diff --git a/src/google/adk/sessions/_session_util.py b/src/google/adk/sessions/_session_util.py
index 68340c8b..0b2f99ee 100644
--- a/src/google/adk/sessions/_session_util.py
+++ b/src/google/adk/sessions/_session_util.py
@@ -19,6 +19,8 @@ from typing import Optional
 from typing import Type
 from typing import TypeVar
 
+from .state import State
+
 M = TypeVar("M")
 
 
@@ -29,3 +31,19 @@ def decode_model(
   if data is None:
     return None
   return model_cls.model_validate(data)
+
+
+def extract_state_delta(
+    state: dict[str, Any],
+) -> dict[str, dict[str, Any]]:
+  """Extracts app, user, and session state deltas from a state dictionary."""
+  deltas = {"app": {}, "user": {}, "session": {}}
+  if state:
+    for key in state.keys():
+      if key.startswith(State.APP_PREFIX):
+        deltas["app"][key.removeprefix(State.APP_PREFIX)] = state[key]
+      elif key.startswith(State.USER_PREFIX):
+        deltas["user"][key.removeprefix(State.USER_PREFIX)] = state[key]
+      elif not key.startswith(State.TEMP_PREFIX):
+        deltas["session"][key] = state[key]
+  return deltas
diff --git a/src/google/adk/sessions/database_session_service.py b/src/google/adk/sessions/database_session_service.py
index 04af695b..6ce14961 100644
--- a/src/google/adk/sessions/database_session_service.py
+++ b/src/google/adk/sessions/database_session_service.py
@@ -465,20 +465,14 @@ class DatabaseSessionService(BaseSessionService):
     # 5. Return the session
 
     with self.database_session_factory() as sql_session:
-
       # Fetch app and user states from storage
       storage_app_state = sql_session.get(StorageAppState, (app_name))
-      storage_user_state = sql_session.get(
-          StorageUserState, (app_name, user_id)
-      )
-
-      app_state = storage_app_state.state if storage_app_state else {}
-      user_state = storage_user_state.state if storage_user_state else {}
-
-      # Create state tables if not exist
       if not storage_app_state:
         storage_app_state = StorageAppState(app_name=app_name, state={})
         sql_session.add(storage_app_state)
+      storage_user_state = sql_session.get(
+          StorageUserState, (app_name, user_id)
+      )
       if not storage_user_state:
         storage_user_state = StorageUserState(
             app_name=app_name, user_id=user_id, state={}
@@ -486,19 +480,16 @@ class DatabaseSessionService(BaseSessionService):
         sql_session.add(storage_user_state)
 
       # Extract state deltas
-      app_state_delta, user_state_delta, session_state = _extract_state_delta(
-          state
-      )
+      state_deltas = _session_util.extract_state_delta(state)
+      app_state_delta = state_deltas["app"]
+      user_state_delta = state_deltas["user"]
+      session_state = state_deltas["session"]
 
       # Apply state delta
-      app_state.update(app_state_delta)
-      user_state.update(user_state_delta)
-
-      # Store app and user state
       if app_state_delta:
-        storage_app_state.state = app_state
+        storage_app_state.state = storage_app_state.state | app_state_delta
       if user_state_delta:
-        storage_user_state.state = user_state
+        storage_user_state.state = storage_user_state.state | user_state_delta
 
       # Store the session
       storage_session = StorageSession(
@@ -513,7 +504,9 @@ class DatabaseSessionService(BaseSessionService):
       sql_session.refresh(storage_session)
 
       # Merge states for response
-      merged_state = _merge_state(app_state, user_state, session_state)
+      merged_state = _merge_state(
+          storage_app_state.state, storage_user_state.state, session_state
+      )
       session = storage_session.to_session(state=merged_state)
     return session
 
@@ -536,19 +529,18 @@ class DatabaseSessionService(BaseSessionService):
       if storage_session is None:
         return None
 
