improve interruption handling, avoid agent from getting stuck (liveki…

…t#1290)

.changeset/silent-oranges-warn.md

@@ -0,0 +1,5 @@
+---
+"livekit-agents": patch
+---
+
+improve interruption handling, avoid agent from getting stuck

livekit-agents/livekit/agents/pipeline/pipeline_agent.py

@@ -714,6 +714,9 @@ async def _synthesize_answer_task(
                     )
                 )
 
+        # we want to add this question even if it's empty. during false positive interruptions,
+        # adding an empty user message gives the LLM context so it could continue from where
+        # it had been interrupted.
         copied_ctx.messages.append(
             ChatMessage.create(text=handle.user_question, role="user")
         )
@@ -1035,7 +1038,7 @@ async def _llm_stream_to_str_generator(
     def _validate_reply_if_possible(self) -> None:
         """Check if the new agent speech should be played"""
 
-        if self._playing_speech is not None:
+        if self._playing_speech and not self._playing_speech.interrupted:
             should_ignore_input = False
             if not self._playing_speech.allow_interruptions:
                 should_ignore_input = True
@@ -1049,19 +1052,24 @@ def _validate_reply_if_possible(self) -> None:
                     "interrupt threshold is not met",
                     extra={"speech_id": self._playing_speech.id},
                 )
+
             if should_ignore_input:
                 self._transcribed_text = ""
                 return
 
         if self._pending_agent_reply is None:
-            if self._opts.preemptive_synthesis or not self._transcribed_text:
+            if self._opts.preemptive_synthesis:
                 return
 
+            # as long as we don't have a pending reply, we need to synthesize it
+            # in order to keep the conversation flowing.
+            # transcript could be empty at this moment, if the user interrupted the agent
+            # but did not generate any transcribed text.
             self._synthesize_agent_reply()
 
         assert self._pending_agent_reply is not None
 
-        # in some bad timing, we could end up with two pushed agent replies inside the speech queue.
+        # due to timing, we could end up with two pushed agent replies inside the speech queue.
         # so make sure we directly interrupt every reply when validating a new one
         for speech in self._speech_q:
             if not speech.is_reply:
@@ -1072,7 +1080,10 @@ def _validate_reply_if_possible(self) -> None:
 
         logger.debug(
             "validated agent reply",
-            extra={"speech_id": self._pending_agent_reply.id},
+            extra={
+                "speech_id": self._pending_agent_reply.id,
+                "text": self._transcribed_text,
+            },
         )
 
         if self._last_speech_time is not None:
@@ -1101,7 +1112,7 @@ def _interrupt_if_possible(self) -> None:
 
     def _should_interrupt(self) -> bool:
         if self._playing_speech is None:
-            return True
+            return False
 
         if (
             not self._playing_speech.allow_interruptions