# Action Rail (Notchset): prompt.md (v1.0.0)

- id: `action-rail` · version 1.0.0 · component · free
- category: Actions
- build: Base UI (one set of files; its dependencies follow the build)
- install (this build): `npx shadcn@latest add https://beautiful-ui.dev/r/action-rail.json`
- npm dependencies: none
- registry dependencies: utils, https://beautiful-ui.dev/r/notchset-foundation.json
- docs: https://beautiful-ui.dev/components/action-rail
- The install command carries everything this item needs (files, CSS, tokens, npm and registry dependencies). Prefer it to copying source by hand.

An expanding button group where one label travels along the rail: the primary keeps its name, the others are icons until you point at one or tab to it, each confirms in place in the past tense with a status line under the rail, and Delete asks twice.

## Build it
- Stack: React 19 (`ref` is a plain prop), TypeScript, Tailwind CSS v4 utilities, a shadcn-initialised project with the `@/*` alias.
- Packages: none beyond React.
- Files: `components/ui/notchset/action-rail.tsx`; shared code: `lib/beautiful-ui/notchset/instrument.tsx`, `lib/beautiful-ui/notchset/root.ts`.
- Registry dependencies, installed with it automatically: shadcn `utils` (cn), `notchset-foundation`.
- Builds: one set of files for both, but its dependencies come in Base UI and Radix builds. Install the one that matches the project (see Install): a free item's bare URL installs the Base UI build of it and its dependencies.
- Exports to keep: `ActionRail`, and every exported type.
- CSS: the install adds the notchset foundation (tokens, keyframes, motion levels) to your global stylesheet once. Nothing to import by hand.
- Re-running `add` (or `--overwrite`) re-applies those rules: put overrides in your own CSS, never in the installed rules.
- Tokens: retheme with the `--notchset-*` custom properties (`--notchset-check`, `--notchset-control-edge`, `--notchset-draw-from`, `--notchset-ease-bloom`, `--notchset-ease-glide`, `--notchset-ease-key-down`, `--notchset-ease-key-up`, `--notchset-ease-travel`, `--notchset-fade`, `--notchset-focus-color`, `--notchset-focus-inset`, `--notchset-grow-to`, `--notchset-key-down`, `--notchset-key-up`, `--notchset-life-from`, `--notchset-life-ms`, `--notchset-node-blink`, `--notchset-node-bloom`, `--notchset-node-delay`, `--notchset-plate-color`, `--notchset-rise-from`, `--notchset-rule`, `--notchset-scan-to`, `--notchset-scroll`, `--notchset-signal`, `--notchset-sweep-to`, `--notchset-travel`). Never add Tailwind colour classes inside the component.

```tsx
import { ActionRail } from "@/components/ui/notchset/action-rail";
```

## Parts

| Part | data-slot | What it is for |
|---|---|---|
| `ActionRail` | `action-rail` | The keys on their plate and the status line. |
| `Key` | `action-rail-key` | One action: icon, travelling label and its result. |

Style a part with `[data-slot="<slot>"]` selectors or its `className`; keep the attributes when editing.

## Sound
- Keep every `data-slot` and `data-sound` attribute: the sound layer reads them.
- Installing this item adds no audio. Nothing plays until the app mounts `SoundProvider` once (install: `npx shadcn@latest add https://beautiful-ui.dev/r/notchset-sound.json`, import from `@/components/ui/notchset/sound-provider`); `useSound()` gives `muted` and `setMuted` for a mute control. Without a provider the audio engine never loads.

## Match the original
- Read `components/ui/notchset/action-rail.tsx` as the reference implementation before changing or recreating anything, and match it: sizes, colours per theme, motion timings, copy and behaviour.
- If you deviate (a prop you can't honour, a style you changed, a dependency you swapped), say so in your reply, part by part.
- Keep the accessibility contract, the keyboard map and the motion levels listed below.

## Use it when
- expanding button group, action bar, row actions, message actions, file actions, icon buttons with labels, two-step delete, Notchset
- A compact action bar on a message, a file or a card, where labels should be one glance away
- Actions that finish in place and deserve a confirmation without a toast (Archive, Copy link)

### Not when
- Choosing a value: use Segmented Control or Toggle
- One or two actions with room to spare: plain labelled buttons read faster
- More than about six actions: use a Dropdown Menu

## Mistakes
- Put the primary first: the label rests on it
- Keep labels to one or two words: they slide out, they don't wrap
- Return a short sentence from onSelect when the result carries news

## Usage

```tsx
"use client";

import { ActionRail } from "@/components/ui/notchset/action-rail";

export function MessageActions({ reply, archive, remove }: { reply: () => void; archive: () => void; remove: () => void }) {
  return (
    <ActionRail
      aria-label="Message actions"
      actions={[
        { id: "reply", label: "REPLY", icon: <span>↩</span>, intent: "primary", onSelect: reply },
        { id: "archive", label: "ARCHIVE", icon: <span>▤</span>, doneLabel: "ARCHIVED", onSelect: () => (archive(), "MOVED TO ARCHIVE") },
        { id: "delete", label: "DELETE", icon: <span>✕</span>, intent: "danger", doneLabel: "DELETED", onSelect: () => (remove(), "MOVED TO TRASH") },
      ]}
    />
  );
}
```