+      query = sql_session.query(StorageEvent).filter(
+          StorageEvent.app_name == app_name,
+          StorageEvent.user_id == user_id,
+          StorageEvent.session_id == storage_session.id,
+      )
+
       if config and config.after_timestamp:
         after_dt = datetime.fromtimestamp(config.after_timestamp)
-        timestamp_filter = StorageEvent.timestamp >= after_dt
-      else:
-        timestamp_filter = True
+        query = query.filter(StorageEvent.timestamp >= after_dt)
 
       storage_events = (
-          sql_session.query(StorageEvent)
-          .filter(StorageEvent.app_name == app_name)
-          .filter(StorageEvent.session_id == storage_session.id)
-          .filter(StorageEvent.user_id == user_id)
-          .filter(timestamp_filter)
-          .order_by(StorageEvent.timestamp.desc())
+          query.order_by(StorageEvent.timestamp.desc())
           .limit(
               config.num_recent_events
               if config and config.num_recent_events
@@ -660,30 +652,21 @@ class DatabaseSessionService(BaseSessionService):
           StorageUserState, (session.app_name, session.user_id)
       )
 
-      app_state = storage_app_state.state if storage_app_state else {}
-      user_state = storage_user_state.state if storage_user_state else {}
-      session_state = storage_session.state
-
       # Extract state delta
-      app_state_delta = {}
-      user_state_delta = {}
-      session_state_delta = {}
-      if event.actions:
-        if event.actions.state_delta:
-          app_state_delta, user_state_delta, session_state_delta = (
-              _extract_state_delta(event.actions.state_delta)
-          )
-
-      # Merge state and update storage
-      if app_state_delta:
-        app_state.update(app_state_delta)
-        storage_app_state.state = app_state
-      if user_state_delta:
-        user_state.update(user_state_delta)
-        storage_user_state.state = user_state
-      if session_state_delta:
-        session_state.update(session_state_delta)
-        storage_session.state = session_state
+      if event.actions and event.actions.state_delta:
+        state_deltas = _session_util.extract_state_delta(
+            event.actions.state_delta
+        )
+        app_state_delta = state_deltas["app"]
+        user_state_delta = state_deltas["user"]
+        session_state_delta = state_deltas["session"]
+        # Merge state and update storage
+        if app_state_delta:
+          storage_app_state.state = storage_app_state.state | app_state_delta
+        if user_state_delta:
+          storage_user_state.state = storage_user_state.state | user_state_delta
+        if session_state_delta:
+          storage_session.state = storage_session.state | session_state_delta
 
       sql_session.add(StorageEvent.from_event(session, event))
 
@@ -698,21 +681,6 @@ class DatabaseSessionService(BaseSessionService):
     return event
 
 
-def _extract_state_delta(state: dict[str, Any]):
-  app_state_delta = {}
-  user_state_delta = {}
-  session_state_delta = {}
-  if state:
-    for key in state.keys():
-      if key.startswith(State.APP_PREFIX):
-        app_state_delta[key.removeprefix(State.APP_PREFIX)] = state[key]
-      elif key.startswith(State.USER_PREFIX):
-        user_state_delta[key.removeprefix(State.USER_PREFIX)] = state[key]
-      elif not key.startswith(State.TEMP_PREFIX):
-        session_state_delta[key] = state[key]
-  return app_state_delta, user_state_delta, session_state_delta
-
-
 def _merge_state(app_state, user_state, session_state):
   # Merge states for response
   merged_state = copy.deepcopy(session_state)
diff --git a/src/google/adk/sessions/in_memory_session_service.py b/src/google/adk/sessions/in_memory_session_service.py
index adc09230..e45cf9d8 100644
--- a/src/google/adk/sessions/in_memory_session_service.py
+++ b/src/google/adk/sessions/in_memory_session_service.py
@@ -22,6 +22,7 @@ import uuid
 
