- URL now uses ?model=gpt-realtime-whisper (was invalid gpt-4o-mini-realtime-preview)
- Cleaned session.update (removed modalities that may not apply)
- Expanded _handle to catch input_audio_transcription.delta and .completed events
- on_error now forwards transcription errors to frontend client
- Per AUDIT + PLAN item 1
Replaces REST-based transcription (gpt-4o-transcribe) with WebSocket
streaming via gpt-realtime-whisper. Frontend captures PCM16 audio and
streams it through the backend to a Realtime transcription session.
- Server-side VAD detects utterance boundaries automatically
- Word-level transcript deltas stream to the client in real-time
- On utterance end, gpt-5.4-nano generates a response
- TTS streams back via with_streaming_response
- Total pipeline: PCM16 → Realtime WS → LLM → streaming TTS