disconnect();
      if (frame.current) cancelAnimationFrame(frame.current);
      frame.current = 0;
    };
  }, [down, up, guard]);

  return { ref, hidden, atTop };
}

export type HideOnScrollProps = {
  bar: React.ReactNode;
  children: React.ReactNode;
  barHeight?: number;
  hideAfter?: number;
  revealAfter?: number;
  topGuard?: number;
  pinned?: boolean;
  maxHeight?: number;
  label?: string;
  onHiddenChange?: (hidden: boolean) => void;
  className?: string;
};

export function HideOnScroll({
  bar,
  children,
  barHeight = 44,
  hideAfter = 14,
  revealAfter = 10,
  topGuard = 24,
  pinned = false,
  maxHeight = 320,
  label = "Scrollable content",
  onHiddenChange,
  className = "",
}: HideOnScrollProps) {
  const [focusWithin, setFocusWithin] = useState(false);

  const { ref, hidden, atTop } = useHideOnScroll<HTMLDivElement>({
    hideAfter,
    revealAfter,
    topGuard,
    pinned: pinned || focusWithin,
  });

  const reduced = useReducedMotion();
  const slide = reduced ? { duration: 0 } : DISCLOSE;
  const fade = reduced ? { duration: 0 } : CROSSFADE;

  const seen = useRef(hidden);
  useEffect(() => {
    if (seen.current === hidden) return;
    seen.current = hidden;
    onHiddenChange?.(hidden);
  }, [hidden, onHiddenChange]);

  return (
    <div
      className={`relative w-full min-w-0 overflow-hidden rounded-[14px] border border-stone-200 bg-white shadow-[0_1px_2px_rgba(28,25,23,0.06),0_4px_10px_-8px_rgba(28,25,23,0.45)] dark:border-white/[0.16] dark:bg-[#1D1D1A] dark:shadow-[0_1px_6px_rgba(0,0,0,0.45)] ${className}`}
    >
      <motion.div
        data-hidden={hidden ? "true" : "false"}
        onFocus={() => setFocusWithin(true)}
        onBlur={() => setFocusWithin(false)}
        style={{ height: barHeight }}
        initial={false}
        animate={{ y: hidden ? -barHeight : 0 }}
        transition={slide}
        className="absolute inset-x-0 top-0 z-10 flex items-center gap-2 bg-white px-3 dark:bg-[#1D1D1A]"
      >
        {bar}

        <motion.span
          aria-hidden
          initial={false}
          animate={{ opacity: atTop ? 0 : 1 }}
          transition={fade}
          className="pointer-events-none absolute inset-x-0 bottom-0 h-px bg-stone-200 dark:bg-white/[0.16]"
        />
      </motion.div>
      <div
        ref={ref}

        // eslint-disable-next-line jsx-a11y/no-noninteractive-tabindex
        tabIndex={0}
        role="region"
        aria-label={label}
        style={{ maxHeight, scrollPaddingTop: barHeight + 8 }}
        className="overflow-y-auto overscroll-y-contain outline-none [scrollbar-gutter:stable] focus-visible:bg-[#4568FF]/[0.06] focus-visible:shadow-[inset_0_0_0_1px_#4568FF] dark:focus-visible:bg-[#93B0FF]/[0.06] dark:focus-visible:shadow-[inset_0_0_0_1px_#93B0FF]"
      >
        <div aria-hidden style={{ height: barHeight }} />
        <div
          aria-hidden
          className="pointer-events-none sticky top-0 -mb-5 h-5 bg-gradient-to-b from-white to-transparent dark:from-[#1D1D1A]"
        />
        {children}
        <div
          aria-hidden
          className="pointer-events-none sticky bottom-0 -mt-5 h-5 bg-gradient-to-t from-white to-transparent dark:from-[#1D1D1A]"
        />
      </div>
    </div>
  );
}
```

---

## Sortable Table · Data

Rows travel to their new order.

Docs: https://yugo.click/docs/sortable-table
Install: `bun add motion`, then copy the source below into `components/yugo/sortable-table.tsx` · or `bunx shadcn@latest add https://yugo.click/r/sortable-table.json`.

Guarantees:
- Sorting a table normally teleports every row and the one you were reading is gone; here each row keeps its element and travels to its new index, so it can be followed rather than found again.
- Rows are placed by transform inside a body whose height is reserved from the row count, so a reorder relayouts nothing and the table never grows, shrinks or shifts the columns under the cursor.
- Sort again mid-flight and the springs resume from where the rows currently are instead of restarting from the order they were leaving.
- DOM order always matches visual order, so a screen reader reads the sorted table, and the result is announced once as a single sentence naming the column, the direction and the row count instead of once per row.
- A third activation of the same header restores the order the rows arrived in, a state most tables make unreachable, and sorting is stable on the original index with empty values held last in both directions.
- Comparison runs through a fixed Intl.Collator and no clock or random source is touched during render, so the server and the client agree on the markup; under prefers-reduced-motion the rows are placed instantly and the announcement still fires.


### Usage

```tsx
"use client";

import { useState } from "react";
import {
  SortableTable,
  type SortState,
} from "@/components/yugo/sortable-table";

type Deploy = {
  id: string;
  service: string;
  duration: number;
  status: string;
  rank: number;
};

const DEPLOYS: Deploy[] = [
  { id: "d1", service: "checkout-api", duration: 184, status: "passed", rank: 0 },
  { id: "d2", service: "web", duration: 62, status: "failed", rank: 2 },
  { id: "d3", service: "search-index", duration: 431, status: "passed", rank: 0 },
];

export function DeployTable() {
  const [sort, setSort] = useState<SortState | null>({
    columnId: "duration",
    direction: "desc",
  });

  return (
    <SortableTable
      label="Recent deploys"
      rows={DEPLOYS}
      getRowId={(d) => d.id}
      getRowLabel={(d) => d.service}
      sort={sort}
      onSortChange={setSort}
      markable
      maxHeight={320}
      columns={[
        { id: "service", header: "Service", value: (d) => d.service },
        {
          id: "duration",
          header: "Build",
          width: "88px",
          align: "end",
          numeric: true,
          value: (d) => d.duration,
          cell: (d) => `${d.duration}s`,
        },
        {
          id: "status",
          header: "Status",
          width: "92px",
          align: "end",
          value: (d) => d.rank,
          cell: (d) => d.status,
        },
      ]}
    />
  );
}
```

### Source (`components/yugo/sortable-table.tsx`)

```tsx
"use client";

import { useCallback, useEffect, useMemo, useRef, useState, type ReactNode } from "react";
import { motion, useReducedMotion } from "motion/react";

const CELL = { type: "spring", stiffness: 520, damping: 34, mass: 0.45 } as const;

const SMALL = { type: "spring", stiffness: 700, damping: 46, mass: 0.5 } as const;

const EASE = [0.23, 1, 0.32, 1] as const;
const LEAVE = [0.4, 0, 1, 1] as const;
const HIDE = { duration: 0.12, ease: LEAVE } as const;
const SHOW = { duration: 0.25, ease: EASE } as const;

const STEP = 0.018;
const STEP_CAP = 8;
const SETTLE_MS = 380;

export type SortDirection = "asc" | "desc";

export type SortState = { columnId: string; direction: SortDirection };

export type SortableColumn<T> = {
  id: string;
  header: string;
  width?: string;
  align?: "start" | "end";
  numeric?: boolean;
  sortable?: boolean;
  value?: (row: T) => string | number | null | undefined;
  cell?: (row: T) => ReactNode;
};

export type OrderedRow<T> = { id: string; row: T; index: number };

export type UseSortableRowsOptions<T> = {
  rows: T[];
  getRowId: (row: T) => string;
  getValue: (row: T, columnId: string) => string | number | null | undefined;
  sort?: SortState | null;
  defaultSort?: SortState | null;
  onSortChange?: (next: SortState | null) => void;
  restoreOriginal?: boolean;
};

export function useSortableRows<T>({
  rows,
  getRowId,
  getValue,
  sort,
  defaultSort = null,
  onSortChange,
  restoreOriginal = true,
}: UseSortableRowsOptions<T>) {
  const [internal, setInternal] = useState<SortState | null>(defaultSort);

  const controlled = sort !== undefined;
  const current = controlled ? sort : internal;

  const collator = useMemo(
    () => new Intl.Collator("en", { numeric: true, sensitivity: "base" }),
    [],
  );

  const ordered = useMemo<OrderedRow<T>[]>(() => {
    const base = rows.map((row, i) => ({ id: getRowId(row), row, i }));

    if (current) {
      const dir = current.direction === "asc" ? 1 : -1;
      base.sort((x, y) => {
        const a = getValue(x.row, current.columnId);
        const b = getValue(y.row, current.columnId);
        const emptyA = a === null || a === undefined || a === "";
        const emptyB = b === null || b === undefined || b === "";
        if (emptyA || emptyB) {
          if (emptyA && emptyB) return x.i - y.i;
          return emptyA ? 1 : -1;
        }
        const d =
          typeof a === "number" && typeof b === "number"
            ? a - b
            : collator.compare(String(a), String(b));
        return d === 0 ? x.i - y.i : d * dir;
      });
    }

    return base.map(({ id, row }, index) => ({ id, row, index }));
  }, [rows, current, getRowId, getValue, collator]);

  const toggle = useCallback(
    (columnId: string) => {
      const next: SortState | null =
        !current || current.columnId !== columnId
          ? { columnId, direction: "asc" }
          : current.direction === "asc"
            ? { columnId, direction: "desc" }
            : restoreOriginal
              ? null
              : { columnId, direction: "asc" };

      if (!controlled) setInternal(next);
      onSortChange?.(next);
    },
    [current, controlled, onSortChange, restoreOriginal],
  );

  const ariaSort = useCallback(
    (columnId: string): "ascending" | "descending" | "none" =>
      current?.columnId === columnId
        ? current.direction === "asc"
          ? "ascending"
          : "descending"
        : "none",
    [current],
  );

  return { sort: current, ordered, toggle, ariaSort };
}

export type SortableTableProps<T> = {
  rows: T[];
  columns: SortableColumn<T>[];
  getRowId: (row: T) => string;
  label: string;
  rowHeight?: number;
  maxHeight?: number;
  sort?: SortState | null;
  defaultSort?: SortState | null;
  onSortChange?: (next: SortState | null) => void;
  markable?: boolean;
  onMarkChange?: (id: string | null) => void;
  getRowLabel?: (row: T) => string;
  className?: string;
};

export function SortableTable<T>({
  rows,
  columns,
  getRowId,
  label,
  rowHeight = 44,
  maxHeight,
  sort,
  defaultSort = null,
  onSortChange,
  markable = false,
  onMarkChange,
  getRowLabel,
  className = "",
}: SortableTableProps<T>) {
  const reduced = useReducedMotion();
  const [marked, setMarked] = useState<string | null>(null);
  const [touched, setTouched] = useState(false);
  const [moving, setMoving] = useState(false);
  const settleTimer = useRef<ReturnType<typeof setTimeout> | null>(null);

  useEffect(
    () => () => {
      if (settleTimer.current) clearTimeout(settleTimer.current);
    },
    [],
  );

  const getValue = useCallback(
    (row: T, columnId: string) => {
      const column = columns.find((c) => c.id === columnId);
      return column?.value ? column.value(row) : null;
    },
    [columns],
  );

  const { sort: current, ordered, toggle, ariaSort } = useSortableRows<T>({
    rows,
    getRowId,
    getValue,
    sort,
    defaultSort,
    onSortChange,
  });

  const template = useMemo(
    () =>
      (markable ? "28px " : "") +
      columns.map((c) => c.width ?? "minmax(0, 1fr)").join(" "),
    [columns, markable],
  );

  const onToggle = (columnId: string) => {
    setTouched(true);
    toggle(columnId);
    if (reduced) return;
    setMoving(true);
    if (settleTimer.current) clearTimeout(settleTimer.current);
    settleTimer.current = setTimeout(() => setMoving(false), SETTLE_MS);
  };

  const onMark = (id: string) => {
    const next = marked === id ? null : id;
    setMarked(next);
    onMarkChange?.(next);
  };

  const nameOf = (row: T) =>
    getRowLabel?.(row) ?? String(columns[0]?.value?.(row) ?? getRowId(row));

  const activeHeader = columns.find((c) => c.id === current?.columnId)?.header;

  const message = !touched
    ? ""
    : current && activeHeader
      ? `Sorted by ${activeHeader}, ${
          current.direction === "asc" ? "ascending" : "descending"
        }. ${rows.length} rows.`
      : `Original order restored. ${rows.length} rows.`;

  return (
    <div
      className={`overflow-hidden rounded-[14px] border border-stone-200 bg-white shadow-[0_1px_2px_rgba(28,25,23,0.06),0_4px_10px_-8px_rgba(28,25,23,0.45)] dark:border-white/[0.16] dark:bg-[#1D1D1A] dark:shadow-[0_1px_6px_rgba(0,0,0,0.45)] ${className}`}
    >
      <div
        role="table"
        aria-label={label}
        aria-rowcount={rows.length + 1}
        aria-colcount={columns.length + (markable ? 1 : 0)}
      >
        <div role="rowgroup">
          <div
            role="row"
            aria-rowindex={1}
            className="grid h-9 items-center gap-x-2 border-b border-stone-200 px-2 dark:border-white/[0.16]"
            style={{ gridTemplateColumns: template }}
          >
            {markable && (
              <div role="columnheader" className="min-w-0">
                <span className="sr-only">Follow</span>
              </div>
            )}

            {columns.map((column) => {
              const state = ariaSort(column.id);
              const active = state !== "none";
              const end = column.align === "end";

              return (
                <div
                  key={column.id}
                  role="columnheader"
                  aria-sort={column.sortable === false ? undefined : state}
                  className="min-w-0"
                >
                  {column.sortable === false ? (
                    <span
                      className={`block truncate px-1.5 text-[11px] font-semibold uppercase tracking-[0.08em] text-stone-500 dark:text-stone-400 ${
                        end ? "text-right" : ""
                      }`}
                    >
                      {column.header}
                    </span>
                  ) : (
                    <button
                      type="button"
                      onClick={() => onToggle(column.id)}
                      className={`group flex h-7 w-full items-center gap-1.5 rounded-[6px] px-1.5 outline-none focus-visible:bg-[#4568FF]/[0.06] focus-visible:shadow-[inset_0_0_0_1px_#4568FF] dark:focus-visible:bg-[#93B0FF]/[0.06] dark:focus-visible:shadow-[inset_0_0_0_1px_#93B0FF] ${
                        end ? "flex-row-reverse" : ""
                      }`}
                    >
                      <span
                        className={`truncate text-[11px] font-semibold uppercase tracking-[0.08em] ${
                          active
                            ? "text-stone-700 dark:text-stone-200"
                            : "text-stone-500 group-hover:text-stone-700 dark:text-stone-400 dark:group-hover:text-stone-200"
                        }`}
                      >
                        {column.header}
                      </span>
                      <motion.span
                        aria-hidden
                        className="shrink-0 text-stone-700 dark:text-stone-200"
                        initial={false}
                        animate={{
                          rotate: state === "descending" ? 180 : 0,
                          opacity: active ? 1 : 0,
                          scale: active ? 1 : 0.72,
                        }}
                        transition={reduced ? { duration: 0 } : SMALL}
                      >
                        <svg width="9" height="9" viewBox="0 0 10 10" fill="none">
                          <path
                            d="M5 8.6V1.6M5 1.6 2.2 4.4M5 1.6l2.8 2.8"
                            stroke="currentColor"
                            strokeWidth="1.4"
                            strokeLinecap="round"
                            strokeLinejoin="round"
                          />
                        </svg>
                      </motion.span>
                    </button>
                  )}
                </div>
              );
            })}
          </div>
        </div>
        <div
          role="rowgroup"
          className={`relative overflow-y-auto overscroll-contain ${
            maxHeight ? "[scrollbar-gutter:stable]" : ""
          }`}
          style={{
            height: (rows.length || 1) * rowHeight,
            maxHeight,
          }}
        >
          {rows.length === 0 && (
            <div
              role="row"
              className="absolute inset-x-0 top-0 flex items-center px-3.5"
              style={{ height: rowHeight }}
            >
              <span
                role="cell"
                className="text-[12.5px] text-stone-500 dark:text-stone-400"
              >
                No rows
              </span>
            </div>
          )}

          {ordered.map(({ id, row, index }) => {
            const isMarked = markable && marked === id;

            return (
              <motion.div
                key={id}
                role="row"
                aria-rowindex={index + 2}
                aria-current={isMarked ? true : undefined}
                initial={false}
                animate={{ y: index * rowHeight }}
                transition={
                  reduced
                    ? { duration: 0 }
                    : { ...CELL, delay: Math.min(index, STEP_CAP) * STEP }
                }
                className={`absolute inset-x-0 top-0 grid items-center gap-x-2 px-2 transition-colors duration-150 ${
                  isMarked ? "bg-stone-100 dark:bg-white/[0.06]" : ""
                }`}
                style={{ height: rowHeight, gridTemplateColumns: template }}
              >
                {markable && (
                  <div role="cell" className="min-w-0">
                    <button
                      type="button"
                      aria-pressed={marked === id}
                      onClick={() => onMark(id)}
                      className={`flex size-[18px] items-center justify-center rounded-[5px] border outline-none focus-visible:border-[#4568FF] focus-visible:shadow-[0_1px_3px_rgba(28,25,23,0.18)] dark:focus-visible:border-[#93B0FF] dark:focus-visible:shadow-[0_1px_3px_rgba(0,0,0,0.5)] ${
                        marked === id
                          ? "border-[#4568FF] bg-[#4568FF] text-white dark:border-[#93B0FF] dark:bg-[#93B0FF] dark:text-stone-900"
                          : "border-stone-200 text-transparent dark:border-white/15"
                      }`}
                    >
                      <span className="sr-only">Follow {nameOf(row)}</span>
                      <motion.svg
                        aria-hidden
                        width="11"
                        height="11"
                        viewBox="0 0 12 12"
                        fill="none"
                        initial={false}
                        animate={{ scale: marked === id ? 1 : 0.4 }}
                        transition={reduced ? { duration: 0 } : CELL}
                      >
                        <path
                          d="M2.6 6.3 4.9 8.6 9.4 3.4"
                          stroke="currentColor"
                          strokeWidth="1.6"
                          strokeLinecap="round"
                          strokeLinejoin="round"
                        />
                      </motion.svg>
                    </button>
                  </div>
                )}

                {columns.map((column, c) => {
                  const raw = column.value?.(row);
                  const content = column.cell
                    ? column.cell(row)
                    : raw === null || raw === undefined || raw === ""
                      ? " - "
                      : String(raw);

                  return (
                    <div
                      key={column.id}
                      role="cell"
                      className={`min-w-0 truncate px-1.5 text-[13px] ${
                        column.align === "end" ? "text-right" : ""
                      } ${column.numeric ? "tabular-nums" : ""} ${
                        c === 0
                          ? "font-medium text-stone-700 dark:text-stone-200"
                          : "text-stone-500 dark:text-stone-400"
                      }`}
                    >
                      {content}
                    </div>
                  );
                })}
              </motion.div>
            );
          })}

          <motion.div
            aria-hidden
            initial={false}
            animate={{ opacity: moving ? 0 : 1 }}
            transition={moving ? HIDE : SHOW}
            className="pointer-events-none absolute inset-0"
          >
            {Array.from({ length: Math.max(0, rows.length - 1) }, (_, i) => (
              <div
                key={i}
                className="absolute inset-x-0 border-t border-stone-200 dark:border-white/[0.16]"
                style={{ top: (i + 1) * rowHeight }}
              />
            ))}
          </motion.div>
        </div>
      </div>
      <div role="status" aria-live="polite" className="sr-only">
        {message}
      </div>
    </div>
  );
}
```

---

## Filter Grid · Data

Filtering rearranges, it does not blink.

Docs: https://yugo.click/docs/filter-grid
Install: `bun add motion`, then copy the source below into `components/yugo/filter-grid.tsx` · or `bunx shadcn@latest add https://yugo.click/r/filter-grid.json`.

Guarantees:
- The grid reserves the height of the whole unfiltered set before the first paint, so narrowing forty cards to three never drags the content below it up the page; past maxRows the box scrolls rather than growing.
- An item that survives a filter change is never unmounted and remounted: it keeps its element and travels to its new slot on transform, while the items that lost are pulled out of flow by popLayout, so the grid rearranges instead of blinking white between two states.
- Counts are computed per filter over the full set, not the visible one, so a chip's width is the same in every reachable state and the chip row cannot reflow when the selection moves.
- Filters clicked in fast succession interrupt: each card's spring resumes from where it currently sits, and no card replays a trip it had already half finished.
- If focus was inside a card that the new filter removed, it lands on the grid container once the exit settles, never on the document body.
- The count is announced once per settled filter change through a polite region rather than per item, and under prefers-reduced-motion the cards are simply in their new slots: the empty state and the counts still arrive.


### Usage

```tsx
"use client";

import { useState } from "react";
import { FilterGrid, type FilterDefinition } from "@/components/yugo/filter-grid";

type Asset = { id: string; name: string; kind: "image" | "clip" | "doc"; size: string };

const FILTERS: FilterDefinition<Asset>[] = [
  { id: "all", label: "All", match: () => true },
  { id: "image", label: "Images", match: (a) => a.kind === "image" },
  { id: "clip", label: "Clips", match: (a) => a.kind === "clip" },
  { id: "doc", label: "Docs", match: (a) => a.kind === "doc" },
];

export function AssetLibrary({ assets }: { assets: Asset[] }) {
  const [kind, setKind] = useState("all");

  return (
    <FilterGrid
      label="Asset type"
      items={assets}
      filters={FILTERS}
      value={kind}
      onValueChange={setKind}
      getKey={(a) => a.id}
      columns={3}
      rowHeight={72}
      maxRows={4}
      renderItem={(a) => (
        <div className="flex h-full flex-col justify-between">
          <p className="truncate text-[12.5px] font-medium text-stone-700 dark:text-stone-200">
            {a.name}
          </p>
          <p className="text-[10.5px] tabular-nums text-stone-500 dark:text-stone-400">
            {a.size}
          </p>
        </div>
      )}
    />
  );
}
```

### Source (`components/yugo/filter-grid.tsx`)

```tsx
"use client";

import {
  useCallback,
  useId,
  useMemo,
  useRef,
  useState,
  type KeyboardEvent,
  type ReactNode,
} from "react";
import { AnimatePresence, motion, useReducedMotion } from "motion/react";

const CELL = { type: "spring", stiffness: 520, damping: 34, mass: 0.45 } as const;
const MOVE = { type: "spring", stiffness: 260, damping: 34, mass: 0.8 } as const;
const EASE = [0.23, 1, 0.32, 1] as const;
const LEAVE = { duration: 0.14, ease: [0.4, 0, 1, 1] } as const;
const INSTANT = { duration: 0 } as const;

export type FilterDefinition<T> = {
  id: string;
  label: string;
  match: (item: T) => boolean;
};

export type UseFilterGridOptions<T> = {
  items: readonly T[];
  filters: readonly FilterDefinition<T>[];
  value?: string;
  defaultValue?: string;
  onValueChange?: (id: string) => void;
};

export type UseFilterGridResult<T> = {
  active: string;
  activeLabel: string;
  select: (id: string) => void;
  visible: T[];
  counts: Record<string, number>;
  total: number;
};

export function useFilterGrid<T>({
  items,
  filters,
  value,
  defaultValue,
  onValueChange,
}: UseFilterGridOptions<T>): UseFilterGridResult<T> {
  const fallback = filters[0]?.id ?? "";
  const [internal, setInternal] = useState(() => defaultValue ?? fallback);

  const requested = value ?? internal;
  const current = filters.find((f) => f.id === requested) ?? filters[0];
  const active = current?.id ?? fallback;

  const emit = useRef(onValueChange);
  emit.current = onValueChange;

  const counts = useMemo(() => {
    const next: Record<string, number> = {};
    for (const filter of filters) {
      let n = 0;
      for (const item of items) if (filter.match(item)) n += 1;
      next[filter.id] = n;
    }
    return next;
  }, [filters, items]);

  const visible = useMemo(() => {
    const filter = filters.find((f) => f.id === active);
    if (!filter) return [...items];
    return items.filter((item) => filter.match(item));
  }, [filters, items, active]);

  const select = useCallback(
    (id: string) => {
      if (value === undefined) setInternal(id);
      if (id !== active) emit.current?.(id);
    },
    [value, active],
  );

  return {
    active,
    activeLabel: current?.label ?? "",
    select,
    visible,
    counts,
    total: items.length,
  };
}

export type FilterGridProps<T> = {
  items: readonly T[];
  filters: readonly FilterDefinition<T>[];
  getKey: (item: T) => string;
  renderItem: (item: T) => ReactNode;
  label: string;
  value?: string;
  defaultValue?: string;
  onValueChange?: (id: string) => void;
  columns?: number;
  rowHeight?: number;
  maxRows?: number;
  gap?: number;
  emptyLabel?: string;
  className?: string;
};

export function FilterGrid<T>({
  items,
  filters,
  getKey,
  renderItem,
  label,
  value,
  defaultValue,
  onValueChange,
  columns = 3,
  rowHeight = 72,
  maxRows = 4,
  gap = 8,
  emptyLabel = "Nothing matches this filter",
  className = "",
}: FilterGridProps<T>) {
  const uid = useId();
  const gridId = `${uid}-grid`;
  const reduced = useReducedMotion();

  const { active, activeLabel, select, visible, counts, total } = useFilterGrid({
    items,
    filters,
    value,
    defaultValue,
    onValueChange,
  });

  const gridRef = useRef<HTMLUListElement>(null);
  const chips = useRef<(HTMLButtonElement | null)[]>([]);
  const heldFocus = useRef(false);

  const cols = Math.max(1, Math.floor(columns));
  const rows = Math.min(Math.max(1, Math.ceil(total / cols)), Math.max(1, maxRows));
  const box = rows * rowHeight + (rows - 1) * gap;

  const index = Math.max(
    0,
    filters.findIndex((f) => f.id === active),
  );

  const choose = useCallback(
    (id: string) => {
      const grid = gridRef.current;
      heldFocus.current =
        !!grid && grid.contains(document.activeElement) && grid !== document.activeElement;
      select(id);
    },
    [select],
  );

  const settle = useCallback(() => {
    if (!heldFocus.current) return;
    heldFocus.current = false;
    const grid = gridRef.current;
    if (grid && !grid.contains(document.activeElement)) grid.focus();
  }, []);

  const go = useCallback(
    (i: number) => {
      const next = filters[(i + filters.length) % filters.length];
      if (!next) return;
      chips.current[(i + filters.length) % filters.length]?.focus();
      choose(next.id);
    },
    [filters, choose],
  );

  const onKeyDown = (e: KeyboardEvent<HTMLButtonElement>, i: number) => {
    if (e.key === "ArrowRight" || e.key === "ArrowDown") {
      e.preventDefault();
      go(i + 1);
    } else if (e.key === "ArrowLeft" || e.key === "ArrowUp") {
      e.preventDefault();
      go(i - 1);
    } else if (e.key === "Home") {
      e.preventDefault();
      go(0);
    } else if (e.key === "End") {
      e.preventDefault();
      go(filters.length - 1);
    }
  };

  const swap = reduced ? INSTANT : CELL;
  const step = reduced ? INSTANT : { layout: MOVE, duration: 0.2, ease: EASE };
  const leave = reduced ? INSTANT : LEAVE;

  const capped = Math.ceil(total / cols) > Math.max(1, maxRows);

  return (
    <div className={`w-full ${className}`}>
      <div
        role="radiogroup"
        aria-label={label}
        aria-controls={gridId}
        className="flex flex-wrap items-center gap-1.5"
      >
        {filters.map((filter, i) => {
          const on = i === index;
          return (
            <button
              key={filter.id}
              ref={(node) => {
                chips.current[i] = node;
              }}
              type="button"
              role="radio"
              aria-checked={on}
              tabIndex={on ? 0 : -1}
              onClick={() => choose(filter.id)}
              onKeyDown={(e) => onKeyDown(e, i)}
              className="group relative inline-grid h-8 select-none place-items-center rounded-[6px] px-3 outline-none focus-visible:shadow-[0_1px_3px_rgba(28,25,23,0.18)] dark:focus-visible:shadow-[0_1px_3px_rgba(0,0,0,0.5)]"
              style={{ touchAction: "manipulation" }}
            >
              {on ? (
                <motion.span
                  aria-hidden
                  layoutId={reduced ? undefined : `${uid}-thumb`}
                  transition={CELL}
                  className="absolute inset-0 rounded-[6px] bg-stone-800 dark:bg-stone-100"
                />
              ) : null}