 from typing_extensions import override
 
+from . import _session_util
 from ..events.event import Event
 from .base_session_service import BaseSessionService
 from .base_session_service import GetSessionConfig
@@ -88,6 +89,17 @@ class InMemorySessionService(BaseSessionService):
       state: Optional[dict[str, Any]] = None,
       session_id: Optional[str] = None,
   ) -> Session:
+    state_deltas = _session_util.extract_state_delta(state)
+    app_state_delta = state_deltas['app']
+    user_state_delta = state_deltas['user']
+    session_state = state_deltas['session']
+    if app_state_delta:
+      self.app_state.setdefault(app_name, {}).update(app_state_delta)
+    if user_state_delta:
+      self.user_state.setdefault(app_name, {}).setdefault(user_id, {}).update(
+          user_state_delta
+      )
+
     session_id = (
         session_id.strip()
         if session_id and session_id.strip()
@@ -97,7 +109,7 @@ class InMemorySessionService(BaseSessionService):
         app_name=app_name,
         user_id=user_id,
         id=session_id,
-        state=state or {},
+        state=session_state or {},
         last_update_time=time.time(),
     )
 
@@ -174,11 +186,13 @@ class InMemorySessionService(BaseSessionService):
         if i >= 0:
           copied_session.events = copied_session.events[i + 1 :]
 
+    # Return a copy of the session object with merged state.
     return self._merge_state(app_name, user_id, copied_session)
 
   def _merge_state(
       self, app_name: str, user_id: str, copied_session: Session
   ) -> Session:
+    """Merges app and user state into session state."""
     # Merge app state
     if app_name in self.app_state:
       for key in self.app_state[app_name].keys():
@@ -269,11 +283,9 @@ class InMemorySessionService(BaseSessionService):
 
   @override
   async def append_event(self, session: Session, event: Event) -> Event:
-    # Update the in-memory session.
-    await super().append_event(session=session, event=event)
-    session.last_update_time = event.timestamp
+    if event.partial:
+      return event
 
-    # Update the storage session
     app_name = session.app_name
     user_id = session.user_id
     session_id = session.id
@@ -293,21 +305,29 @@ class InMemorySessionService(BaseSessionService):
       _warning(f'session_id {session_id} not in sessions[app_name][user_id]')
       return event
 
-    if event.actions and event.actions.state_delta:
-      for key in event.actions.state_delta:
-        if key.startswith(State.APP_PREFIX):
-          self.app_state.setdefault(app_name, {})[
-              key.removeprefix(State.APP_PREFIX)
-          ] = event.actions.state_delta[key]
-
-        if key.startswith(State.USER_PREFIX):
-          self.user_state.setdefault(app_name, {}).setdefault(user_id, {})[
-              key.removeprefix(State.USER_PREFIX)
-          ] = event.actions.state_delta[key]
+    # Update the in-memory session.
+    await super().append_event(session=session, event=event)
+    session.last_update_time = event.timestamp
 
+    # Update the storage session
     storage_session = self.sessions[app_name][user_id].get(session_id)
-    await super().append_event(session=storage_session, event=event)
-
+    storage_session.events.append(event)
     storage_session.last_update_time = event.timestamp
 
+    if event.actions and event.actions.state_delta:
+      state_deltas = _session_util.extract_state_delta(
+          event.actions.state_delta
+      )
+      app_state_delta = state_deltas['app']
+      user_state_delta = state_deltas['user']
+      session_state_delta = state_deltas['session']
+      if app_state_delta:
+        self.app_state.setdefault(app_name, {}).update(app_state_delta)
+      if user_state_delta:
+        self.user_state.setdefault(app_name, {}).setdefault(user_id, {}).update(
+            user_state_delta
+        )
+      if session_state_delta:
+        storage_session.state.update(session_state_delta)
+
     return event
diff --git a/tests/unittests/sessions/test_session_service.py b/tests/unittests/sessions/test_session_service.py
index 0dd4162e..4d92dcea 100644
--- a/tests/unittests/sessions/test_session_service.py
+++ b/tests/unittests/sessions/test_session_service.py
@@ -90,7 +90,7 @@ async def test_create_get_session(service_type):
       await session_service.get_session(
           app_name=app_name, user_id=user_id, session_id=session.id
       )
-      != session
+      is None
   )
 