## Props

| Prop | Type | Default | What it does |
|---|---|---|---|
| `actions` | `{ id, label, icon, doneLabel?, intent?, pressed?, onSelect? }[]` |  | In order; the primary (intent "primary") keeps its name. onSelect may return a sentence for the status line. |
| `intent` | `"primary" \| "danger" \| "toggle"` |  | Primary is ink and always named; danger asks twice; toggle reports aria-pressed from `pressed`. |
| `confirmDelete` | `boolean` |  | Danger actions ask twice. Default true. |
| `status` | `boolean` |  | The status line under the rail. Default true. |
| `labels` | `{ armed, armedStatus, cancelled, hint }` |  | Every word, for other languages. |

Full docs: https://beautiful-ui.dev/components/action-rail

## Customising
- Colours: the component reads your shadcn tokens (`--background`, `--foreground`, `--border` …), refined by the `--notchset-*` tokens. The signal colour is `--notchset-signal` (it falls back to `--destructive`). Set tokens on `:root`, or on any container to retheme one area.
- Dark mode follows the `.dark` class on an ancestor (the shadcn and next-themes convention).
- Update later by re-running the install with `--overwrite` (review the diff if you edited it). Changelog: https://beautiful-ui.dev/r/changelog.json

## Keyboard

| Keys | Action |
|---|---|
| ← → / Home End | Move between keys |
| Enter / Space | Run; on Delete, arm then delete |
| Esc | Cancel an armed delete |

## Performance

- One measurement per label change; the travel is a width transition.

## Responsive

- Folded keys are 40px squares, so a rail of five is the primary's label plus 160px.
- 44px keys on touch screens.

## Motion inventory

| Interaction | What moves |
|---|---|
| Travel | The active key's label widens from nothing to its width (360ms glide); the text fades in after 120ms and out in 100ms |
| Press | The content moves down 1px (90ms linear) |
| Done | The label flips to the past tense for 1.6s |
| Arm | The key fills with signal and the plate turns signal; it disarms after 3s |

## Accessibility contract (preserve when editing)
- A toolbar with one tab stop; ← → move between keys, Home and End jump to the ends
- Every key is named by its action; an armed delete says to press again; toggles report aria-pressed
- The status line is a polite live region

## Install

Base UI project (a base-* style in components.json):

```bash
npx shadcn@latest add https://beautiful-ui.dev/r/action-rail.json
```

Radix project (a radix-*, new-york or default style):

```bash
npx shadcn@latest add https://beautiful-ui.dev/r/radix-nova/action-rail.json
```

Or add the `@beautiful-ui` registry to components.json and run `npx shadcn@latest add @beautiful-ui/action-rail`: the CLI picks the build from your style.