              <span
                aria-hidden
                className={`pointer-events-none absolute inset-0 rounded-[6px] border group-focus-visible:border-[#4568FF] dark:group-focus-visible:border-[#93B0FF] ${
                  on ? "border-transparent" : "border-stone-200 dark:border-white/[0.16]"
                }`}
              />
              <span className="relative col-start-1 row-start-1 inline-grid">
                <motion.span
                  aria-hidden
                  initial={false}
                  animate={{ opacity: on ? 0 : 1 }}
                  transition={swap}
                  className="col-start-1 row-start-1 inline-flex items-center gap-1.5 whitespace-nowrap text-[12.5px] font-medium text-stone-700 dark:text-stone-200"
                >
                  {filter.label}
                  <span className="text-[10.5px] tabular-nums text-stone-500 dark:text-stone-400">
                    {counts[filter.id]}
                  </span>
                </motion.span>
                <motion.span
                  aria-hidden
                  initial={false}
                  animate={{ opacity: on ? 1 : 0 }}
                  transition={swap}
                  className="col-start-1 row-start-1 inline-flex items-center gap-1.5 whitespace-nowrap text-[12.5px] font-medium text-stone-50 dark:text-stone-900"
                >
                  {filter.label}
                  <span className="text-[10.5px] tabular-nums opacity-70">
                    {counts[filter.id]}
                  </span>
                </motion.span>
                <span className="sr-only">
                  {filter.label}, {counts[filter.id]} of {total}
                </span>
              </span>
            </button>
          );
        })}
      </div>
      <div className="relative mt-2.5">
        <ul
          id={gridId}
          ref={gridRef}
          tabIndex={-1}
          className={`relative overflow-y-auto overscroll-contain outline-none ${
            capped ? "[scrollbar-gutter:stable]" : ""
          }`}
          style={{
            display: "grid",
            gridTemplateColumns: `repeat(${cols}, minmax(0, 1fr))`,
            gridAutoRows: `${rowHeight}px`,
            gap: `${gap}px`,
            height: `${box}px`,
          }}
        >
          <AnimatePresence initial={false} mode="popLayout" onExitComplete={settle}>
            {visible.map((item) => (
              <motion.li
                key={getKey(item)}
                layout={reduced ? false : "position"}
                initial={{ opacity: 0, scale: 0.97 }}
                animate={{ opacity: 1, scale: 1 }}
                exit={{ opacity: 0, scale: 0.98, transition: leave }}
                transition={step}
                className="min-w-0 overflow-hidden rounded-[11px] border border-stone-200 bg-white p-2.5 shadow-[0_1px_2px_rgba(28,25,23,0.06),0_4px_10px_-8px_rgba(28,25,23,0.45)] dark:border-white/[0.16] dark:bg-[#1D1D1A] dark:shadow-[0_1px_6px_rgba(0,0,0,0.45)]"
              >
                {renderItem(item)}
              </motion.li>
            ))}
          </AnimatePresence>
        </ul>
        <AnimatePresence initial={false}>
          {visible.length === 0 && (
            <motion.div
              key="empty"
              initial={{ opacity: 0 }}
              animate={{ opacity: 1 }}
              exit={{ opacity: 0, transition: leave }}
              transition={reduced ? INSTANT : { duration: 0.2, ease: EASE }}
              className="pointer-events-none absolute inset-0 grid place-items-center"
            >
              <span className="text-[12.5px] text-stone-500 dark:text-stone-400">
                {emptyLabel}
              </span>
            </motion.div>
          )}
        </AnimatePresence>
      </div>
      <p aria-live="polite" className="sr-only">
        {activeLabel}: {visible.length} of {total} shown
      </p>
    </div>
  );
}
```

---

## Value Flash · Data

Marks what just changed.

Docs: https://yugo.click/docs/value-flash
Install: `bun add motion`, then copy the source below into `components/yugo/value-flash.tsx` · or `bunx shadcn@latest add https://yugo.click/r/value-flash.json`.

Guarantees:
- Nothing flashes on first paint: the previous value is seeded at mount, so a hydrated table does not light every row before the user has done anything.
- A re-render that leaves the value identical is ignored under Object.is, and a change whose delta is zero is ignored too: there is no third, directionless flash, because a blink with no direction is the one nobody can read.
- Direction speaks three ways at once: moss or flag tint for the glance, a solid triangle in a permanently reserved cell for greyscale and colour blindness, and the new number rolling in from the side it moved: so the row never reflows and the change is legible at any speed.
- The tint is an absolutely positioned overlay fading its opacity on a spring, never a width, height or mask animation, and it decays once instead of looping so a stale figure can never keep looking fresh.
- Screen readers get one announcement per settled value: each tick restarts a quiet period, so a fast feed does not read sixty numbers a second into the live region.
- Every timer is cleared on the next change and on unmount, so a row removed mid-flash leaves nothing scheduled and no state set on a dead component.


### Usage

```tsx
"use client";

import { ValueFlash, useValueFlash } from "@/components/yugo/value-flash";

type Quote = { symbol: string; last: number };

const usd = (n: number) =>
  n.toLocaleString("en-US", { style: "currency", currency: "USD" });

export function QuoteRow({ quote }: { quote: Quote }) {
  const { flashing } = useValueFlash(quote.last, { hold: 1200 });

  return (
    <div
      className={`flex items-center justify-between rounded-[9px] border px-3 py-2 ${
        flashing
          ? "border-stone-300 dark:border-white/20"
          : "border-transparent"
      }`}
    >
      <span className="text-[13px] text-stone-700 dark:text-stone-200">
        {quote.symbol}
      </span>

      <ValueFlash
        value={quote.last}
        label={`${quote.symbol} last traded`}
        format={usd}
        hold={1200}
      />
    </div>
  );
}
```

### Source (`components/yugo/value-flash.tsx`)

```tsx
"use client";

import { useEffect, useRef, useState, type ReactNode } from "react";
import { AnimatePresence, motion, useReducedMotion } from "motion/react";

const CELL = { type: "spring", stiffness: 520, damping: 34, mass: 0.45 } as const;

const ROLL = { type: "spring", stiffness: 460, damping: 32, mass: 0.55 } as const;

const POP = { type: "spring", stiffness: 640, damping: 22, mass: 0.7 } as const;

const LIFT = { type: "spring", stiffness: 380, damping: 26, mass: 0.7 } as const;

const SETTLE = { type: "spring", stiffness: 260, damping: 34, mass: 0.8 } as const;

const CLEAR = { duration: 0.16, ease: [0.4, 0, 1, 1] } as const;
const DROP = { duration: 0.14, ease: [0.4, 0, 1, 1] } as const;
const STILL = { duration: 0 } as const;

const GLYPH: Record<"up" | "down", ReactNode> = {
  up: <path d="M128 68 L210 180 H46 Z" />,
  down: <path d="M128 188 L46 76 H210 Z" />,
};

export type FlashDirection = "up" | "down";

export type UseValueFlashOptions<T> = {
  hold?: number;
  compare?: (next: T, previous: T) => number;
};

export type ValueFlashState<T> = {
  direction: FlashDirection | null;
  from: T;
  changeId: number;
  flashing: boolean;
};

export function useValueFlash<T>(
  value: T,
  { hold = 900, compare }: UseValueFlashOptions<T> = {},
): ValueFlashState<T> {
  const [state, setState] = useState<ValueFlashState<T>>({
    direction: null,
    from: value,
    changeId: 0,
    flashing: false,
  });

  const previous = useRef(value);
  const timer = useRef<ReturnType<typeof setTimeout> | null>(null);
  const rank = useRef(compare);

  useEffect(() => {
    rank.current = compare;
  });

  useEffect(() => {
    const prior = previous.current;
    if (Object.is(prior, value)) return;
    previous.current = value;

    const measure = rank.current;
    const delta = measure
      ? measure(value, prior)
      : typeof value === "number" && typeof prior === "number"
        ? value - prior
        : 0;

    if (delta === 0) return;

    setState((prev) => ({
      direction: delta > 0 ? "up" : "down",
      from: prior,
      changeId: prev.changeId + 1,
      flashing: true,
    }));

    if (timer.current) clearTimeout(timer.current);
    timer.current = setTimeout(() => {
      timer.current = null;
      setState((prev) => (prev.flashing ? { ...prev, flashing: false } : prev));
    }, hold);
  }, [value, hold]);

  useEffect(
    () => () => {
      if (timer.current) clearTimeout(timer.current);
    },
    [],
  );

  return state;
}

export type ValueFlashProps = {
  value: number;
  format?: (value: number) => string;
  label?: string;
  hold?: number;
  announceAfter?: number;
  className?: string;
};

export function ValueFlash({
  value,
  format,
  label,
  hold = 900,
  announceAfter = 700,
  className = "",
}: ValueFlashProps) {
  const { direction, flashing, changeId } = useValueFlash(value, { hold });
  const reduced = useReducedMotion();

  const text = format ? format(value) : String(value);
  const [settled, setSettled] = useState(text);

  useEffect(() => {
    const id = setTimeout(() => setSettled(text), announceAfter);
    return () => clearTimeout(id);
  }, [text, announceAfter]);

  const tone = flashing
    ? direction === "up"
      ? "text-emerald-600 dark:text-emerald-400"
      : "text-red-600 dark:text-red-400"
    : "text-stone-700 dark:text-stone-200";

  const tint =
    direction === "up"
      ? "bg-emerald-500/[0.12] dark:bg-emerald-400/[0.14]"
      : "bg-red-500/[0.12] dark:bg-red-400/[0.14]";

  return (
    <motion.span
      initial={false}
      animate={{ scale: reduced ? 1 : flashing ? 1.05 : 1 }}
      transition={reduced ? STILL : flashing ? LIFT : SETTLE}
      className={`relative inline-grid grid-flow-col items-center gap-1.5 rounded-[6px] px-1.5 py-[3px] text-[13px] font-medium tabular-nums transition-colors duration-200 ${tone} ${className}`}
    >
      {direction ? (
        <motion.span
          aria-hidden
          initial={{ opacity: 0 }}
          animate={{ opacity: flashing ? 1 : 0 }}
          transition={reduced ? STILL : flashing ? CELL : CLEAR}
          className={`pointer-events-none absolute inset-0 rounded-[6px] ${tint}`}
        />
      ) : null}

      <span aria-hidden className="relative inline-grid overflow-hidden">
        <AnimatePresence initial={false} mode="popLayout">
          <motion.span
            key={changeId}
            initial={
              reduced
                ? { opacity: 0 }
                : {
                    opacity: 0,
                    y: direction === "down" ? "-0.85em" : "0.85em",
                    filter: "blur(5px)",
                  }
            }
            animate={{ opacity: 1, y: "0em", filter: "blur(0px)" }}
            exit={
              reduced
                ? { opacity: 0, transition: STILL }
                : {
                    opacity: 0,
                    y: direction === "down" ? "0.7em" : "-0.7em",
                    filter: "blur(4px)",
                    transition: DROP,
                  }
            }
            transition={reduced ? STILL : ROLL}
            className="col-start-1 row-start-1"
          >
            {text}
          </motion.span>
        </AnimatePresence>
      </span>
      <span aria-hidden className="relative grid size-[1em] place-items-center">
        <AnimatePresence initial={false}>
          {flashing && direction ? (
            <motion.svg
              key={`${changeId}-${direction}`}
              viewBox="0 0 256 256"
              fill="currentColor"
              initial={
                reduced
                  ? { opacity: 0 }
                  : {
                      opacity: 0,
                      scale: 0.4,
                      y: direction === "up" ? "0.3em" : "-0.3em",
                    }
              }
              animate={{ opacity: 1, scale: 1, y: "0em" }}
              exit={
                reduced
                  ? { opacity: 0, transition: STILL }
                  : { opacity: 0, scale: 0.8, transition: CLEAR }
              }
              transition={reduced ? STILL : POP}
              className="col-start-1 row-start-1 block h-[0.68em] w-[0.68em]"
            >
              {GLYPH[direction]}
            </motion.svg>
          ) : null}
        </AnimatePresence>
      </span>
      <span className="sr-only" aria-live="polite">
        {label ? `${label}: ${settled}` : settled}
      </span>
    </motion.span>
  );
}
```

---

## Poll Results · Data

The winner lands last.

Docs: https://yugo.click/docs/poll-results
Install: `bun add motion`, then copy the source below into `components/yugo/poll-results.tsx` · or `bunx shadcn@latest add https://yugo.click/r/poll-results.json`.

Guarantees:
- The reveal is a race run on physics: every bar leaves the line at the same instant on the same spring, so a longer share is simply a longer road: the biggest number arrives last and the winner is announced by its own landing, not by a stage-managed delay.
- Each percentage is its bar's own motion value written straight to the DOM, so the numbers count up in lockstep with the fills while React renders once per vote, not once per frame.
- Your answer runs in the accent and the rest of the field runs in ink: the one bar that is a response to you is the one drawn in the colour reserved for that.
- The fill is a clipPath sweep over a fully-rounded bar, so the corners never stretch, and the winner's check pops only after the winning bar has landed.
- The material tells the story: before the vote every option is a pressable key: cap material, top light, bottom lip, a pixel of travel under the finger: and the vote turns the key into the slot it was hiding, a recessed well the result sweeps inside. Depth is the state change; colour only signs it.
- Nothing moves but the fills: the percent column and the tally line reserve their space before the first vote exists, and a revealed row refuses further clicks with aria-disabled instead of leaving the accessibility tree.
- Screen readers get the outcome once, as a sentence: who leads, with what share, out of how many votes: after the race has settled; under prefers-reduced-motion the bars are simply at their numbers.


### Usage

```tsx
"use client";

import { useState } from "react";
import { PollResults, type PollOption } from "@/components/yugo/poll-results";

export function FloorPoll({ initial }: { initial: PollOption[] }) {
  const [options, setOptions] = useState(initial);

  return (
    <PollResults
      label="Floor for the front room?"
      options={options}
      onVote={async (id) => {
        setOptions((prev) =>
          prev.map((o) => (o.id === id ? { ...o, votes: o.votes + 1 } : o)),
        );
        await fetch("/api/polls/floor", {
          method: "POST",
          body: JSON.stringify({ choice: id }),
        });
      }}
    />
  );
}
```

### Source (`components/yugo/poll-results.tsx`)

```tsx
"use client";

import { useCallback, useEffect, useRef, useState } from "react";
import {
  animate,
  AnimatePresence,
  motion,
  motionValue,
  useMotionValueEvent,
  useReducedMotion,
  useTransform,
} from "motion/react";

const FILL = { type: "spring", stiffness: 210, damping: 34, mass: 0.9 } as const;

const POP = { type: "spring", stiffness: 640, damping: 22, mass: 0.7 } as const;
const EASE = [0.23, 1, 0.32, 1] as const;
const ENTER = { duration: 0.2, ease: EASE } as const;
const STILL = { duration: 0 } as const;

export type PollOption = {
  id: string;
  label: string;
  votes: number;
};

export type UsePollResultsOptions = {
  options: PollOption[];

  value?: string | null;
  defaultValue?: string | null;
  onVote?: (id: string) => void;
};

export function usePollResults({
  options,
  value,
  defaultValue = null,
  onVote,
}: UsePollResultsOptions) {
  const [internal, setInternal] = useState<string | null>(defaultValue);
  const controlled = value !== undefined;
  const chosen = controlled ? value : internal;

  const emit = useRef(onVote);
  emit.current = onVote;

  const vote = useCallback(
    (id: string) => {
      if (chosen !== null) return;
      if (!controlled) setInternal(id);
      emit.current?.(id);
    },
    [chosen, controlled],
  );

  const total = options.reduce((sum, o) => sum + Math.max(0, o.votes), 0);
  const top = options.reduce(
    (best, o) => (o.votes > best ? o.votes : best),
    0,
  );

  const rows = options.map((option) => ({
    ...option,
    share: total > 0 ? Math.max(0, option.votes) / total : 0,
    winner: total > 0 && option.votes === top,
    mine: option.id === chosen,
  }));

  return {
    rows,
    total,
    chosen,
    revealed: chosen !== null,
    vote,
  };
}

const Tick = (
  <svg viewBox="0 0 256 256" width="11" height="11" fill="none" aria-hidden>
    <polyline
      points="216 72 104 184 48 128"
      stroke="currentColor"
      strokeWidth="26"
      strokeLinecap="round"
      strokeLinejoin="round"
    />
  </svg>
);

type RowProps = {
  label: string;
  share: number;
  winner: boolean;
  mine: boolean;
  revealed: boolean;
  reduced: boolean;
  onPick: () => void;
};

function Row({ label, share, winner, mine, revealed, reduced, onPick }: RowProps) {
  const progress = useRef(motionValue(0)).current;
  const clipPath = useTransform(
    progress,
    (p) => `inset(0 ${((1 - p) * 100).toFixed(2)}% 0 0 round 5px)`,
  );

  const [landed, setLanded] = useState(false);
  const readout = useRef<HTMLSpanElement | null>(null);

  useMotionValueEvent(progress, "change", (p) => {
    const node = readout.current;
    if (!node) return;
    const next = `${Math.round(p * 100)}%`;
    if (node.textContent !== next) node.textContent = next;
  });

  useEffect(() => {
    if (!revealed) return;
    if (reduced) {
      progress.jump(share);
      setLanded(true);
      return;
    }
    const controls = animate(progress, share, FILL);
    void controls.finished.then(() => setLanded(true));
    return () => controls.stop();
  }, [revealed, share, reduced, progress]);

  return (
    // eslint-disable-next-line jsx-a11y/control-has-associated-label
    <button
      type="button"
      onClick={onPick}
      aria-disabled={revealed}
      aria-pressed={revealed ? mine : undefined}
      className={`group relative h-9 w-full overflow-hidden rounded-[8px] border text-left outline-none transition-[border-color,background-color,box-shadow,transform] duration-200 focus-visible:after:pointer-events-none focus-visible:after:absolute focus-visible:after:inset-0 focus-visible:after:rounded-[7px] focus-visible:after:bg-[#4568FF]/[0.06] focus-visible:after:shadow-[inset_0_0_0_1px_#4568FF] dark:focus-visible:after:bg-[#93B0FF]/[0.1] dark:focus-visible:after:shadow-[inset_0_0_0_1px_#93B0FF] ${
        revealed
          ? "cursor-default border-stone-200 bg-stone-100/70 shadow-[inset_0_1px_2px_rgba(28,25,23,0.07)] dark:border-white/[0.08] dark:bg-[#1D1D1A] dark:shadow-[inset_0_1px_2px_rgba(0,0,0,0.45)]"
          : "border-stone-200 bg-white shadow-[inset_0_1.5px_0_rgba(255,255,255,0.95),inset_0_-1px_0_rgba(28,25,23,0.06),0_1px_2px_rgba(28,25,23,0.08)] hover:bg-stone-50 active:translate-y-px active:shadow-[inset_0_1px_2px_rgba(28,25,23,0.06)] dark:border-white/[0.16] dark:bg-[#252522] dark:shadow-[inset_0_1px_0_rgba(255,255,255,0.07),0_1px_2px_rgba(0,0,0,0.4)] dark:hover:bg-[#2A2A27]"
      }`}
    >
      <motion.span
        aria-hidden
        style={{ clipPath }}
        className={`absolute inset-[3px] rounded-[5px] ${
          mine
            ? "bg-[#4568FF]/[0.22] shadow-[inset_0_1px_0_rgba(255,255,255,0.55),inset_0_-1px_0_rgba(69,104,255,0.28)] dark:bg-[#93B0FF]/[0.26] dark:shadow-[inset_0_1px_0_rgba(255,255,255,0.16),inset_0_-1px_0_rgba(0,0,0,0.3)]"
            : "bg-stone-800/[0.10] shadow-[inset_0_1px_0_rgba(255,255,255,0.5),inset_0_-1px_0_rgba(28,25,23,0.1)] dark:bg-white/[0.12] dark:shadow-[inset_0_1px_0_rgba(255,255,255,0.12),inset_0_-1px_0_rgba(0,0,0,0.3)]"
        }`}
      />
      <span className="relative flex h-full items-center gap-2 px-3">
        <span
          className={`min-w-0 flex-1 truncate text-[13px] transition-[color,font-weight] duration-200 ${
            revealed && winner
              ? "font-medium text-stone-800 dark:text-stone-100"
              : "text-stone-600 group-hover:text-stone-800 dark:text-stone-300 dark:group-hover:text-stone-100"
          }`}
        >
          {label}
        </span>
        <span className="grid size-4 shrink-0 place-items-center">
          <AnimatePresence initial={false}>
            {revealed && winner && landed ? (
              <motion.span
                key="win"
                initial={reduced ? { opacity: 0 } : { opacity: 0, scale: 0.4 }}
                animate={{ opacity: 1, scale: 1 }}
                exit={{ opacity: 0, transition: STILL }}
                transition={reduced ? STILL : POP}
                className="text-stone-800 dark:text-stone-100"
              >
                {Tick}
              </motion.span>
            ) : null}
          </AnimatePresence>
        </span>
        <span className="relative grid shrink-0 text-right">
          <span
            aria-hidden
            className="invisible col-start-1 row-start-1 font-mono text-[11px] tabular-nums"
          >
            100%
          </span>
          <motion.span
            ref={readout}
            aria-hidden
            initial={false}
            animate={{ opacity: revealed ? 1 : 0 }}
            transition={reduced ? STILL : ENTER}
            className="col-start-1 row-start-1 font-mono text-[11px] tabular-nums text-stone-500 dark:text-stone-400"
          >
            0%
          </motion.span>
        </span>
      </span>
    </button>
  );
}

export type PollResultsProps = UsePollResultsOptions & {
  label: string;
  className?: string;
};

export function PollResults({
  options,
  value,
  defaultValue,
  onVote,
  label,
  className = "",
}: PollResultsProps) {
  const poll = usePollResults({ options, value, defaultValue, onVote });
  const reduced = useReducedMotion() === true;

  const [spoken, setSpoken] = useState("");
  useEffect(() => {
    if (!poll.revealed) return;
    const winner = poll.rows.find((r) => r.winner);
    const t = setTimeout(
      () =>
        setSpoken(
          winner
            ? `Results: ${winner.label} leads with ${Math.round(winner.share * 100)} percent of ${poll.total} votes`
            : `Results shown, ${poll.total} votes`,
        ),
      700,
    );
    return () => clearTimeout(t);
  }, [poll.revealed, poll.rows, poll.total]);

  return (
    <div role="group" aria-label={label} className={`w-full ${className}`}>
      <p className="mb-2.5 text-[13px] font-medium text-stone-800 dark:text-stone-100">
        {label}
      </p>
      <div className="space-y-1.5">
        {poll.rows.map((row) => (
          <Row
            key={row.id}
            label={row.label}
            share={row.share}
            winner={row.winner}
            mine={row.mine}
            revealed={poll.revealed}
            reduced={reduced}
            onPick={() => poll.vote(row.id)}
          />
        ))}
      </div>
      <p className="mt-2 h-4 font-mono text-[10.5px] tabular-nums text-stone-400 dark:text-stone-500">
        <motion.span
          initial={false}
          animate={{ opacity: poll.revealed ? 1 : 0 }}
          transition={reduced ? STILL : { ...ENTER, delay: 0.4 }}
          className="inline-block"
        >
          {poll.total.toLocaleString("en-US")} votes
        </motion.span>
      </p>
      <span role="status" className="sr-only">
        {spoken}
      </span>
    </div>
  );
}
```

---

## Slider Detents · Gesture

Stops you can feel.

Docs: https://yugo.click/docs/slider-detents
Install: `bun add motion`, then copy the source below into `components/yugo/slider-detents.tsx` · or `bunx shadcn@latest add https://yugo.click/r/slider-detents.json`.

Guarantees:
- A continuous slider cannot be landed on the one value that matters, so within the pull radius the pointer hands the value to the detent and the thumb springs ahead of the finger to show it happened.
- A sticky detent that also swallows the keyboard would make 0.95 unreachable, so arrow keys move by exactly one step and ignore capture entirely; Shift with an arrow, PageUp and PageDown jump detent to detent.
- The readout never reflows: the widest reachable string: every formatted bound and every detent label: is measured into the same grid cell up front, so the number holds still while the label beside it crossfades in.
- The gesture reports discrete values, so React re-renders once per step instead of once per frame; the thumb, the fill and the tick marks are one spring writing transforms, and the fill is a clipped translate rather than an animated width.
- Position is expressed as a percentage translate inside a thumb-inset track, so there is no measurement pass, no zero-width first paint and no jump on hydration.
- Screen readers get one aria-valuetext per committed step: the formatted value plus the detent name when it is parked on one: and the visible readout is aria-hidden so the value is never announced twice.


### Usage

```tsx
"use client";

import { useState } from "react";
import { SliderDetents } from "@/components/yugo/slider-detents";

const SPEEDS = [
  { value: 0.5, label: "0.5×" },
  { value: 1, label: "Normal" },
  { value: 1.5, label: "1.5×" },
  { value: 2, label: "2×" },
];

const speed = (v: number) => `${v.toFixed(2)}×`;

export function PlaybackSpeed({ onCommit }: { onCommit: (rate: number) => void }) {
  const [rate, setRate] = useState(1);

  return (
    <SliderDetents
      label="Playback speed"
      value={rate}
      min={0.25}
      max={2}
      step={0.05}
      detents={SPEEDS}
      format={speed}
      onValueChange={(next) => {
        setRate(next);
        onCommit(next);
      }}
    />
  );
}
```

### Source (`components/yugo/slider-detents.tsx`)

```tsx
"use client";

import { useCallback, useEffect, useId, useMemo, useRef, useState } from "react";
import {
  motion,
  useMotionTemplate,
  useReducedMotion,
  useSpring,
} from "motion/react";

const CARRIAGE = { stiffness: 520, damping: 34, mass: 0.45 } as const;

const GRAB = { type: "spring", stiffness: 700, damping: 46, mass: 0.5 } as const;
const CROSSFADE = {
  type: "spring",
  stiffness: 260,
  damping: 34,
  mass: 0.8,
} as const;
const INSTANT = { duration: 0 } as const;
const THUMB = 18;

const plain = (value: number) => String(value);

function tidy(value: number) {
  return Math.round(value * 1e6) / 1e6;
}

export type SliderDetent = { value: number; label?: string };

const NONE: readonly (number | SliderDetent)[] = [];

export type UseSliderDetentsOptions = {
  value: number;
  onValueChange: (value: number) => void;
  min?: number;
  max?: number;
  step?: number;
  detents?: readonly (number | SliderDetent)[];
  pull?: number;
  thumbSize?: number;
  disabled?: boolean;
  haptic?: boolean;
  format?: (value: number) => string;
  label?: string;
  labelledBy?: string;
};

export function useSliderDetents({
  value,
  onValueChange,
  min = 0,
  max = 100,
  step = 1,
  detents = NONE,
  pull,
  thumbSize = THUMB,
  disabled = false,
  haptic = true,
  format = plain,
  label,
  labelledBy,
}: UseSliderDetentsOptions) {
  const trackRef = useRef<HTMLDivElement>(null);
  const [dragging, setDragging] = useState(false);

  const list = useMemo<SliderDetent[]>(
    () => detents.map((d) => (typeof d === "number" ? { value: d } : d)),
    [detents],
  );

  const range = max - min;
  const grab = pull ?? range * 0.045;

  const emit = useRef(onValueChange);
  emit.current = onValueChange;
  const emitted = useRef(value);
  emitted.current = value;

  const activeDetent = useMemo(
    () => list.findIndex((d) => tidy(d.value) === tidy(value)),
    [list, value],
  );

  const marked = useRef(activeDetent);
  const held = useRef(false);

  const commit = useCallback(
    (next: number) => {
      const settled = Math.min(max, Math.max(min, tidy(next)));
      const index = list.findIndex((d) => tidy(d.value) === settled);
      if (index !== marked.current) {
        marked.current = index;
        if (haptic && index >= 0) navigator.vibrate?.(6);
      }
      if (settled !== emitted.current) {
        emitted.current = settled;
        emit.current(settled);
      }
    },
    [haptic, list, max, min],
  );

  const capture = useCallback(
    (clientX: number) => {
      const el = trackRef.current;
      if (!el || range <= 0) return null;
      const rect = el.getBoundingClientRect();
      const travel = rect.width - thumbSize;
      if (travel <= 0) return null;

      const ratio = (clientX - rect.left - thumbSize / 2) / travel;
      const raw = Math.min(max, Math.max(min, min + ratio * range));

      let index = -1;
      let nearest = grab;
      for (let i = 0; i < list.length; i += 1) {
        const distance = Math.abs(raw - list[i].value);
        if (distance <= nearest) {
          nearest = distance;
          index = i;
        }
      }
      if (index >= 0) return list[index].value;
      return min + Math.round((raw - min) / step) * step;
    },
    [grab, list, max, min, range, step, thumbSize],
  );

  const release = useCallback(() => {
    if (!held.current) return;
    held.current = false;
    setDragging(false);
  }, []);

  const toDetent = useCallback(
    (direction: number) => {
      const sorted = list.map((d) => d.value).toSorted((a, b) => a - b);
      const forward = sorted.find((d) => d > value + 1e-6);
      const backward = sorted.findLast((d) => d < value - 1e-6);
      const target = direction > 0 ? forward : backward;
      commit(target ?? (direction > 0 ? max : min));
    },
    [commit, list, max, min, value],
  );

  useEffect(() => {
    window.addEventListener("blur", release);
    return () => window.removeEventListener("blur", release);
  }, [release]);

  const detentLabel = list[activeDetent]?.label;
  const valueText = detentLabel
    ? `${format(value)}, ${detentLabel}`
    : format(value);

  const percent = range > 0 ? Math.min(1, Math.max(0, (value - min) / range)) : 0;

  const trackProps = {
    role: "slider" as const,
    tabIndex: 0,
    "aria-orientation": "horizontal" as const,
    "aria-valuemin": min,
    "aria-valuemax": max,
    "aria-valuenow": value,
    "aria-valuetext": valueText,
    "aria-disabled": disabled || undefined,
    "aria-label": labelledBy ? undefined : label,
    "aria-labelledby": labelledBy,
    style: { touchAction: "none" as const },
    onPointerDown: (e: React.PointerEvent<HTMLDivElement>) => {
      if (disabled) return;
      if (e.pointerType === "mouse" && e.button !== 0) return;
      e.currentTarget.setPointerCapture?.(e.pointerId);
      e.currentTarget.focus({ preventScroll: true });
      held.current = true;
      setDragging(true);
      const next = capture(e.clientX);
      if (next !== null) commit(next);
    },
    onPointerMove: (e: React.PointerEvent<HTMLDivElement>) => {
      if (!held.current) return;
      const next = capture(e.clientX);
      if (next !== null) commit(next);
    },
    onPointerUp: release,
    onPointerCancel: release,
    onLostPointerCapture: release,
    onKeyDown: (e: React.KeyboardEvent<HTMLDivElement>) => {
      if (disabled) return;
      const forward = e.key === "ArrowRight" || e.key === "ArrowUp";
      const back = e.key === "ArrowLeft" || e.key === "ArrowDown";

      if (forward || back) {
        const direction = forward ? 1 : -1;
        if (e.shiftKey) toDetent(direction);
        else commit(value + direction * step);
      } else if (e.key === "PageUp") {
        toDetent(1);
      } else if (e.key === "PageDown") {
        toDetent(-1);
      } else if (e.key === "Home") {
        commit(min);
      } else if (e.key === "End") {
        commit(max);
      } else {
        return;
      }
      e.preventDefault();
    },
  };

  return {
    trackRef,
    trackProps,
    detents: list,
    activeDetent,
    percent,
    dragging,
    valueText,
  };
}

export type SliderDetentsProps = {
  value: number;
  onValueChange: (value: number) => void;
  min?: number;
  max?: number;
  step?: number;
  detents?: readonly (number | SliderDetent)[];
  pull?: number;
  label?: string;
  format?: (value: number) => string;
  disabled?: boolean;
  haptic?: boolean;
  className?: string;
};

export function SliderDetents({
  value,
  onValueChange,
  min = 0,
  max = 100,
  step = 1,
  detents = NONE,
  pull,
  label = "Value",
  format = plain,
  disabled = false,
  haptic = true,
  className = "",
}: SliderDetentsProps) {
  const labelId = useId();
  const reduced = useReducedMotion();

  const {
    trackRef,
    trackProps,
    detents: list,
    activeDetent,
    percent,
    dragging,
  } = useSliderDetents({
    value,
    onValueChange,
    min,
    max,
    step,
    detents,
    pull,
    disabled,
    haptic,
    format,
    labelledBy: labelId,
  });

  const carriage = useSpring(percent * 100, CARRIAGE);
  const offset = useMotionTemplate`${carriage}%`;

  useEffect(() => {
    const target = percent * 100;
    if (reduced) carriage.jump(target);
    else carriage.set(target);
  }, [carriage, percent, reduced]);

  const widest = useMemo(() => {
    const options = [
      format(min),
      format(max),
      ...list.map((d) =>
        d.label ? `${format(d.value)} · ${d.label}` : format(d.value),
      ),
    ];
    return options.reduce((a, b) => (b.length > a.length ? b : a), "");
  }, [format, list, max, min]);

  const suffix = list[activeDetent]?.label ?? "";

  const lastLabel = useRef(suffix);
  if (suffix) lastLabel.current = suffix;

  const span = max - min;

  return (
    <div className={`w-full select-none ${className}`}>
      <div className="mb-2.5 flex items-baseline justify-between gap-3">
        <span
          id={labelId}
          className="text-[12.5px] text-stone-500 dark:text-stone-400"
        >
          {label}
        </span>
        <span className="grid justify-items-start">
          <span
            aria-hidden
            className="invisible col-start-1 row-start-1 whitespace-pre font-mono text-[11px] tabular-nums"
          >
            {widest}
          </span>
          <span
            aria-hidden
            className="col-start-1 row-start-1 whitespace-pre font-mono text-[11px] tabular-nums text-stone-700 dark:text-stone-200"
          >
            {format(value)}
            <motion.span
              initial={false}
              animate={{ opacity: suffix ? 1 : 0 }}
              transition={reduced ? INSTANT : CROSSFADE}
              className="text-stone-500 dark:text-stone-400"
            >
              {lastLabel.current ? ` · ${lastLabel.current}` : ""}
            </motion.span>
          </span>
        </span>
      </div>
      <div
        ref={trackRef}
        {...trackProps}
        className={`relative h-9 w-full rounded-[9px] outline-none focus-visible:bg-[#4568FF]/[0.06] focus-visible:shadow-[inset_0_0_0_1px_#4568FF] dark:focus-visible:bg-[#93B0FF]/[0.1] dark:focus-visible:shadow-[inset_0_0_0_1px_#93B0FF] ${
          disabled
            ? "pointer-events-none opacity-50"
            : dragging
              ? "cursor-grabbing"
              : "cursor-grab"
        }`}
      >
        <div className="pointer-events-none absolute inset-x-0 top-[9px] h-[10px] overflow-hidden rounded-[5px] bg-stone-200 dark:bg-white/15">
          <div
            className="absolute inset-y-0"
            style={{ left: THUMB / 2, right: THUMB / 2 }}
          >
            <motion.div
              className="absolute inset-y-0 left-0 right-0"
              style={{ x: offset }}
            >
              <div className="absolute inset-y-0 right-full w-[2000px] bg-stone-800 dark:bg-stone-100" />
            </motion.div>
          </div>
        </div>
        <div
          className="pointer-events-none absolute inset-y-0"
          style={{ left: THUMB / 2, right: THUMB / 2 }}
        >

