stt-integration

# STT Integration Skill ## Mission Integrate STT providers that emit reliable interim/final transcripts, interruption signaling, and `stt_latency_ms` metrics. ## Inputs expected from user 1. Ingestion model: streaming WebSocket, SDK callback stream, or HTTP chunk/segment submit. 2. Interim transcript support required or final-only acceptable. 3. Required language/model controls. If user does not answer: - Follow nearest streaming baseline and preserve current transcript packet semantics. ## Hard boundaries In scope: - `api/assistant-api/internal/transformer/<provider>/stt.go` (+ provider option/callback helpers) - `api/assistant-api/internal/transformer/transformer.go` - optional contract updates: `api/assistant-api/internal/type/stt_transformer.go`, `packet.go` - provider STT JSON + UI config files/components Out of scope: - TTS-only transport changes - telephony channel implementation - EOS/VAD algorithm changes ## Transport mapping - WS callback baseline: `deepgram`, `assembly-ai`, `sarvam` - SDK baseline: `azure`, `google`, `aws` - HTTP/other baseline: provider-specific fallback keeping packet contract ## Packet contract Input: - `UserAudioPacket` Required outputs: - `SpeechToTextPacket` (interim/final) - `InterruptionPacket{Source:"word"}` when provider exposes speech-onset word signal - `ConversationEventPacket{Name:"stt", ...}` - `MessageMetricPacket{Name:"stt_latency_ms"}` per utterance ## Implementation workflow 1. Select baseline provider by transport. 2. Implement STT in provider folder and callback/parser helpers. 3. Register provider in STT factory switch. 4. Wire UI model/language metadata and provider form. 5. Validate partial/final ordering and context IDs. 6. Add tests for init, interim/final, reconnect/retry, latency metric. ## Governed lifecycle - Classify work as Fast, Standard, or Governed using `DEVELOPMENT_PROCESS.md`; use the full gated lifecycle only for Governed work. - This skill operates only in its assigned phase and path ownership; it may not approve its own plan or code review. - Governed implementation starts only from a coordinator-attested approved plan; Fast and Standard work follows its lighter documented lifecycle. - Return changed-file and verification evidence to the coordinator, then route the complete verified diff to the read-only `code-reviewer`. ## Validation commands - `go test ./api/assistant-api/internal/transformer/... -run TestSTT` - `go test ./api/assistant-api/internal/transformer/<provider>/...` - `cd ui && yarn test providers` - `./.claude/skills/stt-integration/scripts/validate.sh --check-diff --provider <provider>`