Fix a pipeline freeze when using AWS Nova Sonic. The freeze occurs if the user starts speaking before we've finished sending the "trigger " audio (AWS Nova Sonic can only start speaking in response to a user utterance, so we have a simulated user utterance to "trigger" the bot speaking without the user having actually spoken first).

CHANGELOG.md

@@ -5,6 +5,14 @@ All notable changes to **Pipecat** will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [Unreleased]
+
+### Fixed
+
+- Fix a pipeline freeze when using AWS Nova Sonic, which would occur if the
+  user started early, while the bot was still working through
+  `trigger_assistant_response()`.
+
 ## [0.0.75] - 2025-07-08
 
 ### Added

src/pipecat/services/aws_nova_sonic/aws.py

@@ -474,7 +474,6 @@ class AWSNovaSonicLLMService(LLMService):
         # If we need to, send assistant response trigger (depends on self._connected_time)
         if self._triggering_assistant_response:
             await self._send_assistant_response_trigger()
-            self._triggering_assistant_response = False
 
     async def _disconnect(self):
         try:
@@ -1105,7 +1104,6 @@ class AWSNovaSonicLLMService(LLMService):
         # Send the trigger audio, if we're fully connected and set up
         if self._connected_time is not None:
             await self._send_assistant_response_trigger()
-            self._triggering_assistant_response = False
 
     async def _send_assistant_response_trigger(self):
         if (
@@ -1113,6 +1111,7 @@ class AWSNovaSonicLLMService(LLMService):
         ):  # should never happen
             return
 
+        try:
             logger.debug("Sending assistant response trigger...")
 
             chunk_duration = 0.02  # what we might get from InputAudioRawFrame
@@ -1156,3 +1155,7 @@ class AWSNovaSonicLLMService(LLMService):
             for chunk in audio_chunks:
                 await self._send_user_audio_event(chunk)
                 await asyncio.sleep(chunk_duration)
+        finally:
+            # We need to clean up in case sending the trigger was cancelled, e.g. in the case of a user interruption.
+            # (An asyncio.CancelledError would be raised in that case.)
+            self._triggering_assistant_response = False