# Split View (Lumen Halo): prompt.md (v1.0.0)

- id: `lumen-split-view` · version 1.0.0 · component · pro (All-Access)
- category: Layout
- build: Base UI (one set of files; its dependencies follow the build)
- install (this build): `npx shadcn@latest add @beautiful-ui-pro/lumen-split-view`
- npm dependencies: react-resizable-panels@^4
- registry dependencies: utils, @beautiful-ui-pro/lumen-resizable, @beautiful-ui-pro/lumen-sheet, https://beautiful-ui.dev/r/lumen-foundation.json
- docs: https://beautiful-ui.dev/components/lumen-split-view
- The install command carries everything this item needs (files, CSS, tokens, npm and registry dependencies). Prefer it to copying source by hand.

Two panes side by side (list and detail, table and chart, stream and investigation) split by a Lumen divider you can drag or move with the arrows. It remembers the split, and when its own width is narrow the second pane becomes a full-screen drawer.

## Build it
- Stack: React 19 (`ref` is a plain prop), TypeScript, Tailwind CSS v4 utilities, a shadcn-initialised project with the `@/*` alias.
- Packages: `react-resizable-panels@^4`.
- Files: `components/ui/lumen/controls/split-view.tsx`.
- Registry dependencies, installed with it automatically: shadcn `utils` (cn), `lumen-resizable`, `lumen-sheet`, `lumen-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: `SplitView`, and every exported type.
- CSS: the install merges this item's rules (the registry `css` field) into your global stylesheet, in `@layer components`, and adds the lumen foundation (tokens, keyframes, motion levels) 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 `--lumen-*` custom properties (`--lumen-accent`, `--lumen-accent-text`, `--lumen-bad`, `--lumen-bad-text`, `--lumen-focus`, `--lumen-good`, `--lumen-good-text`, `--lumen-hairline`, `--lumen-ink`, `--lumen-muted-ink`, `--lumen-series-1`, `--lumen-series-2`, `--lumen-series-3`, `--lumen-series-4`, `--lumen-series-5`, `--lumen-series-6`, `--lumen-warn`, `--lumen-warn-text`); this item's CSS also reads `--lumen-font-sans`. Never add Tailwind colour classes inside the component.

```tsx
import { SplitView } from "@/components/ui/lumen/controls/split-view";
```

## Parts

| Part | data-slot | What it is for |
|---|---|---|
| `SplitView` | — | Both panes, the divider and the narrow-screen drawer. |

## 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 `GlassSoundProvider` once (install: `npx shadcn@latest add https://beautiful-ui.dev/r/glass-sound.json`, import from `@/components/beautiful-ui/glass-sound`); `GlassSoundToggle` is its mute control. Without a provider the audio engine never loads.

## Match the original
- Read `components/ui/lumen/controls/split-view.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 view, master detail, list detail, two pane layout, resizable panes, inspector, table and chart, Lumen
- A list whose picked item is read beside it
- A table with its chart, or a chart with its explanation, where both matter at once

### Not when
- One record over a list that should stay full width: use Detail Drawer
- Fixed page columns: use CSS grid

## Mistakes
- Give the Split View a height (it fills its parent)
- Pass secondaryKey, so a phone opens the drawer when someone picks, not on load

## Usage

```tsx
import { SplitView } from "@/components/ui/lumen/controls/split-view";

<SplitView
  primary={<AccountList onPick={setId} />}
  secondary={id && <AccountDetail id={id} />}
  secondaryTitle="Account"
  open={id != null}
  secondaryKey={id}
  onOpenChange={(o) => !o && setId(null)}
  storageKey="accounts-split"
/>
```

## Props

| Prop | Type | Default | What it does |
|---|---|---|---|
| `primary / secondary` | `ReactNode` |  | The two panes. A null secondary shows the main pane alone. |
| `secondaryTitle` | `ReactNode` |  | Names the second pane: its region label, and the drawer's title on narrow screens. |
| `open / onOpenChange` | `boolean` | `true` | Whether the second pane shows; on narrow screens this is the drawer. |
| `secondaryKey` | `string \| number` |  | What the second pane shows. On narrow screens a new value opens the drawer; it never opens on load. |
| `orientation` | `"horizontal" \| "vertical"` | `"horizontal"` | Vertical splits (table over chart) stay stacked on narrow screens. |
| `defaultSize / minSize / primaryMinSize` | `number (percent)` | `40 / 25 / 30` | The second pane's starting and smallest share, and the main pane's smallest. |
| `breakpoint` | `number (px)` | `720` | Below this width of the Split View itself, a horizontal split becomes a drawer. |
| `storageKey` | `string` |  | Remember the split in localStorage under this key. |

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

## Customising
- Colours: set the `--lumen-*` tokens on `:root`, or on a container with the `lumen-scope` class to retheme one area. Add the `lumen-inherit` class to follow your shadcn palette instead (`--chart-N`, `--destructive`).
- 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 |
|---|---|
| ← / → | Move the focused divider (↑ / ↓ when vertical) |
| Enter | Collapse or restore the focused divider |
| Escape | Close the drawer on narrow screens |

## Motion inventory

| Interaction | What moves |
|---|---|
| Drag the divider | The hairline lights into a filament and glows while held |
| Narrow screens | The second pane slides in as a drawer |

## Accessibility contract (preserve when editing)
- The second pane is a region named by secondaryTitle
- The divider is a focusable separator with its value
- On narrow screens the drawer is a modal dialog titled by secondaryTitle

## Install

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

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
- react-resizable-panels (https://github.com/bvaughn/react-resizable-panels)
- Built on shadcn/ui (https://ui.shadcn.com)

The lumen 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/lumen-foundation.json.