# Mention Composer (Notchset): prompt.md (v1.0.0)

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

A ledger thread with inline mentions that never shift the line, and a composer whose typed mentions wash in place, with an @ and # popover anchored at the caret.

## 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/mention-composer.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: `MentionComposer`, `MentionEntry`, `MentionText`, `MentionThread`, 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 { MentionComposer, MentionThread, type MentionEntryData, type MentionPerson, type MentionRef } from "@/components/ui/notchset/mention-composer";
```

## Parts

| Part | data-slot | What it is for |
|---|---|---|
| `MentionComposer` | `mention-composer` | The composer. |
| `MentionThread` | `mention-thread` | The ledger. |
| `MentionEntry` | `mention-entry` | One entry. |

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/mention-composer.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
- mention, @mention, comments, thread, reply box, composer, link a run, Notchset
- Comment threads on runs, evals and incidents, where people and records get linked

### Not when
- Chat with an assistant: use the AI chat components

## Mistakes
- Keep names unique: mentions are matched by their text

## Usage

```tsx
"use client";

import * as React from "react";
import { MentionComposer, MentionThread, type MentionEntryData, type MentionPerson, type MentionRef } from "@/components/ui/notchset/mention-composer";

const people: MentionPerson[] = [
  { name: "Maya Kerr", initials: "MK", role: "ML LEAD", presence: "online" },
  { name: "Jonas Weber", initials: "JW", role: "EVALS", presence: "away" },
];
const runs: MentionRef[] = [{ id: "run_8f3a1", meta: "PLANNER · 2.1S", kind: "ok" }];

export function RunDiscussion() {
  const [entries, setEntries] = React.useState<MentionEntryData[]>([{ id: 1, at: "09:38", initials: "MK", author: "Maya Kerr", text: "#run_8f3a1 looks right. @Jonas Weber can you check citations?" }]);
  return (
    <div className="grid gap-3">
      <MentionThread entries={entries} people={people} refs={runs} />
      <MentionComposer
        people={people}
        refs={runs}
        me={{ initials: "JW" }}
        onPost={(text) => setEntries((e) => [...e, { id: e.length + 1, at: new Date().toTimeString().slice(0, 5), initials: "JW", author: "Jonas Weber", me: true, text }])}
      />
    </div>
  );
}
```

## Props

| Prop | Type | Default | What it does |
|---|---|---|---|
| `MentionComposer` | `{ people, refs, me, onPost, placeholder }` |  | The composer. |
| `MentionThread` | `{ entries, people, refs, fresh }` |  | The ledger. |
| `MentionText` | `{ text, people, refs }` |  | A body with mentions drawn inline. |

Full docs: https://beautiful-ui.dev/components/mention-composer

## 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 |
|---|---|
| @ / # | Open the popover |
| ↑ / ↓ | Move |
| Enter / Tab | Insert |
| Enter | Post |
| Shift+Enter | New line |

## Performance

- Segmenting is one regex over the text; mirrors are plain DOM.

## Responsive

- Fills its container; the 56px left column holds on phones, the hint hides.

## Motion inventory

| Interaction | What moves |
|---|---|
| Popover | Unrolls upward (320ms) from the caret, a dot on its edge |
| Post | The new entry settles up 10px (420ms) |

## Accessibility contract (preserve when editing)
- The thread is a polite log; the reply is a labelled textarea
- The popover is a listbox; Esc dismisses it until the trigger changes

## Install

```bash
npx shadcn@latest add @beautiful-ui-pro/mention-composer
```

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.