feat: Add bidirectional streaming support (bidi_stream_query) to stable AdkApp template.

tests/unit/vertex_adk/test_agent_engine_templates_adk.py

@@ -16,6 +16,7 @@
 import importlib
 import json
 import os
+import asyncio
 import re
 import sys
 from typing import Optional
@@ -308,6 +309,34 @@ async def run_async(self, *args, **kwargs):
             }
         )
 
+    async def run_live(self, *args, **kwargs):
+        from google.adk.events import event
+
+        yield event.Event(
+            **{
+                "author": "currency_exchange_agent",
+                "content": {
+                    "parts": [
+                        {
+                            "thought_signature": b"test_signature",
+                            "function_call": {
+                                "args": {
+                                    "currency_date": "2025-04-03",
+                                    "currency_from": "USD",
+                                    "currency_to": "SEK",
+                                },
+                                "id": "af-c5a57692-9177-4091-a3df-098f834ee849",
+                                "name": "get_exchange_rate",
+                            },
+                        }
+                    ],
+                    "role": "model",
+                },
+                "id": "9aaItGK9",
+                "invocation_id": "e-6543c213-6417-484b-9551-b67915d1d5f7",
+            }
+        )
+
 
 @pytest.mark.usefixtures("google_auth_mock")
 class TestAdkApp:
@@ -904,6 +933,62 @@ def test_span_content_capture_enabled_with_tracing(
         app.set_up()
         assert os.environ["ADK_CAPTURE_MESSAGE_CONTENT_IN_SPANS"] == "true"
 
+    @pytest.mark.asyncio
+    async def test_async_bidi_stream_query(
+        self,
+        default_instrumentor_builder_mock: mock.Mock,
+        get_project_id_mock: mock.Mock,
+    ):
+        app = agent_engines.AdkApp(agent=_TEST_AGENT)
+        assert app._tmpl_attrs.get("runner") is None
+        app.set_up()
+        app._tmpl_attrs["runner"] = _MockRunner()
+        request_queue = asyncio.Queue()
+        request_dict = {
+            "user_id": _TEST_USER_ID,
+            "live_request": {
+                "input": "What is the exchange rate from USD to SEK?",
+            },
+        }
+
+        await request_queue.put(request_dict)
+        await request_queue.put(None)  # Sentinel to end the stream.
+        events = []
+        async for event in app.bidi_stream_query(request_queue):
+            events.append(event)
+        assert len(events) == 1
+
+    @pytest.mark.asyncio
+    async def test_async_bidi_stream_query_with_state(
+        self,
+        default_instrumentor_builder_mock: mock.Mock,
+        get_project_id_mock: mock.Mock,
+    ):
+        app = agent_engines.AdkApp(agent=_TEST_AGENT)
+        assert app._tmpl_attrs.get("runner") is None
+        app.set_up()
+        app._tmpl_attrs["runner"] = _MockRunner()
+        request_queue = asyncio.Queue()
+        request_dict = {
+            "user_id": _TEST_USER_ID,
+            "state": {"test_key": "test_val"},
+            "live_request": {
+                "input": "What is the exchange rate from USD to SEK?",
+            },
+        }
+
+        await request_queue.put(request_dict)
+        await request_queue.put(None)  # Sentinel to end the stream.
+
+        with mock.patch.object(
+            app, "async_create_session", wraps=app.async_create_session
+        ) as mock_create_session:
+            async for _ in app.bidi_stream_query(request_queue):
+                pass
+            mock_create_session.assert_called_once_with(
+                user_id=_TEST_USER_ID, state={"test_key": "test_val"}
+            )
+
 
 def test_dump_event_for_json():
     from google.adk.events import event

vertexai/agent_engines/templates/adk.py

@@ -1754,6 +1754,93 @@ async def async_search_memory(self, *, user_id: str, query: str):
             query=query,
         )
 
+
+    async def bidi_stream_query(
+        self,
+        request_queue: Any,
+    ) -> AsyncIterable[Any]:
+        """Bidi streaming query the ADK application.
+
+        Args:
+            request_queue:
+                The queue of requests to stream responses for, with the type of
+                asyncio.Queue[Any].
+
+        Raises:
+            TypeError: If the request_queue is not an asyncio.Queue instance.
+            ValueError: If the first request does not have a user_id.
+            ValidationError: If failed to convert to LiveRequest.
+
+        Yields:
+            The stream responses of querying the ADK application.
+        """
+        from google.adk.agents.live_request_queue import LiveRequest
+        from google.adk.agents.live_request_queue import LiveRequestQueue
+        from vertexai.agent_engines import _utils
+
+        # Manual type check needed as Pydantic doesn't support asyncio.Queue.
+        if not isinstance(request_queue, asyncio.Queue):
+            raise TypeError("request_queue must be an asyncio.Queue instance.")
+
+        first_request = await request_queue.get()
+        user_id = first_request.get("user_id")
+        if not user_id:
+            raise ValueError("The first request must have a user_id.")
+
+        session_id = first_request.get("session_id")
+        run_config = first_request.get("run_config")
+        first_live_request = first_request.get("live_request")
+
+        if not self._tmpl_attrs.get("runner"):
+            self.set_up()
+        if not session_id:
+            state = first_request.get("state")
+            session = await self.async_create_session(user_id=user_id, state=state)
+            session_id = session["id"] if isinstance(session, dict) else session.id
+        run_config = _validate_run_config(run_config)
+
+        live_request_queue = LiveRequestQueue()
+
+        if first_live_request and isinstance(first_live_request, Dict):
+            live_request_queue.send(LiveRequest.model_validate(first_live_request))
+
+        # Forwards live requests to the agent.
+        async def _forward_requests():
+            while True:
+                request = await request_queue.get()
+                live_request = LiveRequest.model_validate(request)
+                live_request_queue.send(live_request)
+
+        # Forwards events to the client.
+        async def _forward_events():
+            if run_config:
+                events_async = self._tmpl_attrs.get("runner").run_live(
+                    user_id=user_id,
+                    session_id=session_id,
+                    live_request_queue=live_request_queue,
+                    run_config=run_config,
+                )
+            else:
+                events_async = self._tmpl_attrs.get("runner").run_live(
+                    user_id=user_id,
+                    session_id=session_id,
+                    live_request_queue=live_request_queue,
+                )
+            async for event in events_async:
+                yield _utils.dump_event_for_json(event)
+
+        requests_task = asyncio.create_task(_forward_requests())
+
+        try:
+            async for event in _forward_events():
+                yield event
+        finally:
+            requests_task.cancel()
+            try:
+                await requests_task
+            except asyncio.CancelledError:
+                pass
+
     def register_operations(self) -> Dict[str, List[str]]:
         """Registers the operations of the ADK application."""
         return {
@@ -1776,6 +1863,7 @@ def register_operations(self) -> Dict[str, List[str]]:
                 "async_stream_query",
                 "streaming_agent_run_with_events",
             ],
+            "bidi_stream": ["bidi_stream_query"],
         }
 
     def _telemetry_enabled(self) -> Optional[bool]: