# `<ButtonMomentary>`

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## Purpose

`<ButtonMomentary>` is the press-and-hold trigger control. Pressing it
emits `max` into `onChange`; releasing it emits `min`. The release also
fires when the pointer leaves the button while still pressed, so a user
who drags off the button mid-hold doesn't get stuck in the held state.
Keyboard interaction follows the same edge model: Space / Enter down
emit max, the corresponding up emits min, and `event.repeat` is
suppressed so OS auto-repeat doesn't generate a stream of duplicate
"down" events.

The pressed state is tracked locally in `useState` so the visual chrome
updates synchronously with the user input. The schema's numeric value is
informational; the rendered chrome follows the user's gesture rather
than waiting for a round-trip through the binding registry.

## Features

- Press-down / release edge dispatch.
- Pointer-leave releases stuck holds.
- Keyboard activation via Space and Enter with `event.repeat`
  suppression.
- WAI-ARIA `aria-pressed` reflection.
- Telemetry: `control_surface_interactions_total{kind="button-momentary"}`
  on every press.
- `disabled` blocks both pointer and keyboard activation.

## Usage: Basic

```tsx
<ButtonMomentary
    value={triggered ? 1 : 0}
    onChange={(v) => setTriggered(v === 1)}
    min={0}
    max={1}
    label="Trigger"
/>
```

## Usage: Advanced

```tsx
<ButtonMomentary
    value={state}
    onChange={(v) => {
        registry.dispatch(binding, v);
        if (v === 1) sampler.trigger();
    }}
    min={0}
    max={1}
    label="One-shot"
    ariaLabel="Trigger one-shot sample (Space to hold)"
/>
```

## API Reference

- `<ButtonMomentary>` props: `BoundControlProps & { className?, style? }`.

## Implementation Notes

The local `pressed` state guards against double-press without an
intervening release — a second pointer-down with no release is dropped.
This is essential under touch input where rapid taps can interleave. The
pointer-leave handler only fires release when the button is currently
pressed; a stray leave with no prior press is a no-op. Disabled state
short-circuits before the state mutation so a disabled component never
contributes to the press counter.