From 6b93a72b18d46d3781f59f3e570ec98e0a0957b2 Mon Sep 17 00:00:00 2001
From: chelsealong <chelsealong@126.com>
Date: Sat, 1 Aug 2026 08:11:38 +0800
Subject: [PATCH] fix(sessions): preserve original Event.id from raw_event in
 VertexAiSessionService

_from_api_event overwrote the ADK event id with the Vertex resource name, so
the same logical event reported a different id depending on whether it was seen
via streaming or via a reload. Fall back to the resource name only when
raw_event carries no id, which keeps older data working.

Port of #6531 to the v1 line, requested by @ashubham on that PR.
---
 .../adk/sessions/vertex_ai_session_service.py |  5 ++-
 .../test_vertex_ai_session_service.py         | 45 +++++++++++++++++++
 2 files changed, 49 insertions(+), 1 deletion(-)

diff --git a/src/google/adk/sessions/vertex_ai_session_service.py b/src/google/adk/sessions/vertex_ai_session_service.py
index 8c1fdc134e2..85cfb4f9dc3 100644
--- a/src/google/adk/sessions/vertex_ai_session_service.py
+++ b/src/google/adk/sessions/vertex_ai_session_service.py
@@ -436,10 +436,13 @@ def _from_api_event(api_event_obj: vertexai.types.SessionEvent) -> Event:
     event_dict = copy.deepcopy(raw_event_dict)
     timestamp_obj = getattr(api_event_obj, 'timestamp', None)
     event_dict.update({
-        'id': api_event_obj.name.split('/')[-1],
         'invocation_id': getattr(api_event_obj, 'invocation_id', None),
         'author': getattr(api_event_obj, 'author', None),
     })
+    # Preserve the original ADK event id from raw_event so it stays stable
+    # across streaming and reload; only fall back to the Vertex resource
+    # name if raw_event lacks an id (older data).
+    event_dict.setdefault('id', api_event_obj.name.split('/')[-1])
     if timestamp_obj:
       event_dict['timestamp'] = timestamp_obj.timestamp()
     return Event.model_validate(event_dict)
diff --git a/tests/unittests/sessions/test_vertex_ai_session_service.py b/tests/unittests/sessions/test_vertex_ai_session_service.py
index c5c9996ef5e..f87a334aa3a 100644
--- a/tests/unittests/sessions/test_vertex_ai_session_service.py
+++ b/tests/unittests/sessions/test_vertex_ai_session_service.py
@@ -255,6 +255,24 @@ def _generate_mock_events_for_session_5(num_events):
     'user_id': 'user_with_override',
 }
 
+MOCK_EVENT_WITH_RAW_EVENT_ID_JSON = [{
+    'name': (
+        'projects/test-project/locations/test-location/'
+        'reasoningEngines/123/sessions/override/events/658731057016733696'
+    ),
+    'invocationId': 'e-1',
+    'author': 'user_with_override',
+    'timestamp': '2024-12-12T12:12:12.123456Z',
+    'content': {},
+    'actions': {},
+    'rawEvent': {
+        'id': 'c452feb0-b9ad-48b1-b863-c7dd2f085378',
+        'invocationId': 'e-1',
+        'author': 'user_with_override',
+        'content': {},
+    },
+}]
+
 MOCK_SESSION = Session(
     app_name='123',
     user_id='user',
@@ -1311,3 +1329,30 @@ class DummyModel(pydantic.BaseModel):
 
   assert appended_event.actions.compaction is not None
   assert appended_event.actions.compaction.start_timestamp == 1000.0
+
+
+@pytest.mark.asyncio
+@pytest.mark.usefixtures('mock_get_api_client')
+async def test_get_session_preserves_original_event_id_from_raw_event(
+    mock_api_client_instance: MockAsyncClient,
+) -> None:
+  """get_session should keep the original ADK Event.id persisted in raw_event.
+
+  Regression test for the raw_event id being overwritten by the Vertex event
+  resource name, which made the same logical event report a different id
+  depending on whether it was observed via streaming or via a reload.
+  """
+  mock_api_client_instance.session_dict['6'] = MOCK_SESSION_WITH_OVERRIDE_JSON
+  mock_api_client_instance.event_dict['6'] = (
+      copy.deepcopy(MOCK_EVENT_WITH_RAW_EVENT_ID_JSON),
+      None,
+  )
+  session_service = mock_vertex_ai_session_service()
+  session = await session_service.get_session(
+      app_name='123', user_id='user_with_override', session_id='6'
+  )
+  assert session is not None
+  assert len(session.events) == 1
+  assert (
+      session.events[0].id == 'c452feb0-b9ad-48b1-b863-c7dd2f085378'
+  ), 'Event.id should come from raw_event, not the Vertex resource name.'