Document all findings from the integration process directly in the
source code for future reference:
1. Language code mapping: Speechmatics uses ISO 639-3 "cmn" for
Mandarin, but LiveKit LanguageCode auto-normalizes it to "zh".
Must override stt._stt_options.language after construction.
2. Turn detection modes (critical):
- EXTERNAL: unusable — LiveKit never sends FlushSentinel, only
pushes silence frames, so FINAL_TRANSCRIPT never arrives
- ADAPTIVE: unusable — client-side Silero VAD conflicts with
LiveKit's own VAD, produces zero transcription output
- SMART_TURN: correct choice — server-side intelligent turn
detection, auto-emits FINAL_TRANSCRIPT, fully compatible
3. Speaker diarization: is_active flag distinguishes primary speaker
from TTS echo, solving the "speaker confusion" problem
4. Docker deployment: SPEECHMATICS_API_KEY in .env, watch for
COPY layer cache when rebuilding
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
hailin
e8a3e07116