feat(sessions): implement get_user_state method in PerAgentDatabaseSessionService and add corresponding unit tests

- Added `get_user_state(app_name, user_id)` method to `PerAgentDatabaseSessionService` for retrieving user state.
- Created unit tests to validate the functionality of `get_user_state`, ensuring it returns the correct state for existing users and an empty dictionary for non-existent users.
- Removed obsolete `test_get_user_state.py` file as its functionality is now covered by the new tests.

Author: nicolasmota

src/google/adk/cli/utils/local_storage.py

@@ -18,6 +18,7 @@
 import asyncio
 import logging
 from pathlib import Path
+from typing import Any
 from typing import Mapping
 from typing import Optional
 
@@ -205,6 +206,13 @@ async def delete_session(
         app_name=app_name, user_id=user_id, session_id=session_id
     )
 
+  @override
+  async def get_user_state(
+      self, *, app_name: str, user_id: str
+  ) -> dict[str, Any]:
+    service = await self._get_service(app_name)
+    return await service.get_user_state(app_name=app_name, user_id=user_id)
+
   @override
   async def append_event(self, session: Session, event: Event) -> Event:
     service = await self._get_service(session.app_name)

tests/unittests/cli/utils/test_local_storage.py

@@ -19,6 +19,8 @@
 from google.adk.cli.utils.local_storage import create_local_database_session_service
 from google.adk.cli.utils.local_storage import create_local_session_service
 from google.adk.cli.utils.local_storage import PerAgentDatabaseSessionService
+from google.adk.events.event import Event
+from google.adk.events.event_actions import EventActions
 from google.adk.sessions.sqlite_session_service import SqliteSessionService
 import pytest
 
@@ -90,3 +92,28 @@ def test_create_local_database_session_service_returns_sqlite(
   service = create_local_database_session_service(base_dir=tmp_path)
 
   assert isinstance(service, SqliteSessionService)
+
+
+@pytest.mark.asyncio
+async def test_per_agent_session_service_get_user_state(tmp_path: Path) -> None:
+  agent_a = tmp_path / 'agent_a'
+  agent_b = tmp_path / 'agent_b'
+  agent_a.mkdir()
+  agent_b.mkdir()
+
+  service = PerAgentDatabaseSessionService(agents_root=tmp_path)
+
+  session_a = await service.create_session(app_name='agent_a', user_id='user_a')
+  await service.append_event(
+      session_a,
+      Event(
+          author='system',
+          actions=EventActions(state_delta={'user:profile': {'name': 'Alice'}}),
+      ),
+  )
+
+  state_a = await service.get_user_state(app_name='agent_a', user_id='user_a')
+  state_b = await service.get_user_state(app_name='agent_b', user_id='user_b')
+
+  assert state_a == {'profile': {'name': 'Alice'}}
+  assert state_b == {}

tests/unittests/sessions/test_get_user_state.py

@@ -30,6 +30,7 @@
 from google.adk.sessions.database_session_service import DatabaseSessionService
 from google.adk.sessions.in_memory_session_service import InMemorySessionService
 from google.adk.sessions.sqlite_session_service import SqliteSessionService
+from google.adk.sessions.vertex_ai_session_service import VertexAiSessionService
 from google.genai import types
 import pytest
 from sqlalchemy import delete
@@ -1650,3 +1651,124 @@ async def tracking_fn(**kwargs):
   finally:
     database_session_service._select_required_state = original_fn
     await service.close()
+
+
+@pytest.mark.asyncio
+async def test_get_user_state_returns_empty_dict_when_no_state_exists(
+    session_service,
+):
+  state = await session_service.get_user_state(
+      app_name='my_app', user_id='u1'
+  )
+  assert state == {}
+
+
+@pytest.mark.asyncio
+async def test_get_user_state_returns_state_written_via_append_event(
+    session_service,
+):
+  session = await session_service.create_session(
+      app_name='my_app', user_id='u1'
+  )
+  await session_service.append_event(
+      session,
+      Event(
+          author='system',
+          actions=EventActions(
+              state_delta={'user:profile': {'name': 'Alice'}, 'session_key': 1}
+          ),
+      ),
+  )
+
+  state = await session_service.get_user_state(app_name='my_app', user_id='u1')
+
+  assert state == {'profile': {'name': 'Alice'}}
+  assert 'session_key' not in state
+
+
+@pytest.mark.asyncio
+async def test_get_user_state_is_not_visible_across_users(session_service):
+  session = await session_service.create_session(
+      app_name='my_app', user_id='u1'
+  )
+  await session_service.append_event(
+      session,
+      Event(
+          author='system',
+          actions=EventActions(state_delta={'user:secret': 'only-for-u1'}),
+      ),
+  )
+
+  other_state = await session_service.get_user_state(
+      app_name='my_app', user_id='u2'
+  )
+  assert other_state == {}
+
+
+@pytest.mark.asyncio
+async def test_get_user_state_is_not_visible_across_apps(session_service):
+  session = await session_service.create_session(
+      app_name='my_app', user_id='u1'
+  )
+  await session_service.append_event(
+      session,
+      Event(
+          author='system',
+          actions=EventActions(state_delta={'user:data': 'only-app-a'}),
+      ),
+  )
+
+  other_state = await session_service.get_user_state(
+      app_name='other_app', user_id='u1'
+  )
+  assert other_state == {}
+
+
+@pytest.mark.asyncio
+async def test_get_user_state_available_before_session_is_created(
+    session_service,
+):
+  first_session = await session_service.create_session(
+      app_name='my_app', user_id='u1'
+  )
+  await session_service.append_event(
+      first_session,
+      Event(
+          author='system',
+          actions=EventActions(state_delta={'user:ctx': {'v': 1}}),
+      ),
+  )
+
+  state = await session_service.get_user_state(app_name='my_app', user_id='u1')
+  assert state == {'ctx': {'v': 1}}
+
+
+@pytest.mark.asyncio
+async def test_get_user_state_reflects_latest_write(session_service):
+  session = await session_service.create_session(
+      app_name='my_app', user_id='u1'
+  )
+  await session_service.append_event(
+      session,
+      Event(
+          author='system',
+          actions=EventActions(state_delta={'user:counter': 1}),
+      ),
+  )
+  await session_service.append_event(
+      session,
+      Event(
+          author='system',
+          actions=EventActions(state_delta={'user:counter': 2}),
+      ),
+  )
+
+  state = await session_service.get_user_state(app_name='my_app', user_id='u1')
+  assert state['counter'] == 2
+
+
+@pytest.mark.asyncio
+async def test_vertex_ai_session_service_raises_not_implemented_for_get_user_state():
+  service = VertexAiSessionService(project='proj', location='us-central1')
+  with pytest.raises(NotImplementedError):
+    await service.get_user_state(app_name='my_app', user_id='u1')