# ADR 0001: Companion transcription boundaries

Status: accepted for the first stable Companion release.

The MVP uses server-hosted whisper.cpp behind `TranscriptionProvider` and returns captions through `CaptionDeliveryAdapter`. The first concrete boundaries are `WhisperCppServerProvider` and companion-managed OBS native delivery. Session and UI code depend on those interfaces rather than engine, location, or platform details.

Deferred provider implementations are local companion inference and remote providers such as Qwen ASR. Qwen will be a separate provider; it will not impersonate whisper.cpp. Deferred delivery implementations include other streaming platforms and optional open-caption rendering. Open captions are never an implicit fallback for failed Twitch closed captions.

OBS source identity is UUID-based. Multiple tracks, independent internal caption events, primary-track overlap policy, and delivery-enabled fields exist in the server model even though the first usable configuration targets one microphone. Protocol codec negotiation exists even though v1 accepts only PCM.

The companion plugin host is process-oriented so one future integration can fail independently. Official package signature enforcement and Dev Mode unsigned-package handling are deferred with the installer/plugin packaging work. Offline authorization retains the low/normal/severe setting boundary; server inference still stops when Lumi is unreachable.

Core owns only a reusable WebSocket upgrade registration mechanism. Removing or disabling `lumi_transcription` must not leave transcription routes, timers, sockets, workers, or global capabilities active.
