fix: shield toolset cleanup from cancellation

Shields each toolset cleanup task during Runner.close() so caller cancellation does not cancel the underlying toolset.close() coroutine.

PiperOrigin-RevId: 945791744

src/google/adk/runners.py

@@ -2185,10 +2185,12 @@ class Runner:
 
     # This maintains the same task context throughout cleanup
     for toolset in toolsets_to_close:
+      cleanup_task = asyncio.create_task(
+          asyncio.wait_for(toolset.close(), timeout=10.0)
+      )
       try:
         logger.info('Closing toolset: %s', type(toolset).__name__)
-        # Use asyncio.wait_for to add timeout protection
-        await asyncio.wait_for(toolset.close(), timeout=10.0)
+        await asyncio.shield(cleanup_task)
         logger.info('Successfully closed toolset: %s', type(toolset).__name__)
       except asyncio.TimeoutError:
         logger.warning('Toolset %s cleanup timed out', type(toolset).__name__)
@@ -2203,8 +2205,35 @@ class Runner:
         # improved context propagation across task boundaries, and better cancellation
         # handling prevent the cross-task cancel scope violation.
         logger.warning(
-            'Toolset %s cleanup cancelled: %s', type(toolset).__name__, e
+            'Toolset %s cleanup cancellation requested: %s',
+            type(toolset).__name__,
+            e,
         )
+        try:
+          await cleanup_task
+          logger.info(
+              'Successfully closed toolset after cancellation request: %s',
+              type(toolset).__name__,
+          )
+        except asyncio.TimeoutError:
+          cleanup_task.cancel()
+          logger.warning(
+              'Toolset %s cleanup timed out after cancellation request',
+              type(toolset).__name__,
+          )
+        except asyncio.CancelledError as close_cancelled:
+          logger.warning(
+              'Toolset %s cleanup cancelled: %s',
+              type(toolset).__name__,
+              close_cancelled,
+          )
+        except Exception as close_error:
+          logger.error(
+              'Error closing toolset %s after cancellation request: %s',
+              type(toolset).__name__,
+              close_error,
+          )
+        raise
       except Exception as e:
         logger.error('Error closing toolset %s: %s', type(toolset).__name__, e)
 

tests/unittests/test_runners.py

@@ -12,6 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import asyncio
 from contextlib import aclosing
 import importlib
 from pathlib import Path
@@ -36,6 +37,7 @@ from google.adk.plugins.base_plugin import BasePlugin
 from google.adk.runners import Runner
 from google.adk.sessions.in_memory_session_service import InMemorySessionService
 from google.adk.sessions.session import Session
+from google.adk.tools.base_toolset import BaseToolset
 from google.genai import types
 import pytest
 
@@ -1120,6 +1122,52 @@ class TestRunnerWithPlugins:
 
     self.runner.plugin_manager.close.assert_awaited_once()
 
+  @pytest.mark.asyncio
+  async def test_runner_close_does_not_cancel_toolset_cleanup(self):
+    """Caller cancellation should not cancel an in-flight toolset close."""
+
+    class SlowCloseToolset(BaseToolset):
+
+      def __init__(self):
+        super().__init__()
+        self.close_started = asyncio.Event()
+        self.close_finished = asyncio.Event()
+        self.close_cancelled = False
+
+      async def get_tools(self, readonly_context=None):
+        del readonly_context
+        return []
+
+      async def close(self) -> None:
+        self.close_started.set()
+        try:
+          await asyncio.sleep(0.05)
+          self.close_finished.set()
+        except asyncio.CancelledError:
+          self.close_cancelled = True
+          raise
+
+    toolset = SlowCloseToolset()
+    runner = Runner(
+        app_name="test_app",
+        agent=LlmAgent(
+            name="test_agent", model="gemini-1.5-pro", tools=[toolset]
+        ),
+        session_service=self.session_service,
+        artifact_service=self.artifact_service,
+    )
+
+    close_task = asyncio.create_task(runner.close())
+    await toolset.close_started.wait()
+    close_task.cancel()
+
+    with pytest.raises(asyncio.CancelledError):
+      await close_task
+
+    assert close_task.cancelled() is True
+    assert toolset.close_cancelled is False
+    assert toolset.close_finished.is_set()
+
   @pytest.mark.asyncio
   async def test_runner_passes_plugin_close_timeout(self):
     """Test that runner passes plugin_close_timeout to PluginManager."""