## Credits
- Built on shadcn/ui (https://ui.shadcn.com)

## Source (Base UI build)

### components/ui/notchset/action-rail.tsx

```tsx
"use client";

/**
 * Action Rail (Notchset) v1.0.0 · Beautiful UI
 * Docs: https://beautiful-ui.dev/components/action-rail
 * MIT licensed: free to use, change and share.
 */

import * as React from "react";
import { cn } from "@/lib/utils";
import { FlipText, OWN_SOUND, playCue, NOTCHSET_ROOT, useLatest } from "@/lib/beautiful-ui/notchset/instrument";

/*
 * Notchset Action Rail: an expanding button group where one label travels along the rail. The first
 * key is the primary (ink) and keeps its name; the others are icons until you point at one or tab to
 * it, when its name slides out (the rail never gets wider than one label). Leaving the rail hands the
 * label back to the primary. Each key confirms in place, swapping its label to the past tense for
 * 1.6s while the status line under the rail says what happened. Delete asks twice: the first press
 * arms it in signal and the plate turns signal; it disarms after 3s or on Esc.
 */

export type ActionRailAction = {
  id: string;
  label: string;
  icon: React.ReactNode;
  /** The past tense shown on the key after it runs ("ARCHIVED"). */
  doneLabel?: string;
  /** primary: ink, always named (use it on the first action). danger: asks twice. toggle: reports aria-pressed. */
  intent?: "primary" | "danger" | "toggle";
  /** For toggles: on or off. */
  pressed?: boolean;
  /** Runs the action. Return a sentence for the status line ("MOVED TO ARCHIVE · ⌘Z UNDOES"). */
  onSelect?: () => string | void;
};

const ARM_MS = 3000;
const DONE_MS = 1600;

export type ActionRailProps = Omit<React.ComponentProps<"div">, "children"> & {
  actions: readonly ActionRailAction[];
  /** Danger actions ask twice. Default true. */
  confirmDelete?: boolean;
  /** The status line under the rail. Default true. */
  status?: boolean;
  labels?: Partial<{ armed: string; armedStatus: string; cancelled: string; hint: (n: number) => string }>;
};

function ActionRail({ actions, confirmDelete = true, status: showStatus = true, labels, className, ref, ...props }: ActionRailProps) {
  const L = {
    armed: "CONFIRM DELETE",
    armedStatus: "PRESS AGAIN TO DELETE · ESC CANCELS",
    cancelled: "DELETE CANCELLED",
    hint: (n: number) => `${n} ACTIONS · ← → MOVE`,
    ...labels,
  };
  const primaryIndex = Math.max(0, actions.findIndex((a) => a.intent === "primary"));
  const [hovered, setHovered] = React.useState<number | null>(null);
  const [focus, setFocus] = React.useState(primaryIndex);
  const [armed, setArmed] = React.useState<number | null>(null);
  const [done, setDone] = React.useState<Record<string, string>>({});
  const [status, setStatus] = React.useState<{ text: string; signal?: boolean } | null>(null);
  const keys = React.useRef<(HTMLButtonElement | null)[]>([]);
  const latest = useLatest(actions);

  // The armed key disarms by itself.
  React.useEffect(() => {
    if (armed === null) return;
    const t = setTimeout(() => {
      setArmed(null);
      setStatus({ text: L.cancelled });
    }, ARM_MS);
    return () => clearTimeout(t);
  }, [armed, L.cancelled]);

  // Past-tense labels go back after a moment, each on its own clock.
  const doneTimers = React.useRef<Record<string, ReturnType<typeof setTimeout>>>({});
  React.useEffect(() => () => Object.values(doneTimers.current).forEach(clearTimeout), []);

  const active = armed ?? hovered ?? primaryIndex;

  const run = (i: number) => {
    const action = latest.current[i];
    if (!action) return;
    const el = keys.current[i];
    if (action.intent === "danger" && confirmDelete && armed !== i) {
      playCue(el, "signal");
      setArmed(i);
      setStatus({ text: L.armedStatus, signal: true });
      return;
    }
    setArmed(null);
    playCue(el, action.intent === "danger" ? "confirm" : "done");
    const message = action.onSelect?.();
    if (action.doneLabel) {
      setDone((d) => ({ ...d, [action.id]: action.doneLabel! }));
      clearTimeout(doneTimers.current[action.id]);
      doneTimers.current[action.id] = setTimeout(() => setDone((d) => {
        const next = { ...d };
        delete next[action.id];
        return next;
      }), DONE_MS);
    }
    if (message) setStatus({ text: `✓ ${message}` });
  };

  const onKeyDown = (e: React.KeyboardEvent<HTMLDivElement>) => {
    props.onKeyDown?.(e);
    if (e.defaultPrevented) return;
    if (e.key === "Escape" && armed !== null) {
      e.preventDefault();
      setArmed(null);
      setStatus({ text: L.cancelled });
      return;
    }
    const n = actions.length;
    const rtl = getComputedStyle(e.currentTarget).direction === "rtl";
    const step = e.key === (rtl ? "ArrowLeft" : "ArrowRight") ? 1 : e.key === (rtl ? "ArrowRight" : "ArrowLeft") ? -1 : 0;
    const to = e.key === "Home" ? 0 : e.key === "End" ? n - 1 : step ? (focus + step + n) % n : -1;
    if (to < 0) return;
    e.preventDefault();
    keys.current[to]?.focus();
  };

  return (
    <div {...NOTCHSET_ROOT} data-slot="action-rail" className={cn("inline-flex max-w-full flex-col gap-2.5", className)}>
