refactor: Remove the session events dependency from A2aAgentExecutor

PiperOrigin-RevId: 893590774

Author: google-genai-bot

src/google/adk/a2a/executor/a2a_agent_executor_impl.py

@@ -38,6 +38,7 @@
 from typing_extensions import override
 
 from ...runners import Runner
+from ...sessions import base_session_service
 from ...utils.context_utils import Aclosing
 from ..agent.interceptors.new_integration_extension import _NEW_A2A_ADK_INTEGRATION_EXTENSION
 from ..converters.from_adk_event import create_error_status_event
@@ -287,6 +288,8 @@ async def _resolve_session(
         app_name=runner.app_name,
         user_id=user_id,
         session_id=session_id,
+        # Checking existence doesn't require event history.
+        config=base_session_service.GetSessionConfig(num_recent_events=0),
     )
     if session is None:
       session = await runner.session_service.create_session(

src/google/adk/sessions/base_session_service.py

@@ -27,7 +27,16 @@
 
 
 class GetSessionConfig(BaseModel):
-  """The configuration of getting a session."""
+  """The configuration of getting a session.
+
+  Attributes:
+    num_recent_events: The limit of recent events to get for the session.
+      Optional: if None, the filter is not applied; if greater than 0, returns
+        at most given number of recent events; if 0, no events are returned.
+    after_timestamp: The earliest timestamp of events to get for the session.
+      Optional: if None, the filter is not applied; otherwise, returns events
+        with timestamp >= the given time.
+  """
 
   num_recent_events: Optional[int] = None
   after_timestamp: Optional[float] = None

src/google/adk/sessions/in_memory_session_service.py

@@ -178,10 +178,13 @@ def _get_session_impl(
     copied_session = copy.deepcopy(session)
 
     if config:
-      if config.num_recent_events:
-        copied_session.events = copied_session.events[
-            -config.num_recent_events :
-        ]
+      if config.num_recent_events is not None:
+        if config.num_recent_events == 0:
+          copied_session.events = []
+        else:
+          copied_session.events = copied_session.events[
+              -config.num_recent_events :
+          ]
       if config.after_timestamp:
         i = len(copied_session.events) - 1
         while i >= 0:

src/google/adk/sessions/sqlite_session_service.py

@@ -261,11 +261,14 @@ async def get_session(
 
       query_parts.append("ORDER BY timestamp DESC")
 
-      if config and config.num_recent_events:
+      if config and config.num_recent_events is not None:
         query_parts.append("LIMIT ?")
         params.append(config.num_recent_events)
 
-      event_rows = await db.execute_fetchall(" ".join(query_parts), params)
+      if config and config.num_recent_events == 0:
+        event_rows = []
+      else:
+        event_rows = await db.execute_fetchall(" ".join(query_parts), params)
       storage_events_data = [row["event_data"] for row in event_rows]
 
       # Fetch states from storage

src/google/adk/sessions/vertex_ai_session_service.py

@@ -172,13 +172,19 @@ async def get_session(
         }
 
       try:
-        get_session_response, events_iterator = await asyncio.gather(
-            api_client.agent_engines.sessions.get(name=session_resource_name),
-            api_client.agent_engines.sessions.events.list(
-                name=session_resource_name,
-                **list_events_kwargs,
-            ),
-        )
+        if config and config.num_recent_events == 0:
+          get_session_response = await api_client.agent_engines.sessions.get(
+              name=session_resource_name
+          )
+          events_iterator = []
+        else:
+          get_session_response, events_iterator = await asyncio.gather(
+              api_client.agent_engines.sessions.get(name=session_resource_name),
+              api_client.agent_engines.sessions.events.list(
+                  name=session_resource_name,
+                  **list_events_kwargs,
+              ),
+          )
       except ClientError as e:
         if e.code == 404:
           logger.debug(

tests/unittests/a2a/executor/test_a2a_agent_executor_impl.py

@@ -36,6 +36,7 @@
 from google.adk.events.event_actions import EventActions
 from google.adk.runners import RunConfig
 from google.adk.runners import Runner
+from google.adk.sessions.base_session_service import GetSessionConfig
 from google.genai.types import Content
 import pytest
 
@@ -659,6 +660,7 @@ async def test_resolve_session_creates_new_session(self):
         app_name=self.mock_runner.app_name,
         user_id="test-user",
         session_id="old-session-id",
+        config=GetSessionConfig(num_recent_events=0, after_timestamp=None),
     )
     self.mock_runner.session_service.create_session.assert_called_once_with(
         app_name=self.mock_runner.app_name,