 
@@ -151,20 +151,17 @@ async def test_list_sessions_all_users(service_type):
       state={'key': 'value2a'},
   )
 
-  # List sessions for user1
+  # List sessions for user1 - should contain merged state
   list_sessions_response_1 = await session_service.list_sessions(
       app_name=app_name, user_id=user_id_1
   )
   sessions_1 = list_sessions_response_1.sessions
   assert len(sessions_1) == 2
-  assert {s.id for s in sessions_1} == {'session1a', 'session1b'}
-  for session in sessions_1:
-    if session.id == 'session1a':
-      assert session.state == {'key': 'value1a'}
-    else:
-      assert session.state == {'key': 'value1b'}
+  sessions_1_map = {s.id: s for s in sessions_1}
+  assert sessions_1_map['session1a'].state == {'key': 'value1a'}
+  assert sessions_1_map['session1b'].state == {'key': 'value1b'}
 
-  # List sessions for user2
+  # List sessions for user2 - should contain merged state
   list_sessions_response_2 = await session_service.list_sessions(
       app_name=app_name, user_id=user_id_2
   )
@@ -173,151 +170,170 @@ async def test_list_sessions_all_users(service_type):
   assert sessions_2[0].id == 'session2a'
   assert sessions_2[0].state == {'key': 'value2a'}
 
-  # List sessions for all users
+  # List sessions for all users - should contain merged state
   list_sessions_response_all = await session_service.list_sessions(
       app_name=app_name, user_id=None
   )
   sessions_all = list_sessions_response_all.sessions
   assert len(sessions_all) == 3
-  assert {s.id for s in sessions_all} == {'session1a', 'session1b', 'session2a'}
+  sessions_all_map = {s.id: s for s in sessions_all}
+  assert sessions_all_map['session1a'].state == {'key': 'value1a'}
+  assert sessions_all_map['session1b'].state == {'key': 'value1b'}
+  assert sessions_all_map['session2a'].state == {'key': 'value2a'}
 
 
 @pytest.mark.asyncio
 @pytest.mark.parametrize(
     'service_type', [SessionServiceType.IN_MEMORY, SessionServiceType.DATABASE]
 )
-async def test_session_state(service_type):
+async def test_app_state_is_shared_by_all_users_of_app(service_type):
   session_service = get_session_service(service_type)
   app_name = 'my_app'
-  user_id_1 = 'user1'
-  user_id_2 = 'user2'
-  user_id_malicious = 'malicious'
-  session_id_11 = 'session11'
-  session_id_12 = 'session12'
-  session_id_2 = 'session2'
-  state_11 = {'key11': 'value11'}
-  state_12 = {'key12': 'value12'}
-
-  session_11 = await session_service.create_session(
-      app_name=app_name,
-      user_id=user_id_1,
-      state=state_11,
-      session_id=session_id_11,
+  # User 1 creates a session, establishing app:k1
+  session1 = await session_service.create_session(
+      app_name=app_name, user_id='u1', session_id='s1', state={'app:k1': 'v1'}
   )
-  await session_service.create_session(
-      app_name=app_name,
-      user_id=user_id_1,
-      state=state_12,
-      session_id=session_id_12,
-  )
-  await session_service.create_session(
-      app_name=app_name, user_id=user_id_2, session_id=session_id_2
-  )
-
-  await session_service.create_session(
-      app_name=app_name, user_id=user_id_malicious, session_id=session_id_11
-  )
-
-  assert session_11.state.get('key11') == 'value11'
-
+  # User 1 appends an event to session1, establishing app:k2
   event = Event(
-      invocation_id='invocation',
+      invocation_id='inv1',
       author='user',
-      content=types.Content(role='user', parts=[types.Part(text='text')]),
-      actions=EventActions(
-          state_delta={
-              'app:key': 'value',
-              'user:key1': 'value1',
-              'temp:key': 'temp',
-              'key11': 'value11_new',
-          }
-      ),
+      actions=EventActions(state_delta={'app:k2': 'v2'}),
   )
-  await session_service.append_event(session=session_11, event=event)
+  await session_service.append_event(session=session1, event=event)
 