          {list.map((d) => (
            <span
              key={String(d.value)}
              aria-hidden
              className="absolute top-[26px] block h-[5px] w-[2px] -translate-x-1/2 bg-stone-800/35 dark:bg-stone-100/35"
              style={{
                left: span > 0 ? `${((d.value - min) / span) * 100}%` : "0%",
              }}
            />
          ))}
        </div>
        <div
          className="pointer-events-none absolute inset-y-0"
          style={{ left: THUMB / 2, right: THUMB / 2 }}
        >
          <motion.div
            className="absolute inset-y-0 left-0 right-0"
            style={{ x: offset }}
          >
            <motion.div
              className="absolute top-[4px] h-[20px] w-[18px] rounded-[6px] border-2 border-white bg-stone-800 dark:border-stone-900 dark:bg-stone-100"
              style={{ marginLeft: -THUMB / 2 }}
              initial={false}
              animate={{ scale: dragging ? 1.08 : 1 }}
              transition={reduced ? INSTANT : GRAB}
            />
          </motion.div>
        </div>
      </div>
    </div>
  );
}
```

---

## Swipe Deck · Gesture

A stack you decide through.

Docs: https://yugo.click/docs/swipe-deck
Install: `bun add motion`, then copy the source below into `components/yugo/swipe-deck.tsx` · or `bunx shadcn@latest add https://yugo.click/r/swipe-deck.json`.

Guarantees:
- The deck reserves height + 26 pixels before the first card is drawn, and every card, the fanned stack behind it and the empty state are absolutely positioned inside that one rectangle, so a decision never moves the page underneath it.
- Drag distance is reported as one of six discrete steps per side rather than a float, so a 300-pixel swipe costs six renders instead of one per frame, and the cells state where the commit point is before you cross it rather than after.
- A card that snaps back was never decided: the commit rule lives in useSwipeDeck and asks for either the full threshold or a genuine flick, so a card cannot leave on a twitch.
- Every decision is kept, so Undo restores the card and flies it back in from the side it left; a mis-swipe costs one keystroke, not a lost record.
- The deck is a focusable group where the arrow keys decide and Backspace reverses, and the same three actions exist as real buttons, so the interaction is not reachable by pointer alone.
- Screen readers get one polite announcement per settled card, its label and its position in the queue, never the drag offset; under prefers-reduced-motion the card still leaves and the counter still moves, only the fly-out is skipped.


### Usage

```tsx
"use client";

import { useState } from "react";
import { SwipeDeck, type SwipeChoice } from "@/components/yugo/swipe-deck";

type Ticket = { id: string; subject: string; from: string };

export function TriageQueue({ tickets }: { tickets: Ticket[] }) {
  const [routed, setRouted] = useState<Record<string, SwipeChoice>>({});

  return (
    <SwipeDeck
      items={tickets}
      itemKey={(t) => t.id}
      itemLabel={(t) => `${t.subject}, from ${t.from}`}
      label="Support triage"
      leftLabel="Archive"
      rightLabel="Escalate"
      emptyLabel="Queue empty. Undo reopens the last ticket."
      height={168}
      threshold={104}
      onDecide={(t, choice) => {
        setRouted((prev) => ({ ...prev, [t.id]: choice }));
        void fetch(`/api/tickets/${t.id}`, {
          method: "PATCH",
          body: JSON.stringify({ state: choice === "right" ? "escalated" : "archived" }),
        });
      }}
      onUndo={(t) => {
        setRouted((prev) => {
          const next = { ...prev };
          delete next[t.id];
          return next;
        });
        void fetch(`/api/tickets/${t.id}`, {
          method: "PATCH",
          body: JSON.stringify({ state: "open" }),
        });
      }}
    >
      {(t) => (
        <div className="flex h-full flex-col justify-between p-4">
          <p className="mt-6 text-[13px] font-medium">{t.subject}</p>
          <p className="text-[11.5px] text-stone-500">{t.from}</p>
        </div>
      )}
    </SwipeDeck>
  );
}
```

### Source (`components/yugo/swipe-deck.tsx`)

```tsx
"use client";

import { useCallback, useEffect, useId, useRef, useState } from "react";
import {
  AnimatePresence,
  animate,
  motion,
  useMotionValue,
  useReducedMotion,
  useTransform,
} from "motion/react";

const CELL = { type: "spring", stiffness: 520, damping: 34, mass: 0.45 } as const;
const DISCLOSE = { type: "spring", stiffness: 150, damping: 27, mass: 1 } as const;
const CROSSFADE = { type: "spring", stiffness: 260, damping: 34, mass: 0.8 } as const;
const LEAVE = [0.4, 0, 1, 1] as const;

export type SwipeChoice = "left" | "right";

export type SwipeIntent = { dir: -1 | 0 | 1; step: number };

export type SwipeDeckFlow = { dir: -1 | 1; kind: "decide" | "undo" };

const BLANK: SwipeIntent = { dir: 0, step: 0 };

const spent = (out: boolean) => (out ? "opacity-0" : "");

export type UseSwipeDeckOptions = {
  count: number;
  threshold?: number;
  steps?: number;
  flick?: number;
  onDecide?: (index: number, choice: SwipeChoice) => void;
  onUndo?: (index: number) => void;
  disabled?: boolean;
};

export function useSwipeDeck({
  count,
  threshold = 92,
  steps = 6,
  flick = 520,
  onDecide,
  onUndo,
  disabled = false,
}: UseSwipeDeckOptions) {
  const total = Math.max(0, Math.floor(count));
  const grain = Math.max(1, Math.floor(steps));
  const reach = Math.max(1, threshold);

  const [decisions, setDecisions] = useState<SwipeChoice[]>([]);
  const [flow, setFlow] = useState<SwipeDeckFlow>({ dir: 1, kind: "decide" });
  const [intent, setIntent] = useState<SwipeIntent>(BLANK);

  const index = Math.min(decisions.length, total);

  const len = useRef(decisions.length);
  len.current = decisions.length;
  const size = useRef(total);
  size.current = total;
  const made = useRef(decisions);
  made.current = decisions;

  const decided = useRef(onDecide);
  decided.current = onDecide;
  const reverted = useRef(onUndo);
  reverted.current = onUndo;

  const clear = useCallback(() => {
    setIntent((prev) => (prev.step === 0 && prev.dir === 0 ? prev : BLANK));
  }, []);

  const decide = useCallback(
    (choice: SwipeChoice) => {
      if (disabled) return;
      const at = len.current;
      if (at >= size.current) return;
      len.current = at + 1;
      setDecisions((prev) => [...prev, choice]);
      setFlow({ dir: choice === "right" ? 1 : -1, kind: "decide" });
      setIntent(BLANK);
      decided.current?.(at, choice);
    },
    [disabled],
  );

  const undo = useCallback(() => {
    if (disabled) return;
    const at = len.current;
    if (at === 0) return;
    const last = made.current[at - 1];
    len.current = at - 1;
    setDecisions((prev) => prev.slice(0, prev.length - 1));
    setFlow({ dir: last === "right" ? 1 : -1, kind: "undo" });
    setIntent(BLANK);
    reverted.current?.(at - 1);
  }, [disabled]);

  const report = useCallback(
    (dx: number) => {
      const step = Math.min(grain, Math.round((Math.abs(dx) / reach) * grain));
      const dir: -1 | 0 | 1 = step === 0 ? 0 : dx > 0 ? 1 : -1;
      setIntent((prev) =>
        prev.dir === dir && prev.step === step ? prev : { dir, step },
      );
    },
    [grain, reach],
  );

  const release = useCallback(
    (dx: number, vx: number) => {
      const far = Math.abs(dx) >= reach;
      const fast = Math.abs(vx) >= flick && Math.abs(dx) >= reach * 0.35;
      if (!far && !fast) {
        clear();
        return;
      }
      decide((far ? dx : vx) > 0 ? "right" : "left");
    },
    [reach, flick, clear, decide],
  );

  const onKeyDown = useCallback(
    (event: React.KeyboardEvent) => {
      if (event.target !== event.currentTarget) return;
      if (event.key === "ArrowLeft") {
        event.preventDefault();
        decide("left");
      } else if (event.key === "ArrowRight") {
        event.preventDefault();
        decide("right");
      } else if (event.key === "Backspace" || event.key === "Delete") {
        event.preventDefault();
        undo();
      } else if (event.key === "Escape") {
        clear();
      }
    },
    [decide, undo, clear],
  );

  useEffect(() => {
    const bail = () => clear();
    const hidden = () => document.hidden && clear();
    window.addEventListener("blur", bail);
    document.addEventListener("visibilitychange", hidden);
    return () => {
      window.removeEventListener("blur", bail);
      document.removeEventListener("visibilitychange", hidden);
    };
  }, [clear]);

  return {
    index,
    count: total,
    remaining: total - index,
    done: index >= total,
    decisions,
    flow,
    intent,
    steps: grain,
    threshold: reach,
    armed: intent.step >= grain,
    canUndo: decisions.length > 0,
    decide,
    undo,
    clear,
    report,
    release,
    deckProps: {
      role: "group" as const,
      "aria-roledescription": "card deck",
      tabIndex: 0,
      onKeyDown,
    },
  };
}

export type UseSwipeDeckResult = ReturnType<typeof useSwipeDeck>;

const ICON_LEFT = (
  <svg width="12" height="12" viewBox="0 0 256 256" fill="none" aria-hidden="true">
    <line
      x1="200"
      y1="56"
      x2="56"
      y2="200"
      stroke="currentColor"
      strokeWidth="16"
      strokeLinecap="round"
    />
    <line
      x1="200"
      y1="200"
      x2="56"
      y2="56"
      stroke="currentColor"
      strokeWidth="16"
      strokeLinecap="round"
    />
  </svg>
);

const ICON_RIGHT = (
  <svg width="12" height="12" viewBox="0 0 256 256" fill="none" aria-hidden="true">
    <polyline
      points="216 72 104 184 48 128"
      stroke="currentColor"
      strokeWidth="16"
      strokeLinecap="round"
      strokeLinejoin="round"
    />
  </svg>
);

const ICON_UNDO = (
  <svg width="12" height="12" viewBox="0 0 256 256" fill="none" aria-hidden="true">
    <polyline
      points="72 104 24 104 24 56"
      stroke="currentColor"
      strokeWidth="16"
      strokeLinecap="round"
      strokeLinejoin="round"
    />
    <path
      d="M67.6,192.1a88,88,0,1,0,0-128.2L24,104"
      stroke="currentColor"
      strokeWidth="16"
      strokeLinecap="round"
      strokeLinejoin="round"
    />
  </svg>
);

type DeckCardProps = {
  depth: number;
  height: number;
  entryX: number;
  active: boolean;
  reduced: boolean;
  label: string;
  leftLabel: string;
  rightLabel: string;
  intent: SwipeIntent;
  steps: number;
  onMove: (dx: number) => void;
  onRelease: (dx: number, vx: number) => void;
  children: React.ReactNode;
};

function DeckCard({
  depth,
  height,
  entryX,
  active,
  reduced,
  label,
  leftLabel,
  rightLabel,
  intent,
  steps,
  onMove,
  onRelease,
  children,
}: DeckCardProps) {
  const x = useMotionValue(entryX);
  const rotate = useTransform(x, [-200, 0, 200], [-8, 0, 8], { clamp: false });
  const fade = useTransform(x, [-340, -150, 0, 150, 340], [0, 1, 1, 1, 0]);

  const skip = useRef(reduced);
  skip.current = reduced;

  useEffect(() => {
    if (x.get() === 0) return;
    const controls = animate(x, 0, skip.current ? { duration: 0 } : DISCLOSE);
    return () => controls.stop();
  }, [x, entryX]);

  const commit = active ? 0 : depth === 1 ? intent.step / steps : 0;
  const y = depth * 10 - commit * 10;
  const scale = 1 - depth * 0.045 + commit * 0.045;

  const badge = (side: -1 | 1, text: string, place: string) => {
    const on = intent.dir === side;
    return (
      <motion.span
        aria-hidden
        initial={false}
        animate={{
          opacity: on ? intent.step / steps : 0,
          scale: on ? 1 : 0.94,
        }}
        transition={reduced ? { duration: 0 } : CELL}
        className={`pointer-events-none absolute top-3 whitespace-nowrap rounded-[6px] border bg-white px-2 py-1 text-[10.5px] font-semibold uppercase tracking-[0.08em] transition-colors duration-150 dark:bg-[#1D1D1A] ${
          on && intent.step >= steps
            ? "border-[#4568FF] text-[#4568FF] dark:border-[#93B0FF] dark:text-[#93B0FF]"
            : "border-stone-300 text-stone-700 dark:border-white/20 dark:text-stone-200"
        } ${place}`}
      >
        {text}
      </motion.span>
    );
  };

  return (
    <motion.div
      role="group"
      aria-label={label}
      aria-hidden={!active}
      inert={!active}
      variants={{
        exit: (dir: number) => ({
          x: dir * 560,
          zIndex: 12,
          borderColor: "rgba(0,0,0,0)",
          transition: reduced
            ? { duration: 0 }
            : {
                x: { duration: 0.3, ease: LEAVE },
                borderColor: { duration: 0.1, ease: "linear" },
              },
        }),
      }}
      initial={{ y, scale }}
      animate={{ y, scale }}
      exit="exit"
      transition={
        reduced
          ? { duration: 0 }
          : active
            ? { ...CROSSFADE, delay: 0.1 }
            : CROSSFADE
      }
      drag={active ? "x" : false}
      dragDirectionLock
      dragMomentum={false}
      dragElastic={1}
      dragConstraints={{ left: 0, right: 0 }}
      dragTransition={{ bounceStiffness: 260, bounceDamping: 34 }}
      whileDrag={reduced ? undefined : { scale: 1.03 }}
      onDrag={(_event, info) => onMove(info.offset.x)}
      onDragEnd={(_event, info) => onRelease(info.offset.x, info.velocity.x)}
      style={{
        x,
        rotate,
        opacity: fade,
        height,
        zIndex: 10 - depth,
        transformOrigin: "50% 100%",
        touchAction: "pan-y",
      }}
      className={`absolute inset-x-5 top-0 select-none overflow-hidden rounded-[14px] border border-stone-200 bg-white dark:border-white/[0.16] dark:bg-[#1D1D1A] ${
        active
          ? "cursor-grab shadow-[0_1px_2px_rgba(28,25,23,0.06),0_16px_32px_-18px_rgba(28,25,23,0.55)] active:cursor-grabbing dark:shadow-[0_2px_16px_rgba(0,0,0,0.6)]"
          : "shadow-[0_1px_2px_rgba(28,25,23,0.05),0_6px_14px_-12px_rgba(28,25,23,0.4)] dark:shadow-[0_1px_6px_rgba(0,0,0,0.45)]"
      }`}
    >
      {children}
      {active ? badge(-1, leftLabel, "left-3") : null}
      {active ? badge(1, rightLabel, "right-3") : null}
    </motion.div>
  );
}

export type SwipeDeckProps<T> = {
  items: readonly T[];
  itemKey: (item: T) => string;
  itemLabel: (item: T) => string;
  children: (item: T) => React.ReactNode;
  onDecide?: (item: T, choice: SwipeChoice) => void;
  onUndo?: (item: T) => void;
  label?: string;
  leftLabel?: string;
  rightLabel?: string;
  undoLabel?: string;
  emptyLabel?: string;
  height?: number;
  threshold?: number;
  steps?: number;
  peek?: number;
  className?: string;
};

export function SwipeDeck<T>({
  items,
  itemKey,
  itemLabel,
  children,
  onDecide,
  onUndo,
  label = "Card deck",
  leftLabel = "Skip",
  rightLabel = "Keep",
  undoLabel = "Undo",
  emptyLabel = "Deck cleared",
  height = 180,
  threshold = 92,
  steps = 6,
  peek = 3,
  className = "",
}: SwipeDeckProps<T>) {
  const hintId = useId();
  const reduced = useReducedMotion() === true;

  const deck = useSwipeDeck({
    count: items.length,
    threshold,
    steps,
    onDecide: (at, choice) => {
      const item = items[at];
      if (item !== undefined) onDecide?.(item, choice);
    },
    onUndo: (at) => {
      const item = items[at];
      if (item !== undefined) onUndo?.(item);
    },
  });

  const stack = items.slice(deck.index, deck.index + Math.max(1, peek));
  const current = items[deck.index];

  const control =
    "inline-flex h-8 items-center gap-1.5 rounded-[9px] border border-stone-200 bg-white px-2.5 text-[12px] font-medium text-stone-700 outline-none transition-[background-color,border-color,opacity] duration-150 hover:bg-stone-100 focus-visible:border-[#4568FF] dark:border-white/[0.16] dark:bg-[#1D1D1A] dark:text-stone-200 dark:hover:bg-white/10 dark:focus-visible:border-[#93B0FF]";

  return (
    <div className={`w-full ${className}`}>
      <div
        aria-label={label}
        aria-describedby={hintId}
        style={{ height: height + 26 }}
        className="relative w-full overflow-hidden rounded-[14px] outline-none focus-visible:shadow-[0_0_0_1px_#4568FF] dark:focus-visible:shadow-[0_0_0_1px_#93B0FF]"
        {...deck.deckProps}
      >
        <div className="absolute inset-0 overflow-hidden [mask-image:linear-gradient(to_right,transparent,black_20px,black_calc(100%-20px),transparent)]">
          <motion.div
            aria-hidden={!deck.done}
            initial={false}
            animate={{ opacity: deck.done ? 1 : 0 }}
            transition={reduced ? { duration: 0 } : CROSSFADE}
            style={{ height }}
            className="absolute inset-x-5 top-0 z-0 grid place-items-center rounded-[14px] bg-stone-100/70 px-4 text-center text-[12.5px] text-stone-500 shadow-[inset_0_1px_2px_rgba(28,25,23,0.07)] dark:bg-[#252522] dark:text-stone-400 dark:shadow-[inset_0_1px_2px_rgba(0,0,0,0.45)]"
          >
            {emptyLabel}
          </motion.div>
          <AnimatePresence initial={false} custom={deck.flow.dir}>
            {stack.map((item, depth) => (
              <DeckCard
              key={itemKey(item)}
              depth={depth}
              height={height}
              entryX={
                depth === 0 && deck.flow.kind === "undo" ? deck.flow.dir * 560 : 0
              }
              active={depth === 0}
              reduced={reduced}
              label={itemLabel(item)}
              leftLabel={leftLabel}
              rightLabel={rightLabel}
              intent={deck.intent}
              steps={deck.steps}
              onMove={deck.report}
              onRelease={deck.release}
            >
                {children(item)}
              </DeckCard>
            ))}
          </AnimatePresence>
        </div>
      </div>
      <div className="mt-3 grid h-8 grid-cols-[1fr_auto_1fr] items-center gap-3">
        <button
          type="button"
          onClick={() => deck.decide("left")}
          inert={deck.done}
          className={`${control} justify-self-start ${spent(deck.done)}`}
        >
          {ICON_LEFT}
          <span>{leftLabel}</span>
        </button>
        <span className="flex items-center gap-2 font-mono text-[10.5px] tabular-nums text-stone-500 dark:text-stone-400">
          <span aria-hidden className="inline-grid justify-items-end">
            <span className="invisible col-start-1 row-start-1">
              {items.length}
            </span>
            <span className="col-start-1 row-start-1">{deck.remaining}</span>
          </span>
          <span aria-hidden>left</span>
          <button
            type="button"
            onClick={deck.undo}
            inert={!deck.canUndo}
            className={`inline-flex items-center gap-1 rounded-[5px] px-1 py-0.5 text-stone-700 outline-none transition-[background-color,box-shadow,opacity] duration-150 hover:bg-stone-100 focus-visible:bg-[#4568FF]/[0.06] focus-visible:shadow-[inset_0_0_0_1px_#4568FF] dark:text-stone-200 dark:hover:bg-white/10 dark:focus-visible:bg-[#93B0FF]/[0.1] dark:focus-visible:shadow-[inset_0_0_0_1px_#93B0FF] ${spent(
              !deck.canUndo,
            )}`}
          >
            {ICON_UNDO}
            <span>{undoLabel}</span>
          </button>
        </span>
        <button
          type="button"
          onClick={() => deck.decide("right")}
          inert={deck.done}
          className={`${control} justify-self-end ${spent(deck.done)}`}
        >
          <span>{rightLabel}</span>
          {ICON_RIGHT}
        </button>
      </div>
      <p aria-live="polite" aria-atomic className="sr-only">
        {deck.done || current === undefined
          ? emptyLabel
          : `${itemLabel(current)}. Card ${deck.index + 1} of ${items.length}.`}
      </p>
      <span id={hintId} className="sr-only">
        Left and right arrow keys decide the top card. Backspace brings the last
        one back.
      </span>
    </div>
  );
}
```

---

## Reorder List · Gesture

The gap the siblings open is the drop target.

Docs: https://yugo.click/docs/reorder-list
Install: `bun add motion`, then copy the source below into `components/yugo/reorder-list.tsx` · or `bunx shadcn@latest add https://yugo.click/r/reorder-list.json`.

Guarantees:
- There is no ghost. The thing you are dragging is the row itself, lifted off the surface, and the gap the siblings open is the drop target: a floating copy would be one statement too many.
- Siblings close and open the gap with a layout spring; the dragged row never animates its height and the list never reflows more than the two rows trading places.
- The keyboard is a second complete implementation: Space grabs, arrows carry the row a slot at a time, Space drops, Escape restores the order from before the grab: pointer drags get the same Escape.
- A grabbed row wears the accent, because the system is responding to you right now; a merely hovered row only lifts.
- One announcement per move: 'position 2 of 5': never a stream, and blurring a grabbed row cancels instead of leaving it stranded.
- onReorder keeps the preview live while onCommit fires once at the drop, so persistence code runs when the person decides, not while they are deciding.
- Under prefers-reduced-motion the rows trade places instantly; the order still changes, only the travel is skipped.


### Usage

```tsx
"use client";

import { useState } from "react";
import { ReorderList } from "@/components/yugo/reorder-list";

type Step = { id: string; name: string };

export function PipelineEditor({ initial }: { initial: Step[] }) {
  const [steps, setSteps] = useState(initial);

  return (
    <ReorderList
      items={steps}
      getId={(s) => s.id}
      getLabel={(s) => s.name}
      onReorder={setSteps}
      onCommit={(next) =>
        void fetch("/api/pipeline", {
          method: "POST",
          body: JSON.stringify(next.map((s) => s.id)),
        })
      }
      label="Pipeline steps"
    >
      {(s) => <span className="text-[13px]">{s.name}</span>}
    </ReorderList>
  );
}
```

### Source (`components/yugo/reorder-list.tsx`)

