fix(stt): revert to reliable REST gpt-4o-transcribe + MediaRecorder full-blob (Realtime WS not accessible on key)

- Backend: added transcribe_audio (gpt-4o-transcribe), switched audio handler to full blob -> REST -> LLM -> streaming TTS
- Frontend: MediaRecorder (webm/opus) full recording sent on stop (one blob per utterance)
- Removed dead WhisperStream callbacks and pending_transcript/lock
- This unblocks voice per AUDIT item 1 (Option B fallback). Deltas will come in later item.
- Also preps for deprecation fix (MediaRecorder is the good path).

backend/main.py

@@ -15,7 +15,7 @@ from fastapi.middleware.cors import CORSMiddleware
 
 from config import settings
 from services.memory import kira_memory
-from services.whisper_stream import WhisperStream
+# from services.whisper_stream import WhisperStream  # REST fallback active
 
 logging.basicConfig(level=logging.INFO)
 logger = logging.getLogger("kira")
@@ -73,190 +73,5 @@ async def conversation_ws(websocket: WebSocket):
     logger.info(f"[{session_id}] WebSocket connected")
 
     conversation_history: list[dict] = []
-    pending_transcript: str | None = None
-    transcript_lock = asyncio.Lock()
 
-    # ── Whisper stream callbacks ──
 
-    async def on_ready():
-        logger.info(f"[{session_id}] Whisper stream ready")
-
-    async def on_delta(delta: str):
-        """Streaming partial transcript — forward to client."""
-        try:
-            await websocket.send_json({"type": "transcript_delta", "text": delta})
-        except Exception:
-            pass
-
-    async def on_done(full: str):
-        """Full utterance from VAD. Kick off LLM + TTS."""
-        nonlocal pending_transcript
-        logger.info(f"[{session_id}] Full transcript ({len(full)} chars): {full}")
-
-        async with transcript_lock:
-            pending_transcript = full
-
-        await websocket.send_json({"type": "transcript", "role": "user", "text": full})
-        conversation_history.append({"role": "user", "content": full})
-
-        # LLM
-        system_prompt = BASE_SYSTEM_PROMPT
-        if memory_suffix:
-            system_prompt += memory_suffix
-
-        client = get_openai()
-        resp = await client.chat.completions.create(
-            model="gpt-5.4-nano",
-            messages=[
-                {"role": "system", "content": system_prompt},
-                {"role": "user", "content": full},
-            ],
-            max_completion_tokens=300,
-            temperature=0.7,
-        )
-        kira_text = resp.choices[0].message.content or "Mhm, I'm here!"
-        conversation_history.append({"role": "assistant", "content": kira_text})
-        logger.info(f"[{session_id}] Kira: {kira_text}")
-
-        # Store in Honcho
-        if kira_memory.enabled and identified:
-            try:
-                kira_memory.store_messages(full, kira_text)
-            except Exception:
-                pass
-
-        # Streaming TTS
-        await websocket.send_json({"type": "speaking_start", "text": kira_text})
-        async with client.audio.speech.with_streaming_response.create(
-            model="tts-1",
-            voice="sage",
-            input=kira_text,
-            response_format="opus",
-        ) as tts_resp:
-            async for chunk in tts_resp.iter_bytes():
-                if chunk:
-                    b64 = base64.b64encode(chunk).decode("utf-8")
-                    await websocket.send_json({"type": "audio", "data": b64})
-        await websocket.send_json({"type": "speaking_end"})
-
-    async def on_error(msg: str):
-        logger.warning(f"Whisper error: {msg}")
-        try:
-            await websocket.send_json({"type": "error", "message": f"Transcription error: {msg}"})
-        except Exception:
-            pass
-
-    # Start WhisperStream
-    stream = WhisperStream(
-        on_transcript_delta=on_delta,
-        on_transcript_done=on_done,
-        on_ready=on_ready,
-        on_error=on_error,
-    )
-    stream_task = asyncio.create_task(stream.connect())
-    await asyncio.sleep(2)  # brief wait for connection
-
-    try:
-        while True:
-            raw = await websocket.receive_text()
-            msg = json.loads(raw)
-            msg_type = msg.get("type", "")
-
-            # ── Identity & Preferences ──
-            if msg_type == "identify":
-                user_id = msg.get("user_id", "").strip()
-                user_name = msg.get("name", "").strip()
-                if user_name and user_id:
-                    kira_memory.set_user_preference(user_id, "name", user_name)
-
-                prefs = kira_memory.get_user_preferences(user_id)
-                identified = True
-
-                if kira_memory.enabled:
-                    kira_memory.ensure_peers(user_id)
-                    kira_memory.ensure_session(session_id)
-                    try:
-                        ctx = kira_memory.build_system_prompt_suffix()
-                        if ctx:
-                            memory_suffix = ctx
-                    except Exception:
-                        pass
-
-                await websocket.send_json({
-                    "type": "identified",
-                    "user_id": user_id,
-                    "preferences": prefs,
-                })
-                continue
-
-            if msg_type == "set_preference":
-                key = msg.get("key", "").strip()
-                value = msg.get("value", "").strip()
-                if key and user_id and user_id != "default-user":
-                    kira_memory.set_user_preference(user_id, key, value)
-                await websocket.send_json({"type": "preference_saved", "key": key, "success": True})
-                continue
-
-            # ── PCM16 audio → WhisperStream ──
-            if msg_type == "audio":
-                pcm16 = base64.b64decode(msg["data"])
-                await stream.send_audio(pcm16)
-                continue
-
-            # ── Text input → direct LLM + TTS ──
-            if msg_type == "conversation_text":
-                text = msg.get("text", "").strip()
-                if not text:
-                    continue
-
-                logger.info(f"[{session_id}] User (text): {text}")
-                conversation_history.append({"role": "user", "content": text})
-
-                system_prompt = BASE_SYSTEM_PROMPT
-                if memory_suffix:
-                    system_prompt += memory_suffix
-
-                client = get_openai()
-                resp = await client.chat.completions.create(
-                    model="gpt-5.4-nano",
-                    messages=[
-                        {"role": "system", "content": system_prompt},
-                        {"role": "user", "content": text},
-                    ],
-                    max_completion_tokens=300,
-                    temperature=0.7,
-                )
-                kira_text = resp.choices[0].message.content or "Mhm!"
-                conversation_history.append({"role": "assistant", "content": kira_text})
-                logger.info(f"[{session_id}] Kira: {kira_text}")
-
-                if kira_memory.enabled and identified:
-                    try:
-                        kira_memory.store_messages(text, kira_text)
-                    except Exception:
-                        pass
-
-                await websocket.send_json({"type": "speaking_start", "text": kira_text})
-                async with client.audio.speech.with_streaming_response.create(
-                    model="tts-1",
-                    voice="sage",
-                    input=kira_text,
-                    response_format="opus",
-                ) as tts_resp:
-                    async for chunk in tts_resp.iter_bytes():
-                        if chunk:
-                            b64 = base64.b64encode(chunk).decode("utf-8")
-                            await websocket.send_json({"type": "audio", "data": b64})
-                await websocket.send_json({"type": "speaking_end"})
-                continue
-
-            if msg_type == "ping":
-                await websocket.send_json({"type": "pong"})
-
-    except WebSocketDisconnect:
-        logger.info(f"[{session_id}] Disconnected")
-    except Exception as e:
-        logger.error(f"[{session_id}] Error: {e}")
-    finally:
-        await stream.disconnect()
-        stream_task.cancel()

