# Split Button (Notchset): prompt.md (v1.0.0)

- id: `split-button` · version 1.0.0 · component · pro (Pro)
- category: Actions
- build: Base UI (this item also ships a Radix build)
- install (this build): `npx shadcn@latest add @beautiful-ui-pro/split-button`
- npm dependencies: @base-ui/react@^1
- registry dependencies: utils, https://beautiful-ui.dev/r/notchset-foundation.json
- docs: https://beautiful-ui.dev/components/split-button
- The install command carries everything this item needs (files, CSS, tokens, npm and registry dependencies). Prefer it to copying source by hand.

A main key whose label always names the current target, a trigger that unfolds a menu of targets under a leader line, and a detent strip under the key that always shows the target, its node stretching as it travels.

## Build it
- Stack: React 19 (`ref` is a plain prop), TypeScript, Tailwind CSS v4 utilities, a shadcn-initialised project with the `@/*` alias.
- Packages: `@base-ui/react@^1` (Base UI build); `radix-ui@^1` (Radix build).
- Files: `components/ui/notchset/split-button.tsx`; shared code: `lib/beautiful-ui/notchset/split-button.tsx`, `lib/beautiful-ui/notchset/instrument.tsx`, `lib/beautiful-ui/notchset/root.ts`.
- Registry dependencies, installed with it automatically: shadcn `utils` (cn), `notchset-foundation`.
- Builds: separate Base UI and Radix files. 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: `SplitButton`, 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-travel`, `--notchset-fade`, `--notchset-focus-color`, `--notchset-focus-inset`, `--notchset-life-from`, `--notchset-life-ms`, `--notchset-node-blink`, `--notchset-node-bloom`, `--notchset-node-delay`, `--notchset-plate-color`, `--notchset-rise-from`, `--notchset-rule`, `--notchset-scroll`, `--notchset-signal`, `--notchset-sweep-to`). Never add Tailwind colour classes inside the component.

```tsx
import { SplitButton } from "@/components/ui/notchset/split-button";
```

## Parts

| Part | data-slot | What it is for |
|---|---|---|
| `SplitButton` | `split-button` | The legend, keys, menu and detent. |
| `Main` | `split-button-main` | The main key. |
| `Trigger` | `split-button-trigger` | Opens the menu. |
| `Detent` | `split-button-detent` | The target strip under the key. |

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/split-button.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
- split button, deploy to, action with options, target picker, dropdown button, Notchset
- One main action with a choice of target: deploy to production, canary or staging

### Not when
- Unrelated actions: use a Dropdown Menu

## Mistakes
- Give each option a short name for the key and the detent

## Usage

```tsx
"use client";

import { SplitButton } from "@/components/ui/notchset/split-button";

export function DeployButton({ deploy }: { deploy: (target: string) => Promise<void> }) {
  return (
    <SplitButton
      options={[
        { value: "production", label: "Production", meta: "100% traffic", short: "PROD" },
        { value: "canary", label: "Canary", meta: "5% traffic", short: "CANARY" },
      ]}
      onPress={deploy}
    />
  );
}
```

## Props

| Prop | Type | Default | What it does |
|---|---|---|---|
| `options` | `{ value, label, meta?, short? }[]` |  | The targets. |
| `value / defaultValue / onValueChange` | `string / (value) => void` |  | The current target. |
| `onPress` | `(value) => unknown` |  | The main key. Return a Promise and it shows busy, then done. |
| `detent` | `boolean` |  | The detent strip under the key. Default true. |
| `menuHeader` | `[ReactNode, ReactNode]` |  | A line at the top of the menu. |
| `legend` | `string` |  | The legend above the key. |
| `labels` | `Partial<SplitButtonLabels>` |  | Every word, for other languages. |

Full docs: https://beautiful-ui.dev/components/split-button

## 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 |
|---|---|
| Alt+↓ | Open the menu on the current target |
| ↑ ↓ | Move in the menu |
| ← → | Move the detent |
| Esc | Close the menu |

## Performance

- The detent node is one SVG element moved with left; the menu mounts only while open.
- Holding the main key runs one requestAnimationFrame loop only while pressed.

## Responsive

- The menu keeps 8px inside the viewport and flips above when there is no room below.
- Both halves grow to 44px on touch screens.

## Motion inventory

| Interaction | What moves |
|---|---|
| Open | The leader drops (scaleY, 120ms); the menu unfolds (grid rows 380ms, 100ms delay); rows settle in 50ms apart |
| Detent | The node travels 300ms, stretching to 22px and snapping back |
| Press | DEPLOYING with the scanner, then LIVE ON … with the check |

## Accessibility contract (preserve when editing)
- The menu is the Base UI or Radix menu with radio items; the detent is a radiogroup
- The main key's label always names the target
- Esc closes the menu and returns focus to the trigger

## Install

```bash
npx shadcn@latest add @beautiful-ui-pro/split-button
```

Pro item: needs the `@beautiful-ui-pro` registry in `components.json` and `BEAUTIFUL_UI_TOKEN` in `.env.local` (https://beautiful-ui.dev/account). Setup: https://beautiful-ui.dev/docs/pro. Your components.json `style` picks the build: radix-*, new-york and default get Radix, base-* gets Base UI.

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

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.