# `dmx` handler

## Purpose

The `dmx` handler is the binding-registry slot reserved for DMX universe /
channel updates. The `@suaveplan/react-dmx` integration has not yet shipped,
so this default throws `REACT_CONTROL_SURFACE.BINDING_HANDLER_MISSING`
unconditionally. When the DMX integration lands the production handler will
replace this default with a closure that writes the scaled value into the
named universe/channel via the DMX transport.

Throwing here is doubly important: stage-lighting bindings tend to be
load-bearing in live performance, and a silent drop of a DMX update can
plunge a stage into darkness mid-cue. Failing loud at the default ensures
operators see the gap before they take the surface live.

## Features

- Strongly-typed signature `(binding: DmxBinding, value: number) => never`.
- Error context preserves `universe`, `channel`, and the dropped `value`.
- Default behaviour matches the other unwired handlers for uniform
  error-handling at the call site.

## Usage: Basic

```ts
import { BindingRegistry } from "@suaveplan/react-control-surface/runtime/binding-registry";

const registry = new BindingRegistry({
    dmx: (binding, value) =>
        dmxTransport.send(binding.universe, binding.channel, value),
});
```

## Usage: Advanced

```ts
import { dmxHandler } from "@suaveplan/react-control-surface/runtime/binding-registry";

expect(() =>
    dmxHandler({ kind: "dmx", universe: 1, channel: 33 }, 0.75)
).toThrow(/BINDING_HANDLER_MISSING/);
```

## API Reference

- `dmxHandler(binding: DmxBinding, value: number): never`
  — always throws with code `REACT_CONTROL_SURFACE.BINDING_HANDLER_MISSING`.

## Implementation Notes

DMX traffic must be ordered and rate-limited; the production handler will
need to coalesce rapid drag-driven updates. None of that is the default's
problem — the default's only job is to refuse to silently drop traffic.