# OpenSpec Change: enterprise-dmx

- **Change ID**: enterprise-dmx
- **Package**: `@suaveplan/dmx`
- **Category**: universal
- **Target path**: `universal/media/dmx`
- **Status**: PROPOSED
- **Date**: 2026-04-24
- **Reference spec**: `/mnt/s/web/suaveplan/enterprise/dmx.md`

---

## Summary

Deliver `@suaveplan/dmx` on the genesis branch from scratch at enterprise quality. The package is a DMX512 lighting control engine: universe management (512 channels per universe), fixture definition and addressing, scene/chase/cue building, fade interpolation with injectable clock, transport-agnostic output (serial, WebSocket, UDP/Art-Net), and a chase sequencer with BPM clock sync. Pure TypeScript with no platform hard deps — transport is an injectable adapter.

---

## Current-state audit (genesis)

The package does not exist on genesis yet — this is a fresh build. No prior source, no test results, no coverage data. The main-branch package had 99.28% coverage.

---

## Available workspace deps on genesis

| Package | Role |
|---|---|
| `@suaveplan/error` (`workspace:^`) | Base class for `DmxError`; `DMX.*` codes |
| `@suaveplan/types` (`workspace:^`) | `LoggerLike`, `Clock` injectable clock |
| `@suaveplan/events` (`workspace:^`) | Event bus for universe-update notifications |
| `zod` (`catalog:forms`) | Zod schemas for all public option types |
| `@opentelemetry/api` (`catalog:observability`) | Spans + counters |

Dev deps: `vitest`, `@vitest/coverage-istanbul`, `fast-check`, `mitata` (all `catalog:testing`).

---

## Public API

### Core types

```ts
class DmxError extends SuaveplanError

const DMX_UNIVERSE_SIZE = 512
const DMX_MIN_VALUE = 0
const DMX_MAX_VALUE = 255

type DmxChannel = number          // 1–512
type DmxValue   = number          // 0–255
type DmxUniverse = Uint8Array     // length 512

interface FixtureDefinition {
  name: string
  channelCount: number
  channels: FixtureChannel[]
}

interface FixtureChannel {
  offset: number          // 0-based offset within fixture
  name: string
  defaultValue?: DmxValue
}

interface FixtureInstance {
  id: string
  definition: FixtureDefinition
  startChannel: DmxChannel
  universeId: string
}

interface Scene {
  id: string
  values: Map<string, DmxValue>   // fixtureId:channelName → value
}

interface FadeOptions {
  durationMs: number
  easing?: 'linear' | 'ease-in' | 'ease-out' | 'ease-in-out'
}

interface DmxTransport {
  send(universe: DmxUniverse, universeId: string): Promise<void>
  connect?(): Promise<void>
  disconnect?(): Promise<void>
}

interface DmxEngineOptions {
  transport: DmxTransport
  clock?: Clock
  logger?: LoggerLike
  refreshRateHz?: number    // default: 40 (25ms frame)
}

class DmxEngine {
  constructor(options: DmxEngineOptions)
  addUniverse(id: string): void
  removeUniverse(id: string): void
  addFixture(instance: FixtureInstance): void
  removeFixture(id: string): void
  setChannel(universeId: string, channel: DmxChannel, value: DmxValue): void
  getChannel(universeId: string, channel: DmxChannel): DmxValue
  getUniverse(id: string): Readonly<DmxUniverse>
  applyScene(scene: Scene, fade?: FadeOptions): Promise<void>
  blackout(universeId?: string): void
  start(): void
  stop(): void
}

function createDmxEngine(options: DmxEngineOptions): DmxEngine
function buildScene(id: string, values: Record<string, DmxValue>): Scene
function interpolate(from: DmxValue, to: DmxValue, t: number): DmxValue
```

### Chase sequencer

```ts
interface CueStep {
  scene: Scene
  holdMs: number
  fade?: FadeOptions
}

class ChaseSequencer {
  constructor(engine: DmxEngine, clock: Clock)
  addStep(step: CueStep): void
  start(looping?: boolean): void
  stop(): void
  jumpToStep(index: number): void
  readonly currentStep: number
  readonly running: boolean
}
```

### Error codes

```ts
type DmxErrorCode =
  | 'DMX_UNIVERSE_NOT_FOUND'
  | 'DMX_FIXTURE_NOT_FOUND'
  | 'DMX_CHANNEL_OUT_OF_RANGE'
  | 'DMX_VALUE_OUT_OF_RANGE'
  | 'DMX_TRANSPORT_FAILED'
  | 'DMX_ADDRESS_CONFLICT'

const DMX_ERROR_METADATA: Readonly<Record<DmxErrorCode, CodeMetadata>>
function registerDmxErrorCodes(): void
```

### Zod schemas

```ts
FixtureDefinitionSchema
FixtureInstanceSchema
SceneSchema
FadeOptionsSchema
DmxEngineOptionsSchema
CueStepSchema
```

---

## New additions for genesis

1. **`DmxTransport` interface** — injectable; `NullTransport` ships for tests (captures send calls).
2. **`ChaseSequencer`** — BPM-based step timing; uses injectable `Clock`; emits events via `@suaveplan/events`.
3. **Fade interpolation** — four easing functions; frame-rate controlled by `refreshRateHz`.
4. **`blackout`** — sets all channels in one or all universes to 0 immediately, bypassing any active fade.
5. **Address-conflict detection** — `addFixture` throws `DmxError(DMX_ADDRESS_CONFLICT)` if channel range overlaps an existing fixture in the same universe.
6. **OTel instrumentation** — counter `dmx.frame_total`, histogram `dmx.frame_render_ms`, counter `dmx.scene_apply_total`.
7. **Property-based tests** — channel value clamping invariant, fade interpolation monotonicity, scene application round-trip.
8. **Benchmark suite** — single-universe 512-channel render loop, 8-fixture scene apply.

---

## File layout

```text
universal/media/dmx/
  package.json
  tsconfig.json
  vitest.config.ts
  src/
    index.ts
    error-codes.ts
    constants/
      index.ts
    types/
      common.ts
      common.md
    core/
      dmx-engine/
        dmx-engine.ts
        dmx-engine.md
        dmx-engine.types.ts
        dmx-engine.test.ts
        index.ts
      chase-sequencer/
        chase-sequencer.ts
        chase-sequencer.md
        chase-sequencer.types.ts
        chase-sequencer.test.ts
        index.ts
    transports/
      null-transport/
        null-transport.ts
        null-transport.md
        null-transport.test.ts
        index.ts
    utils/
      interpolate.ts
      interpolate.md
      interpolate.test.ts
      scene.ts
      scene.md
      scene.test.ts
    __benchmarks__/
      dmx.bench.ts
  tests/
    integration.test.ts
    property.test.ts
```

---

## Impact

**Downstream**: `@suaveplan/r3f-dmx` (React layer), any live-event lighting integrations.
**Breaking changes**: none — fresh build.
**Prerequisites**: `@suaveplan/error`, `@suaveplan/types`, `@suaveplan/events` published to Verdaccio.