-  # User and app state is stored, temp state is filtered.
-  assert session_11.state.get('app:key') == 'value'
-  assert session_11.state.get('key11') == 'value11_new'
-  assert session_11.state.get('user:key1') == 'value1'
-  assert not session_11.state.get('temp:key')
-
-  session_12 = await session_service.get_session(
-      app_name=app_name, user_id=user_id_1, session_id=session_id_12
+  # User 2 creates a new session session2, it should see app:k1 and app:k2
+  session2 = await session_service.create_session(
+      app_name=app_name, user_id='u2', session_id='s2'
   )
-  # After getting a new instance, the session_12 got the user and app state,
-  # even append_event is not applied to it, temp state has no effect
-  assert session_12.state.get('key12') == 'value12'
-  assert not session_12.state.get('temp:key')
+  assert session2.state == {'app:k1': 'v1', 'app:k2': 'v2'}
 
-  # The user1's state is not visible to user2, app state is visible
-  session_2 = await session_service.get_session(
-      app_name=app_name, user_id=user_id_2, session_id=session_id_2
+  # If we get session session1 again, it should also see both
+  session1_got = await session_service.get_session(
+      app_name=app_name, user_id='u1', session_id='s1'
   )
-  assert session_2.state.get('app:key') == 'value'
-  assert not session_2.state.get('user:key1')
-
-  assert not session_2.state.get('user:key1')
-
-  # The change to session_11 is persisted
-  session_11 = await session_service.get_session(
-      app_name=app_name, user_id=user_id_1, session_id=session_id_11
-  )
-  assert session_11.state.get('key11') == 'value11_new'
-  assert session_11.state.get('user:key1') == 'value1'
-  assert not session_11.state.get('temp:key')
-
-  # Make sure a malicious user cannot obtain a session and events not belonging to them
-  session_mismatch = await session_service.get_session(
-      app_name=app_name, user_id=user_id_malicious, session_id=session_id_11
-  )
-
-  assert len(session_mismatch.events) == 0
+  assert session1_got.state.get('app:k1') == 'v1'
+  assert session1_got.state.get('app:k2') == 'v2'
 
 
 @pytest.mark.asyncio
 @pytest.mark.parametrize(
     'service_type', [SessionServiceType.IN_MEMORY, SessionServiceType.DATABASE]
 )
-async def test_create_new_session_will_merge_states(service_type):
+async def test_user_state_is_shared_only_by_user_sessions(service_type):
   session_service = get_session_service(service_type)
   app_name = 'my_app'
-  user_id = 'user'
-  session_id_1 = 'session1'
-  session_id_2 = 'session2'
-  state_1 = {'key1': 'value1'}
-
-  session_1 = await session_service.create_session(
-      app_name=app_name, user_id=user_id, state=state_1, session_id=session_id_1
+  # User 1 creates a session, establishing user:k1 for user 1
+  session1 = await session_service.create_session(
+      app_name=app_name, user_id='u1', session_id='s1', state={'user:k1': 'v1'}
   )
-
+  # User 1 appends an event to session1, establishing user:k2 for user 1
   event = Event(
-      invocation_id='invocation',
+      invocation_id='inv1',
       author='user',
-      content=types.Content(role='user', parts=[types.Part(text='text')]),
-      actions=EventActions(
-          state_delta={
-              'app:key': 'value',
-              'user:key1': 'value1',
-              'temp:key': 'temp',
-          }
-      ),
+      actions=EventActions(state_delta={'user:k2': 'v2'}),
   )
-  await session_service.append_event(session=session_1, event=event)
+  await session_service.append_event(session=session1, event=event)
 