```tsx
"use client";

import { useCallback, useId, useRef, useState } from "react";
import { Reorder, useReducedMotion } from "motion/react";

const CELL = { type: "spring", stiffness: 520, damping: 34, mass: 0.45 } as const;
const INSTANT = { duration: 0 } as const;

const moveItem = <T,>(list: readonly T[], from: number, to: number): T[] => {
  const next = [...list];
  const [taken] = next.splice(from, 1);
  next.splice(to, 0, taken);
  return next;
};

export type UseReorderListOptions<T> = {
  items: readonly T[];
  getId: (item: T) => string;
  getLabel: (item: T) => string;
  onReorder: (next: T[]) => void;
  onCommit?: (next: T[]) => void;
  disabled?: boolean;
};

export function useReorderList<T>({
  items,
  getId,
  getLabel,
  onReorder,
  onCommit,
  disabled = false,
}: UseReorderListOptions<T>) {
  const [grabbed, setGrabbed] = useState<string | null>(null);
  const [dragging, setDragging] = useState<string | null>(null);
  const [spoken, setSpoken] = useState("");

  const emit = useRef(onReorder);
  emit.current = onReorder;
  const settle = useRef(onCommit);
  settle.current = onCommit;
  const live = useRef(items);
  live.current = items;
  const snapshot = useRef<readonly T[] | null>(null);

  const indexOf = useCallback(
    (id: string) => live.current.findIndex((item) => getId(item) === id),
    [getId],
  );

  const grab = useCallback(
    (id: string) => {
      snapshot.current = live.current;
      setGrabbed(id);
      const at = indexOf(id);
      const item = live.current[at];
      setSpoken(
        `${getLabel(item)} grabbed, position ${at + 1} of ${live.current.length}.`,
      );
    },
    [getLabel, indexOf],
  );

  const drop = useCallback(
    (id: string) => {
      snapshot.current = null;
      setGrabbed(null);
      const at = indexOf(id);
      const item = live.current[at];
      setSpoken(`${getLabel(item)} dropped at position ${at + 1}.`);
      settle.current?.([...live.current]);
    },
    [getLabel, indexOf],
  );

  const cancel = useCallback(() => {
    if (snapshot.current) emit.current([...snapshot.current]);
    snapshot.current = null;
    setGrabbed(null);
    setSpoken("Reorder cancelled, original order restored.");
  }, []);

  const step = useCallback(
    (id: string, delta: -1 | 1) => {
      const from = indexOf(id);
      const to = from + delta;
      if (from < 0 || to < 0 || to >= live.current.length) return;
      const next = moveItem(live.current, from, to);
      emit.current(next);
      const item = next[to];
      setSpoken(
        `${getLabel(item)}, position ${to + 1} of ${next.length}.`,
      );
      if (snapshot.current === null) settle.current?.(next);
    },
    [getLabel, indexOf],
  );

  const rowKeyDown = useCallback(
    (id: string) => (event: React.KeyboardEvent<HTMLElement>) => {
      if (disabled || event.target !== event.currentTarget) return;
      const held = grabbed === id;
      if (event.key === " " || event.key === "Enter") {
        event.preventDefault();
        if (held) drop(id);
        else grab(id);
        return;
      }
      if ((event.key === "ArrowUp" || event.key === "ArrowDown") && held) {
        event.preventDefault();
        step(id, event.key === "ArrowUp" ? -1 : 1);
        return;
      }
      if (event.key === "Escape" && held) {
        event.preventDefault();
        cancel();
      }
    },
    [disabled, grabbed, grab, drop, step, cancel],
  );

  const onDragStart = useCallback(
    (id: string) => {
      snapshot.current = live.current;
      setDragging(id);
    },
    [],
  );

  const onDragEnd = useCallback(
    (id: string) => {
      snapshot.current = null;
      setDragging(null);
      const at = indexOf(id);
      const item = live.current[at];
      setSpoken(`${getLabel(item)} dropped at position ${at + 1}.`);
      settle.current?.([...live.current]);
    },
    [getLabel, indexOf],
  );

  return {
    grabbed,
    dragging,
    spoken,
    grab,
    drop,
    cancel,
    step,
    rowKeyDown,
    onDragStart,
    onDragEnd,
  };
}

export type ReorderListProps<T> = UseReorderListOptions<T> & {
  children: (item: T) => React.ReactNode;
  label: string;
  className?: string;
};

const GRIP = (
  <svg width="10" height="14" viewBox="0 0 10 14" fill="currentColor" aria-hidden>
    <circle cx="2.5" cy="2.5" r="1.2" />
    <circle cx="7.5" cy="2.5" r="1.2" />
    <circle cx="2.5" cy="7" r="1.2" />
    <circle cx="7.5" cy="7" r="1.2" />
    <circle cx="2.5" cy="11.5" r="1.2" />
    <circle cx="7.5" cy="11.5" r="1.2" />
  </svg>
);

export function ReorderList<T>({
  children,
  label,
  className = "",
  ...options
}: ReorderListProps<T>) {
  const { items, getId, getLabel, onReorder, disabled = false } = options;
  const list = useReorderList(options);
  const reduced = useReducedMotion() === true;
  const hintId = useId();

  return (
    <div className={`w-full ${className}`}>
      <Reorder.Group
        axis="y"
        values={items as T[]}
        onReorder={onReorder}
        aria-label={label}
        className="m-0 list-none space-y-1.5 p-0"
      >
        {items.map((item) => {
          const id = getId(item);
          const held = list.grabbed === id;
          const lifted = held || list.dragging === id;
          return (
            <Reorder.Item
              key={id}
              value={item}
              drag={disabled ? false : "y"}
              dragListener={!disabled}
              tabIndex={disabled ? -1 : 0}
              aria-describedby={hintId}
              aria-pressed={held}
              role="button"
              onKeyDown={list.rowKeyDown(id)}
              onDragStart={() => list.onDragStart(id)}
              onDragEnd={() => list.onDragEnd(id)}
              onBlur={() => held && list.cancel()}
              transition={reduced ? INSTANT : CELL}
              whileDrag={reduced ? undefined : { scale: 1.02 }}
              style={{ touchAction: "pan-x" }}
              className={`relative flex items-center gap-2.5 rounded-[9px] border bg-white px-3 py-2.5 outline-none transition-[border-color,box-shadow,background-color] duration-150 focus-visible:outline-none dark:bg-[#1D1D1A] ${
                lifted
                  ? "z-10 cursor-grabbing border-stone-200 shadow-[0_1px_2px_rgba(28,25,23,0.08),0_14px_28px_-16px_rgba(28,25,23,0.5)] dark:border-white/[0.16] dark:shadow-[0_2px_14px_rgba(0,0,0,0.55)]"
                  : "cursor-grab border-stone-200 shadow-[0_1px_2px_rgba(28,25,23,0.06)] dark:border-white/[0.16] dark:shadow-[0_1px_6px_rgba(0,0,0,0.45)]"
              } ${
                held
                  ? "border-[#4568FF] bg-[#4568FF]/[0.04] dark:border-[#93B0FF] dark:bg-[#93B0FF]/[0.08]"
                  : "focus-visible:bg-[#4568FF]/[0.06] focus-visible:shadow-[inset_0_0_0_1px_#4568FF] dark:focus-visible:bg-[#93B0FF]/[0.1] dark:focus-visible:shadow-[inset_0_0_0_1px_#93B0FF]"
              }`}
            >
              <span
                aria-hidden
                className={`shrink-0 transition-colors duration-150 ${
                  lifted
                    ? "text-stone-500 dark:text-stone-300"
                    : "text-stone-300 dark:text-stone-600"
                }`}
              >
                {GRIP}
              </span>
              <span className="sr-only">{getLabel(item)}</span>
              <div aria-hidden className="min-w-0 flex-1">
                {children(item)}
              </div>
            </Reorder.Item>
          );
        })}
      </Reorder.Group>
      <span id={hintId} className="sr-only">
        Drag to reorder. With the keyboard, Space grabs the row, the arrow keys
        move it, Space drops it, and Escape puts everything back.
      </span>
      <span role="status" aria-live="polite" className="sr-only">
        {list.spoken}
      </span>
    </div>
  );
}
```

---

## Long Press · Gesture

Intent confirmed by time, and cancelled by everything else.

Docs: https://yugo.click/docs/long-press
Install: `bun add motion`, then copy the source below into `components/yugo/long-press.tsx` · or `bunx shadcn@latest add https://yugo.click/r/long-press.json`.

Guarantees:
- Drifting more than eight pixels cancels the press. On a phone this is the difference between holding a row and scrolling past it, and it is the reason most long-press implementations feel broken on touch.
- The click that follows a completed press is swallowed. Otherwise the element runs its normal tap action immediately after the hold already ran.
- Progress is reported in discrete steps, not as a float, so a 550ms press costs twelve renders instead of thirty-three.
- Losing the window, hiding the tab, a pointercancel from the browser taking over the gesture, or Escape all end the press. A hold that survives you switching apps is not a hold.
- Space and Enter hold too, so the gesture is reachable without a pointer, and the duration is announced through a described-by hint.
- The native touch callout and context menu are suppressed on the target, because on touch platforms they are the default answer to a long press.


### Usage

```tsx
import { LongPressButton, useLongPress } from "@/components/yugo/long-press";

export function ArchiveRow({ onArchive }: { onArchive: () => void }) {
  return <LongPressButton onLongPress={onArchive}>Hold to archive</LongPressButton>;
}

export function Tile({ onOpen }: { onOpen: () => void }) {
  const { bind, step, steps, holding } = useLongPress({
    onLongPress: onOpen,
    duration: 700,
  });

  return (
    <div {...bind} tabIndex={0} role="button" data-holding={holding}>
      Press and hold
      <span>{step} / {steps}</span>
    </div>
  );
}
```

### Source (`components/yugo/long-press.tsx`)

```tsx
"use client";

import { useCallback, useEffect, useId, useRef, useState } from "react";
import { motion, useReducedMotion } from "motion/react";

const EASE = [0.23, 1, 0.32, 1] as const;
const CELL = { type: "spring", stiffness: 520, damping: 34, mass: 0.45 } as const;
const POP = { duration: 0.26, times: [0, 0.35, 1], ease: EASE };
const INSTANT = { duration: 0 } as const;

export type UseLongPressOptions = {
  onLongPress: () => void;
  duration?: number;
  steps?: number;
  moveTolerance?: number;
  haptic?: boolean;
  disabled?: boolean;
  onCancel?: () => void;
};

type Phase = "idle" | "holding" | "fired";

export function useLongPress({
  onLongPress,
  duration = 550,
  steps = 12,
  moveTolerance = 8,
  haptic = true,
  disabled = false,
  onCancel,
}: UseLongPressOptions) {
  const cells = Math.max(1, Math.round(steps));

  const [step, setStep] = useState(0);
  const [holding, setHolding] = useState(false);

  const phase = useRef<Phase>("idle");
  const raf = useRef(0);
  const startedAt = useRef(0);
  const origin = useRef<{ x: number; y: number } | null>(null);
  const settle = useRef<ReturnType<typeof setTimeout> | null>(null);

  const fire = useRef(onLongPress);
  fire.current = onLongPress;
  const cancelled = useRef(onCancel);
  cancelled.current = onCancel;

  const reset = useCallback(() => {
    cancelAnimationFrame(raf.current);
    raf.current = 0;
    if (settle.current) {
      clearTimeout(settle.current);
      settle.current = null;
    }
    origin.current = null;
    phase.current = "idle";
    setHolding(false);
    setStep(0);
  }, []);

  const end = useCallback(() => {
    if (phase.current !== "holding") return;
    reset();
    cancelled.current?.();
  }, [reset]);

  const begin = useCallback(
    (point?: { x: number; y: number }) => {
      if (disabled || phase.current !== "idle") return;

      phase.current = "holding";
      origin.current = point ?? null;
      startedAt.current = performance.now();
      setHolding(true);
      setStep(0);

      const tick = (now: number) => {
        const p = Math.min(1, (now - startedAt.current) / duration);

        const s = Math.floor(p * cells);
        setStep((prev) => (prev === s ? prev : s));

        if (p < 1) {
          raf.current = requestAnimationFrame(tick);
          return;
        }

        raf.current = 0;
        phase.current = "fired";
        setStep(cells);
        if (haptic) navigator.vibrate?.(12);
        fire.current();

        settle.current = setTimeout(() => {
          if (phase.current === "fired") reset();
        }, 260);
      };

      raf.current = requestAnimationFrame(tick);
    },
    [disabled, duration, cells, haptic, reset],
  );

  useEffect(() => {
    const bail = () => end();
    const onVisibility = () => document.hidden && end();
    window.addEventListener("blur", bail);
    document.addEventListener("visibilitychange", onVisibility);
    return () => {
      window.removeEventListener("blur", bail);
      document.removeEventListener("visibilitychange", onVisibility);
      cancelAnimationFrame(raf.current);
      if (settle.current) clearTimeout(settle.current);
    };
  }, [end]);

  const bind = {
    onPointerDown: (e: React.PointerEvent) => {
      if (e.button !== 0 && e.pointerType === "mouse") return;
      e.currentTarget.setPointerCapture?.(e.pointerId);
      begin({ x: e.clientX, y: e.clientY });
    },
    onPointerMove: (e: React.PointerEvent) => {
      const from = origin.current;
      if (phase.current !== "holding" || !from) return;
      if (Math.hypot(e.clientX - from.x, e.clientY - from.y) > moveTolerance) {
        end();
      }
    },
    onPointerUp: end,
    onPointerCancel: end,
    onPointerLeave: end,
    onKeyDown: (e: React.KeyboardEvent) => {
      if (e.repeat) return;
      if (e.key === " " || e.key === "Enter") {
        e.preventDefault();
        begin();
      }
    },
    onKeyUp: (e: React.KeyboardEvent) => {
      if (e.key === " " || e.key === "Enter") end();
      if (e.key === "Escape") end();
    },
    onBlur: end,
    onClick: (e: React.MouseEvent) => {
      if (phase.current === "fired") {
        e.preventDefault();
        e.stopPropagation();
      }
    },
    onContextMenu: (e: React.MouseEvent) => e.preventDefault(),
  };

  return {
    bind,
    step,
    steps: cells,
    holding,
    fired: step === cells,
    progress: step / cells,
  };
}

export type LongPressButtonProps = {
  onLongPress: () => void;
  children: React.ReactNode;
  duration?: number;
  steps?: number;
  disabled?: boolean;
  className?: string;
};

export function LongPressButton({
  onLongPress,
  children,
  duration = 550,
  steps = 12,
  disabled = false,
  className = "",
}: LongPressButtonProps) {
  const hintId = useId();
  const reduced = useReducedMotion() === true;
  const { bind, step, steps: cells, holding, fired } = useLongPress({
    onLongPress,
    duration,
    steps,
    disabled,
  });

  const progress = fired ? 1 : step / cells;

  return (
    <motion.button
      type="button"
      aria-disabled={disabled}
      aria-describedby={hintId}
      initial={false}
      animate={{ scale: reduced ? 1 : fired ? [1, 1.045, 1] : 1 }}
      transition={reduced ? INSTANT : POP}
      className={`group relative inline-flex h-9 select-none items-center rounded-[9px] border px-3.5 text-[13px] font-medium outline-none transition-[border-color,background-color,box-shadow,transform] duration-150 focus-visible:border-[#4568FF] focus-visible:shadow-[0_1px_2px_rgba(28,25,23,0.08),0_10px_20px_-14px_rgba(69,104,255,0.6)] dark:focus-visible:border-[#93B0FF] dark:focus-visible:shadow-[0_10px_20px_-14px_rgba(147,176,255,0.5)] ${
        holding
          ? "translate-y-px border-stone-200 bg-stone-100/70 shadow-[inset_0_1px_2px_rgba(28,25,23,0.07)] dark:border-white/[0.08] dark:bg-[#1D1D1A] dark:shadow-[inset_0_1px_2px_rgba(0,0,0,0.45)]"
          : fired
            ? "border-[#4568FF] bg-[#4568FF]/[0.07] dark:border-[#93B0FF] dark:bg-[#93B0FF]/[0.12]"
            : "border-stone-200 bg-white shadow-[inset_0_1.5px_0_rgba(255,255,255,0.95),inset_0_-1px_0_rgba(28,25,23,0.06),0_1px_2px_rgba(28,25,23,0.08)] hover:bg-stone-50 dark:border-white/[0.16] dark:bg-[#252522] dark:shadow-[inset_0_1px_0_rgba(255,255,255,0.07),0_1px_2px_rgba(0,0,0,0.4)] dark:hover:bg-[#2A2A27]"
      } ${disabled ? "cursor-not-allowed opacity-50" : "cursor-pointer"} ${className}`}
      style={{ touchAction: "manipulation", WebkitTouchCallout: "none" }}
      {...bind}
    >
      <span className="relative grid">
        <span className="col-start-1 row-start-1 whitespace-nowrap text-stone-700 dark:text-stone-200">
          {children}
        </span>
        <motion.span
          aria-hidden
          initial={false}
          animate={{
            clipPath: `inset(0 ${((1 - progress) * 100).toFixed(2)}% 0 0)`,
          }}
          transition={reduced ? INSTANT : CELL}
          className="col-start-1 row-start-1 whitespace-nowrap text-[#4568FF] dark:text-[#93B0FF]"
        >
          {children}
        </motion.span>
      </span>
      <span id={hintId} className="sr-only">
        Press and hold for {Math.round(duration / 100) / 10} seconds to confirm
      </span>
    </motion.button>
  );
}
```

---

## Lightbox · Gesture

Zoom that returns where it started.

Docs: https://yugo.click/docs/lightbox
Install: `bun add motion`, then copy the source below into `components/yugo/lightbox.tsx` · or `bunx shadcn@latest add https://yugo.click/r/lightbox.json`.

Guarantees:
- The image returns to the rect its trigger occupies at the moment of closing, not the one cached when it opened, so a scroll, a resize, or a reflow behind the overlay cannot make it land beside the thumbnail.
- The wheel zooms toward the cursor, so the detail under the pointer stays under the pointer; double-click toggles between fit and a close-up centred on the click, and a single drag pans while zoomed.
- Pan is clamped against the image's own edges at every scale, so the picture cannot be flung past the frame and abandoned in empty space, and any release under 1.05x snaps back to exactly 1.0 rather than to 1.01.
- Escape unwinds the zoom on the first press and closes on the second, so a close-up is never a one way trip out of the viewer; the trigger gets focus back when the overlay leaves, and only if it is still in the document.
- Scale and offset are written to the node through motion values, so a drag does not re-render React; the zoom readout moves in whole cells and the screen reader is told the settled level once, 220ms after the wheel stops.
- Reduced motion keeps the overlay, the zoom and the return, and drops only the travel between them; the body scroll lock adds the scrollbar's width to the padding the page already had, so nothing underneath shifts.


### Usage

```tsx
"use client";

import { useRef, useState } from "react";
import { Lightbox } from "@/components/yugo/lightbox";

type Shot = { src: string; title: string };

export function ProjectGallery({ shots }: { shots: Shot[] }) {
  const [active, setActive] = useState(shots[0]);
  const [open, setOpen] = useState(false);
  const originRef = useRef<HTMLElement | null>(null);

  return (
    <div className="grid grid-cols-3 gap-2">
      {shots.map((shot) => (
        <button
          key={shot.src}
          type="button"
          aria-label={`Open ${shot.title}`}
          onClick={(e) => {
            originRef.current = e.currentTarget;
            setActive(shot);
            setOpen(true);
          }}
          className="aspect-[3/2] overflow-hidden rounded-[9px] border border-stone-200 dark:border-white/[0.16]"
        >
          <img
            src={shot.src}
            alt=""
            width={1200}
            height={800}
            className="size-full object-cover"
          />
        </button>
      ))}

      <Lightbox
        open={open}
        onClose={() => setOpen(false)}
        originRef={originRef}
        src={active.src}
        alt={active.title}
        caption={active.title}
        width={1200}
        height={800}
        maxScale={5}
      />
    </div>
  );
}
```

### Source (`components/yugo/lightbox.tsx`)

```tsx
"use client";

import {
  useCallback,
  useEffect,
  useId,
  useLayoutEffect,
  useRef,
  useState,
} from "react";
import { createPortal } from "react-dom";
import {
  AnimatePresence,
  animate,
  motion,
  useMotionValue,
  useReducedMotion,
} from "motion/react";

const CELL = {
  type: "spring",
  stiffness: 520,
  damping: 34,
  mass: 0.45,
} as const;

const HOME = {
  type: "spring",
  stiffness: 150,
  damping: 27,
  mass: 1,
} as const;

const VEIL = {
  type: "spring",
  stiffness: 260,
  damping: 34,
  mass: 0.8,
} as const;

const EASE = [0.23, 1, 0.32, 1] as const;
const EXIT = { duration: 0.2, ease: [0.4, 0, 1, 1] } as const;

const GLYPH = {
  type: "spring",
  stiffness: 700,
  damping: 46,
  mass: 0.5,
} as const;

const TOGGLE = 2.5;
const KEY_ZOOM = 1.6;
const KEY_PAN = 56;
const WHEEL_RATE = 140;
const SLOP = 8;
const NEAR_HOME = 1.02;
const SNAP_HOME = 1.05;

const CHROME_BUTTON =
  "grid size-8 place-items-center rounded-[9px] border border-stone-200 bg-white text-stone-500 outline-none transition-[border-color,color,box-shadow] duration-150 hover:border-stone-300 hover:text-stone-700 focus-visible:border-[#4568FF] focus-visible:shadow-[0_1px_2px_rgba(28,25,23,0.08),0_10px_20px_-14px_rgba(69,104,255,0.6)] dark:border-white/[0.16] dark:bg-[#1D1D1A] dark:text-stone-400 dark:hover:border-white/20 dark:hover:text-stone-200 dark:focus-visible:border-[#93B0FF] dark:focus-visible:shadow-[0_10px_20px_-14px_rgba(147,176,255,0.5)]";

type Spring = {
  type: "spring";
  stiffness: number;
  damping: number;
  mass: number;
};

const clamp = (v: number, lo: number, hi: number) =>
  Math.min(hi, Math.max(lo, v));

type Drag = {
  id: number;
  from: { x: number; y: number };
  x: number;
  y: number;
};

export type UseLightboxOptions = {
  maxScale?: number;
  steps?: number;
  disabled?: boolean;
  onDismiss?: () => void;
};

export function useLightbox<
  Frame extends HTMLElement = HTMLDivElement,
  Content extends HTMLElement = HTMLImageElement,
>({
  maxScale = 4,
  steps = 8,
  disabled = false,
  onDismiss,
}: UseLightboxOptions = {}) {
  const cells = Math.max(1, Math.round(steps));
  const top = Math.max(1.1, maxScale);

  const frameRef = useRef<Frame>(null);
  const contentRef = useRef<Content>(null);

  const scale = useMotionValue(1);
  const x = useMotionValue(0);
  const y = useMotionValue(0);

  const [step, setStep] = useState(0);
  const [settled, setSettled] = useState(0);

  const stepRef = useRef(0);
  const settledRef = useRef(0);
  const timer = useRef<ReturnType<typeof setTimeout> | null>(null);
  const drag = useRef<Drag | null>(null);
  const onContent = useRef(false);

  const reduced = useReducedMotion();
  const dismiss = useRef(onDismiss);
  dismiss.current = onDismiss;

  const toStep = useCallback(
    (s: number) => clamp(Math.round(((s - 1) / (top - 1)) * cells), 0, cells),
    [cells, top],
  );

  const mark = useCallback(
    (s: number) => {
      const next = toStep(s);
      if (stepRef.current === next) return;
      stepRef.current = next;
      setStep(next);
    },
    [toStep],
  );

  const settle = useCallback(
    (s: number) => {
      if (timer.current) {
        clearTimeout(timer.current);
        timer.current = null;
      }
      const next = toStep(s);
      if (settledRef.current === next) return;
      settledRef.current = next;
      setSettled(next);
    },
    [toStep],
  );

  const settleSoon = useCallback(
    (s: number) => {
      if (timer.current) clearTimeout(timer.current);
      timer.current = setTimeout(() => {
        timer.current = null;
        settle(s);
      }, 220);
    },
    [settle],
  );

  const limit = useCallback((s: number) => {
    const frame = frameRef.current;
    const content = contentRef.current;
    if (!frame || !content) return { mx: 0, my: 0 };
    return {
      mx: Math.max(0, (content.offsetWidth * s - frame.clientWidth) / 2),
      my: Math.max(0, (content.offsetHeight * s - frame.clientHeight) / 2),
    };
  }, []);

  const place = useCallback(
    (s: number, nx: number, ny: number) => {
      const { mx, my } = limit(s);
      scale.set(s);
      x.set(clamp(nx, -mx, mx));
      y.set(clamp(ny, -my, my));
      mark(s);
    },
    [limit, mark, scale, x, y],
  );

  const glide = useCallback(
    (s: number, nx: number, ny: number, spring: Spring = CELL) => {
      const { mx, my } = limit(s);
      const tx = clamp(nx, -mx, mx);
      const ty = clamp(ny, -my, my);
      if (reduced) {
        scale.set(s);
        x.set(tx);
        y.set(ty);
      } else {
        animate(scale, s, spring);
        animate(x, tx, spring);
        animate(y, ty, spring);
      }
      mark(s);
      settle(s);
    },
    [limit, mark, reduced, scale, settle, x, y],
  );

  const reset = useCallback(() => {
    glide(1, 0, 0, HOME);
  }, [glide]);

  const zoomAt = useCallback(
    (next: number, cx: number, cy: number, animated: boolean) => {
      const frame = frameRef.current;
      if (!frame) return;
      const r = frame.getBoundingClientRect();
      const px = cx - (r.left + r.width / 2);
      const py = cy - (r.top + r.height / 2);
      const s0 = scale.get();
      const ax = (px - x.get()) / s0;
      const ay = (py - y.get()) / s0;
      const s = clamp(next, 1, top);
      const nx = px - ax * s;
      const ny = py - ay * s;
      if (animated) {
        glide(s, nx, ny, s <= 1 ? HOME : CELL);
        return;
      }
      place(s, nx, ny);
      settleSoon(s);
    },
    [glide, place, scale, settleSoon, top, x, y],
  );

  const finish = useCallback(() => {
    const s0 = scale.get();
    if (s0 < SNAP_HOME) reset();
    else settle(s0);
  }, [reset, scale, settle]);

  const release = (e: React.PointerEvent) => {
    const held = drag.current;
    if (!held || held.id !== e.pointerId) return;
    drag.current = null;
    const moved = Math.hypot(e.clientX - held.from.x, e.clientY - held.from.y);
    if (moved < SLOP && !onContent.current && scale.get() <= NEAR_HOME) {
      dismiss.current?.();
      return;
    }
    finish();
  };

  const cancel = (e: React.PointerEvent) => {
    const held = drag.current;
    if (!held || held.id !== e.pointerId) return;
    drag.current = null;
    finish();
  };

  const onKeyDown = (e: React.KeyboardEvent) => {
    const frame = frameRef.current;
    if (!frame || disabled) return;
    const r = frame.getBoundingClientRect();
    const cx = r.left + r.width / 2;
    const cy = r.top + r.height / 2;
    const s0 = scale.get();

    if (e.key === "+" || e.key === "=") {
      e.preventDefault();
      zoomAt(s0 * KEY_ZOOM, cx, cy, true);
      return;
    }
    if (e.key === "-" || e.key === "_") {
      e.preventDefault();
      zoomAt(s0 / KEY_ZOOM, cx, cy, true);
      return;
    }
    if (e.key === "0") {
      e.preventDefault();
      reset();
      return;
    }
    if (e.key === "Escape" && s0 > NEAR_HOME) {
      e.preventDefault();
      e.stopPropagation();
      reset();
      return;
    }
    if (s0 > NEAR_HOME && e.key.startsWith("Arrow")) {
      e.preventDefault();
      const dx =
        e.key === "ArrowLeft" ? KEY_PAN : e.key === "ArrowRight" ? -KEY_PAN : 0;
      const dy =
        e.key === "ArrowUp" ? KEY_PAN : e.key === "ArrowDown" ? -KEY_PAN : 0;
      glide(s0, x.get() + dx, y.get() + dy);
    }
  };

  const bind = {
    onPointerDown: (e: React.PointerEvent) => {
      if (disabled) return;
      if (e.pointerType === "mouse" && e.button !== 0) return;
      const content = contentRef.current;
      onContent.current = content ? content.contains(e.target as Node) : false;
      e.currentTarget.setPointerCapture?.(e.pointerId);
      drag.current = {
        id: e.pointerId,
        from: { x: e.clientX, y: e.clientY },
        x: x.get(),
        y: y.get(),
      };
    },
    onPointerMove: (e: React.PointerEvent) => {
      const held = drag.current;
      if (!held || held.id !== e.pointerId) return;
      if (scale.get() <= 1) return;
      place(
        scale.get(),
        held.x + (e.clientX - held.from.x),
        held.y + (e.clientY - held.from.y),
      );
    },
    onPointerUp: release,
    onPointerCancel: cancel,
    onLostPointerCapture: cancel,
    onDoubleClick: (e: React.MouseEvent) => {
      if (disabled) return;
      zoomAt(
        scale.get() > SNAP_HOME ? 1 : Math.min(TOGGLE, top),
        e.clientX,
        e.clientY,
        true,
      );
    },
    onKeyDown,
  };

  useEffect(() => {
    const frame = frameRef.current;
    if (!frame) return;
    const onWheel = (e: WheelEvent) => {
      if (disabled) return;
      e.preventDefault();
      zoomAt(
        scale.get() * Math.exp(-e.deltaY / WHEEL_RATE),
        e.clientX,
        e.clientY,
        false,
      );
    };
    frame.addEventListener("wheel", onWheel, { passive: false });
    return () => frame.removeEventListener("wheel", onWheel);
  }, [disabled, scale, zoomAt]);

  useEffect(() => {
    const bail = () => {
      drag.current = null;
    };
    window.addEventListener("blur", bail);
    return () => {
      window.removeEventListener("blur", bail);
      if (timer.current) clearTimeout(timer.current);
    };
  }, []);

  return {
    frameRef,
    contentRef,
    bind,
    scale,
    x,
    y,
    step,
    steps: cells,
    zoom: 1 + (step / cells) * (top - 1),
    settledZoom: 1 + (settled / cells) * (top - 1),
    zoomed: step > 0,
    reset,
    zoomAt,
  };
}

export type LightboxProps = {
  open: boolean;
  onClose: () => void;
  src: string;
  alt: string;
  originRef?: React.RefObject<HTMLElement | null>;
  caption?: string;
  width?: number;
  height?: number;
  maxScale?: number;
  className?: string;
};

type Landing = { dx: number; dy: number; s: number; o: number; r: number };

function Stage({
  onClose,
  src,
  alt,
  originRef,
  caption,
  width,
  height,
  maxScale = 4,
  className = "",
}: LightboxProps) {
  const reduced = useReducedMotion();
  const titleId = useId();
  const hintId = useId();

  const fx = useMotionValue(0);
  const fy = useMotionValue(0);
  const fs = useMotionValue(1);
  const fo = useMotionValue(0);
  const fr = useMotionValue(14);

  const {
    frameRef,
    contentRef,
    bind,
    scale,
    x,
    y,
    zoomed,
    settledZoom,
    reset,
    zoomAt,
  } = useLightbox({ maxScale, onDismiss: onClose });

  const shellRef = useRef<HTMLDivElement>(null);

  const toggleZoom = useCallback(() => {
    const frame = frameRef.current;
    if (!frame) return;
    if (zoomed) {
      reset();
      return;
    }
    const r = frame.getBoundingClientRect();
    zoomAt(
      Math.min(TOGGLE, Math.max(1.1, maxScale)),
      r.left + r.width / 2,
      r.top + r.height / 2,
      true,
    );
  }, [frameRef, maxScale, reset, zoomAt, zoomed]);

  const landing = useCallback((): Landing => {
    const frame = frameRef.current;
    const content = contentRef.current;
    const origin = originRef?.current;
    if (frame && content && origin && content.offsetWidth > 0) {
      const r = frame.getBoundingClientRect();
      const o = origin.getBoundingClientRect();
      if (o.width > 0) {
        const s = o.width / content.offsetWidth;
        const rad =
          Number.parseFloat(getComputedStyle(origin).borderTopLeftRadius) || 9;
        return {
          dx: o.left + o.width / 2 - (r.left + r.width / 2),
          dy: o.top + o.height / 2 - (r.top + r.height / 2),
          s,
          o: 1,
          r: rad / s,
        };
      }
    }
    return { dx: 0, dy: 10, s: 0.97, o: 0, r: 14 };
  }, [contentRef, frameRef, originRef]);

  useLayoutEffect(() => {
    if (reduced) {
      fx.set(0);
      fy.set(0);
      fs.set(1);
      fo.set(1);
      fr.set(14);
      return;
    }
    const d = landing();
    fx.set(d.dx);
    fy.set(d.dy);
    fs.set(d.s);
    fo.set(d.o);
    fr.set(d.r);

    const runs = [
      animate(fx, 0, HOME),
      animate(fy, 0, HOME),
      animate(fs, 1, HOME),
      animate(fo, 1, HOME),
      animate(fr, 14, HOME),
    ];
    return () => runs.forEach((r) => r.stop());
  }, [fo, fr, fs, fx, fy, landing, reduced]);

  const away = useCallback(() => {
    if (reduced) return { opacity: 0, transition: { duration: 0.12 } };
    const d = landing();
    animate(fr, d.r, HOME);
    return {
      x: d.dx,
      y: d.dy,
      scale: d.s,
      opacity: d.o,
      filter: "blur(4px)",
      transition: HOME,
    };
  }, [fr, landing, reduced]);

  const unwind = useCallback(
    () => ({
      x: 0,
      y: 0,
      scale: 1,
      transition: reduced ? { duration: 0 } : HOME,
    }),
    [reduced],
  );