      <span
        className="relative inline-flex self-start [--notchset-plate-color:var(--notchset-control-edge,var(--input))] data-[armed]:[--notchset-plate-color:var(--notchset-signal-text,var(--destructive))]"
        data-armed={armed !== null || undefined}
      >
        <span aria-hidden data-slot="plate" className={`notchset-plate`} />
        <div
          {...props}
          ref={ref}
          role="toolbar"
          data-slot="action-rail-keys"
          onKeyDown={onKeyDown}
          onPointerLeave={() => setHovered(null)}
          onBlur={(e) => {
            if (!e.currentTarget.contains(e.relatedTarget as Node | null)) setHovered(null);
          }}
          className="relative flex border border-solid border-foreground bg-background"
        >
          {actions.map((a, i) => (
            <RailKey
              key={a.id}
              ref={(el) => {
                keys.current[i] = el;
              }}
              action={a}
              label={armed === i ? L.armed : (done[a.id] ?? a.label)}
              open={active === i}
              armed={armed === i}
              primary={i === primaryIndex}
              afterPrimary={i === primaryIndex + 1}
              first={i === 0}
              tabIndex={focus === i ? 0 : -1}
              onEnter={() => setHovered(i)}
              onFocus={() => {
                setFocus(i);
                setHovered(i);
              }}
              onPress={() => run(i)}
            />
          ))}
        </div>
      </span>
      {showStatus && (
        <span role="status" className={cn("font-mono text-[11px] tracking-[0.1em] whitespace-nowrap uppercase", status ? (status.signal ? "text-[color:var(--notchset-signal-text,var(--destructive))]" : "text-foreground") : "text-muted-foreground")}>
          {status?.text ?? L.hint(actions.length)}
        </span>
      )}
    </div>
  );
}

function RailKey({
  action,
  label,
  open,
  armed,
  primary,
  afterPrimary,
  first,
  tabIndex,
  onEnter,
  onFocus,
  onPress,
  ref,
}: {
  action: ActionRailAction;
  label: string;
  open: boolean;
  armed: boolean;
  primary: boolean;
  afterPrimary: boolean;
  first: boolean;
  tabIndex: number;
  onEnter: () => void;
  onFocus: () => void;
  onPress: () => void;
  ref: React.Ref<HTMLButtonElement>;
}) {
  const inner = React.useRef<HTMLSpanElement>(null);
  const [width, setWidth] = React.useState(0);
  // The label's natural width, read again when it changes (DELETE → CONFIRM DELETE → DELETED) or fonts load.
  React.useLayoutEffect(() => {
    const el = inner.current;
    if (!el) return;
    const measure = () => setWidth(Math.ceil(el.scrollWidth) + 3);
    measure();
    document.fonts?.ready.then(measure).catch(() => {});
  }, [label]);
  const danger = action.intent === "danger";
  return (
    <button
      {...OWN_SOUND}
      ref={ref}
      type="button"
      tabIndex={tabIndex}
      data-slot="action-rail-key"
      data-open={open || undefined}
      aria-label={armed ? `${action.label}: press again to confirm` : action.label}
      aria-pressed={action.intent === "toggle" ? Boolean(action.pressed) : undefined}
      onPointerEnter={onEnter}
      onFocus={onFocus}
      onClick={onPress}
      className={cn(
        `notchset-focus`,
        "group/key relative flex h-10 cursor-pointer items-center border-0 bg-transparent px-3 font-mono text-[12px] font-medium tracking-[0.05em] uppercase transition-colors duration-(--notchset-fade) ease-(--notchset-ease-fade) pointer-coarse:h-11 [--notchset-focus-inset:-4px]",
        !first && "border-s border-solid",
        !first && (afterPrimary ? "border-foreground" : "border-[var(--notchset-rule,var(--border))]"),
        primary ? "bg-primary text-primary-foreground" : open ? "bg-[var(--notchset-field,var(--accent))] text-foreground" : "text-foreground",
        danger && !primary && "text-[color:var(--notchset-signal-text,var(--destructive))] [--notchset-focus-color:var(--notchset-signal-text,var(--destructive))]",
        armed && "!bg-[var(--notchset-signal-text,var(--destructive))] !text-primary-foreground",
      )}
    >
      {/* Press: the content moves down a pixel, mechanically. */}
      <span className="flex items-center transition-transform duration-[90ms] ease-linear group-active/key:translate-y-px">
        <span aria-hidden className="flex size-4 flex-none items-center justify-center [&_svg]:size-4">
          {action.icon}
        </span>
        <span
          aria-hidden
          className="overflow-hidden transition-[width] duration-[360ms] ease-[cubic-bezier(.65,0,.35,1)] motion-reduce:transition-none"
          style={{ width: open ? width : 0 }}
        >
          <span
            ref={inner}
            className={cn("inline-block ps-2 whitespace-nowrap transition-opacity", open ? "opacity-100 duration-[180ms] [transition-delay:120ms]" : "opacity-0 duration-[100ms]")}
          >
            <FlipText>{label}</FlipText>
          </span>
        </span>
      </span>
    </button>
  );
}

export { ActionRail };
```

