fix: preserve nontransparent live resumption

Author: he-yufeng

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

@@ -533,11 +533,15 @@ async def run_live(
           attempt += 1
           if not llm_request.live_connect_config:
             llm_request.live_connect_config = types.LiveConnectConfig()
-          if not llm_request.live_connect_config.session_resumption:
+          session_resumption = (
+              llm_request.live_connect_config.session_resumption
+          )
+          if not session_resumption:
+            session_resumption = types.SessionResumptionConfig()
             llm_request.live_connect_config.session_resumption = (
-                types.SessionResumptionConfig()
+                session_resumption
             )
-          llm_request.live_connect_config.session_resumption.handle = (
+          session_resumption.handle = (
               invocation_context.live_session_resumption_handle
           )
 

tests/unittests/flows/llm_flows/test_base_llm_flow.py

@@ -748,6 +748,78 @@ async def mock_receive_2():
       assert invocation_context.live_session_resumption_handle == 'test_handle'
 
 
+@pytest.mark.asyncio
+async def test_run_live_reconnect_preserves_nontransparent_resumption():
+  """Test that reconnect does not force transparent resumption."""
+  from google.adk.agents.live_request_queue import LiveRequestQueue
+  from websockets.exceptions import ConnectionClosed
+
+  real_model = Gemini()
+  mock_connection = mock.AsyncMock()
+
+  async def mock_receive():
+    yield LlmResponse(
+        live_session_resumption_update=types.LiveServerSessionResumptionUpdate(
+            new_handle='test_handle'
+        )
+    )
+    raise ConnectionClosed(None, None)
+
+  mock_connection.receive = mock.Mock(side_effect=mock_receive)
+
+  agent = Agent(name='test_agent', model=real_model)
+  invocation_context = await testing_utils.create_invocation_context(
+      agent=agent
+  )
+  invocation_context.live_request_queue = LiveRequestQueue()
+
+  flow = BaseLlmFlowForTesting()
+
+  async def mock_preprocess(ctx, req):
+    req.live_connect_config.session_resumption = types.SessionResumptionConfig(
+        transparent=False
+    )
+    if False:
+      yield
+
+  with mock.patch.object(
+      flow, '_preprocess_async', side_effect=mock_preprocess
+  ):
+    with mock.patch.object(flow, '_send_to_model', new_callable=AsyncMock):
+      mock_connection_2 = mock.AsyncMock()
+
+      class StopError(Exception):
+        pass
+
+      async def mock_receive_2():
+        yield LlmResponse(
+            content=types.Content(parts=[types.Part.from_text(text='hi')])
+        )
+        raise StopError('stop')
+
+      mock_connection_2.receive = mock.Mock(side_effect=mock_receive_2)
+
+      mock_aenter = mock.AsyncMock()
+      mock_aenter.side_effect = [mock_connection, mock_connection_2]
+
+      with mock.patch(
+          'google.adk.models.google_llm.Gemini.connect'
+      ) as mock_connect:
+        mock_connect.return_value.__aenter__ = mock_aenter
+
+        try:
+          async for _ in flow.run_live(invocation_context):
+            pass
+        except StopError:
+          pass
+
+        reconnect_request = mock_connect.call_args_list[1].args[0]
+        assert (
+            reconnect_request.live_connect_config.session_resumption.transparent
+            is False
+        )
+
+
 @pytest.mark.asyncio
 async def test_run_live_skips_send_history_on_resumption():
   """Test that run_live skips send_history when resuming a session."""