# Metric Header (Lumen Halo): prompt.md (v1.0.0)

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

The row above a chart: each metric shows its value on rolling digits, the change against a named period in its good or bad tone, an optional target meter and uncertainty band, and choosing one lights a filament and switches the chart.

## 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/lumen/controls/metric-header.tsx`.
- Registry dependencies, installed with it automatically: shadcn `utils` (cn), `lumen-stat`, `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: `MetricHeader`, `MetricHeaderItem`, 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-mono`, `--lumen-font-sans`, `--lumen-radius-k`. Never add Tailwind colour classes inside the component.

```tsx
import { MetricHeader, MetricHeaderItem } from "@/components/ui/lumen/controls/metric-header";
```

## Parts

| Part | data-slot | What it is for |
|---|---|---|
| `MetricHeader` | — | The row, its selection and keyboard. |
| `MetricHeaderItem` | — | One metric: value, change, target, band, spark. |

## 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/metric-header.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
- metric header, KPI tabs, comparison header, metric switcher, dashboard header, period comparison, target progress, Lumen
- A chart that can show one of several metrics, with each metric's headline and change always visible

### Not when
- A standalone KPI grid with no chart to drive: use Stat
- Switching views of different kinds: use Tabs

## Mistakes
- Name the comparison period; a bare +10% leaves people guessing
- Set goodDirection="down" for metrics where less is better

## Usage

```tsx
import { MetricHeader, MetricHeaderItem } from "@/components/ui/lumen/controls/metric-header";

<MetricHeader value={metric} onValueChange={setMetric} comparison="vs previous 30 days" controls="trend">
  <MetricHeaderItem value="revenue" label="Revenue" current={482300} previous={436100} format={{ style: "currency" }} target={500000} />
  <MetricHeaderItem value="churn" label="Churn" current={0.021} previous={0.024} format={{ style: "percent" }} goodDirection="down" />
</MetricHeader>
<div id="trend">{/* the chart for the chosen metric */}</div>
```

## Props

| Prop | Type | Default | What it does |
|---|---|---|---|
| `value / defaultValue / onValueChange` | `string` |  | The chosen metric. Uncontrolled starts at the first item. |
| `comparison` | `ReactNode` |  | The comparison period, named once for every metric, e.g. "vs previous 30 days". |
| `controls` | `string` |  | The id of the chart or panel the chosen metric drives (aria-controls). |
| `motion` | `"full" \| "subtle" \| "off"` | `"full"` | Reduced motion always wins. |
| `MetricHeaderItem current / previous` | `number \| null` |  | The value and the comparison period's value; the change and its tone are worked out. |
| `MetricHeaderItem format` | `StatFormat` |  | Number, currency, percent, unit or duration, with locale. |
| `MetricHeaderItem goodDirection` | `"up" \| "down"` | `"up"` | "down" for churn, latency, cost: a fall reads good. |
| `MetricHeaderItem target` | `number` |  | Draws a meter of ten cells and says how far along it is. |
| `MetricHeaderItem interval` | `[number, number]` |  | The low–high band when the value is an estimate; shown as ±, read as a range. |
| `MetricHeaderItem spark` | `number[]` |  | Recent values, oldest first. |

Full docs: https://beautiful-ui.dev/components/lumen-metric-header

## Customising
- Motion: `motion="full"` (default) | `"subtle"` | `"off"`. prefers-reduced-motion is always respected.
- 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 to the previous or next metric and show it |
| Home / End | First or last metric |
| Enter / Space | Show the focused metric |

## Motion inventory

| Interaction | What moves |
|---|---|
| Choose a metric | A filament ignites along its edge from the centre |
| Values change | Digits roll like an odometer; the target meter's cells light in order |

## Accessibility contract (preserve when editing)
- A tablist; each metric is a tab with its value, change and target in its name
- The change is read in words ("Up, on track"), not only colour
- An estimate's band is read as a range
- aria-controls points at the chart it drives

## Install

```bash
npx shadcn@latest add @beautiful-ui-pro/lumen-metric-header
```

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 conventions (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.