Fix Deepgram broken pipe: wait for WebSocket before starting audio

Audio capture started immediately after spawning the WebSocket thread,
but the WebSocket hadn't connected yet. Audio chunks sent to the
unconnected WebSocket caused a broken pipe error.

Fix: added a threading.Event that start_recording() waits on (up to
15s) before opening the audio stream. The event is set in _ws_lifecycle
after the WebSocket connects and handshake completes.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

client/deepgram_transcription.py

@@ -156,12 +156,23 @@ class DeepgramTranscriptionEngine:
             return True
 
         self._stop_event.clear()
+        self._ws_connected = threading.Event()
         self._is_recording = True
 
         # Start the asyncio event-loop thread (handles WS send/receive)
         self._thread = threading.Thread(target=self._run_event_loop, daemon=True)
         self._thread.start()
 
+        # Wait for the WebSocket to connect before starting audio capture.
+        # Without this, audio chunks arrive before the WS is open -> broken pipe.
+        if not self._ws_connected.wait(timeout=15):
+            logger.error("Timed out waiting for Deepgram WebSocket connection")
+            print("ERROR: Timed out waiting for Deepgram WebSocket connection")
+            self._last_error = "Timed out connecting to Deepgram"
+            self._is_recording = False
+            self._stop_event.set()
+            return False
+
         # Start the audio capture stream
         try:
             self._start_audio_stream()
@@ -285,6 +296,11 @@ class DeepgramTranscriptionEngine:
                 if not await self._managed_handshake():
                     return
 
+            # Signal that the WebSocket is connected and ready
+            logger.info("WebSocket connected to Deepgram")
+            if hasattr(self, '_ws_connected'):
+                self._ws_connected.set()
+
             # Run send and receive concurrently
             await asyncio.gather(
                 self._send_loop(),