### lib/beautiful-ui/notchset/instrument.tsx

```tsx
"use client";

import * as React from "react";
import { createPortal } from "react-dom";
import { cn } from "@/lib/utils";

/*
 * Notchset instrument parts, shared by every member of a pack: the node (a round light that reports
 * state), the legend printed above a control, the plate a key presses onto, the traced check, the
 * five-tick scanner, and the glyph flip that lands a changed label left to right. Nodes and checks
 * are inline SVG (round at every DPR); the CSS lives in the Notchset foundation. Also: the one motion
 * policy (reduced motion or a data-motion="off" ancestor), ref composition, the portal container
 * and the sound attributes every Notchset root carries.
 */

// ---------------------------------------------------------------------------------------------
// Motion, refs, portals, sound
// ---------------------------------------------------------------------------------------------

/**
 * Whether motion is off for an element, kept live: it follows the OS reduced-motion setting and any
 * data-motion attribute change above it, so a preference switched mid-playback stops decoration at once.
 */
export function useMotionOff(ref: React.RefObject<Element | null>) {
  const [off, setOff] = React.useState(false);
  React.useEffect(() => {
    const read = () => setOff(motionOff(ref.current));
    const r = requestAnimationFrame(read);
    const mq = window.matchMedia?.("(prefers-reduced-motion: reduce)");
    mq?.addEventListener?.("change", read);
    const mo = new MutationObserver(read);
    mo.observe(document.documentElement, { attributes: true, attributeFilter: ["data-motion"], subtree: true });
    return () => {
      cancelAnimationFrame(r);
      mq?.removeEventListener?.("change", read);
      mo.disconnect();
    };
  }, [ref]);
  return off;
}

/**
 * The microphone, or a rejection after `timeoutMs` (a prompt left open, a denied permission). A stream
 * that arrives after the timeout is stopped at once, so a late "Allow" never leaves the mic on.
 */
export function requestMic(timeoutMs = 5000): Promise<MediaStream> {
  if (typeof navigator === "undefined" || !navigator.mediaDevices?.getUserMedia) return Promise.reject(new Error("no mic"));
  const ask = navigator.mediaDevices.getUserMedia({ audio: true });
  return new Promise((resolve, reject) => {
    let late = false;
    const t = setTimeout(() => {
      late = true;
      reject(new Error("timeout"));
    }, timeoutMs);
    ask.then(
      (stream) => {
        clearTimeout(t);
        if (late) stream.getTracks().forEach((track) => track.stop());
        else resolve(stream);
      },
      (err) => {
        clearTimeout(t);
        reject(err);
      },
    );
  });
}

/** True under prefers-reduced-motion or inside a data-motion="off" scope. Checked when an effect runs. */
export function motionOff(el: Element | null | undefined) {
  if (typeof window === "undefined") return true;
  if (window.matchMedia?.("(prefers-reduced-motion: reduce)").matches) return true;
  return Boolean(el?.closest('[data-motion="off"]'));
}

function assignRef<T>(ref: React.Ref<T> | undefined, node: T | null): () => void {
  if (typeof ref === "function") {
    const cleanup = ref(node);
    return typeof cleanup === "function" ? cleanup : () => ref(null);
  }
  if (ref) (ref as React.RefObject<T | null>).current = node;
  return () => {
    if (ref) (ref as React.RefObject<T | null>).current = null;
  };
}

/**
 * Puts text on the clipboard. Resolves true once it is there and false when the browser refuses (no
 * permission, an insecure page, no clipboard API), so a "copied" state is only ever shown for a copy.
 */
export async function copyText(text: string): Promise<boolean> {
  try {
    await navigator.clipboard.writeText(text);
    return true;
  } catch {
    return false;
  }
}

/** The glide easing shared by travelling marks (selection blocks, highlights, runs). */
export const GLIDE = "cubic-bezier(.65,0,.35,1)";

/** Base UI's className may be a function of state: merges ours with it in either form. */
export const withClass =
  <S,>(base: string, className: string | ((state: S) => string | undefined) | undefined) =>
  (state: S) =>
    cn(base, typeof className === "function" ? className(state) : className);

/** Composes two refs, keeping React 19 ref cleanups. */
export function useComposedRefs<T>(a: React.Ref<T> | undefined, b: React.Ref<T> | undefined): React.RefCallback<T> {
  return React.useCallback(
    (node: T | null) => {
      const release = [assignRef(a, node), assignRef(b, node)];
      return () => release.forEach((f) => f());
    },
    [a, b],
  );
}

/**
 * Runs each step on its own animation frame, in order (the first on the next frame), and returns one
 * cancel that stops whichever frame is pending. A no-op step just waits a frame: frames(set pre, wait,
 * go) lets the browser paint the start state before the transition begins.
 */
export function frames(...steps: (() => void)[]): () => void {
  let id = 0;
  let i = 0;
  const tick = () => {