  useEffect(() => {
    const frame = frameRef.current;
    const previous =
      document.activeElement instanceof HTMLElement
        ? document.activeElement
        : null;
    const body = document.body;
    const overflow = body.style.overflow;
    const padding = body.style.paddingRight;
    const gap = window.innerWidth - document.documentElement.clientWidth;
    const base = Number.parseFloat(getComputedStyle(body).paddingRight) || 0;
    body.style.overflow = "hidden";
    if (gap > 0) body.style.paddingRight = `${base + gap}px`;
    frame?.focus({ preventScroll: true });
    return () => {
      body.style.overflow = overflow;
      body.style.paddingRight = padding;
      if (previous?.isConnected) previous.focus({ preventScroll: true });
    };
  }, [frameRef]);

  useEffect(() => {
    const shell = shellRef.current;
    if (!shell) return;

    const onKeyDown = (e: KeyboardEvent) => {
      if (e.key === "Escape") {
        if (zoomed) return;
        e.preventDefault();
        onClose();
        return;
      }
      if (e.key !== "Tab") return;
      const nodes = Array.from(
        shell.querySelectorAll<HTMLElement>('[data-lightbox-focus="1"]'),
      );
      if (nodes.length === 0) return;
      e.preventDefault();
      const here =
        document.activeElement instanceof HTMLElement
          ? nodes.indexOf(document.activeElement)
          : -1;
      const next = e.shiftKey
        ? here <= 0
          ? nodes.length - 1
          : here - 1
        : here === -1 || here === nodes.length - 1
          ? 0
          : here + 1;
      nodes[next]?.focus();
    };

    shell.addEventListener("keydown", onKeyDown);
    return () => shell.removeEventListener("keydown", onKeyDown);
  }, [onClose, zoomed]);

  return (
    <div
      ref={shellRef}
      role="dialog"
      aria-modal="true"
      aria-labelledby={titleId}
      className={`fixed inset-0 z-50 ${className}`}
    >
      <motion.div
        aria-hidden
        initial={{ opacity: 0 }}
        animate={{ opacity: 1 }}
        exit={{
          opacity: 0,
          transition: reduced ? { duration: 0 } : { duration: 0.3, ease: EASE },
        }}
        transition={reduced ? { duration: 0 } : VEIL}
        className="absolute inset-0 bg-stone-950/80"
      />
      <div
        ref={frameRef}
        data-lightbox-focus="1"
        tabIndex={-1}
        role="group"
        aria-labelledby={titleId}
        aria-describedby={hintId}
        style={{ touchAction: "none", WebkitTouchCallout: "none" }}
        className={`absolute inset-0 overflow-hidden outline-none select-none focus-visible:shadow-[inset_0_0_0_1px_#93B0FF] ${
          zoomed ? "cursor-grab active:cursor-grabbing" : "cursor-zoom-in"
        }`}
        {...bind}
      >
        <motion.div
          style={{ x: fx, y: fy, scale: fs, opacity: fo }}
          initial={reduced ? false : { filter: "blur(6px)" }}
          animate={{ filter: "blur(0px)" }}
          variants={{ away }}
          exit="away"
          transition={
            reduced
              ? { duration: 0 }
              : { filter: { duration: 0.35, ease: EASE } }
          }
          className="absolute inset-0 flex items-center justify-center p-4 sm:p-14"
        >
          <motion.img
            ref={contentRef}
            src={src}
            alt={alt}
            width={width}
            height={height}
            draggable={false}
            style={{ x, y, scale, borderRadius: fr }}
            variants={{ away: unwind }}
            exit="away"
            className="max-h-full max-w-full object-contain"
          />
        </motion.div>
      </div>
      <motion.div
        initial={{ opacity: 0 }}
        animate={{ opacity: 1 }}
        exit={{ opacity: 0, transition: reduced ? { duration: 0 } : EXIT }}
        transition={reduced ? { duration: 0 } : VEIL}
        className="pointer-events-none absolute inset-0 flex items-start justify-between gap-3 p-3 sm:p-4"
      >
        <p
          id={titleId}
          className="pointer-events-auto max-w-[65%] truncate rounded-[9px] border border-stone-200 bg-white px-2.5 py-1.5 text-[12.5px] text-stone-700 dark:border-white/[0.16] dark:bg-[#1D1D1A] dark:text-stone-200"
        >
          {caption ?? alt}
        </p>
        <div className="pointer-events-auto flex items-center gap-2">
          <button
            data-lightbox-focus="1"
            type="button"
            onClick={toggleZoom}
            aria-label={zoomed ? "Zoom out" : "Zoom in"}
            className={CHROME_BUTTON}
          >
            <svg
              viewBox="0 0 256 256"
              className="size-[15px]"
              fill="none"
              stroke="currentColor"
              strokeWidth={16}
              strokeLinecap="round"
              strokeLinejoin="round"
              aria-hidden
            >
              <circle cx="116" cy="116" r="84" />
              <path d="M175.4 175.4 224 224M84 116h64" />
              <motion.path
                d="M116 84v64"
                initial={false}
                animate={{ opacity: zoomed ? 0 : 1 }}
                transition={reduced ? { duration: 0 } : GLYPH}
              />
            </svg>
          </button>
          <button
            data-lightbox-focus="1"
            type="button"
            onClick={onClose}
            aria-label="Close"
            className={CHROME_BUTTON}
          >
            <svg
              viewBox="0 0 256 256"
              className="size-[15px]"
              fill="none"
              stroke="currentColor"
              strokeWidth={16}
              strokeLinecap="round"
              strokeLinejoin="round"
              aria-hidden
            >
              <path d="M200 56 56 200M200 200 56 56" />
            </svg>
          </button>
        </div>
      </motion.div>
      <p id={hintId} className="sr-only">
        Scroll to zoom toward the pointer, or press plus and minus. Drag or use
        the arrow keys to pan, and double-click to switch between fit and
        close-up. Press zero to return to the starting frame; Escape returns
        home first, then closes.
      </p>
      <p role="status" className="sr-only">
        Zoom {settledZoom.toFixed(1)} times
      </p>
    </div>
  );
}

export function Lightbox(props: LightboxProps) {
  const [mounted, setMounted] = useState(false);

  useEffect(() => {
    setMounted(true);
  }, []);

  if (!mounted) return null;

  return createPortal(
    <AnimatePresence>
      {props.open ? <Stage key="lightbox" {...props} /> : null}
    </AnimatePresence>,
    document.body,
  );
}
```

---

## Tilt Card · Gesture

The card leans away from the cursor, lit from where you point.

Docs: https://yugo.click/docs/tilt-card
Install: `bun add `, then copy the source below into `components/yugo/tilt-card.tsx` · or `bunx shadcn@latest add https://yugo.click/r/tilt-card.json`.

Guarantees:
- Kept as written: the 15 degree limit, the 1.05 hover scale, the 1200px perspective and the 0.2s ease-out transition are all unchanged.
- evade leans the card away from the pointer and gravitate leans it toward, which is one sign flip on both rotations.
- The tilt is a CSS transition on transform rather than a spring, so an interrupted move eases to the new angle from wherever it is, and the return to flat on pointer leave takes the same 0.2s.
- The spotlight is a 200% radial gradient in white at 0.15 alpha, positioned by percentage from the pointer and cross-faded over 0.3s. It halves its opacity in dark mode.
- Both the transform string and the spotlight position are React state, so every pointer move re-renders the component.
- It is a pointer-only affordance: there is no focus, keyboard or reduced-motion branch, and the tilt does not respond to touch.


### Usage

```tsx
"use client";

import { TiltCard } from "@/components/yugo/tilt-card";

export function Card() {
  return (
    <TiltCard tiltLimit={15} scale={1.05} perspective={1200}>
      <div className="h-48 w-80 rounded-2xl bg-neutral-100 p-6 dark:bg-neutral-900">
        Your content here
      </div>
    </TiltCard>
  );
}
```

### Source (`components/yugo/tilt-card.tsx`)

```tsx
"use client"

import { useRef, useState, useCallback } from "react"

export interface TiltCardProps {
  /** Maximum tilt angle in degrees */
  tiltLimit?: number
  /** Scale factor on hover */
  scale?: number
  /** Perspective distance in pixels */
  perspective?: number
  /** Tilt direction: "gravitate" follows cursor, "evade" tilts away */
  effect?: "gravitate" | "evade"
  /** Show a spotlight that follows the cursor on hover */
  spotlight?: boolean
  /** Additional class name */
  className?: string
  /** Additional inline styles */
  style?: React.CSSProperties
  /** Card content */
  children?: React.ReactNode
}

export function TiltCard({
  tiltLimit = 15,
  scale = 1.05,
  perspective = 1200,
  effect = "evade",
  spotlight = true,
  className = "",
  style,
  children,
}: TiltCardProps) {
  const cardRef = useRef<HTMLDivElement>(null)
  const [transform, setTransform] = useState(
    `perspective(${perspective}px) rotateX(0deg) rotateY(0deg) scale3d(1, 1, 1)`
  )
  const [spotlightPos, setSpotlightPos] = useState({ x: 50, y: 50 })
  const [isHovered, setIsHovered] = useState(false)

  const dir = effect === "evade" ? -1 : 1

  const handlePointerMove = useCallback(
    (e: React.PointerEvent) => {
      const el = cardRef.current
      if (!el) return
      const rect = el.getBoundingClientRect()
      const px = (e.clientX - rect.left) / rect.width
      const py = (e.clientY - rect.top) / rect.height
      const xRot = (py - 0.5) * (tiltLimit * 2) * dir
      const yRot = (px - 0.5) * -(tiltLimit * 2) * dir
      setTransform(
        `perspective(${perspective}px) rotateX(${xRot}deg) rotateY(${yRot}deg) scale3d(${scale}, ${scale}, ${scale})`
      )
      if (spotlight) {
        setSpotlightPos({ x: px * 100, y: py * 100 })
      }
    },
    [tiltLimit, scale, perspective, dir, spotlight]
  )

  const handlePointerEnter = useCallback(() => {
    setIsHovered(true)
  }, [])

  const handlePointerLeave = useCallback(() => {
    setTransform(
      `perspective(${perspective}px) rotateX(0deg) rotateY(0deg) scale3d(1, 1, 1)`
    )
    setIsHovered(false)
  }, [perspective])

  return (
    <div
      ref={cardRef}
      onPointerEnter={handlePointerEnter}
      onPointerMove={handlePointerMove}
      onPointerLeave={handlePointerLeave}
      className={`will-change-transform relative overflow-hidden ${className}`}
      style={{
        transform,
        transition: "transform 0.2s ease-out",
        transformStyle: "preserve-3d",
        ...style,
      }}
    >
      {children}
      {spotlight && (
        <div
          className="pointer-events-none absolute inset-0 z-10 overflow-hidden"
          style={{ opacity: isHovered ? 1 : 0, transition: "opacity 0.3s" }}
        >
          <div
            className="absolute w-[200%] h-[200%] rounded-full opacity-100 dark:opacity-50"
            style={{
              left: `${spotlightPos.x}%`,
              top: `${spotlightPos.y}%`,
              transform: "translate(-50%, -50%)",
              background:
                "radial-gradient(circle, rgba(255,255,255,0.15) 0%, transparent 40%)",
            }}
          />
        </div>
      )}
    </div>
  )
}
```

---

## Cursor · Gesture

The pointer replaced, inside one frame only.

Docs: https://yugo.click/docs/cursor
Install: `bun add motion`, then copy the source below into `components/yugo/cursor.tsx` · or `bunx shadcn@latest add https://yugo.click/r/cursor.json`.

Guarantees:
- The mark is portalled into document.body, like every fixed surface in the set: position fixed is enough right up until an ancestor grows a transform or a filter, at which point the layer silently becomes a child of that box instead of the page, and the mark draws offset from the real pointer by exactly that box's origin.
- It does nothing on a coarse pointer. A touch device has no cursor to replace, and hiding one there means hiding nothing while still paying for the listener, so a pointer: fine media query gates the whole component.
- The position is written straight into two MotionValues. React re-renders when the mark arrives and when it leaves, and at no point in between: nothing in this file re-renders at 60fps to move a square.
- The first sample is a jump rather than a trip. A mark that springs in from the top-left corner on the first move is a mark that lied about where the pointer was.
- The full abandonment surface is covered: pointerleave, pointercancel, a window blur and the tab going to the background all take the mark down, so it can never be left stranded over a page nobody is on.
- The native cursor is restored from the value that was there before, on the element it was taken from, so a component that unmounts mid-hover does not leave the page with no pointer.
- A ref that has not resolved never falls through to the page: attachTo with a null current draws nothing rather than quietly claiming the whole document.
- Under prefers-reduced-motion the spring is dropped and the mark sits on the pointer, because a trailing cursor is precisely the thing that preference is asking for less of.


### Usage

```tsx
"use client";

import { useRef } from "react";
import { Cursor } from "@/components/yugo/cursor";

const TRAIL = { stiffness: 520, damping: 34, mass: 0.45 } as const;

export function Canvas() {
  const area = useRef<HTMLDivElement>(null);

  return (
    <div ref={area} className="relative h-80 w-full overflow-hidden">
      <p>Move inside the frame</p>
      <Cursor attachTo={area} spring={TRAIL}>
        <span className="block size-[10px] rounded-[2px] bg-[#4568FF]" />
      </Cursor>
    </div>
  );
}
```

### Source (`components/yugo/cursor.tsx`)

```tsx
"use client";

import { useEffect, useRef, useState } from "react";
import { createPortal } from "react-dom";
import {
  AnimatePresence,
  motion,
  useMotionValue,
  useReducedMotion,
  useSpring,
  type MotionValue,
  type SpringOptions,
} from "motion/react";

const EASE = [0.23, 1, 0.32, 1] as const;
const LEAVE = [0.4, 0, 1, 1] as const;

const INSTANT = { duration: 0 } as const;

const FINE = "(pointer: fine)";

export type UseCursorOptions = {
  /** the element the cursor belongs to. Omitted, it follows the whole page. */
  attachTo?: React.RefObject<HTMLElement | null>;
  /** a spring to lag behind the pointer with, or null to sit exactly on it */
  spring?: SpringOptions | null;
  hideNative?: boolean;
  onMove?: (x: number, y: number) => void;
};

export type UseCursorResult = {
  x: MotionValue<number>;
  y: MotionValue<number>;
  visible: boolean;
  /** false on touch, where replacing the pointer would replace nothing */
  fine: boolean;
};

/**
 * The pointer, as two MotionValues. Nothing here re-renders on a move: the
 * position is written straight into the values and React only hears about
 * the mark arriving and leaving. §5h
 */
export function useCursor({
  attachTo,
  spring = null,
  hideNative = true,
  onMove,
}: UseCursorOptions = {}): UseCursorResult {
  const reduced = useReducedMotion();
  const x = useMotionValue(0);
  const y = useMotionValue(0);
  const sx = useSpring(x, spring ?? INSTANT);
  const sy = useSpring(y, spring ?? INSTANT);

  const [fine, setFine] = useState(false);
  const [visible, setVisible] = useState(false);
  const landed = useRef(false);

  const report = useRef(onMove);
  report.current = onMove;

  // A trailing cursor under reduced motion is the one thing the preference
  // is asking for less of, so the lag is dropped and the mark sits on the
  // pointer. The information — where you are — still arrives.
  const trailing = Boolean(spring) && !reduced;

  useEffect(() => {
    const query = window.matchMedia(FINE);
    const read = () => setFine(query.matches);
    read();
    query.addEventListener("change", read);
    return () => query.removeEventListener("change", read);
  }, []);

  useEffect(() => {
    if (!fine) return;

    const host = attachTo?.current ?? null;
    // A ref that has not resolved must never fall through to the page: that
    // is how a cursor scoped to one card ends up owning the whole document.
    if (attachTo && !host) return;

    const move = (event: MouseEvent) => {
      if (host && !host.contains(event.target as Node | null)) {
        setVisible(false);
        return;
      }
      x.set(event.clientX);
      y.set(event.clientY);
      // The first sample is a jump, not a trip: a mark that springs in from
      // the top-left corner is a mark that lied about where the pointer was.
      if (!landed.current) {
        landed.current = true;
        sx.jump(event.clientX);
        sy.jump(event.clientY);
      }
      setVisible(true);
      report.current?.(event.clientX, event.clientY);
    };

    const hide = () => setVisible(false);
    const backgrounded = () => {
      if (document.hidden) hide();
    };

    document.addEventListener("mousemove", move);
    document.addEventListener("pointercancel", hide);
    document.documentElement.addEventListener("mouseleave", hide);
    window.addEventListener("blur", hide);
    document.addEventListener("visibilitychange", backgrounded);

    return () => {
      document.removeEventListener("mousemove", move);
      document.removeEventListener("pointercancel", hide);
      document.documentElement.removeEventListener("mouseleave", hide);
      window.removeEventListener("blur", hide);
      document.removeEventListener("visibilitychange", backgrounded);
    };
  }, [fine, attachTo, x, y, sx, sy]);

  useEffect(() => {
    if (!fine || !hideNative || !visible) return;
    const host = attachTo?.current ?? document.body;
    const previous = host.style.cursor;
    host.style.cursor = "none";
    return () => {
      host.style.cursor = previous;
    };
  }, [fine, hideNative, visible, attachTo]);

  return {
    x: trailing ? sx : x,
    y: trailing ? sy : y,
    visible: visible && fine,
    fine,
  };
}

export type CursorProps = UseCursorOptions & {
  children?: React.ReactNode;
  className?: string;
};

export function Cursor({ children, className = "", ...options }: CursorProps) {
  const reduced = useReducedMotion();
  const { x, y, visible } = useCursor(options);

  // Portalled, like every fixed surface in the set: position fixed is enough
  // right up until an ancestor grows a transform or a filter, at which point
  // the layer silently becomes a child of that box instead of the page — and
  // that ancestor is rarely yours. §16
  const [host, setHost] = useState<HTMLElement | null>(null);
  useEffect(() => setHost(document.body), []);

  if (!host) return null;

  return createPortal(
    <motion.div
      aria-hidden="true"
      className={`pointer-events-none fixed left-0 top-0 z-50 ${className}`}
      style={{ x, y, translateX: "-50%", translateY: "-50%" }}
    >
      <AnimatePresence>
        {visible ? (
          <motion.div
            key="mark"
            initial={reduced ? { opacity: 0 } : { opacity: 0, scale: 0.9 }}
            animate={{ opacity: 1, scale: 1 }}
            exit={
              reduced
                ? { opacity: 0, transition: { duration: 0.1 } }
                : {
                    opacity: 0,
                    scale: 0.94,
                    transition: { duration: 0.12, ease: LEAVE },
                  }
            }
            transition={reduced ? INSTANT : { duration: 0.18, ease: EASE }}
          >
            {children ?? (
              <span className="block size-[10px] rounded-[2px] bg-[#4568FF] shadow-[0_1px_3px_rgba(28,25,23,0.35)] dark:bg-[#93B0FF]" />
            )}
          </motion.div>
        ) : null}
      </AnimatePresence>
    </motion.div>,
    host,
  );
}
```

---

## Text Reveal · Content

Words arrive in reading order.

Docs: https://yugo.click/docs/text-reveal
Install: `bun add motion`, then copy the source below into `components/yugo/text-reveal.tsx` · or `bunx shadcn@latest add https://yugo.click/r/text-reveal.json`.

Guarantees:
- Every word occupies its final wrap position before the first one lights up, so the paragraph never re-wraps mid-reveal and nothing below it moves.
- Only opacity and transform are animated; no width, height, blur or mask-image, so a long paragraph neither relayouts nor repaints a filter on any frame.
- The stagger is clamped by maxDuration, so a four-hundred-word block finishes in the same window as a twelve-word one instead of running for half a minute.
- Screen readers get one complete copy of the sentence and the animated spans are aria-hidden, so nobody hears the text delivered a word at a time.
- Under prefers-reduced-motion the delay and the blur are dropped and the text lands at its final state; the words still arrive, only the trip is skipped.
- Order comes from the unit index, never from a random offset or a timer, so server and client markup agree and there is nothing left running after unmount.


### Usage

```tsx
"use client";

import { useState } from "react";
import { TextReveal } from "@/components/yugo/text-reveal";

export function AnswerCard({ answer }: { answer: string }) {
  const [asked, setAsked] = useState(false);

  return (
    <section className="rounded-[14px] border border-stone-200 p-4 dark:border-white/[0.16]">
      <TextReveal
        text={answer}
        play={asked}
        startOnView={false}
        stagger={0.05}
        maxDuration={1.6}
        className="block text-[13.5px] leading-relaxed"
      />

      <button
        type="button"
        onClick={() => setAsked(true)}
        disabled={asked}
        className="mt-3 h-9 rounded-[9px] border border-stone-200 px-3 text-[13px] font-medium text-stone-700 disabled:opacity-50 dark:border-white/[0.16] dark:text-stone-200"
      >
        Ask
      </button>
    </section>
  );
}
```

### Source (`components/yugo/text-reveal.tsx`)

```tsx
"use client";

import { Fragment, useMemo, useRef } from "react";
import { motion, useInView, useReducedMotion } from "motion/react";

const EASE = [0.23, 1, 0.32, 1] as const;
const DURATION = 0.6;

const HIDDEN = { opacity: 0, y: 10, filter: "blur(8px)" } as const;
const SHOWN = { opacity: 1, y: 0, filter: "blur(0px)" } as const;

export type TextRevealSplit = "word" | "character";

export type TextRevealUnit = {
  key: string;
  text: string;
  index: number;
};

export type TextRevealGroup = {
  key: string;
  units: TextRevealUnit[];
};

export type UseTextRevealOptions = {
  text: string;
  by?: TextRevealSplit;
  stagger?: number;
  maxDuration?: number;
  startOnView?: boolean;
  play?: boolean;
  once?: boolean;
  amount?: number;
};

export function useTextReveal<T extends HTMLElement = HTMLSpanElement>({
  text,
  by = "word",
  stagger = 0.055,
  maxDuration = 1.6,
  startOnView = true,
  play = true,
  once = true,
  amount = 0.35,
}: UseTextRevealOptions) {
  const ref = useRef<T>(null);
  const inView = useInView(ref, { once, amount });
  const reduced = useReducedMotion();

  const { groups, step, count } = useMemo(() => {
    const words = text.trim().length ? text.trim().split(/\s+/) : [];

    let index = 0;
    const built: TextRevealGroup[] = words.map((word, w) => {
      if (by === "character") {
        return {
          key: `w${w}`,
          units: Array.from(word).map((char, c) => ({
            key: `w${w}c${c}`,
            text: char,
            index: index++,
          })),
        };
      }
      return {
        key: `w${w}`,
        units: [{ key: `w${w}`, text: word, index: index++ }],
      };
    });

    const total = index;
    const span = Math.max(0, maxDuration - DURATION);

    return {
      groups: built,
      count: total,
      step: total > 1 ? Math.min(stagger, span / (total - 1)) : 0,
    };
  }, [text, by, stagger, maxDuration]);

  const started = play && (!startOnView || inView);

  return {
    ref,
    groups,
    step,
    count,
    started,
    reduced: Boolean(reduced),
    duration: count > 1 ? (count - 1) * step + DURATION : DURATION,
  };
}

export type TextRevealProps = UseTextRevealOptions & {
  className?: string;
};

export function TextReveal({
  text,
  by = "word",
  stagger = 0.055,
  maxDuration = 1.6,
  startOnView = true,
  play = true,
  once = true,
  amount = 0.35,
  className = "",
}: TextRevealProps) {
  const { ref, groups, step, started, reduced } = useTextReveal<HTMLSpanElement>(
    { text, by, stagger, maxDuration, startOnView, play, once, amount },
  );

  return (
    <span ref={ref} className={`text-stone-700 dark:text-stone-200 ${className}`}>
      <span className="sr-only">{text}</span>

      <span aria-hidden="true">
        {groups.map((group, g) => (
          <Fragment key={group.key}>
            {g > 0 ? " " : null}
            <span className="inline-block whitespace-nowrap align-baseline">
              {group.units.map((unit) => (
                <motion.span
                  key={unit.key}
                  className="inline-block align-baseline"
                  initial={reduced ? false : HIDDEN}
                  animate={started ? SHOWN : HIDDEN}
                  transition={
                    reduced
                      ? { duration: 0 }
                      : {
                          duration: DURATION,
                          ease: EASE,
                          delay: started ? unit.index * step : 0,
                        }
                  }
                >
                  {unit.text}
                </motion.span>
              ))}
            </span>
          </Fragment>
        ))}
      </span>
    </span>
  );
}
```

---

## Logo Marquee · Content

Stops when you look at it.

Docs: https://yugo.click/docs/logo-marquee
Install: `bun add motion`, then copy the source below into `components/yugo/logo-marquee.tsx` · or `bunx shadcn@latest add https://yugo.click/r/logo-marquee.json`.

Guarantees:
- Pointer or keyboard entry ramps the strip to a stop and resumes from the pixel it stopped on, so a logo never slides out from under a cursor that was already aiming at it, and leaving never restarts the run from the beginning.
- Tabbing to a logo pulls that logo inside the viewport before its focus ring can be painted off-screen, and the viewport's scrollLeft is pinned to zero so the browser's own focus scrolling can never desync the scroll position from the transform.
- The transport is one requestAnimationFrame writing a single transform to the track through a ref; React never re-renders to move it, the loop is unsubscribed entirely while the strip is off-screen, and the frame delta is clamped so returning from a background tab resumes instead of teleporting.
- The number of repeats is measured from the viewport width and one group's width with a ResizeObserver, so a wide screen never runs out of content and the wrap always lands on a position that is pixel-identical to the one before it.
- Only one copy is real: the repeats are aria-hidden and hold nothing focusable, so a screen reader reads the list of companies once and tab order visits each logo once.
- Under prefers-reduced-motion the strip stops being a transport and becomes a single scrollable row that keyboard users can reach and move; every logo is still present, none of it is hidden.


### Usage

```tsx
"use client";

import { LogoMarquee } from "@/components/yugo/logo-marquee";

const CUSTOMERS = [
  { id: "atlas", label: "Atlas", href: "/customers/atlas" },
  { id: "meridian", label: "Meridian", href: "/customers/meridian" },
  { id: "kelvin", label: "Kelvin", href: "/customers/kelvin" },
  { id: "northbeam", label: "Northbeam", href: "/customers/northbeam" },
  { id: "orbit", label: "Orbit", href: "/customers/orbit" },
];

export function TrustedBy() {
  return (
    <section className="mx-auto w-full max-w-3xl px-6 py-14">
      <p className="mb-4 text-center text-[11px] font-semibold uppercase tracking-[0.08em] text-stone-500 dark:text-stone-400">
        Trusted by
      </p>

      <LogoMarquee
        items={CUSTOMERS}
        label="Customers"
        speed={38}
        gap={44}
        direction="left"
      />
    </section>
  );
}
```

### Source (`components/yugo/logo-marquee.tsx`)

