RuntimeError: aclose(): asynchronous generator is already running

[gisce-ti-sentry]

Sentry Issue: GAB-F

ExceptionGroup: unhandled errors in a TaskGroup
  File "starlette/_utils.py", line 81, in collapse_excgroups
    yield
  File "starlette/responses.py", line 274, in __call__
    async with anyio.create_task_group() as task_group:
  File "anyio/_backends/_asyncio.py", line 799, in __aexit__
    raise BaseExceptionGroup(

RuntimeError: aclose(): asynchronous generator is already running
(15 additional frame(s) were not displayed)
...
  File "contextlib.py", line 162, in __exit__
    self.gen.throw(value)
  File "starlette/_utils.py", line 87, in collapse_excgroups
    raise exc
  File "starlette/responses.py", line 277, in wrap
    await func()
  File "starlette/responses.py", line 250, in stream_response
    async for chunk in self.body_iterator:
  File "github_agent_bridge/backend.py", line 325, in _journal_stream_events
    await stream.aclose()

This issue was automatically created by Sentry via Github Issue

[giscebot]

Fix prepared in upstream PR pilipilisbot#175.

Root cause: on an SSE client disconnect, cancellation could interrupt _journal_stream_events while its anext(stream) task was still running; the finally block then called stream.aclose() concurrently and raised the reported RuntimeError. The patch cancels and awaits pending read/shutdown tasks before closing the generator and adds a regression test reproducing the exact race.

Validation: focused regression tests pass (2/2); full clean-environment suite passes (342 tests).