    steps[i++]?.();
    if (i < steps.length) id = requestAnimationFrame(tick);
  };
  id = requestAnimationFrame(tick);
  return () => cancelAnimationFrame(id);
}
export const wait = () => {};

let idSeq = 0;
/** A unique id for something the user creates (a milestone, a note): random where the browser can, else a counter. */
export const newId = () => (typeof crypto !== "undefined" && "randomUUID" in crypto ? crypto.randomUUID() : `id-${Date.now()}-${++idSeq}`);

/**
 * True while an input method (Japanese, Chinese, Korean…) is composing: Enter, Tab and delimiters
 * then belong to the composition, not to the component. keyCode 229 covers Safari's late flag.
 */
export function composing(e: React.KeyboardEvent | KeyboardEvent) {
  const native = "nativeEvent" in e ? e.nativeEvent : e;
  return native.isComposing || native.keyCode === 229;
}

const hotkeyOwners = new Map<string, number[]>();
let hotkeySeq = 0;
/**
 * A page-wide shortcut ("/" or "mod+k", mod being ⌘ or Ctrl) with a single owner: when several
 * components claim the same key, only the one mounted last answers, so one press never opens two.
 * A plain key is ignored while typing in a field.
 */
export function useHotkey(combo: string | undefined, run: () => void) {
  const latest = useLatest(run);
  React.useEffect(() => {
    if (!combo) return;
    const me = ++hotkeySeq;
    const stack = hotkeyOwners.get(combo) ?? [];
    stack.push(me);
    hotkeyOwners.set(combo, stack);
    const mod = combo.startsWith("mod+");
    const key = (mod ? combo.slice(4) : combo).toLowerCase();
    const onKey = (e: KeyboardEvent) => {
      if (hotkeyOwners.get(combo)?.at(-1) !== me || e.key.toLowerCase() !== key) return;
      if (mod ? !(e.metaKey || e.ctrlKey) : e.metaKey || e.ctrlKey || e.altKey) return;
      if (!mod && (e.target as HTMLElement | null)?.closest("input, textarea, select, [contenteditable=true]")) return;
      e.preventDefault();
      latest.current();
    };
    window.addEventListener("keydown", onKey);
    return () => {
      window.removeEventListener("keydown", onKey);
      const s = hotkeyOwners.get(combo) ?? [];
      s.splice(s.indexOf(me), 1);
    };
  }, [combo, latest]);
}

/** Keeps the latest value in a ref, for callbacks read inside timers and animation frames. */
export function useLatest<T>(value: T) {
  const ref = React.useRef(value);
  React.useLayoutEffect(() => {
    ref.current = value;
  });
  return ref;
}

/*
 * Where Notchset overlays (menus, popovers, tooltips) portal to. Unset, document.body, as shadcn's
 * do. Provide an element to keep them inside a scoped theme: a preview, a widget, a shadow root.
 */
export const NotchsetPortalContext = React.createContext<HTMLElement | null>(null);
export function useNotchsetPortal(): HTMLElement | undefined {
  return React.useContext(NotchsetPortalContext) ?? undefined;
}

const subscribeNothing = () => () => {};

/**
 * A scope that turns motion or sound off for everything inside it, popups included. A plain
 * data-motion="off" wrapper can't reach a menu that portals to the body; this one also gives its
 * overlays a portal host carrying the same preferences (inside any outer scope's host), so motionOff
 * and the cues see them there too.
 */
export function NotchsetScope({ motion, sound, children, ...props }: React.ComponentProps<"div"> & { motion?: "off"; sound?: "off" }) {
  const outer = React.useContext(NotchsetPortalContext);
  const [host, setHost] = React.useState<HTMLElement | null>(null);
  const client = React.useSyncExternalStore(subscribeNothing, () => true, () => false);
  return (
    <div data-motion={motion} data-sound={sound} {...props}>
      <NotchsetPortalContext value={host ?? outer}>{children}</NotchsetPortalContext>
      {client && createPortal(<div ref={setHost} data-slot="notchset-scope-host" data-motion={motion} data-sound={sound} />, outer ?? document.body)}
    </div>
  );
}

export { NOTCHSET_ROOT, OWN_SOUND } from "@/lib/beautiful-ui/notchset/root";

// ---------------------------------------------------------------------------------------------
// Parts
// ---------------------------------------------------------------------------------------------

export type NodeState = "off" | "on" | "live" | "signal";

/** The node: a 9×9 ring whose dot blooms on (`on`), blinks (`live`) or turns signal. */
function Node({ state = "off", delay, className, style, ...props }: Omit<React.ComponentProps<"svg">, "children"> & { state?: NodeState; delay?: number }) {
  return (
    <svg
      aria-hidden
      data-slot="indicator"
      data-state={state}
      width="9"
      height="9"
      viewBox="0 0 9 9"
      className={cn(`notchset-node`, className)}
      style={delay ? ({ "--notchset-node-delay": `${delay}ms`, ...style } as React.CSSProperties) : style}
      {...props}
    >
      <circle data-slot="indicator-ring" cx="4.5" cy="4.5" r="3.25" fill="none" strokeWidth="1" />
      <circle data-slot="indicator-dot" cx="4.5" cy="4.5" />
    </svg>
  );
}

/** A small solid round mark (the node where a leader meets a popup, a pointer): SVG, round at every DPR. */
