feat: support audio_stream_end for realtime input

src/google/adk/agents/live_request_queue.py

@@ -24,34 +24,26 @@
 
 
 class LiveRequest(BaseModel):
-  """Request send to live agents."""
+  """Request send to live agents.
+
+  When multiple fields are set, they are processed by priority (highest first):
+  activity_start > activity_end > audio_stream_end > blob > content.
+  """
 
   model_config = ConfigDict(ser_json_bytes='base64', val_json_bytes='base64')
   """The pydantic model config."""
 
   content: Optional[types.Content] = None
-  """If set, send the content to the model in turn-by-turn mode.
-
-  When multiple fields are set, they are processed by priority (highest first):
-  activity_start > activity_end > blob > content.
-  """
+  """If set, send the content to the model in turn-by-turn mode."""
   blob: Optional[types.Blob] = None
-  """If set, send the blob to the model in realtime mode.
-
-  When multiple fields are set, they are processed by priority (highest first):
-  activity_start > activity_end > blob > content.
-  """
+  """If set, send the blob to the model in realtime mode."""
   activity_start: Optional[types.ActivityStart] = None
-  """If set, signal the start of user activity to the model.
-
-  When multiple fields are set, they are processed by priority (highest first):
-  activity_start > activity_end > blob > content.
-  """
+  """If set, signal the start of user activity to the model."""
   activity_end: Optional[types.ActivityEnd] = None
-  """If set, signal the end of user activity to the model.
-
-  When multiple fields are set, they are processed by priority (highest first):
-  activity_start > activity_end > blob > content.
+  """If set, signal the end of user activity to the model."""
+  audio_stream_end: bool = False
+  """If set, signal the end of the audio stream to the model.
+  This is only used when Voice Activity Detection is enabled.
   """
   close: bool = False
   """If set, close the queue. queue.shutdown() is only supported in Python 3.13+."""
@@ -80,6 +72,10 @@ def send_activity_end(self):
     """Sends an activity end signal to mark the end of user input."""
     self._queue.put_nowait(LiveRequest(activity_end=types.ActivityEnd()))
 
+  def send_audio_stream_end(self):
+    """Sends an audio stream end signal to force flush audio."""
+    self._queue.put_nowait(LiveRequest(audio_stream_end=True))
+
   def send(self, req: LiveRequest):
     self._queue.put_nowait(req)
 

src/google/adk/flows/llm_flows/base_llm_flow.py

@@ -308,6 +308,10 @@ async def _send_to_model(
         await llm_connection.send_realtime(types.ActivityStart())
       elif live_request.activity_end:
         await llm_connection.send_realtime(types.ActivityEnd())
+      elif live_request.audio_stream_end:
+        await llm_connection.send_realtime(
+            types.LiveClientRealtimeInput(audio_stream_end=True)
+        )
       elif live_request.blob:
         # Cache input audio chunks before flushing
         self.audio_cache_manager.cache_audio(

src/google/adk/models/gemini_llm_connection.py

@@ -28,7 +28,12 @@
 
 logger = logging.getLogger('google_adk.' + __name__)
 
-RealtimeInput = Union[types.Blob, types.ActivityStart, types.ActivityEnd]
+RealtimeInput = Union[
+    types.Blob,
+    types.ActivityStart,
+    types.ActivityEnd,
+    types.LiveClientRealtimeInput,
+]
 from typing import TYPE_CHECKING
 
 if TYPE_CHECKING:
@@ -136,6 +141,13 @@ async def send_realtime(self, input: RealtimeInput):
     elif isinstance(input, types.ActivityEnd):
       logger.debug('Sending LLM activity end signal.')
       await self._gemini_session.send_realtime_input(activity_end=input)
+
+    elif isinstance(input, types.LiveClientRealtimeInput):
+      if input.audio_stream_end:
+        logger.debug('Sending LLM audio stream end signal.')
+        await self._gemini_session.send_realtime_input(audio_stream_end=True)
+      else:
+        logger.warning('Unary LiveClientRealtimeInput not fully supported yet.')
     else:
       raise ValueError('Unsupported input type: %s' % type(input))
 

tests/unittests/models/test_gemini_llm_connection.py

@@ -69,6 +69,22 @@ async def test_send_realtime_default_behavior(
   mock_gemini_session.send.assert_not_called()
 
 
+@pytest.mark.asyncio
+async def test_send_realtime_audiostreamend(
+    gemini_connection, mock_gemini_session
+):
+  """Test send_realtime with LiveClientRealtimeInput(audio_stream_end=True)."""
+  input_signal = types.LiveClientRealtimeInput(audio_stream_end=True)
+  await gemini_connection.send_realtime(input_signal)
+
+  # Should call send_realtime_input with audio_stream_end=True
+  mock_gemini_session.send_realtime_input.assert_called_once_with(
+      audio_stream_end=True
+  )
+  # Should not call .send function
+  mock_gemini_session.send.assert_not_called()
+
+
 @pytest.mark.asyncio
 async def test_send_history(gemini_connection, mock_gemini_session):
   """Test send_history method."""