fix: cancel pipeline on peer disconnect

backend/services/pipecat/pipeline_events.py

@@ -7,7 +7,7 @@ from loguru import logger
 from pipecat.frames.frames import (
     BotStartedSpeakingFrame,
     BotStoppedSpeakingFrame,
-    EndFrame,
+    CancelFrame,
     OutputTransportMessageUrgentFrame,
     TTSSpeakFrame,
 )
@@ -218,8 +218,11 @@ def bind_cascade_pipeline_events(
 
     @transport.event_handler("on_client_disconnected")
     async def on_client_disconnected(_transport, _client):
-        logger.info("对端断开,结束管线")
-        await worker.queue_frame(EndFrame())
+        # The peer can no longer consume queued audio. EndFrame would wait for
+        # graceful playback and can deadlock on SmallWebRTC's pending audio
+        # future, so a transport disconnect must stop output immediately.
+        logger.info("对端断开,立即取消管线")
+        await worker.queue_frame(CancelFrame(reason="client_disconnected"))
 
 
 def bind_realtime_pipeline_events(
@@ -296,5 +299,5 @@ def bind_realtime_pipeline_events(
 
     @transport.event_handler("on_client_disconnected")
     async def on_client_disconnected(_transport, _client):
-        logger.info("Realtime 对端断开,结束管线")
-        await worker.queue_frame(EndFrame())
+        logger.info("Realtime 对端断开,立即取消管线")
+        await worker.queue_frame(CancelFrame(reason="client_disconnected"))