feat: emit a TaskStatusUpdateEvent for ADK events with no output parts but with event.actions

PiperOrigin-RevId: 896929519

src/google/adk/a2a/converters/from_adk_event.py

@@ -218,6 +218,23 @@ def convert_event_to_a2a_events(
               ),
           )
       )
+    elif _serialize_value(event.actions) is not None:
+      a2a_events.append(
+          TaskStatusUpdateEvent(
+              task_id=task_id,
+              context_id=context_id,
+              status=TaskStatus(
+                  state=TaskState.working,
+                  message=Message(
+                      message_id=str(uuid.uuid4()),
+                      role=Role.agent,
+                      parts=[],
+                  ),
+                  timestamp=datetime.now(timezone.utc).isoformat(),
+              ),
+              final=False,
+          )
+      )
 
     a2a_events = _add_event_metadata(event, a2a_events)
     return a2a_events
@@ -280,7 +297,10 @@ def _add_event_metadata(
       metadata[_get_adk_metadata_key(field_name)] = value
 
   for a2a_event in a2a_events:
-    if isinstance(a2a_event, TaskStatusUpdateEvent):
+    if (
+        isinstance(a2a_event, TaskStatusUpdateEvent)
+        and a2a_event.status.message
+    ):
       a2a_event.status.message.metadata = metadata.copy()
     elif isinstance(a2a_event, TaskArtifactUpdateEvent):
       a2a_event.artifact.metadata = metadata.copy()

tests/unittests/a2a/integration/test_client_server.py

@@ -21,6 +21,7 @@ from a2a.types import TaskState
 from a2a.types import TextPart
 from google.adk.agents.remote_a2a_agent import A2A_METADATA_PREFIX
 from google.adk.events.event import Event
+from google.adk.events.event_actions import EventActions
 from google.adk.platform import uuid as platform_uuid
 from google.adk.runners import Runner
 from google.adk.sessions.in_memory_session_service import InMemorySessionService
@@ -47,6 +48,11 @@ def create_streaming_mock_run_async(received_requests: list):
         content=types.Content(parts=[types.Part(text=" world")]),
         partial=True,
     )
+    yield Event(
+        author="FakeAgent",
+        partial=True,
+        actions=EventActions(artifact_delta={"file1": 1}),
+    )
     yield Event(
         author="FakeAgent",
         content=types.Content(parts=[types.Part(text="Hello world")]),
@@ -92,6 +98,7 @@ async def test_streaming_adk_to_streaming_a2a():
   new_message = types.Content(parts=[types.Part(text="Hi")], role="user")
 
   texts = []
+  actions = []
   async for event in client_runner.run_async(
       user_id="test_user", session_id="test_session", new_message=new_message
   ):
@@ -99,11 +106,15 @@ async def test_streaming_adk_to_streaming_a2a():
       for p in event.content.parts:
         if p.text:
           texts.append(p.text)
+    if event.actions and event.actions.artifact_delta:
+      actions.append(event.actions)
 
   assert len(received_requests) == 1
   assert received_requests[0]["session_id"] is not None
 
   assert texts == ["Hello", " world", "Hello world"]
+  assert len(actions) == 1
+  assert actions[0].artifact_delta == {"file1": 1}
 
 
 @pytest.mark.asyncio