```tsx
"use client";

import { useCallback, useEffect, useRef, useState } from "react";
import { useIsomorphicLayoutEffect, useReducedMotion } from "motion/react";

const RAMP = 0.19;
const SETTLE = 0.16;
const MAX_COPIES = 14;

export type MarqueeDirection = "left" | "right";

export type UseLogoMarqueeOptions = {
  speed?: number;
  direction?: MarqueeDirection;
  gap?: number;
  paused?: boolean;
};

function fold(x: number, loop: number) {
  const m = x % loop;
  return m > 0 ? m - loop : m;
}

function clamp(x: number, min: number, max: number) {
  return x < min ? min : x > max ? max : x;
}

export function useLogoMarquee({
  speed = 44,
  direction = "left",
  gap = 40,
  paused = false,
}: UseLogoMarqueeOptions = {}) {
  const viewportRef = useRef<HTMLDivElement>(null);
  const trackRef = useRef<HTMLDivElement>(null);
  const groupRef = useRef<HTMLUListElement>(null);

  const [copies, setCopies] = useState(4);
  const [held, setHeld] = useState(false);
  const [near, setNear] = useState(false);

  const reduced = useReducedMotion() === true;
  const stopped = held || paused;

  const reducedRef = useRef(reduced);
  reducedRef.current = reduced;
  const movingRef = useRef(false);
  movingRef.current = !stopped && !reduced;

  const offset = useRef(0);
  const nudge = useRef(0);
  const rate = useRef(0);
  const span = useRef(0);

  const paint = useCallback(() => {
    const track = trackRef.current;
    if (!track) return;
    const x = reducedRef.current ? 0 : offset.current - span.current;
    track.style.transform = `translate3d(${x.toFixed(2)}px, 0, 0)`;
  }, []);

  useIsomorphicLayoutEffect(() => {
    const viewport = viewportRef.current;
    const group = groupRef.current;
    if (!viewport || !group) return;

    const measure = () => {
      const width = group.getBoundingClientRect().width;
      const loop = width > 0 ? width + gap : 0;
      const room = viewport.getBoundingClientRect().width;
      span.current = loop;
      offset.current = loop > 0 ? clamp(offset.current, -loop, loop) : 0;
      paint();

      const next =
        reduced || loop <= 0
          ? 4
          : clamp(Math.ceil(room / loop) + 3, 4, MAX_COPIES);
      setCopies((prev) => (prev === next ? prev : next));
    };

    measure();
    const observer = new ResizeObserver(measure);
    observer.observe(viewport);
    observer.observe(group);
    return () => observer.disconnect();
  }, [gap, paint, reduced]);

  useEffect(() => {
    const viewport = viewportRef.current;
    if (!viewport) return;
    if (typeof IntersectionObserver === "undefined") {
      setNear(true);
      return;
    }

    const observer = new IntersectionObserver(
      (entries) => {
        const entry = entries[entries.length - 1];
        if (entry) setNear(entry.isIntersecting);
      },
      { rootMargin: "96px" },
    );
    observer.observe(viewport);
    return () => observer.disconnect();
  }, []);

  useEffect(() => {
    if (reduced || !near) return;

    let frame = 0;
    let last = 0;
    const sign = direction === "right" ? 1 : -1;

    const tick = (now: number) => {
      frame = requestAnimationFrame(tick);

      const dt = last ? Math.min((now - last) / 1000, 0.05) : 0;
      last = now;

      const loop = span.current;
      if (loop <= 0) return;

      rate.current +=
        ((movingRef.current ? 1 : 0) - rate.current) * (1 - Math.exp(-dt / RAMP));

      const pull = nudge.current * (1 - Math.exp(-dt / SETTLE));
      nudge.current -= pull;

      let x = offset.current + sign * speed * rate.current * dt + pull;
      if (rate.current > 0.002 && Math.abs(nudge.current) < 0.25) {
        nudge.current = 0;
        x = fold(x, loop);
      } else {
        x = clamp(x, -loop, loop);
      }

      offset.current = x;
      paint();
    };

    frame = requestAnimationFrame(tick);
    return () => cancelAnimationFrame(frame);
  }, [reduced, near, speed, direction, paint]);

  useEffect(() => {
    const viewport = viewportRef.current;
    if (!viewport) return;

    const pin = () => {
      if (reducedRef.current) return;
      if (viewport.scrollLeft !== 0) viewport.scrollLeft = 0;
      if (viewport.scrollTop !== 0) viewport.scrollTop = 0;
    };

    viewport.addEventListener("scroll", pin, { passive: true });
    return () => viewport.removeEventListener("scroll", pin);
  }, []);

  useEffect(() => {
    const release = () => setHeld(false);
    window.addEventListener("blur", release);
    return () => window.removeEventListener("blur", release);
  }, []);

  const reveal = useCallback((node: HTMLElement) => {
    const viewport = viewportRef.current;
    const loop = span.current;
    if (!viewport || reducedRef.current || loop <= 0) return;
    if (node === viewport) return;

    const view = viewport.getBoundingClientRect();
    const box = node.getBoundingClientRect();
    const pad = 12;

    let delta = 0;
    if (box.left < view.left + pad) delta = view.left + pad - box.left;
    else if (box.right > view.right - pad) delta = view.right - pad - box.right;
    if (delta === 0) return;

    const target = clamp(offset.current + nudge.current + delta, -loop, loop);
    nudge.current = target - offset.current;
  }, []);

  const bind = {
    onPointerEnter: (e: React.PointerEvent) => {
      if (e.pointerType !== "touch") setHeld(true);
    },
    onPointerDown: () => setHeld(true),
    onPointerUp: (e: React.PointerEvent) => {
      if (e.pointerType === "touch") setHeld(false);
    },
    onPointerCancel: () => setHeld(false),
    onPointerLeave: () => setHeld(false),
    onFocus: (e: React.FocusEvent) => {
      setHeld(true);
      reveal(e.target as HTMLElement);
    },
    onBlur: () => setHeld(false),
  };

  return {
    viewportRef,
    trackRef,
    groupRef,
    copies,
    paused: stopped,
    reduced,
    bind,
  };
}

export type LogoMarqueeItem = {
  id: string;
  label: string;
  href?: string;
  mark?: React.ReactNode;
};

export type LogoMarqueeProps = {
  items: LogoMarqueeItem[];
  label?: string;
  speed?: number;
  direction?: MarqueeDirection;
  gap?: number;
  paused?: boolean;
  onSelect?: (item: LogoMarqueeItem) => void;
  className?: string;
};

const FACE =
  "inline-flex h-10 shrink-0 items-center gap-2 whitespace-nowrap rounded-[9px] px-3 text-[13px] font-medium tracking-[-0.01em] text-stone-500 dark:text-stone-400";

const HIT =
  "outline-none transition-colors duration-150 hover:text-stone-700 focus-visible:bg-[#4568FF]/[0.06] focus-visible:text-stone-700 focus-visible:shadow-[inset_0_0_0_1px_#4568FF] dark:hover:text-stone-200 dark:focus-visible:bg-[#93B0FF]/[0.10] dark:focus-visible:text-stone-200 dark:focus-visible:shadow-[inset_0_0_0_1px_#93B0FF]";

function face(item: LogoMarqueeItem) {
  if (!item.mark) return item.label;
  return (
    <>
      <span aria-hidden>{item.mark}</span>
      <span className="sr-only">{item.label}</span>
    </>
  );
}

export function LogoMarquee({
  items,
  label = "Logos",
  speed = 44,
  direction = "left",
  gap = 40,
  paused = false,
  onSelect,
  className = "",
}: LogoMarqueeProps) {
  const { viewportRef, trackRef, groupRef, copies, reduced, bind } =
    useLogoMarquee({ speed, direction, gap, paused });

  const groups = reduced ? 1 : copies;
  const live = reduced ? 0 : 1;

  return (
    <section
      aria-label={label}
      className={`relative isolate w-full min-w-0 max-w-full overflow-hidden rounded-[14px] border border-stone-200 bg-white shadow-[0_1px_2px_rgba(28,25,23,0.06),0_4px_10px_-8px_rgba(28,25,23,0.45)] dark:border-white/[0.16] dark:bg-[#1D1D1A] dark:shadow-[0_1px_6px_rgba(0,0,0,0.45)] ${className}`}
      {...bind}
    >
      <div
        ref={viewportRef}

        // eslint-disable-next-line jsx-a11y/no-noninteractive-tabindex
        tabIndex={reduced ? 0 : undefined}
        style={{ overflowX: reduced ? "auto" : "hidden" }}
        className="overflow-y-hidden py-2 outline-none focus-visible:bg-[#4568FF]/[0.06] focus-visible:shadow-[inset_0_0_0_1px_#4568FF] dark:focus-visible:bg-[#93B0FF]/[0.10] dark:focus-visible:shadow-[inset_0_0_0_1px_#93B0FF]"
      >
        <div
          ref={trackRef}
          style={{ gap, willChange: "transform" }}
          className="flex w-max items-center"
        >
          {Array.from({ length: groups }, (_, copy) => (
            <ul
              key={copy}
              ref={copy === live ? groupRef : undefined}
              aria-hidden={copy === live ? undefined : true}
              style={{ gap }}
              className="flex w-max items-center"
            >
              {items.map((item) => (
                <li key={item.id} className="shrink-0">
                  {copy !== live ? (
                    <span className={FACE}>{item.mark ?? item.label}</span>
                  ) : item.href ? (
                    <a href={item.href} className={`${FACE} ${HIT}`}>
                      {face(item)}
                    </a>
                  ) : onSelect ? (
                    <button
                      type="button"
                      onClick={() => onSelect(item)}
                      className={`${FACE} ${HIT}`}
                    >
                      {face(item)}
                    </button>
                  ) : (
                    <span className={FACE}>{face(item)}</span>
                  )}
                </li>
              ))}
            </ul>
          ))}
        </div>
      </div>
      <div
        aria-hidden
        className="pointer-events-none absolute inset-y-0 left-0 w-10 bg-gradient-to-r from-white to-white/0 dark:from-stone-900 dark:to-stone-900/0"
      />
      <div
        aria-hidden
        className="pointer-events-none absolute inset-y-0 right-0 w-10 bg-gradient-to-l from-white to-white/0 dark:from-stone-900 dark:to-stone-900/0"
      />
    </section>
  );
}
```

---

## Blur-up Image · Content

Placeholder resolves into the photo.

Docs: https://yugo.click/docs/blur-up-image
Install: `bun add motion`, then copy the source below into `components/yugo/blur-up-image.tsx` · or `bunx shadcn@latest add https://yugo.click/r/blur-up-image.json`.

Guarantees:
- The box is reserved from width and height as an aspect ratio, so the caption under a photo sits in its final position before a single byte arrives, and the frame keeps that space when the URL is dead instead of collapsing the page.
- An image that is already in the browser cache is detected in a layout effect before paint and revealed with a zero-duration transition, so a cached photo never flashes its own placeholder or plays a fade nobody asked for.
- The reveal waits on decode(), not on the load event, because a load event only promises the bytes arrived: swapping there can hand the compositor an undecoded bitmap and drop the frame the swap happens on.
- The blur is a constant on a static placeholder; only opacity and scale animate, because an animated filter repaints the full image every frame and cannot be composited.
- A failed load lands on a drawn glyph in the same frame at the same size, so a broken URL degrades to a state rather than to a browser default and a reflow.
- Under prefers-reduced-motion the photo replaces the placeholder immediately; nothing is hidden, only the crossfade is skipped, and the alt text is on the real element the whole time so it is available before the image is.


### Usage

```tsx
import { BlurUpImage } from "@/components/yugo/blur-up-image";

type Shot = {
  id: string;
  url: string;
  lqip: string;
  tone: string;
  caption: string;
};

export function ProjectGrid({ shots }: { shots: Shot[] }) {
  return (
    <ul className="grid grid-cols-2 gap-3">
      {shots.map((shot, i) => (
        <li key={shot.id}>
          <BlurUpImage
            src={shot.url}
            alt={shot.caption}
            width={1200}
            height={800}
            placeholder={shot.lqip}
            color={shot.tone}
            radius={11}
            sizes="(min-width: 768px) 320px, 45vw"
            loading={i < 2 ? "eager" : "lazy"}
            fetchPriority={i === 0 ? "high" : undefined}
          />
          <p className="mt-2 text-[12.5px] text-stone-500 dark:text-stone-400">
            {shot.caption}
          </p>
        </li>
      ))}
    </ul>
  );
}
```

### Source (`components/yugo/blur-up-image.tsx`)

```tsx
"use client";

import { useRef, useState } from "react";
import {
  motion,
  useIsomorphicLayoutEffect,
  useReducedMotion,
} from "motion/react";

const DEVELOP = { duration: 0.65, ease: [0.23, 1, 0.32, 1] } as const;

const INSTANT = { duration: 0 } as const;

export type BlurUpStatus = "loading" | "ready" | "error";

export type UseBlurUpImageOptions = {
  src?: string;
  srcSet?: string;
  onReady?: () => void;
  onError?: () => void;
};

export function useBlurUpImage({
  src,
  srcSet,
  onReady,
  onError,
}: UseBlurUpImageOptions) {
  const ref = useRef<HTMLImageElement>(null);
  const [state, setState] = useState<{
    status: BlurUpStatus;
    instant: boolean;
  }>({ status: "loading", instant: false });

  const ready = useRef(onReady);
  ready.current = onReady;
  const failed = useRef(onError);
  failed.current = onError;

  useIsomorphicLayoutEffect(() => {
    const img = ref.current;

    const set = (status: BlurUpStatus, instant: boolean) =>
      setState((prev) =>
        prev.status === status && prev.instant === instant
          ? prev
          : { status, instant },
      );

    if (!img || !src) {
      set("loading", false);
      return;
    }

    let alive = true;

    const cached = img.complete && img.naturalWidth > 0;

    const reveal = () => {
      if (!alive) return;
      set("ready", cached);
      ready.current?.();
    };

    const fail = () => {
      if (!alive) return;
      set("error", cached);
      failed.current?.();
    };

    if (img.complete) {
      if (cached) reveal();
      else fail();
      return () => {
        alive = false;
      };
    }

    set("loading", false);

    const onLoad = () => {
      if (!alive) return;
      if (typeof img.decode === "function") {
        img.decode().then(reveal, fail);
        return;
      }
      reveal();
    };

    img.addEventListener("load", onLoad);
    img.addEventListener("error", fail);

    return () => {
      alive = false;
      img.removeEventListener("load", onLoad);
      img.removeEventListener("error", fail);
    };
  }, [src, srcSet]);

  return {
    ref,
    status: state.status,
    instant: state.instant,
    loaded: state.status === "ready",
  };
}

export type BlurUpImageProps = {
  src?: string;
  alt: string;
  width: number;
  height: number;
  placeholder?: string;
  color?: string;
  blur?: number;
  radius?: 5 | 6 | 9 | 11 | 14;
  srcSet?: string;
  sizes?: string;
  loading?: "lazy" | "eager";
  fetchPriority?: "high" | "low" | "auto";
  onReady?: () => void;
  onError?: () => void;
  className?: string;
};

export function BlurUpImage({
  src,
  alt,
  width,
  height,
  placeholder,
  color,
  blur = 14,
  radius = 11,
  srcSet,
  sizes,
  loading = "lazy",
  fetchPriority,
  onReady,
  onError,
  className = "",
}: BlurUpImageProps) {
  const reduced = useReducedMotion();
  const { ref, status, instant } = useBlurUpImage({
    src,
    srcSet,
    onReady,
    onError,
  });

  const shown = status === "ready";
  const still = reduced === true || instant;
  const transition = still ? INSTANT : DEVELOP;

  return (
    <div
      aria-busy={status === "loading"}
      style={{
        aspectRatio: `${width} / ${height}`,
        borderRadius: radius,
        backgroundColor: color,
      }}
      className={`relative w-full overflow-hidden bg-stone-200 dark:bg-white/15 ${className}`}
    >
      {placeholder ? (
        // eslint-disable-next-line @next/next/no-img-element
        <img
          src={placeholder}
          alt=""
          aria-hidden
          draggable={false}
          className="absolute inset-0 h-full w-full object-cover"
          style={{ filter: `blur(${blur}px)`, transform: "scale(1.08)" }}
        />
      ) : null}

      <motion.img
        ref={ref}
        src={src}
        srcSet={srcSet}
        sizes={sizes}
        alt={alt}
        width={width}
        height={height}
        loading={loading}
        fetchPriority={fetchPriority}
        decoding="async"
        draggable={false}
        className="absolute inset-0 h-full w-full object-cover"
        initial={false}
        animate={
          still
            ? { opacity: shown ? 1 : 0 }
            : shown
              ? {
                  opacity: 1,
                  filter: "blur(0px) saturate(1)",
                  scale: 1,
                }
              : {
                  opacity: 0,
                  filter: "blur(18px) saturate(0.6)",
                  scale: 1.06,
                }
        }
        transition={transition}
      />

      {status === "error" ? (
        <motion.div
          aria-hidden
          initial={{ opacity: 0 }}
          animate={{ opacity: 1 }}
          transition={transition}
          className="absolute inset-0 grid place-items-center bg-white text-stone-400 dark:bg-[#1D1D1A] dark:text-stone-500"
        >
          <svg width="22" height="22" viewBox="0 0 256 256" fill="currentColor">
            <path d="M216,40H40A16,16,0,0,0,24,56V200a16,16,0,0,0,16,16h64a8,8,0,0,0,7.59-5.47l14.83-44.48L163,151.43a8.07,8.07,0,0,0,4.46-4.46l14.62-36.55,44.48-14.83A8,8,0,0,0,232,88V56A16,16,0,0,0,216,40ZM112.41,157.47,98.23,200H40V172l52-52,30.42,30.42L117,152.57A8,8,0,0,0,112.41,157.47ZM216,82.23,173.47,96.41a8,8,0,0,0-4.9,4.62l-14.72,36.82L138.58,144l-35.27-35.27a16,16,0,0,0-22.62,0L40,149.37V56H216Zm12.68,33a8,8,0,0,0-7.21-1.1l-23.8,7.94a8,8,0,0,0-4.9,4.61l-14.31,35.77-35.77,14.31a8,8,0,0,0-4.61,4.9l-7.94,23.8A8,8,0,0,0,137.73,216H216a16,16,0,0,0,16-16V121.73A8,8,0,0,0,228.68,115.24ZM216,200H148.83l3.25-9.75,35.51-14.2a8.07,8.07,0,0,0,4.46-4.46l14.2-35.51,9.75-3.25Z" />
          </svg>
        </motion.div>
      ) : null}
    </div>
  );
}
```

---

## Show More · Content

Height animates, text does not reflow.

Docs: https://yugo.click/docs/show-more
Install: `bun add motion`, then copy the source below into `components/yugo/show-more.tsx` · or `bunx shadcn@latest add https://yugo.click/r/show-more.json`.

Guarantees:
- The collapsed state is a measured pixel height, never `-webkit-line-clamp`, so no ellipsis is added to or removed from the last visible line and the paragraph breaks in exactly the same places open or shut.
- The animated height is a number read from a ResizeObserver rather than `auto`, so a toggle interrupted mid-flight springs from the height the box currently has instead of snapping to a freshly measured one.
- Content taller than `maxHeight` scrolls instead of expanding without bound, and the scrollbar gutter is reserved from the first paint whenever the content overflows, so the scrollbar's arrival cannot narrow the column and re-wrap the text.
- Before hydration the box is clamped in CSS at `lines × 1lh`, so server-rendered markup already shows the collapsed height rather than painting the whole paragraph and collapsing it once JavaScript lands.
- The trigger's two labels occupy one grid cell and its row keeps its height even when the content is short enough that no trigger is offered, so nothing below the block ever moves.
- Under `prefers-reduced-motion` the height, the edge fade and the chevron all settle instantly, and the clipped text stays in the accessibility tree while collapsed, so the information arrives either way.


### Usage

```tsx
"use client";

import { useState } from "react";
import { ShowMore } from "@/components/yugo/show-more";

export function ReleaseNote({ body }: { body: string }) {
  const [expanded, setExpanded] = useState(false);

  return (
    <article className="rounded-[14px] border border-stone-200 bg-white p-4 dark:border-white/[0.16] dark:bg-[#1D1D1A]">
      <h3 className="text-[13px] font-medium text-stone-800 dark:text-stone-100">
        Release 4.2.0
      </h3>

      <ShowMore
        lines={3}
        maxHeight={240}
        label="Release notes"
        expanded={expanded}
        onExpandedChange={setExpanded}
        className="mt-2"
      >
        <p>{body}</p>
      </ShowMore>
    </article>
  );
}
```

### Source (`components/yugo/show-more.tsx`)

```tsx
"use client";

import { useCallback, useId, useRef, useState } from "react";
import {
  motion,
  useIsomorphicLayoutEffect,
  useReducedMotion,
} from "motion/react";

const DISCLOSE = {
  type: "spring",
  stiffness: 190,
  damping: 30,
  mass: 1,
} as const;

const SMALL = {
  type: "spring",
  stiffness: 700,
  damping: 46,
  mass: 0.5,
} as const;

const INSTANT = { duration: 0 } as const;

type Metrics = { line: number; full: number };

export type UseShowMoreOptions = {
  lines?: number;
  maxHeight?: number;
  defaultExpanded?: boolean;
  expanded?: boolean;
  onExpandedChange?: (expanded: boolean) => void;
};

export type UseShowMoreResult = {
  contentRef: React.RefObject<HTMLDivElement | null>;
  expanded: boolean;
  open: boolean;
  toggle: () => void;
  setExpanded: (next: boolean) => void;
  height: number | null;
  collapsedHeight: number | null;
  fullHeight: number | null;
  expandable: boolean;
  capped: boolean;
  scrollable: boolean;
};

export function useShowMore({
  lines = 3,
  maxHeight = 320,
  defaultExpanded = false,
  expanded: expandedProp,
  onExpandedChange,
}: UseShowMoreOptions = {}): UseShowMoreResult {
  const [uncontrolled, setUncontrolled] = useState(defaultExpanded);
  const [metrics, setMetrics] = useState<Metrics | null>(null);
  const contentRef = useRef<HTMLDivElement | null>(null);

  const expanded = expandedProp ?? uncontrolled;

  const notify = useRef(onExpandedChange);
  notify.current = onExpandedChange;

  const setExpanded = useCallback(
    (next: boolean) => {
      if (expandedProp === undefined) setUncontrolled(next);
      notify.current?.(next);
    },
    [expandedProp],
  );

  const toggle = useCallback(
    () => setExpanded(!expanded),
    [setExpanded, expanded],
  );

  useIsomorphicLayoutEffect(() => {
    const el = contentRef.current;
    if (!el) return;

    const read = () => {
      const styles = getComputedStyle(el);
      const parsed = Number.parseFloat(styles.lineHeight);
      const line = Number.isFinite(parsed)
        ? parsed
        : Number.parseFloat(styles.fontSize) * 1.5;
      const full = el.scrollHeight;

      setMetrics((prev) =>
        prev && prev.line === line && prev.full === full
          ? prev
          : { line, full },
      );
    };

    read();

    const observer = new ResizeObserver(read);
    observer.observe(el);
    return () => observer.disconnect();
  }, []);

  const clamped = metrics ? metrics.line * lines : 0;
  const expandable = metrics ? metrics.full - clamped > 1 : true;
  const capped = metrics ? metrics.full > maxHeight : false;
  const collapsedHeight = metrics ? Math.min(clamped, metrics.full) : null;
  const fullHeight = metrics ? Math.min(metrics.full, maxHeight) : null;
  const open = expanded && expandable;

  return {
    contentRef,
    expanded,
    open,
    toggle,
    setExpanded,
    height: open ? fullHeight : collapsedHeight,
    collapsedHeight,
    fullHeight,
    expandable,
    capped,
    scrollable: open && capped,
  };
}

export type ShowMoreProps = UseShowMoreOptions & {
  children: React.ReactNode;
  moreLabel?: string;
  lessLabel?: string;
  label?: string;
  className?: string;
};

export function ShowMore({
  children,
  moreLabel = "Show more",
  lessLabel = "Show less",
  label = "Details",
  lines = 3,
  maxHeight = 320,
  defaultExpanded,
  expanded,
  onExpandedChange,
  className = "",
}: ShowMoreProps) {
  const reduced = useReducedMotion();
  const regionId = useId();
  const regionRef = useRef<HTMLDivElement>(null);

  const { contentRef, open, toggle, height, expandable, capped, scrollable } =
    useShowMore({
      lines,
      maxHeight,
      defaultExpanded,
      expanded,
      onExpandedChange,
    });

  const press = () => {
    if (open) regionRef.current?.scrollTo({ top: 0 });
    toggle();
  };

  const veiled = expandable && (!open || scrollable);

  return (
    <div
      className={`text-[13.5px] leading-relaxed text-stone-700 dark:text-stone-200 ${className}`}
    >
      <div className="relative">
        <motion.div
          ref={regionRef}
          id={regionId}
          role={scrollable ? "region" : undefined}
          aria-label={scrollable ? label : undefined}
          tabIndex={scrollable ? 0 : undefined}
          initial={false}
          animate={height === null ? {} : { height }}
          transition={reduced ? INSTANT : DISCLOSE}
          style={{
            maxHeight: height === null ? `${lines}lh` : undefined,
            overflowY: scrollable ? "auto" : "hidden",

            scrollbarGutter: capped ? "stable" : undefined,
          }}
          className="overflow-hidden overscroll-contain rounded-[6px] outline-none focus-visible:bg-[#4568FF]/[0.06] focus-visible:shadow-[inset_0_0_0_1px_#4568FF] dark:focus-visible:bg-[#93B0FF]/[0.10] dark:focus-visible:shadow-[inset_0_0_0_1px_#93B0FF]"
        >
          <div ref={contentRef}>{children}</div>
        </motion.div>
        <motion.div
          aria-hidden
          initial={false}
          animate={{ opacity: veiled ? 1 : 0 }}
          transition={reduced ? INSTANT : SMALL}
          className="pointer-events-none absolute inset-x-0 bottom-0 h-9 bg-gradient-to-t from-white to-white/0 dark:from-stone-900 dark:to-stone-900/0"
        />
      </div>
      <div className="mt-2 flex h-8 items-center">
        {/* eslint-disable-next-line jsx-a11y/control-has-associated-label */}
        <button
          type="button"
          onClick={press}
          aria-expanded={open}
          aria-controls={regionId}
          className={`inline-flex h-8 select-none items-center gap-2 rounded-[9px] border border-stone-200 bg-white px-2.5 text-[12.5px] font-medium text-stone-700 outline-none transition-[border-color,box-shadow] duration-150 hover:border-stone-300 focus-visible:border-[#4568FF] focus-visible:shadow-[0_1px_2px_rgba(28,25,23,0.08),0_10px_20px_-14px_rgba(69,104,255,0.6)] dark:border-white/[0.16] dark:bg-[#1D1D1A] dark:text-stone-200 dark:hover:border-white/20 dark:focus-visible:border-[#93B0FF] dark:focus-visible:shadow-[0_10px_20px_-14px_rgba(147,176,255,0.5)] ${
            expandable ? "" : "pointer-events-none invisible"
          }`}
        >
          <span className="grid text-left">
            <motion.span
              aria-hidden={open}
              className="col-start-1 row-start-1"
              initial={false}
              animate={{ opacity: open ? 0 : 1 }}
              transition={reduced ? INSTANT : SMALL}
            >
              {moreLabel}
            </motion.span>
            <motion.span
              aria-hidden={!open}
              className="col-start-1 row-start-1"
              initial={false}
              animate={{ opacity: open ? 1 : 0 }}
              transition={reduced ? INSTANT : SMALL}
            >
              {lessLabel}
            </motion.span>
          </span>
          <motion.svg
            aria-hidden
            width="12"
            height="12"
            viewBox="0 0 256 256"
            fill="none"
            className="text-stone-500 dark:text-stone-400"
            initial={false}
            animate={{ rotate: open ? 180 : 0 }}
            transition={reduced ? INSTANT : SMALL}
          >
            <polyline
              points="208 96 128 176 48 96"
              stroke="currentColor"
              strokeWidth="16"
              strokeLinecap="round"
              strokeLinejoin="round"
            />
          </motion.svg>
        </button>
      </div>
    </div>
  );
}
```

---

## Text Loop · Content

One line, rotating, in a box that never moves.

Docs: https://yugo.click/docs/text-loop
Install: `bun add motion`, then copy the source below into `components/yugo/text-loop.tsx` · or `bunx shadcn@latest add https://yugo.click/r/text-loop.json`.

Guarantees:
- Every phrase is drawn once, invisibly, in the same grid cell, so the box is already as wide and as tall as the longest one and the line beside it never reflows mid-rotation.
- The timer only runs while the loop is on screen and the tab is in front: an IntersectionObserver and a visibilitychange listener gate it, so a rotation nobody is looking at costs nothing.
- The new phrase arrives from below over 0.28s and the old one leaves upward over 0.16s, because an exit that takes as long as an entrance reads as the two smearing through each other.
- There is no aria-live. A region that announces every two seconds forever is worse than none; the current phrase is real text and is read when a screen reader reaches it.
- Under prefers-reduced-motion the rotation still happens and the travel does not: the information arrives, the trip is skipped.
- useTextLoop is the rotation with nothing drawn, and returns go, next and prev so the same timer can drive a carousel of anything.


### Usage

```tsx
"use client";

import { TextLoop } from "@/components/yugo/text-loop";

const STEPS = [
  "Resolving 412 modules",
  "Type-checking 68 files",
  "Bundling the client",
  "Uploading to the edge",
];

export function DeployLine({ running }: { running: boolean }) {
  return (
    <p className="text-[13px] font-medium">
      <TextLoop play={running} interval={1.8}>
        {STEPS.map((step) => (
          <span key={step}>{step}</span>
        ))}
      </TextLoop>
    </p>
  );
}
```

### Source (`components/yugo/text-loop.tsx`)

```tsx
"use client";

import { Children, useCallback, useEffect, useRef, useState } from "react";
import {
  AnimatePresence,
  motion,
  useInView,
  useReducedMotion,
} from "motion/react";

const EASE = [0.23, 1, 0.32, 1] as const;
const LEAVE = [0.4, 0, 1, 1] as const;
const INSTANT = { duration: 0 } as const;

const ENTER = 0.28;
const EXIT = 0.16;

const FROM = { opacity: 0, y: 10, filter: "blur(6px)" } as const;
const HERE = { opacity: 1, y: 0, filter: "blur(0px)" } as const;
const AWAY = { opacity: 0, y: -6, filter: "blur(3px)" } as const;

const ALIGN = {
  start: "justify-items-start",
  center: "justify-items-center",
  end: "justify-items-end",
} as const;

export type TextLoopAlign = keyof typeof ALIGN;

export type UseTextLoopOptions = {
  length: number;
  interval?: number;
  play?: boolean;
  index?: number;
  defaultIndex?: number;
  onIndexChange?: (index: number) => void;
};

export type UseTextLoopResult<T extends HTMLElement> = {
  ref: React.RefObject<T | null>;
  index: number;
  running: boolean;
  go: (index: number) => void;
  next: () => void;
  prev: () => void;
};

/**
 * The rotation, with nothing drawn. It advances only while the loop is on
 * screen and the tab is in front: a belt nobody is watching should not be
 * costing frames.
 */
export function useTextLoop<T extends HTMLElement = HTMLSpanElement>({
  length,
  interval = 2,
  play = true,
  index: controlled,
  defaultIndex = 0,
  onIndexChange,
}: UseTextLoopOptions): UseTextLoopResult<T> {
  const ref = useRef<T>(null);
  const inView = useInView(ref);
  const [uncontrolled, setUncontrolled] = useState(defaultIndex);
  const [awake, setAwake] = useState(true);

  const raw = controlled ?? uncontrolled;
  const index = length > 0 ? ((raw % length) + length) % length : 0;

  const emit = useRef(onIndexChange);
  emit.current = onIndexChange;

  const live = useRef({ index, length, controlled });
  live.current = { index, length, controlled };

  const go = useCallback((next: number) => {
    const { length: total, controlled: outside } = live.current;
    if (total <= 0) return;
    const at = ((next % total) + total) % total;
    if (outside === undefined) setUncontrolled(at);
    emit.current?.(at);
  }, []);

  const step = useCallback(
    (delta: number) => go(live.current.index + delta),
    [go],
  );

  const next = useCallback(() => step(1), [step]);
  const prev = useCallback(() => step(-1), [step]);

  useEffect(() => {
    const read = () => setAwake(!document.hidden);
    read();
    document.addEventListener("visibilitychange", read);
    return () => document.removeEventListener("visibilitychange", read);
  }, []);

  const running = play && awake && inView && length > 1 && interval > 0;

  useEffect(() => {
    if (!running) return;
    const timer = setInterval(() => step(1), interval * 1000);
    return () => clearInterval(timer);
  }, [running, interval, step]);

  return { ref, index, running, go, next, prev };
}

export type TextLoopProps = Omit<UseTextLoopOptions, "length"> & {
  children: React.ReactNode;
  align?: TextLoopAlign;
  className?: string;
};

export function TextLoop({
  children,
  align = "start",
  className = "",
  ...options
}: TextLoopProps) {
  const reduced = useReducedMotion();
  const items = Children.toArray(children);

  const { ref, index } = useTextLoop<HTMLSpanElement>({
    ...options,
    length: items.length,
  });

  return (
    <span
      ref={ref}
      className={`inline-grid ${ALIGN[align]} text-stone-700 dark:text-stone-200 ${className}`}
    >
      {/* Every phrase, drawn once and invisibly, so the cell is already as
          wide and as tall as the longest one and nothing around it reflows
          when the rotation lands on it. */}
      {items.map((item, i) => (
        <span
          key={`slot-${i}`}
          aria-hidden="true"
          className="invisible col-start-1 row-start-1 whitespace-nowrap"
        >
          {item}
        </span>
      ))}