-  # User and app state is stored, temp state is filtered.
-  assert session_1.state.get('app:key') == 'value'
-  assert session_1.state.get('key1') == 'value1'
-  assert session_1.state.get('user:key1') == 'value1'
-  assert not session_1.state.get('temp:key')
-
-  session_2 = await session_service.create_session(
-      app_name=app_name, user_id=user_id, state={}, session_id=session_id_2
+  # Another session for User 1 should see user:k1 and user:k2
+  session1b = await session_service.create_session(
+      app_name=app_name, user_id='u1', session_id='s1b'
   )
-  # Session 2 has the persisted states
-  assert session_2.state.get('app:key') == 'value'
-  assert session_2.state.get('user:key1') == 'value1'
-  assert not session_2.state.get('key1')
-  assert not session_2.state.get('temp:key')
+  assert session1b.state == {'user:k1': 'v1', 'user:k2': 'v2'}
+
+  # A session for User 2 should NOT see user:k1 or user:k2
+  session2 = await session_service.create_session(
+      app_name=app_name, user_id='u2', session_id='s2'
+  )
+  assert session2.state == {}
+
+
+@pytest.mark.asyncio
+@pytest.mark.parametrize(
+    'service_type', [SessionServiceType.IN_MEMORY, SessionServiceType.DATABASE]
+)
+async def test_session_state_is_not_shared(service_type):
+  session_service = get_session_service(service_type)
+  app_name = 'my_app'
+  # User 1 creates a session session1, establishing sk1 only for session1
+  session1 = await session_service.create_session(
+      app_name=app_name, user_id='u1', session_id='s1', state={'sk1': 'v1'}
+  )
+  # User 1 appends an event to session1, establishing sk2 only for session1
+  event = Event(
+      invocation_id='inv1',
+      author='user',
+      actions=EventActions(state_delta={'sk2': 'v2'}),
+  )
+  await session_service.append_event(session=session1, event=event)
+
+  # Getting session1 should show sk1 and sk2
+  session1_got = await session_service.get_session(
+      app_name=app_name, user_id='u1', session_id='s1'
+  )
+  assert session1_got.state.get('sk1') == 'v1'
+  assert session1_got.state.get('sk2') == 'v2'
+
+  # Creating another session session1b for User 1 should NOT see sk1 or sk2
+  session1b = await session_service.create_session(
+      app_name=app_name, user_id='u1', session_id='s1b'
+  )
+  assert session1b.state == {}
+
+
+@pytest.mark.asyncio
+@pytest.mark.parametrize(
+    'service_type', [SessionServiceType.IN_MEMORY, SessionServiceType.DATABASE]
+)
+async def test_temp_state_is_not_persisted_in_state_or_events(service_type):
+  session_service = get_session_service(service_type)
+  app_name = 'my_app'
+  user_id = 'u1'
+  session = await session_service.create_session(
+      app_name=app_name, user_id=user_id, session_id='s1'
+  )
+  event = Event(
+      invocation_id='inv1',
+      author='user',
+      actions=EventActions(state_delta={'temp:k1': 'v1', 'sk': 'v2'}),
+  )
+  await session_service.append_event(session=session, event=event)
+
+  # Refetch session and check state and event
+  session_got = await session_service.get_session(
+      app_name=app_name, user_id=user_id, session_id='s1'
+  )
+  # Check session state does not contain temp keys
+  assert session_got.state.get('sk') == 'v2'
+  assert 'temp:k1' not in session_got.state
+  # Check event as stored in session does not contain temp keys in state_delta
+  assert 'temp:k1' not in session_got.events[0].actions.state_delta
+  assert session_got.events[0].actions.state_delta.get('sk') == 'v2'
+
+
+@pytest.mark.asyncio
+@pytest.mark.parametrize(
+    'service_type', [SessionServiceType.IN_MEMORY, SessionServiceType.DATABASE]
+)
+async def test_get_session_respects_user_id(service_type):
+  session_service = get_session_service(service_type)
+  app_name = 'my_app'
+  # u1 creates session 's1' and adds an event
+  session1 = await session_service.create_session(
+      app_name=app_name, user_id='u1', session_id='s1'
+  )
+  event = Event(invocation_id='inv1', author='user')
+  await session_service.append_event(session1, event)
+  # u2 creates a session with the same session_id 's1'
+  await session_service.create_session(
+      app_name=app_name, user_id='u2', session_id='s1'
+  )
+  # Check that getting s1 for u2 returns u2's session (with no events)
+  # not u1's session.
+  session2_got = await session_service.get_session(
+      app_name=app_name, user_id='u2', session_id='s1'
+  )
+  assert session2_got.user_id == 'u2'
+  assert len(session2_got.events) == 0
 