function Dot({ size = 7, className, style }: { size?: number; className?: string; style?: React.CSSProperties }) {
  return (
    <svg aria-hidden width={size} height={size} viewBox={`0 0 ${size} ${size}`} className={cn("pointer-events-none absolute overflow-visible", className)} style={style}>
      <circle cx={size / 2} cy={size / 2} r={size / 2} fill="currentColor" />
    </svg>
  );
}

/** The legend: a mono label above a control, with an optional node (or any trailing reading). */
function Legend({ label, node, children, className, ...props }: React.ComponentProps<"div"> & { label?: React.ReactNode; node?: NodeState }) {
  return (
    <div data-slot="legend" className={cn(`notchset-legend`, className)} {...props}>
      <span data-slot="legend-label">{label}</span>
      {(children != null || node) && (
        <span data-slot="legend-reading" className="flex items-center gap-2">
          {children}
          {node && <Node state={node} />}
        </span>
      )}
    </div>
  );
}

/** A key on its plate: the plate is an offset frame behind the child; `--notchset-plate-color` tints it. */
function Plated({ className, children, ...props }: React.ComponentProps<"span">) {
  return (
    <span data-slot="plated" className={cn("relative inline-flex", className)} {...props}>
      <span aria-hidden data-slot="plate" className={`notchset-plate`} />
      {children}
    </span>
  );
}

/**
 * The success check. Mounted, it traces itself in over --notchset-check (instant under reduced
 * motion); pass `drawn` to drive the trace yourself.
 */
function Check({ drawn, size = 16 }: { drawn?: boolean; size?: number }) {
  return (
    <svg aria-hidden data-slot="check" width={size} height={size} viewBox="0 0 24 24">
      <path
        d="M4 12.5 L9.5 18 L20 6"
        fill="none"
        stroke="currentColor"
        strokeWidth={1.75}
        strokeLinecap="square"
        pathLength={1}
        strokeDasharray={1}
        className={drawn === undefined ? `notchset-check-draw` : undefined}
        style={drawn === undefined ? undefined : { strokeDashoffset: drawn ? 0 : 1, transition: "stroke-dashoffset var(--notchset-check) var(--notchset-ease-travel)" }}
      />
    </svg>
  );
}

/** The scanner: five 1px ticks fading in turn while something works (static, centre lit, when motion is off). */
function Scanner({ height = 12 }: { height?: number }) {
  return (
    <span aria-hidden data-slot="scanner" className={cn(`notchset-scanner`, "inline-flex items-end gap-[2px]")} style={{ height }}>
      {[0.82, 0.66, 1, 0.66, 0.82].map((h, i) => (
        <span key={i} className="w-px bg-current" style={{ height: height * h, animationDelay: `${i * 140 - 700}ms` }} />
      ))}
    </span>
  );
}

// ---------------------------------------------------------------------------------------------
// Glyph flip: each character cycles through glyphs and lands at 110 + i·14ms, left to right
// ---------------------------------------------------------------------------------------------

const GLYPHS = "ABCDEFGHJKLMNPRSTUVWXYZ0123456789#/+=";
const STILL = new Set([" ", "·", "/", ".", ":"]);
const FLIP_CHARS = 24;

export function scramble(text: string, elapsed: number) {
  let out = "";
  for (let i = 0; i < text.length; i++) {
    const ch = text[i]!;
    // Characters past the 24th land with the 24th, so a long label flips as briefly as a short one.
    out += STILL.has(ch) || elapsed >= 110 + Math.min(i, FLIP_CHARS) * 14 ? ch : GLYPHS[(Math.floor(elapsed / 36) * 5 + i * 11) % GLYPHS.length];
  }
  return out;
}

/**
 * The text to show for `text`: when it changes, a few frames of glyphs that land left to right.
 * Runs on requestAnimationFrame only while a flip is active; the settled text is never state. Off
 * under reduced motion, inside data-motion="off" (pass the element) or with `off`.
 */
export function useGlyphFlip(text: string, { off = false, el }: { off?: boolean; el?: React.RefObject<Element | null> } = {}) {
  const [frame, setFrame] = React.useState<{ for: string; shown: string } | null>(null);
  const first = React.useRef(true);
  React.useEffect(() => {
    if (first.current) {
      first.current = false;
      return;
    }
    if (off || motionOff(el?.current)) return;
    let raf = 0;
    const t0 = performance.now();
    const end = 110 + Math.min(text.length, FLIP_CHARS) * 14 + 40;
    const step = (now: number) => {
      const elapsed = now - t0;
      if (elapsed >= end) {
        setFrame(null);
        return;
      }
      setFrame({ for: text, shown: scramble(text, elapsed) });
      raf = requestAnimationFrame(step);
    };
    raf = requestAnimationFrame(step);
    return () => cancelAnimationFrame(raf);
  }, [text, off, el]);
  // Turned off mid-flip, the label shows its text at once (the cancelled frame never lingers).
  return !off && frame && frame.for === text ? frame.shown : text;
}

/** A label that flips when its text changes; screen readers read the final text only. */