      <AnimatePresence initial={false} mode="sync">
        <motion.span
          key={index}
          className="col-start-1 row-start-1 whitespace-nowrap"
          initial={reduced ? false : FROM}
          animate={HERE}
          exit={
            reduced
              ? { opacity: 0, transition: INSTANT }
              : { ...AWAY, transition: { duration: EXIT, ease: LEAVE } }
          }
          transition={reduced ? INSTANT : { duration: ENTER, ease: EASE }}
        >
          {items[index]}
        </motion.span>
      </AnimatePresence>
    </span>
  );
}
```

---

## Text Morph · Content

Letters travel to their new word.

Docs: https://yugo.click/docs/text-morph
Install: `bun add motion`, then copy the source below into `components/yugo/text-morph.tsx` · or `bunx shadcn@latest add https://yugo.click/r/text-morph.json`.

Guarantees:
- A character's identity is its letter plus how many times that letter has already appeared, case-folded, so the e in seven and the E in Eleven are the same element and travel to their new slot rather than crossfade.
- The travel is layout="position" on siblings, never a shared layoutId: a shared id lets an exiting letter and an arriving one claim the same identity mid-flight, and the morph turns into a pile-up.
- The travel is the 700/46/0.5 spring the rest of the set uses for small moves, because a soft surface spring on a glyph crossing twelve pixels reaches the target fast and then crawls, which nobody reads as damping and everybody reads as slow.
- Opacity is separated from the layout: in over 0.18s, out over 0.1s on the leaving curve, so departures never take as long as arrivals.
- reserve is the difference between a morph and a reflow. Without it the box is as wide as whatever is in it, and every sibling moves each time a letter is added.
- The character layer is aria-hidden and the string is carried by a single sr-only node, so a screen reader gets the word and not twelve separate letters.
- Under prefers-reduced-motion the layout animation is switched off with layout={false} rather than given a zero duration, because a layout animation cannot be handed duration: 0.
- Array.from, not split(''): splitting a string on empty cuts surrogate pairs in half and an emoji becomes two broken glyphs mid-morph.


### Usage

```tsx
"use client";

import { useState } from "react";
import { TextMorph } from "@/components/yugo/text-morph";

const TIERS = ["seventeen", "forty-one", "one hundred"];

export function SeatCount() {
  const [seats, setSeats] = useState(TIERS[0]);

  return (
    <div>
      <TextMorph
        text={seats}
        reserve={TIERS}
        announce
        className="text-[27px] font-medium tracking-[-0.03em]"
      />
      {TIERS.map((tier) => (
        <button key={tier} type="button" onClick={() => setSeats(tier)}>
          {tier}
        </button>
      ))}
    </div>
  );
}
```

### Source (`components/yugo/text-morph.tsx`)

```tsx
"use client";

import { useEffect, useId, useMemo, useState } from "react";
import { AnimatePresence, motion, useReducedMotion } from "motion/react";

const EASE = [0.23, 1, 0.32, 1] as const;
const LEAVE = [0.4, 0, 1, 1] as const;

const SMALL = {
  type: "spring",
  stiffness: 700,
  damping: 46,
  mass: 0.5,
} as const;

const INSTANT = { duration: 0 } as const;

const SETTLE = 400;
const SPACE = " ";

export type TextMorphCharacter = {
  /** stable across renders: the nth occurrence of this letter, case-folded */
  id: string;
  label: string;
};

/**
 * Splits a string into characters that keep their identity between two
 * strings. The key is the letter plus how many times it has already appeared,
 * case-folded, so the "e" in "seven" and the "E" in "Eleven" are the same
 * object and travel rather than crossfade.
 */
export function useTextMorph(text: string): TextMorphCharacter[] {
  const base = useId();

  return useMemo(() => {
    const seen: Record<string, number> = {};

    return Array.from(text).map((char) => {
      const key = char.toLowerCase();
      seen[key] = (seen[key] ?? 0) + 1;
      return {
        id: `${base}-${key}-${seen[key]}`,
        label: char === " " ? SPACE : char,
      };
    });
  }, [text, base]);
}

export type TextMorphProps = {
  text: string;
  as?: React.ElementType;
  reserve?: readonly string[];
  announce?: boolean;
  className?: string;
};

export function TextMorph({
  text,
  as: Component = "span",
  reserve,
  announce = false,
  className = "",
}: TextMorphProps) {
  const reduced = useReducedMotion();
  const characters = useTextMorph(text);
  const [said, setSaid] = useState("");

  // Announce late: a value that morphs through four strings while a number
  // ticks should be one sentence, not four. §18
  useEffect(() => {
    if (!announce) return;
    const timer = setTimeout(() => setSaid(text), SETTLE);
    return () => clearTimeout(timer);
  }, [announce, text]);

  return (
    <Component className={`inline-grid ${className}`}>
      {/* Every string this box can ever hold, drawn invisibly in the same
          cell, so the column is already at its widest and the letters morph
          inside a box that never moves. */}
      {reserve?.map((phrase) => (
        <span
          key={phrase}
          aria-hidden="true"
          className="invisible col-start-1 row-start-1 whitespace-pre"
        >
          {phrase}
        </span>
      ))}

      <span
        aria-hidden="true"
        className="col-start-1 row-start-1 whitespace-pre"
      >
        {/* Surviving letters keep their key, so they stay mounted and travel
            to their new slot with layout="position". No layoutId: a shared id
            here means an exiting letter and an arriving one can claim the
            same identity mid-flight and pile up. §5i */}
        <AnimatePresence mode="popLayout" initial={false}>
          {characters.map((character) => (
            <motion.span
              key={character.id}
              layout={reduced ? false : "position"}
              className="inline-block"
              initial={{ opacity: 0 }}
              animate={{ opacity: 1 }}
              exit={{
                opacity: 0,
                transition: reduced
                  ? INSTANT
                  : { duration: 0.08, ease: LEAVE },
              }}
              transition={
                reduced
                  ? INSTANT
                  : {
                      ...SMALL,
                      // Entrants wait for the leavers to clear: 60ms is under
                      // perception as a delay and over it as a smear.
                      opacity: { duration: 0.16, ease: EASE, delay: 0.06 },
                    }
              }
            >
              {character.label}
            </motion.span>
          ))}
        </AnimatePresence>
      </span>

      <span className="sr-only" aria-live={announce ? "polite" : undefined}>
        {announce ? said : text}
      </span>
    </Component>
  );
}
```

---

## Text Shimmer · Content

A spinner made of words.

Docs: https://yugo.click/docs/text-shimmer
Install: `bun add motion`, then copy the source below into `components/yugo/text-shimmer.tsx` · or `bunx shadcn@latest add https://yugo.click/r/text-shimmer.json`.

Guarantees:
- A shimmer is a spinner made of words: unknown duration, constant speed, one pass. That is the whole defence for a loop in a set that bans them, and it is why the sweep is linear and why active is a prop rather than an assumption.
- When active goes false the gradient is dropped entirely and the text renders in ordinary ink, so a finished line never sits half-lit waiting for a frame that is not coming.
- The sweep only runs while the text is on screen and the tab is in front. Off screen or backgrounded it is not a slower animation, it is no animation.
- The lit and base tones are CSS variables on the element, so a caller can retune both modes from the outside without forking the file.
- Under prefers-reduced-motion nothing sweeps and the text sits at its resting ink; the sentence itself is what says work is happening, which is the channel that was always doing the real work.
- useTextShimmer is the gate alone: a ref and a running flag, for drawing the same wait some other way.


### Usage

```tsx
"use client";

import { TextShimmer } from "@/components/yugo/text-shimmer";

export function ToolLine({ done, path }: { done: boolean; path: string }) {
  return (
    <TextShimmer active={!done} className="text-[13px]">
      {done ? "Read " + path : "Reading " + path}
    </TextShimmer>
  );
}
```

### Source (`components/yugo/text-shimmer.tsx`)

```tsx
"use client";

import { useEffect, useMemo, useRef, useState } from "react";
import { motion, useInView, useReducedMotion } from "motion/react";

const INSTANT = { duration: 0 } as const;

const SWEEP = 2;
const SPREAD = 2;
const MIN_BAND = 12;

/**
 * A shimmer is a spinner made of words: unknown duration, constant speed, one
 * pass. That is why it moves `linear` and why it is gated on `active` — a
 * sweep that keeps running after the work landed is decoration, and this set
 * does not ship decoration.
 */
const RESTING =
  "text-stone-700 dark:text-stone-200";

const SHIMMERING =
  "bg-clip-text text-transparent [background-repeat:no-repeat,padding-box] [--lit:#1c1917] [--base:#a8a29e] dark:[--lit:#f5f5f4] dark:[--base:#78716c]";

export type UseTextShimmerOptions = {
  active?: boolean;
};

export type UseTextShimmerResult<T extends HTMLElement> = {
  ref: React.RefObject<T | null>;
  running: boolean;
};

export function useTextShimmer<T extends HTMLElement = HTMLSpanElement>({
  active = true,
}: UseTextShimmerOptions = {}): UseTextShimmerResult<T> {
  const ref = useRef<T>(null);
  const inView = useInView(ref);
  const reduced = useReducedMotion();
  const [awake, setAwake] = useState(true);

  useEffect(() => {
    const read = () => setAwake(!document.hidden);
    read();
    document.addEventListener("visibilitychange", read);
    return () => document.removeEventListener("visibilitychange", read);
  }, []);

  return { ref, running: Boolean(active) && awake && inView && !reduced };
}

export type TextShimmerProps = UseTextShimmerOptions & {
  children: string;
  as?: React.ElementType;
  duration?: number;
  spread?: number;
  className?: string;
};

export function TextShimmer({
  children,
  as: Component = "span",
  active = true,
  duration = SWEEP,
  spread = SPREAD,
  className = "",
}: TextShimmerProps) {
  const { ref, running } = useTextShimmer<HTMLElement>({ active });

  // motion.create() mints a component type. Calling it in the render body
  // makes a new type every render, which remounts the node and restarts the
  // sweep on every parent update.
  const Motion = useMemo(
    () => motion.create(Component as "span"),
    [Component],
  );

  const band = Math.max(MIN_BAND, children.length * spread);

  return (
    <Motion
      ref={ref}
      className={`relative inline-block ${running ? SHIMMERING : RESTING} ${className}`}
      style={
        running
          ? {
              backgroundImage: `linear-gradient(90deg, transparent calc(50% - ${band}px), var(--lit), transparent calc(50% + ${band}px)), linear-gradient(var(--base), var(--base))`,
              backgroundSize: "250% 100%, auto",
            }
          : undefined
      }
      initial={running ? { backgroundPosition: "100% center" } : false}
      animate={
        running ? { backgroundPosition: ["100% center", "0% center"] } : {}
      }
      transition={
        running
          ? { duration, ease: "linear", repeat: Infinity }
          : INSTANT
      }
    >
      {children}
    </Motion>
  );
}
```

---

## Text Shimmer Wave · Content

The same wait, read letter by letter.

Docs: https://yugo.click/docs/text-shimmer-wave
Install: `bun add motion`, then copy the source below into `components/yugo/text-shimmer-wave.tsx` · or `bunx shadcn@latest add https://yugo.click/r/text-shimmer-wave.json`.

Guarantees:
- Same defence as text-shimmer, spent on a longer phrase: an unknown duration reported at a constant rate. It is gated on active for the same reason, and stops dead when the work lands.
- The three-dimensional properties default to nothing. A perspective and a preserve-3d on a text run that never leaves the plane is a compositor layer bought for no reason, so both are only written when z or rotateY are asked for.
- Only the properties that were actually given a distance become keyframes; the rest are set once. A wave with default props animates two values per character, not six.
- The whole phrase is carried by one sr-only node and the character layer is aria-hidden, so nothing is read out letter by letter.
- Array.from, not split(''), so an emoji stays one glyph.
- It stops off screen and in a background tab, and under prefers-reduced-motion it never starts: every character sits at the lit tone and the phrase reads normally.


### Usage

```tsx
"use client";

import { TextShimmerWave } from "@/components/yugo/text-shimmer-wave";

export function Working({ busy }: { busy: boolean }) {
  return (
    <TextShimmerWave
      active={busy}
      duration={1.1}
      spread={1.4}
      className="text-[15px]"
    >
      Generating the migration
    </TextShimmerWave>
  );
}
```

### Source (`components/yugo/text-shimmer-wave.tsx`)

```tsx
"use client";

import { useEffect, useMemo, useRef, useState } from "react";
import { motion, useInView, useReducedMotion } from "motion/react";

const INSTANT = { duration: 0 } as const;

const BASE = "var(--base)";
const LIT = "var(--lit)";

const TONES =
  "[--lit:#1c1917] [--base:#a8a29e] dark:[--lit:#f5f5f4] dark:[--base:#78716c]";

/** The gap between one pass and the next, so the wave reads as a pass rather
 *  than as a permanent ripple. */
const REST_PER_CHARACTER = 0.05;

export type UseTextShimmerWaveOptions = {
  active?: boolean;
};

export type UseTextShimmerWaveResult<T extends HTMLElement> = {
  ref: React.RefObject<T | null>;
  running: boolean;
};

export function useTextShimmerWave<T extends HTMLElement = HTMLSpanElement>({
  active = true,
}: UseTextShimmerWaveOptions = {}): UseTextShimmerWaveResult<T> {
  const ref = useRef<T>(null);
  const inView = useInView(ref);
  const reduced = useReducedMotion();
  const [awake, setAwake] = useState(true);

  useEffect(() => {
    const read = () => setAwake(!document.hidden);
    read();
    document.addEventListener("visibilitychange", read);
    return () => document.removeEventListener("visibilitychange", read);
  }, []);

  return { ref, running: Boolean(active) && awake && inView && !reduced };
}

export type TextShimmerWaveProps = UseTextShimmerWaveOptions & {
  children: string;
  as?: React.ElementType;
  duration?: number;
  spread?: number;
  xDistance?: number;
  yDistance?: number;
  zDistance?: number;
  scaleDistance?: number;
  rotateYDistance?: number;
  className?: string;
};

export function TextShimmerWave({
  children,
  as: Component = "span",
  active = true,
  duration = 1,
  spread = 1,
  xDistance = 0,
  yDistance = -2,
  zDistance = 0,
  scaleDistance = 1.06,
  rotateYDistance = 0,
  className = "",
}: TextShimmerWaveProps) {
  const { ref, running } = useTextShimmerWave<HTMLElement>({ active });

  const Motion = useMemo(
    () => motion.create(Component as "span"),
    [Component],
  );

  // Array.from, not split(""): split cuts surrogate pairs in half and an
  // emoji becomes two broken glyphs mid-wave.
  const characters = useMemo(() => Array.from(children), [children]);

  // Depth is only paid for when it is asked for. A perspective and a
  // preserve-3d on a text run that never leaves the plane is a compositor
  // layer for nothing.
  const dimensional = zDistance !== 0 || rotateYDistance !== 0;

  return (
    <Motion
      ref={ref}
      className={`relative inline-block ${TONES} ${dimensional ? "[perspective:500px]" : ""} ${className}`}
      style={{ color: running ? BASE : undefined }}
    >
      <span className="sr-only">{children}</span>

      <span aria-hidden="true">
        {characters.map((character, i) => {
          const delay = (i * duration * (1 / spread)) / characters.length;

          return (
            <motion.span
              key={`${i}-${character}`}
              className={`inline-block whitespace-pre ${dimensional ? "[transform-style:preserve-3d]" : ""}`}
              initial={false}
              animate={
                running
                  ? {
                      x: xDistance === 0 ? 0 : [0, xDistance, 0],
                      y: yDistance === 0 ? 0 : [0, yDistance, 0],
                      z: zDistance === 0 ? 0 : [0, zDistance, 0],
                      scale:
                        scaleDistance === 1 ? 1 : [1, scaleDistance, 1],
                      rotateY:
                        rotateYDistance === 0
                          ? 0
                          : [0, rotateYDistance, 0],
                      color: [BASE, LIT, BASE],
                    }
                  : { x: 0, y: 0, z: 0, scale: 1, rotateY: 0, color: LIT }
              }
              transition={
                running
                  ? {
                      duration,
                      delay,
                      repeat: Infinity,
                      repeatDelay:
                        (characters.length * REST_PER_CHARACTER) / spread,
                      ease: "easeInOut",
                    }
                  : INSTANT
              }
            >
              {character}
            </motion.span>
          );
        })}
      </span>
    </Motion>
  );
}
```

---

## Spinning Text · Content

A seal, turning at one rate.

Docs: https://yugo.click/docs/spinning-text
Install: `bun add motion`, then copy the source below into `components/yugo/spinning-text.tsx` · or `bunx shadcn@latest add https://yugo.click/r/spinning-text.json`.

Guarantees:
- The ring has a real box: width and height are derived from the radius and the font size, so it reserves its space like everything else instead of being a zero-sized layer that only works once its parent is told to be relative.
- One rate, no easing. A rotation that reports nothing turns at a constant speed, which is the same defence the spinner has and the reason this is a loop the set allows.
- Letters are placed with a single static transform each and the whole ring turns as one element, so there are N spans and one moving value, not N animations.
- The angle is accumulated per frame into a MotionValue rather than declared as animate: rotate 360, because a declared target has no way to pause: withdrawing it animates the ring back to zero, and the seal visibly unwinds. Pausing here just stops accumulating.
- The string is carried once by an sr-only node and every glyph is aria-hidden, so nobody has to hear a seal read out one letter at a time.
- It stops off screen and in a background tab, holding its angle, and under prefers-reduced-motion it never starts turning with the text still legible.
- useSpinningText returns the letters with their angles already computed, for drawing a ring that is not made of spans.


### Usage

```tsx
"use client";

import { SpinningText } from "@/components/yugo/spinning-text";

export function Seal() {
  return (
    <div className="relative grid place-items-center">
      <SpinningText
        text="the last twenty percent · yugo design · "
        duration={16}
        radius={5.2}
        fontSize={0.66}
      />
      <span aria-hidden className="absolute size-[5px] rounded-[1.5px] bg-[#4568FF]" />
    </div>
  );
}
```

### Source (`components/yugo/spinning-text.tsx`)

```tsx
"use client";

import { useEffect, useMemo, useRef, useState } from "react";
import {
  motion,
  useAnimationFrame,
  useInView,
  useMotionValue,
  useReducedMotion,
} from "motion/react";

const TURN = 12;
const RADIUS = 5;
const SIZE = 1;

export type SpinningTextLetter = {
  key: string;
  label: string;
  /** degrees around the ring, measured from twelve o'clock */
  angle: number;
};

export type UseSpinningTextOptions = {
  text: string;
  play?: boolean;
};

export type UseSpinningTextResult<T extends HTMLElement> = {
  ref: React.RefObject<T | null>;
  letters: SpinningTextLetter[];
  running: boolean;
};

/**
 * The ring, with nothing drawn. A rotation that reports nothing turns at one
 * rate — the spinner's own defence — so the caller gets `running` and a set
 * of angles, and nothing here decides what a letter looks like.
 */
export function useSpinningText<T extends HTMLElement = HTMLDivElement>({
  text,
  play = true,
}: UseSpinningTextOptions): UseSpinningTextResult<T> {
  const ref = useRef<T>(null);
  const inView = useInView(ref);
  const reduced = useReducedMotion();
  const [awake, setAwake] = useState(true);

  useEffect(() => {
    const read = () => setAwake(!document.hidden);
    read();
    document.addEventListener("visibilitychange", read);
    return () => document.removeEventListener("visibilitychange", read);
  }, []);

  const letters = useMemo(() => {
    const glyphs = Array.from(text);
    const step = glyphs.length > 0 ? 360 / glyphs.length : 0;
    return glyphs.map((label, i) => ({
      key: `${i}-${label}`,
      label,
      angle: i * step,
    }));
  }, [text]);

  return {
    ref,
    letters,
    running: play && awake && inView && !reduced && letters.length > 0,
  };
}

export type SpinningTextProps = UseSpinningTextOptions & {
  duration?: number;
  reverse?: boolean;
  radius?: number;
  fontSize?: number;
  className?: string;
};

export function SpinningText({
  text,
  play = true,
  duration = TURN,
  reverse = false,
  radius = RADIUS,
  fontSize = SIZE,
  className = "",
}: SpinningTextProps) {
  const { ref, letters, running } = useSpinningText<HTMLDivElement>({
    text,
    play,
  });

  // The angle is accumulated, not declared. `animate={{ rotate: 360 }}` has
  // no way to pause: withdrawing it animates the ring BACK to zero, which
  // reads as the seal unwinding. A MotionValue stepped per frame holds its
  // angle the instant `running` goes false and continues from it. §5h
  const angle = useMotionValue(0);
  useAnimationFrame((_, delta) => {
    if (!running) return;
    const step = (delta / 1000) * (360 / duration) * (reverse ? -1 : 1);
    angle.set((angle.get() + step) % 360);
  });

  // The ring has a real box. A zero-sized seal that only exists once its
  // parent is told to be `relative` is a component that reserves nothing,
  // and invariant 1 says every state pays for its space up front.
  const extent = `calc(${radius * 2}ch + 1em)`;

  return (
    <div
      ref={ref}
      className={`relative select-none text-stone-700 dark:text-stone-200 ${className}`}
      style={{ fontSize: `${fontSize}rem`, width: extent, height: extent }}
    >
      <span className="sr-only">{text}</span>

      <motion.div
        aria-hidden="true"
        className="absolute inset-0"
        style={{ rotate: angle }}
      >
        {letters.map((letter) => (
          <span
            key={letter.key}
            className="absolute left-1/2 top-1/2 inline-block"
            style={{
              transform: `translate(-50%, -50%) rotate(${letter.angle}deg) translateY(${-radius}ch)`,
              transformOrigin: "center",
            }}
          >
            {letter.label}
          </span>
        ))}
      </motion.div>
    </div>
  );
}
```

---

## Sound Cues · Sound

Fourteen cues, auditioned before you commit to one.

Docs: https://yugo.click/docs/sound-cues
Install: `bun add @yugo.click/sound motion`, then copy the source below into `components/yugo/sound-cues.tsx` · or `bunx shadcn@latest add https://yugo.click/r/sound-cues.json`.

Guarantees:
- Sound starts muted, and auditioning a cue turns it on. Clicking a sound in order to hear it is consent; nothing plays before that.
- The preference is written under one key that Sound Toggle also reads, so the whole palette answers to a single switch rather than each component holding its own idea of whether audio is allowed.
- Storage is read in an effect rather than during render, so the server markup and the first client paint agree and there is no hydration mismatch to chase.
- The list is a real listbox with a roving tab stop: arrows walk it, Home and End jump, and the whole palette costs one Tab instead of fourteen.
- The engine reports every cue that reaches the speakers, including ones fired by bind() elsewhere on the page, so a row lights whether you played it or something else did.
- The selected row's surface is one shared element that travels between rows, not a background that appears in one place and disappears in another.
- Storage failures — private mode, a full quota, a blocked origin — are swallowed. A preference that cannot be saved is not a reason to refuse to make sound.


### Usage

```tsx
"use client";

import { SoundCues, useSoundCues } from "@/components/yugo/sound-cues";

export function SoundSettings() {
  return <SoundCues defaultVolume={0.6} />;
}

export function SaveBar({ onSave }: { onSave: () => Promise<void> }) {
  const { play, enabled } = useSoundCues();

  async function submit() {
    try {
      await onSave();
      play("success");
    } catch {
      play("error");
    }
  }

  return (
    <button onClick={submit} aria-describedby={enabled ? undefined : "muted"}>
      Save
    </button>
  );
}
```

### Source (`components/yugo/sound-cues.tsx`)

```tsx
"use client";

import {
  useCallback,
  useEffect,
  useId,
  useMemo,
  useRef,
  useState,
} from "react";
import { motion, useReducedMotion } from "motion/react";
import {
  getVolume,
  isEnabled,
  play as playCue,
  setEnabled as setEngineEnabled,
  setVolume as setEngineVolume,
  sounds,
  subscribe,
  type SoundName,
} from "@yugo.click/sound";

const MARK = {
  type: "spring",
  stiffness: 420,
  damping: 38,
  mass: 0.7,
} as const;
const FLASH = {
  type: "spring",
  stiffness: 300,
  damping: 30,
  mass: 0.6,
} as const;
const INSTANT = { duration: 0 } as const;

const CHARACTER: Record<SoundName, string> = {
  chime: "Soft two-note ascending bell",
  sparkle: "Quick four-note twinkle",
  droplet: "Single note gliding down",
  bloom: "Warm slow swell",
  whisper: "Breathy quiet swell",
  tick: "Crisp instant tick",
  press: "Dull muted knock",
  release: "Brighter springy tick",
  toggle: "Mechanical click-clack",
  success: "Warm three-note confirmation",
  error: "Soft knock and descending refusal",
  page: "Papery flick with a glass tick",
  loading: "Brief unresolved rising shimmer",
  ready: "Focus tick with a harmonic bloom",
};

const DEFAULT_VOLUME = 0.7;
const DEFAULT_KEY = "yugo-sound";

function clamp(value: number) {
  return Math.min(1, Math.max(0, value));
}

function readStored(key: string | null): { enabled?: boolean; volume?: number } {
  if (!key || typeof window === "undefined") return {};
  try {
    const raw = window.localStorage.getItem(key);
    if (!raw) return {};
    const parsed: unknown = JSON.parse(raw);
    if (!parsed || typeof parsed !== "object") return {};
    const { enabled, volume } = parsed as Record<string, unknown>;
    return {
      enabled: typeof enabled === "boolean" ? enabled : undefined,
      volume: typeof volume === "number" && Number.isFinite(volume) ? clamp(volume) : undefined,
    };
  } catch {
    return {};
  }
}

function writeStored(key: string | null, enabled: boolean, volume: number) {
  if (!key || typeof window === "undefined") return;
  try {
    window.localStorage.setItem(key, JSON.stringify({ enabled, volume }));
  } catch {
    return;
  }
}

export type Cue = {
  name: SoundName;
  character: string;
};

export type UseSoundCuesOptions = {
  defaultEnabled?: boolean;
  defaultVolume?: number;
  storageKey?: string | null;
};

export function useSoundCues({
  defaultEnabled = false,
  defaultVolume = DEFAULT_VOLUME,
  storageKey = DEFAULT_KEY,
}: UseSoundCuesOptions = {}) {
  const [enabled, setEnabledState] = useState(defaultEnabled);
  const [volume, setVolumeState] = useState(() => clamp(defaultVolume));
  const [hydrated, setHydrated] = useState(false);
  const [lastCue, setLastCue] = useState<SoundName | null>(null);
  const [plays, setPlays] = useState(0);

  useEffect(() => {
    const stored = readStored(storageKey);
    const nextEnabled = stored.enabled ?? defaultEnabled;
    const nextVolume = stored.volume ?? clamp(defaultVolume);
    setEnabledState(nextEnabled);
    setVolumeState(nextVolume);
    setEngineEnabled(nextEnabled);
    setEngineVolume(nextVolume);
    setHydrated(true);
  }, [defaultEnabled, defaultVolume, storageKey]);

  useEffect(
    () =>
      subscribe((sound) => {
        setLastCue(sound);
        setPlays((n) => n + 1);
      }),
    [],
  );

  const setEnabled = useCallback(
    (next: boolean) => {
      setEnabledState(next);
      setEngineEnabled(next);
      writeStored(storageKey, next, getVolume());
    },
    [storageKey],
  );

  const setVolume = useCallback(
    (next: number) => {
      const settled = clamp(next);
      setVolumeState(settled);
      setEngineVolume(settled);
      writeStored(storageKey, isEnabled(), settled);
    },
    [storageKey],
  );

  const play = useCallback((name: SoundName, options?: { volume?: number }) => {
    playCue(name, options);
  }, []);

  const cues = useMemo<Cue[]>(
    () => sounds.map((name) => ({ name, character: CHARACTER[name] })),
    [],
  );

  return {
    cues,
    enabled,
    setEnabled,
    volume,
    setVolume,
    play,
    lastCue,
    plays,
    hydrated,
  };
}

function SpeakerIcon({ muted }: { muted: boolean }) {
  return (
    <svg viewBox="0 0 20 20" width="13" height="13" fill="none" aria-hidden>
      <path
        d="M10.5 3.8 6.6 7H4.2a.7.7 0 0 0-.7.7v4.6a.7.7 0 0 0 .7.7h2.4l3.9 3.2Z"
        fill="currentColor"
      />
      {muted ? (
        <path
          d="m13.6 8 3.4 4M17 8l-3.4 4"
          stroke="currentColor"
          strokeWidth="1.4"
          strokeLinecap="round"
        />
      ) : (
        <path
          d="M13.4 7.4a3.6 3.6 0 0 1 0 5.2M15.6 5.4a6.6 6.6 0 0 1 0 9.2"
          stroke="currentColor"
          strokeWidth="1.4"
          strokeLinecap="round"
        />
      )}
    </svg>
  );
}

export type SoundCuesProps = {
  defaultEnabled?: boolean;
  defaultVolume?: number;
  storageKey?: string | null;
  onCue?: (name: SoundName) => void;
  className?: string;
};

export function SoundCues({
  defaultEnabled = false,
  defaultVolume = DEFAULT_VOLUME,
  storageKey = DEFAULT_KEY,
  onCue,
  className = "",
}: SoundCuesProps) {
  const labelId = useId();
  const reduced = useReducedMotion();
  const { cues, enabled, setEnabled, play, lastCue, plays } = useSoundCues({
    defaultEnabled,
    defaultVolume,
    storageKey,
  });

  const [active, setActive] = useState(0);
  const rowRefs = useRef<Array<HTMLButtonElement | null>>([]);

  const audition = useCallback(
    (index: number) => {
      const cue = cues[index];
      if (!cue) return;
      setActive(index);
      if (!enabled) setEnabled(true);
      play(cue.name);
      onCue?.(cue.name);
    },
    [cues, enabled, onCue, play, setEnabled],
  );

  const focusRow = useCallback((index: number) => {
    setActive(index);
    rowRefs.current[index]?.focus();
  }, []);

  function onKeyDown(event: React.KeyboardEvent<HTMLDivElement>) {
    const last = cues.length - 1;
    if (event.key === "ArrowDown") focusRow(Math.min(last, active + 1));
    else if (event.key === "ArrowUp") focusRow(Math.max(0, active - 1));
    else if (event.key === "Home") focusRow(0);
    else if (event.key === "End") focusRow(last);
    else return;
    event.preventDefault();
  }

  return (
    <div
      className={`w-full text-stone-800 dark:text-stone-100 ${className}`}
    >
      <div className="mb-2 flex items-center justify-between gap-3">
        <span id={labelId} className="text-[12.5px] text-stone-500 dark:text-stone-400">
          Cues
        </span>
        <button
          type="button"
          onClick={() => setEnabled(!enabled)}
          aria-pressed={enabled}
          className="inline-flex h-[22px] items-center gap-1.5 rounded-[6px] px-1.5 text-[11px] text-stone-500 outline-none hover:text-stone-800 focus-visible:shadow-[0_0_0_2px_#4568FF] dark:text-stone-400 dark:hover:text-stone-100 dark:focus-visible:shadow-[0_0_0_2px_#93B0FF]"
        >
          <SpeakerIcon muted={!enabled} />
          {enabled ? "On" : "Muted"}
        </button>
      </div>