 
 @pytest.mark.asyncio
@@ -390,6 +406,9 @@ async def test_append_event_complete(service_type):
       error_code='error_code',
       error_message='error_message',
       interrupted=True,
+      grounding_metadata=types.GroundingMetadata(
+          web_search_queries=['query1'],
+      ),
       usage_metadata=types.GenerateContentResponseUsageMetadata(
           prompt_token_count=1, candidates_token_count=1, total_token_count=2
       ),
@@ -474,72 +493,20 @@ async def test_get_session_with_config(service_type):
 @pytest.mark.parametrize(
     'service_type', [SessionServiceType.IN_MEMORY, SessionServiceType.DATABASE]
 )
-async def test_append_event_with_fields(service_type):
-  session_service = get_session_service(service_type)
-  app_name = 'my_app'
-  user_id = 'test_user'
-  session = await session_service.create_session(
-      app_name=app_name, user_id=user_id, state={}
-  )
-
-  event = Event(
-      invocation_id='invocation',
-      author='user',
-      content=types.Content(role='user', parts=[types.Part(text='text')]),
-      long_running_tool_ids={'tool1', 'tool2'},
-      partial=False,
-      turn_complete=True,
-      error_code='ERROR_CODE',
-      error_message='error message',
-      interrupted=True,
-      grounding_metadata=types.GroundingMetadata(
-          web_search_queries=['query1'],
-      ),
-      custom_metadata={'custom_key': 'custom_value'},
-  )
-  await session_service.append_event(session, event)
-
-  retrieved_session = await session_service.get_session(
-      app_name=app_name, user_id=user_id, session_id=session.id
-  )
-  assert retrieved_session
-  assert len(retrieved_session.events) == 1
-  retrieved_event = retrieved_session.events[0]
-
-  assert retrieved_event == event
-
-
-@pytest.mark.asyncio
-@pytest.mark.parametrize(
-    'service_type', [SessionServiceType.IN_MEMORY, SessionServiceType.DATABASE]
-)
-async def test_append_event_should_trim_temp_delta_state(service_type):
+async def test_partial_events_are_not_persisted(service_type):
   session_service = get_session_service(service_type)
   app_name = 'my_app'
   user_id = 'user'
-
   session = await session_service.create_session(
       app_name=app_name, user_id=user_id
   )
-
-  event = Event(
-      invocation_id='invocation',
-      author='user',
-      content=types.Content(role='user', parts=[types.Part(text='text')]),
-      actions=EventActions(
-          state_delta={
-              'app:key': 'app_value',
-              'temp:key': 'temp_value',
-          }
-      ),
-  )
-
+  event = Event(author='user', partial=True)
   await session_service.append_event(session, event)
 
-  updated_session = await session_service.get_session(
+  # Check in-memory session
+  assert len(session.events) == 0
+  # Check persisted session
+  session_got = await session_service.get_session(
       app_name=app_name, user_id=user_id, session_id=session.id
   )
-
-  last_event = updated_session.events[-1]
-  assert 'temp:key' not in last_event.actions.state_delta
-  assert last_event.actions.state_delta['app:key'] == 'app_value'
+  assert len(session_got.events) == 0