feat: add support for session TTL and expiration in Vertex AI session service

PiperOrigin-RevId: 917111472

Author: vertex-sdk-bot

agentplatform/agent_engines/templates/adk.py

@@ -1568,6 +1568,10 @@ async def async_create_session(
                 will be be generated for the session.
             state (dict[str, Any]):
                 Optional. The initial state of the session.
+            ttl (str):
+                Optional. The time-to-live for the session.
+            expire_time (str):
+                Optional. The expiration time for the session.
             **kwargs (dict[str, Any]):
                 Optional. Additional keyword arguments to pass to the
                 session service.

tests/unit/vertex_adk/test_agent_engine_templates_adk.py

@@ -554,6 +554,30 @@ async def test_async_create_session(self, get_project_id_mock: mock.Mock):
         assert session2["user_id"] == _TEST_USER_ID
         assert session2["id"] == "test_session_id"
 
+    @pytest.mark.asyncio
+    async def test_async_create_session_with_kwargs(
+        self, get_project_id_mock: mock.Mock
+    ):
+        mock_session_service = mock.AsyncMock()
+        app = agent_engines.AdkApp(
+            agent=_TEST_AGENT,
+            session_service_builder=lambda: mock_session_service,
+        )
+        await app.async_create_session(
+            user_id=_TEST_USER_ID,
+            ttl="7200s",
+            expire_time="2026-03-01T00:00:00Z",
+        )
+        mock_session_service.create_session.assert_called_once_with(
+            app_name=app._app_name(),
+            user_id=_TEST_USER_ID,
+            session_id=None,
+            state=None,
+            ttl="7200s",
+            expire_time="2026-03-01T00:00:00Z",
+        )
+
+
     @pytest.mark.asyncio
     async def test_async_get_session(self, get_project_id_mock: mock.Mock):
         app = agent_engines.AdkApp(agent=_TEST_AGENT)