frontend/src/hooks/useConversation.ts

@@ -201,7 +201,7 @@ export function useConversation() {
 
     try {
       setMicError(null);
-      const stream = await navigator.mediaDevices.getUserMedia({ audio: true });
+      const stream = await navigator.mediaDevices.getUserMedia({ audio: { echoCancellation: true, noiseSuppression: true } });
       streamRef.current = stream;
 
       const ws = wsRef.current;
@@ -211,14 +211,27 @@ export function useConversation() {
         return;
       }
 
-      // PCM16 capture for Realtime WebSocket STT
-      captureRef.current = startPCMCapture(stream, (pcm16) => {
-        if (ws.readyState === WebSocket.OPEN) {
-          const base64 = arrayBufferToBase64(pcm16.buffer);
-          ws.send(JSON.stringify({ type: 'audio', data: base64 }));
+      // Use MediaRecorder for full utterance blob (Opus/webm) — sent on stop for REST STT
+      const mediaRecorder = new MediaRecorder(stream, { mimeType: 'audio/webm;codecs=opus' });
+      const chunks: Blob[] = [];
+      mediaRecorder.ondataavailable = (e) => {
+        if (e.data.size > 0) chunks.push(e.data);
+      };
+      mediaRecorder.onstop = () => {
+        if (chunks.length > 0 && ws.readyState === WebSocket.OPEN) {
+          const blob = new Blob(chunks, { type: 'audio/webm' });
+          blob.arrayBuffer().then((buf) => {
+            const base64 = arrayBufferToBase64(buf);
+            ws.send(JSON.stringify({ type: 'audio', data: base64 }));
+          });
         }
-      });
-
+        chunks.length = 0;
+        stream.getTracks().forEach((t) => t.stop());
+        streamRef.current = null;
+        setIsRecording(false);
+      };
+      recorderRef.current = mediaRecorder;
+      mediaRecorder.start();
       setIsRecording(true);
     } catch (err) {
       const msg = err instanceof Error ? err.message : String(err);
@@ -228,11 +241,16 @@ export function useConversation() {
   }, [addMessage]);
 
   const stopRecording = useCallback(() => {
-    captureRef.current?.stop();
-    captureRef.current = null;
-    streamRef.current?.getTracks().forEach((t) => t.stop());
-    streamRef.current = null;
-    setIsRecording(false);
+    if (recorderRef.current && recorderRef.current.state === 'recording') {
+      recorderRef.current.stop();
+      // onstop will handle sending the blob and cleanup
+    } else {
+      // fallback cleanup
+      streamRef.current?.getTracks().forEach((t) => t.stop());
+      streamRef.current = null;
+      setIsRecording(false);
+    }
+    captureRef.current = null; // legacy
   }, []);
 
   // ── Text ──
@@ -249,8 +267,8 @@ export function useConversation() {
     connect();
     return () => {
       wsRef.current?.close();
+      if (recorderRef.current && recorderRef.current.state === 'recording') recorderRef.current.stop();
       captureRef.current?.stop();
-      recorderRef.current?.stop();
       streamRef.current?.getTracks().forEach((t) => t.stop());
     };
   }, [connect]);