      <div
        role="listbox"
        tabIndex={-1}
        aria-labelledby={labelId}
        onKeyDown={onKeyDown}
        className="max-h-[268px] overflow-y-auto overscroll-contain rounded-[10px] bg-stone-100 p-1 dark:bg-white/[0.06]"
      >
        {cues.map((cue, index) => {
          const selected = index === active;
          return (
            <button
              key={cue.name}
              type="button"
              role="option"
              aria-selected={selected}
              tabIndex={selected ? 0 : -1}
              ref={(node) => {
                rowRefs.current[index] = node;
              }}
              onClick={() => audition(index)}
              onFocus={() => setActive(index)}
              className={`relative flex h-[32px] w-full items-center gap-2.5 rounded-[7px] px-2 text-left outline-none focus-visible:shadow-[inset_0_0_0_2px_#4568FF] dark:focus-visible:shadow-[inset_0_0_0_2px_#93B0FF] ${
                selected ? "" : "hover:bg-stone-200/70 dark:hover:bg-white/[0.06]"
              }`}
            >
              {selected && (
                <motion.span
                  layoutId={`${labelId}-row`}
                  aria-hidden
                  transition={reduced ? INSTANT : MARK}
                  className="absolute inset-0 rounded-[7px] bg-white shadow-[0_1px_2px_rgba(0,0,0,0.08),0_0_0_1px_rgba(0,0,0,0.06)] dark:bg-white/10 dark:shadow-[0_0_0_1px_rgba(255,255,255,0.08)]"
                />
              )}
              <motion.span
                key={cue.name === lastCue ? plays : "idle"}
                aria-hidden
                initial={reduced ? false : { scale: 0.6, opacity: 0.5 }}
                animate={{ scale: 1, opacity: 1 }}
                transition={reduced ? INSTANT : FLASH}
                className="relative block size-[6px] shrink-0 rounded-[2px]"
                style={{
                  background:
                    cue.name === lastCue
                      ? "#4568FF"
                      : selected
                        ? "currentColor"
                        : "rgb(168 162 158)",
                }}
              />
              <span
                className={`relative truncate text-[13px] ${
                  selected ? "font-medium" : "text-stone-600 dark:text-stone-300"
                }`}
              >
                {cue.name}
              </span>
              <span className="relative ml-auto hidden truncate text-[11px] text-stone-500 sm:block dark:text-stone-400">
                {cue.character}
              </span>
            </button>
          );
        })}
      </div>
    </div>
  );
}
```

---

## Sound Toggle · Sound

The preference the whole palette answers to.

Docs: https://yugo.click/docs/sound-toggle
Install: `bun add @yugo.click/sound motion`, then copy the source below into `components/yugo/sound-toggle.tsx` · or `bunx shadcn@latest add https://yugo.click/r/sound-toggle.json`.

Guarantees:
- Off by default. Sound is the one kind of feedback that arrives whether or not anyone is looking at the screen, so it is the one that has to be asked for.
- Turning it on plays a cue; turning it off is silent. The confirmation that muting worked is the silence.
- It is a native button carrying role=switch and aria-checked, so Space and Enter are the browser's, not a second keyboard implementation that has to be kept honest.
- The state word sits in a grid over an invisible twin sized to the longest string it can hold, so On and Muted occupy the same box and the row never reflows.
- Writes merge into the stored object instead of replacing it, so toggling sound never clobbers the volume another component saved under the same key.
- toggle() asks the engine what the current state is rather than trusting local state, so a mute triggered from anywhere else on the page is not silently undone by a stale render.
- Under prefers-reduced-motion the thumb is where it belongs immediately; the state still changes, the trip is skipped.


### Usage

```tsx
"use client";

import { SoundToggle, useSoundToggle } from "@/components/yugo/sound-toggle";

export function PreferencesPanel() {
  return (
    <SoundToggle
      label="Interface sound"
      onChange={(enabled) => track("sound", { enabled })}
    />
  );
}

export function HeaderMuteButton() {
  const { enabled, switchProps } = useSoundToggle({ cue: "tick" });

  return (
    <button {...switchProps} aria-label="Interface sound">
      {enabled ? <SpeakerIcon /> : <MutedIcon />}
    </button>
  );
}
```

### Source (`components/yugo/sound-toggle.tsx`)

```tsx
"use client";

import { useCallback, useEffect, useId, useState } from "react";
import { motion, useReducedMotion } from "motion/react";
import {
  isEnabled,
  play,
  setEnabled as setEngineEnabled,
  type SoundName,
} from "@yugo.click/sound";

const THUMB = {
  type: "spring",
  stiffness: 620,
  damping: 42,
  mass: 0.6,
} as const;
const TRACK = {
  type: "spring",
  stiffness: 340,
  damping: 34,
  mass: 0.7,
} as const;
const INSTANT = { duration: 0 } as const;

const DEFAULT_KEY = "yugo-sound";
const TRAVEL = 18;

function readStored(key: string | null): boolean | null {
  if (!key || typeof window === "undefined") return null;
  try {
    const raw = window.localStorage.getItem(key);
    if (!raw) return null;
    const parsed: unknown = JSON.parse(raw);
    if (!parsed || typeof parsed !== "object") return null;
    const { enabled } = parsed as Record<string, unknown>;
    return typeof enabled === "boolean" ? enabled : null;
  } catch {
    return null;
  }
}

function writeStored(key: string | null, enabled: boolean) {
  if (!key || typeof window === "undefined") return;
  try {
    const raw = window.localStorage.getItem(key);
    const previous: unknown = raw ? JSON.parse(raw) : {};
    const base = previous && typeof previous === "object" ? previous : {};
    window.localStorage.setItem(key, JSON.stringify({ ...base, enabled }));
  } catch {
    return;
  }
}

export type UseSoundToggleOptions = {
  defaultEnabled?: boolean;
  storageKey?: string | null;
  cue?: SoundName | null;
  onChange?: (enabled: boolean) => void;
};

export function useSoundToggle({
  defaultEnabled = false,
  storageKey = DEFAULT_KEY,
  cue = "toggle",
  onChange,
}: UseSoundToggleOptions = {}) {
  const [enabled, setEnabledState] = useState(defaultEnabled);
  const [hydrated, setHydrated] = useState(false);

  useEffect(() => {
    const stored = readStored(storageKey);
    const next = stored ?? defaultEnabled;
    setEnabledState(next);
    setEngineEnabled(next);
    setHydrated(true);
  }, [defaultEnabled, storageKey]);

  const setEnabled = useCallback(
    (next: boolean) => {
      setEnabledState(next);
      setEngineEnabled(next);
      writeStored(storageKey, next);
      if (next && cue) play(cue);
      onChange?.(next);
    },
    [cue, onChange, storageKey],
  );

  const toggle = useCallback(() => {
    setEnabled(!isEnabled());
  }, [setEnabled]);

  const switchProps = {
    type: "button" as const,
    role: "switch" as const,
    "aria-checked": enabled,
    onClick: toggle,
  };

  return { enabled, setEnabled, toggle, switchProps, hydrated };
}

function WaveIcon({ on }: { on: boolean }) {
  return (
    <svg viewBox="0 0 16 16" width="11" height="11" fill="none" aria-hidden>
      {on ? (
        <path
          d="M3 8h1.6l1.5-3.6L8.6 12l1.6-5.4L11.6 8H13"
          stroke="currentColor"
          strokeWidth="1.5"
          strokeLinecap="round"
          strokeLinejoin="round"
        />
      ) : (
        <path
          d="M3 8h10"
          stroke="currentColor"
          strokeWidth="1.5"
          strokeLinecap="round"
        />
      )}
    </svg>
  );
}

export type SoundToggleProps = {
  label?: string;
  hint?: string;
  defaultEnabled?: boolean;
  storageKey?: string | null;
  cue?: SoundName | null;
  onChange?: (enabled: boolean) => void;
  disabled?: boolean;
  className?: string;
};

export function SoundToggle({
  label = "Interface sound",
  hint,
  defaultEnabled = false,
  storageKey = DEFAULT_KEY,
  cue = "toggle",
  onChange,
  disabled = false,
  className = "",
}: SoundToggleProps) {
  const labelId = useId();
  const hintId = useId();
  const reduced = useReducedMotion();
  const { enabled, switchProps } = useSoundToggle({
    defaultEnabled,
    storageKey,
    cue,
    onChange,
  });

  return (
    <div
      className={`flex w-full items-center justify-between gap-6 ${className}`}
    >
      <span className="grid min-w-0 gap-0.5">
        <span
          id={labelId}
          className="truncate text-[13px] text-stone-800 dark:text-stone-100"
        >
          {label}
        </span>
        <span className="grid">
          <span
            aria-hidden
            className="invisible col-start-1 row-start-1 text-[11.5px]"
          >
            {hint ?? "Muted"}
          </span>
          <span
            id={hintId}
            className="col-start-1 row-start-1 truncate text-[11.5px] text-stone-500 dark:text-stone-400"
          >
            {hint ?? (enabled ? "On" : "Muted")}
          </span>
        </span>
      </span>

      <button
        {...switchProps}
        disabled={disabled}
        aria-labelledby={labelId}
        aria-describedby={hintId}
        className="relative h-[24px] w-[42px] shrink-0 rounded-[8px] outline-none disabled:pointer-events-none disabled:opacity-50 focus-visible:shadow-[0_0_0_2px_#4568FF] dark:focus-visible:shadow-[0_0_0_2px_#93B0FF]"
      >
        <motion.span
          aria-hidden
          initial={false}
          animate={{
            backgroundColor: enabled
              ? "#4568FF"
              : "rgba(120, 113, 108, 0.28)",
          }}
          transition={reduced ? INSTANT : TRACK}
          className="absolute inset-0 rounded-[8px] shadow-[inset_0_1px_2px_rgba(0,0,0,0.12)]"
        />
        <motion.span
          aria-hidden
          initial={false}
          animate={{ x: enabled ? TRAVEL : 0 }}
          transition={reduced ? INSTANT : THUMB}
          className="absolute left-[3px] top-[3px] grid size-[18px] place-items-center rounded-[6px] bg-white text-stone-500 shadow-[0_1px_2px_rgba(0,0,0,0.24)]"
        >
          <WaveIcon on={enabled} />
        </motion.span>
      </button>
    </div>
  );
}
```

---

## Cue Button · Sound

Press, release, and the outcome, each with its own sound.

Docs: https://yugo.click/docs/cue-button
Install: `bun add @yugo.click/sound motion`, then copy the source below into `components/yugo/cue-button.tsx` · or `bunx shadcn@latest add https://yugo.click/r/cue-button.json`.

Guarantees:
- Press plays on pointerdown and release on pointerup, but only when the press was never abandoned. Drifting past eight pixels, a pointercancel, losing the window, hiding the tab, or Escape all end it in silence.
- The release cue is not a click sound. A press that turned into a scroll should sound like nothing at all, and getting that wrong is what makes most sounded buttons feel broken on touch.
- The loading cue waits out a delay before it fires. Work that finishes faster than the delay gets only its outcome cue, because two sounds for one instant action reads as a stutter rather than as feedback.
- A second press supersedes the first: the outcome of a superseded run is never played and never writes over the state of the run that replaced it.
- The status mark holds its box whether or not anything is in it, so the label sits still through idle, pending, done and failed.
- Activation hangs off click rather than pointerup, so the keyboard path is the browser's own and the pointer path cannot fire the handler twice.
- The state is announced in a polite live region as a word, not as an icon a screen reader has to guess at.
- Under prefers-reduced-motion there is no press depth and no spinner rotation, but the mark still changes, so the outcome still arrives.


### Usage

```tsx
"use client";

import { CueButton, useCueButton } from "@/components/yugo/cue-button";

export function PublishButton({ id }: { id: string }) {
  return <CueButton onPress={() => publish(id)}>Publish</CueButton>;
}

export function IconAction({ onRemove }: { onRemove: () => Promise<void> }) {
  const { bind, held, state } = useCueButton({
    onPress: onRemove,
    cues: { press: "press", release: "release", error: "error" },
    pendingDelay: 400,
  });

  return (
    <button {...bind} data-held={held} aria-busy={state === "pending"}>
      <TrashIcon />
    </button>
  );
}
```

### Source (`components/yugo/cue-button.tsx`)

```tsx
"use client";

import { useCallback, useEffect, useRef, useState } from "react";
import { motion, useReducedMotion } from "motion/react";
import { play, type SoundName } from "@yugo.click/sound";

const DEPTH = {
  type: "spring",
  stiffness: 760,
  damping: 44,
  mass: 0.45,
} as const;
const SWAP = {
  type: "spring",
  stiffness: 380,
  damping: 34,
  mass: 0.6,
} as const;
const INSTANT = { duration: 0 } as const;

const MOVE_TOLERANCE = 8;
const PENDING_DELAY = 260;
const SETTLE_MS = 1400;

const DEFAULT_CUES = {
  press: "press",
  release: "release",
  pending: "loading",
  success: "success",
  error: "error",
} as const;

export type CueSet = {
  press?: SoundName | null;
  release?: SoundName | null;
  pending?: SoundName | null;
  success?: SoundName | null;
  error?: SoundName | null;
};

export type CueButtonState = "idle" | "pending" | "done" | "failed";

export type UseCueButtonOptions = {
  onPress?: () => unknown;
  cues?: CueSet;
  moveTolerance?: number;
  pendingDelay?: number;
  settleAfter?: number;
  disabled?: boolean;
};

export function useCueButton({
  onPress,
  cues,
  moveTolerance = MOVE_TOLERANCE,
  pendingDelay = PENDING_DELAY,
  settleAfter = SETTLE_MS,
  disabled = false,
}: UseCueButtonOptions = {}) {
  const set = { ...DEFAULT_CUES, ...cues };
  const [held, setHeld] = useState(false);
  const [state, setState] = useState<CueButtonState>("idle");

  const holding = useRef(false);
  const origin = useRef({ x: 0, y: 0 });
  const pendingTimer = useRef<ReturnType<typeof setTimeout> | null>(null);
  const settleTimer = useRef<ReturnType<typeof setTimeout> | null>(null);
  const run = useRef(0);

  const cue = useRef(set);
  cue.current = set;
  const handler = useRef(onPress);
  handler.current = onPress;

  const abandon = useCallback(() => {
    if (!holding.current) return;
    holding.current = false;
    setHeld(false);
  }, []);

  const lift = useCallback(() => {
    if (!holding.current) return;
    holding.current = false;
    setHeld(false);
    if (cue.current.release) play(cue.current.release);
  }, []);

  useEffect(() => {
    const onBlur = () => abandon();
    const onVisibility = () => {
      if (document.visibilityState === "hidden") abandon();
    };
    window.addEventListener("blur", onBlur);
    document.addEventListener("visibilitychange", onVisibility);
    return () => {
      window.removeEventListener("blur", onBlur);
      document.removeEventListener("visibilitychange", onVisibility);
    };
  }, [abandon]);

  useEffect(
    () => () => {
      if (pendingTimer.current) clearTimeout(pendingTimer.current);
      if (settleTimer.current) clearTimeout(settleTimer.current);
    },
    [],
  );

  const activate = useCallback(() => {
    if (disabled) return;
    const result = handler.current?.();
    if (!(result instanceof Promise)) {
      if (cue.current.success) play(cue.current.success);
      return;
    }

    const ticket = ++run.current;
    setState("pending");
    if (settleTimer.current) clearTimeout(settleTimer.current);
    if (cue.current.pending) {
      pendingTimer.current = setTimeout(() => {
        if (run.current === ticket && cue.current.pending) play(cue.current.pending);
      }, pendingDelay);
    }

    const finish = (next: CueButtonState, sound: SoundName | null | undefined) => {
      if (run.current !== ticket) return;
      if (pendingTimer.current) clearTimeout(pendingTimer.current);
      setState(next);
      if (sound) play(sound);
      settleTimer.current = setTimeout(() => {
        if (run.current === ticket) setState("idle");
      }, settleAfter);
    };

    result.then(
      () => finish("done", cue.current.success),
      () => finish("failed", cue.current.error),
    );
  }, [disabled, pendingDelay, settleAfter]);

  const bind = {
    onPointerDown: (event: React.PointerEvent<HTMLElement>) => {
      if (disabled) return;
      if (event.pointerType === "mouse" && event.button !== 0) return;
      event.currentTarget.setPointerCapture?.(event.pointerId);
      holding.current = true;
      origin.current = { x: event.clientX, y: event.clientY };
      setHeld(true);
      if (cue.current.press) play(cue.current.press);
    },
    onPointerMove: (event: React.PointerEvent<HTMLElement>) => {
      if (!holding.current) return;
      const dx = event.clientX - origin.current.x;
      const dy = event.clientY - origin.current.y;
      if (Math.hypot(dx, dy) > moveTolerance) abandon();
    },
    onPointerUp: lift,
    onPointerCancel: abandon,
    onLostPointerCapture: abandon,
    onKeyDown: (event: React.KeyboardEvent<HTMLElement>) => {
      if (disabled) return;
      if (event.key === "Escape") {
        abandon();
        return;
      }
      if (event.key !== " " && event.key !== "Enter") return;
      if (event.repeat || holding.current) return;
      holding.current = true;
      setHeld(true);
      if (cue.current.press) play(cue.current.press);
    },
    onKeyUp: (event: React.KeyboardEvent<HTMLElement>) => {
      if (event.key !== " " && event.key !== "Enter") return;
      lift();
    },
    onClick: activate,
  };

  return { bind, held, state, pending: state === "pending", activate };
}

function SpinnerIcon() {
  return (
    <svg viewBox="0 0 16 16" width="13" height="13" fill="none" aria-hidden>
      <circle cx="8" cy="8" r="6" stroke="currentColor" strokeWidth="2" opacity="0.28" />
      <path
        d="M14 8a6 6 0 0 0-6-6"
        stroke="currentColor"
        strokeWidth="2"
        strokeLinecap="round"
      />
    </svg>
  );
}

function CheckIcon() {
  return (
    <svg viewBox="0 0 16 16" width="13" height="13" fill="none" aria-hidden>
      <path
        d="m3.6 8.4 2.9 2.9 5.9-6"
        stroke="currentColor"
        strokeWidth="2"
        strokeLinecap="round"
        strokeLinejoin="round"
      />
    </svg>
  );
}

function CrossIcon() {
  return (
    <svg viewBox="0 0 16 16" width="13" height="13" fill="none" aria-hidden>
      <path
        d="m4.4 4.4 7.2 7.2M11.6 4.4l-7.2 7.2"
        stroke="currentColor"
        strokeWidth="2"
        strokeLinecap="round"
      />
    </svg>
  );
}

export type CueButtonProps = {
  children: React.ReactNode;
  onPress?: () => unknown;
  cues?: CueSet;
  moveTolerance?: number;
  pendingDelay?: number;
  settleAfter?: number;
  disabled?: boolean;
  className?: string;
};

export function CueButton({
  children,
  onPress,
  cues,
  moveTolerance = MOVE_TOLERANCE,
  pendingDelay = PENDING_DELAY,
  settleAfter = SETTLE_MS,
  disabled = false,
  className = "",
}: CueButtonProps) {
  const reduced = useReducedMotion();
  const { bind, held, state } = useCueButton({
    onPress,
    cues,
    moveTolerance,
    pendingDelay,
    settleAfter,
    disabled,
  });

  const mark =
    state === "pending" ? (
      <motion.span
        aria-hidden
        animate={reduced ? undefined : { rotate: 360 }}
        transition={
          reduced ? INSTANT : { duration: 0.9, ease: "linear", repeat: Infinity }
        }
        className="flex"
      >
        <SpinnerIcon />
      </motion.span>
    ) : state === "done" ? (
      <CheckIcon />
    ) : state === "failed" ? (
      <CrossIcon />
    ) : null;

  return (
    <motion.button
      type="button"
      {...bind}
      disabled={disabled}
      aria-busy={state === "pending"}
      initial={false}
      animate={{ scale: held && !reduced ? 0.97 : 1 }}
      transition={reduced ? INSTANT : DEPTH}
      style={{ touchAction: "manipulation" }}
      className={`inline-flex h-[38px] select-none items-center gap-2 rounded-[10px] bg-stone-900 pl-4 pr-3.5 text-[13px] font-medium text-white outline-none disabled:pointer-events-none disabled:opacity-50 focus-visible:shadow-[0_0_0_2px_#4568FF] dark:bg-stone-100 dark:text-stone-900 dark:focus-visible:shadow-[0_0_0_2px_#93B0FF] ${className}`}
    >
      <span>{children}</span>
      <span className="grid size-[14px] shrink-0 place-items-center">
        <motion.span
          key={state}
          initial={reduced ? false : { opacity: 0, scale: 0.7 }}
          animate={{ opacity: 1, scale: 1 }}
          transition={reduced ? INSTANT : SWAP}
          className="col-start-1 row-start-1 flex"
          style={{
            color:
              state === "failed"
                ? "#F5897F"
                : state === "done"
                  ? "#5BD79C"
                  : "currentColor",
          }}
        >
          {mark}
        </motion.span>
      </span>
      <span aria-live="polite" className="sr-only">
        {state === "pending"
          ? "Working"
          : state === "done"
            ? "Done"
            : state === "failed"
              ? "Failed"
              : ""}
      </span>
    </motion.button>
  );
}
```

---

## Waveform Scope · Sound

What is actually reaching the speakers.

Docs: https://yugo.click/docs/waveform-scope
Install: `bun add @yugo.click/sound`, then copy the source below into `components/yugo/waveform-scope.tsx` · or `bunx shadcn@latest add https://yugo.click/r/waveform-scope.json`.

Guarantees:
- The analyser sits on the shared output after the limiter, so the trace is what leaves for the speakers rather than what the recipe asked for before compression got to it.
- The loop stops. Once the signal has been below the noise floor for the idle window, the animation frame is cancelled and the canvas holds a flat line, so a scope nobody is feeding costs nothing.
- Nothing is drawn through React. Every frame writes to the canvas directly, and the component re-renders only when the cue name or the live flag changes: twice per sound, not sixty times a second.
- The stroke is currentColor read off the canvas, so the scope inherits whatever theme it is dropped into instead of shipping its own palette.
- The backing store is resized from a ResizeObserver at device pixel ratio, capped at 2, so the trace is sharp on a retina display without paying for a 3× buffer.
- It waits for the first cue before touching the AudioContext, so mounting a scope does not spin up audio hardware for a page that may never make a sound.
- Under prefers-reduced-motion the loop never starts and the flat line stays, but the cue name still updates: the information that a sound played arrives without the movement.


### Usage

```tsx
"use client";

import { WaveformScope, useWaveformScope } from "@/components/yugo/waveform-scope";

export function SoundPanel() {
  return <WaveformScope label="Output" height={158} />;
}

export function BareScope() {
  const { canvasRef, live, lastCue } = useWaveformScope({ idleAfter: 1200 });

  return (
    <figure data-live={live}>
      <canvas ref={canvasRef} className="h-24 w-full text-slate-700" />
      <figcaption>{lastCue ?? "no signal"}</figcaption>
    </figure>
  );
}
```

### Source (`components/yugo/waveform-scope.tsx`)

```tsx
"use client";

import { useCallback, useEffect, useRef, useState } from "react";
import { getAnalyser, subscribe, type SoundName } from "@yugo.click/sound";

const IDLE_AFTER = 900;
const SILENCE = 0.004;
const TRACE_GAIN = 2.5;
const GRID_COLUMNS = 12;
const LINE_WIDTH = 1.5;

function prefersReduced(): boolean {
  if (typeof window === "undefined") return false;
  return window.matchMedia("(prefers-reduced-motion: reduce)").matches;
}

function deviation(samples: Uint8Array): number {
  let peak = 0;
  for (let i = 0; i < samples.length; i += 1) {
    const value = Math.abs(samples[i] / 128 - 1);
    if (value > peak) peak = value;
  }
  return peak;
}

export type UseWaveformScopeOptions = {
  idleAfter?: number;
  gain?: number;
};

export function useWaveformScope({
  idleAfter = IDLE_AFTER,
  gain = TRACE_GAIN,
}: UseWaveformScopeOptions = {}) {
  const canvasRef = useRef<HTMLCanvasElement>(null);
  const analyser = useRef<AnalyserNode | null>(null);
  const samples = useRef<Uint8Array<ArrayBuffer> | null>(null);
  const frame = useRef(0);
  const lastSound = useRef(0);
  const [live, setLive] = useState(false);
  const [lastCue, setLastCue] = useState<SoundName | null>(null);

  const paint = useCallback(
    (data: Uint8Array<ArrayBuffer> | null) => {
      const canvas = canvasRef.current;
      const context = canvas?.getContext("2d");
      if (!canvas || !context) return;

      const { width, height } = canvas;
      const dpr = width / Math.max(1, canvas.clientWidth);
      const stroke = getComputedStyle(canvas).color;
      const middle = height / 2;

      context.clearRect(0, 0, width, height);

      context.globalAlpha = 0.09;
      context.strokeStyle = stroke;
      context.lineWidth = 1;
      for (let i = 1; i < GRID_COLUMNS; i += 1) {
        const x = Math.round((width / GRID_COLUMNS) * i) + 0.5;
        context.beginPath();
        context.moveTo(x, 0);
        context.lineTo(x, height);
        context.stroke();
      }

      context.globalAlpha = 1;
      context.strokeStyle = stroke;
      context.lineWidth = LINE_WIDTH * dpr;
      context.lineJoin = "round";
      context.beginPath();

      if (!data) {
        context.globalAlpha = 0.32;
        context.moveTo(0, middle);
        context.lineTo(width, middle);
        context.stroke();
        return;
      }

      const step = width / (data.length - 1);
      for (let i = 0; i < data.length; i += 1) {
        const amplitude = (data[i] / 128 - 1) * gain;
        const y = middle - amplitude * middle;
        if (i === 0) context.moveTo(0, y);
        else context.lineTo(i * step, y);
      }
      context.stroke();
    },
    [gain],
  );

  const measure = useCallback(() => {
    const canvas = canvasRef.current;
    if (!canvas) return;
    const dpr = Math.min(2, window.devicePixelRatio || 1);
    const width = Math.max(1, Math.round(canvas.clientWidth * dpr));
    const height = Math.max(1, Math.round(canvas.clientHeight * dpr));
    if (canvas.width !== width || canvas.height !== height) {
      canvas.width = width;
      canvas.height = height;
    }
  }, []);

  const loop = useCallback(() => {
    const node = analyser.current;
    const buffer = samples.current;
    if (!node || !buffer) return;

    node.getByteTimeDomainData(buffer);
    const level = deviation(buffer);
    if (level > SILENCE) lastSound.current = performance.now();

    if (performance.now() - lastSound.current > idleAfter) {
      frame.current = 0;
      setLive(false);
      paint(null);
      return;
    }

    paint(buffer);
    frame.current = requestAnimationFrame(loop);
  }, [idleAfter, paint]);

  const start = useCallback(() => {
    if (prefersReduced()) return;
    if (!analyser.current) {
      const node = getAnalyser();
      if (!node) return;
      analyser.current = node;
      samples.current = new Uint8Array(node.fftSize);
    }
    lastSound.current = performance.now();
    if (frame.current) return;
    setLive(true);
    frame.current = requestAnimationFrame(loop);
  }, [loop]);

  useEffect(() => {
    measure();
    paint(null);
    const canvas = canvasRef.current;
    if (!canvas) return;
    const observer = new ResizeObserver(() => {
      measure();
      if (!frame.current) paint(null);
    });
    observer.observe(canvas);
    return () => observer.disconnect();
  }, [measure, paint]);

  useEffect(
    () =>
      subscribe((sound) => {
        setLastCue(sound);
        start();
      }),
    [start],
  );

  useEffect(
    () => () => {
      if (frame.current) cancelAnimationFrame(frame.current);
      frame.current = 0;
    },
    [],
  );

  return { canvasRef, live, lastCue, start };
}

export type WaveformScopeProps = {
  label?: string;
  height?: number;
  idleAfter?: number;
  gain?: number;
  className?: string;
};

export function WaveformScope({
  label = "Output",
  height = 132,
  idleAfter = IDLE_AFTER,
  gain = TRACE_GAIN,
  className = "",
}: WaveformScopeProps) {
  const { canvasRef, live, lastCue } = useWaveformScope({ idleAfter, gain });

  return (
    <div className={`w-full ${className}`}>
      <div className="mb-2 flex items-baseline justify-between gap-3">
        <span className="text-[12.5px] text-stone-500 dark:text-stone-400">
          {label}
        </span>
        <span className="grid justify-items-end">
          <span
            aria-hidden
            className="invisible col-start-1 row-start-1 font-mono text-[11px]"
          >
            no signal
          </span>
          <span
            className="col-start-1 row-start-1 font-mono text-[11px]"
            style={{ color: live ? "#4568FF" : "rgb(120 113 108)" }}
          >
            {lastCue ?? "no signal"}
          </span>
        </span>
      </div>
      <div
        className="w-full overflow-hidden rounded-[10px] bg-stone-100 dark:bg-white/[0.06]"
        style={{ height }}
      >
        <canvas
          ref={canvasRef}
          role="img"
          aria-label={
            lastCue ? `Waveform of the ${lastCue} cue` : "Waveform, no signal"
          }
          className="block h-full w-full text-stone-700 dark:text-stone-200"
        />
      </div>
    </div>
  );
}
```