fix: interrupt message output before tool result

backend/services/pipecat/call_lifecycle.py

@@ -19,6 +19,8 @@ class CallEndCoordinator:
         self._ending = False
         self._armed = False
         self._speaking = False
+        self._speech_stopped = asyncio.Event()
+        self._speech_stopped.set()
         self._response_speech_started = False
         self._tracked_speeches = 0
         self._tracked_speech_completions: deque[asyncio.Future[None]] = deque()
@@ -30,6 +32,15 @@ class CallEndCoordinator:
     def ending(self) -> bool:
         return self._ending
 
+    @property
+    def speaking(self) -> bool:
+        """Whether transport output is currently producing bot speech."""
+        return self._speaking
+
+    async def wait_until_silent(self) -> None:
+        """Wait for the transport-owned bot speech boundary."""
+        await self._speech_stopped.wait()
+
     def begin(self, reason: str) -> None:
         self._ending = True
         self._reason = reason or "completed"
@@ -74,9 +85,11 @@ class CallEndCoordinator:
     async def observe(self, frame) -> None:
         if isinstance(frame, BotStartedSpeakingFrame):
             self._speaking = True
+            self._speech_stopped.clear()
             self._response_speech_started = True
         elif isinstance(frame, BotStoppedSpeakingFrame) and self._speaking:
             self._speaking = False
+            self._speech_stopped.set()
             if self._tracked_speeches > 0:
                 self._tracked_speeches -= 1
                 completion = self._tracked_speech_completions.popleft()