function FlipText({ children, off, className, ref: refProp, ...props }: Omit<React.ComponentProps<"span">, "children"> & { children: string; off?: boolean }) {
  const ref = React.useRef<HTMLSpanElement>(null);
  const refs = useComposedRefs<HTMLSpanElement>(refProp, ref);
  const shown = useGlyphFlip(children, { off, el: ref });
  return (
    <span {...props} ref={refs} data-slot="flip-text" className={cn("relative whitespace-nowrap", className)}>
      <span aria-hidden>{shown}</span>
      <span className="sr-only">{children}</span>
    </span>
  );
}

// ---------------------------------------------------------------------------------------------
// Sound: Notchset components announce cues; the page's beautiful-ui-sound layer (opt-in) plays them.
// ---------------------------------------------------------------------------------------------

/** The Notchset cues, in the shared sound layer's names (played in the mechanical voice). */
export const NOTCHSET_CUES = { tap: "tap", latch: "lock", signal: "destructive", confirm: "halt", done: "success", tick: "tick" } as const;
export type NotchsetCue = keyof typeof NOTCHSET_CUES;

export function playCue(el: Element | null, cue: NotchsetCue) {
  if (!el || typeof CustomEvent === "undefined" || el.closest('[data-sound="off"]')) return;
  el.dispatchEvent(new CustomEvent("beautiful-ui:sound", { bubbles: true, detail: { cue: NOTCHSET_CUES[cue] } }));
}

// ---------------------------------------------------------------------------------------------
// Shortcuts: "⌘↵" → "Meta+Enter Control+Enter" (aria-keyshortcuts)
// ---------------------------------------------------------------------------------------------

const KEY_NAMES: Record<string, string> = { "⌘": "Meta", "⌃": "Control", "⌥": "Alt", "⇧": "Shift", "↵": "Enter", "⏎": "Enter", "⎋": "Escape", "⌫": "Backspace", "⇥": "Tab", "␣": "Space" };

export function kbdToShortcut(kbd: string | undefined): string | undefined {
  if (!kbd) return undefined;
  const parts = [...kbd.replace(/\s+/g, "")].map((c) => KEY_NAMES[c] ?? c.toUpperCase());
  if (!parts.length) return undefined;
  const combo = parts.join("+");
  // ⌘ on a Mac is Ctrl elsewhere: announce both.
  return combo.includes("Meta") ? `${combo} ${combo.replace("Meta", "Control")}` : combo;
}

/**
 * Digits that roll: each digit is a 0–9 strip; the ones digit moves first and each digit to its left
 * 40ms later, counting digits only (620ms, a small overshoot). `delay` offsets the whole text. Other
 * characters (",", "$", "%", letters) sit still. Screen readers get the plain text. The one
 * implementation behind RollingNumber and the calendar's RollingLabel.
 */
export function DigitRoll({ text, height, delay = 0, className }: { text: string; height: number; delay?: number; className?: string }) {
  const chars = [...text];
  let k = 0;
  const order = chars.map((_, i) => (/\d/.test(chars[chars.length - 1 - i]!) ? k++ : 0)).reverse();
  return (
    <span className={cn("relative inline-flex flex-none overflow-hidden tabular-nums", className)} style={{ height, lineHeight: `${height}px` }}>
      <span className="sr-only">{text}</span>
      <span aria-hidden className="flex">
        {chars.map((d, i) =>
          /\d/.test(d) ? (
            <span
              key={chars.length - i}
              className="flex flex-col transition-transform duration-[620ms] ease-[cubic-bezier(.34,1.15,.5,1)] motion-reduce:transition-none"
              style={{ transform: `translateY(${-Number(d) * height}px)`, transitionDelay: `${delay + order[i]! * 40}ms` }}
            >
              {Array.from({ length: 10 }, (_, n) => (
                <span key={n} style={{ height }}>
                  {n}
                </span>
              ))}
            </span>
          ) : (
            <span key={`s${chars.length - i}`}>{d}</span>
          ),
        )}
      </span>
    </span>
  );
}

/** A number that rolls (DigitRoll at the readout's own size). `delay` offsets it (rows 60ms apart). */
function RollingNumber({ value, height = 32, delay = 0, className }: { value: string | number; height?: number; delay?: number; className?: string }) {
  return <DigitRoll text={String(value)} height={height} delay={delay} {...(className ? { className } : {})} />;
}

export { Check, Dot, FlipText, Legend, Node, Plated, RollingNumber, Scanner };
```

### lib/beautiful-ui/notchset/root.ts

```tsx
/*
 * Notchset's root attributes, server-safe (no client directive), so server components can spread
 * them too. Every Notchset root (and portalled popup) carries data-notchset (the motion policy's
 * scope), plays its own cues in the mechanical voice, and keeps the page's click layer out.
 */
export const NOTCHSET_ROOT = { "data-notchset": "", "data-sound": "none", "data-sound-voice": "analogue" } as const;

/** On every interactive element: it plays its own cues, so the page's click layer adds no tap. */
export const OWN_SOUND = { "data-sound": "none" } as const;
```

The notchset foundation (the tokens listed above, keyframes and motion levels) installs once with the first component; its CSS is public at https://beautiful-ui.dev/r/notchset-foundation.json.
