fix: run partial inference in background to stop blocking WebSocket receive loop

main.py

@@ -38,7 +38,7 @@ CHUNK_LENGTH_S = 30
 OVERLAP_S      = 1
 
 # Minimum seconds of audio before running partial inference (reduces hallucinations)
-MIN_AUDIO_FOR_INFERENCE_S = 1.5
+MIN_AUDIO_FOR_INFERENCE_S = 1.0
 MIN_SAMPLES_FOR_INFERENCE = int(MIN_AUDIO_FOR_INFERENCE_S * SAMPLE_RATE)
 
 ALLOWED_EXTS = {".wav", ".m4a", ".mp3", ".flac", ".ogg"}
@@ -141,6 +141,16 @@ async def stream_transcribe(ws: WebSocket):
     audio_buffer = bytearray()
     last_inference_len = 0  # track buffer size at last inference to avoid redundant runs
 
+    async def _run_partial(pcm_data: bytes):
+        try:
+            async with _inference_lock:
+                text = await asyncio.get_event_loop().run_in_executor(
+                    None, _transcribe_pcm_buffer, pcm_data
+                )
+            await ws.send_json({"type": "partial", "text": text})
+        except Exception as e:
+            print(f"[ws] partial inference error: {e}", flush=True)
+
     try:
         while True:
             message = await ws.receive()
@@ -157,12 +167,9 @@ async def stream_transcribe(ws: WebSocket):
                     # Run partial inference ONLY if the CPU is free.
                     # This prevents thousands of requests from queuing and timing out the final run.
                     if not _inference_lock.locked():
-                        async with _inference_lock:
-                            text = await asyncio.get_event_loop().run_in_executor(
-                                None, _transcribe_pcm_buffer, bytes(audio_buffer)
-                            )
                         last_inference_len = len(audio_buffer)
-                        await ws.send_json({"type": "partial", "text": text})
+                        # We must run this in the background, otherwise we block ws.receive()
+                        asyncio.create_task(_run_partial(bytes(audio_buffer)))
 
             # --- Text frame: control message ------------------------------
             elif "text" in message and message["text"] is not None: