RuntimeError: Task attached to a different loop

Root cause

Background WebhookDispatcher task and asyncio.Queue were initialized during a session-scoped FastAPI app/client fixture before pytest-asyncio reset the event loop for the individual async test. The request handler then awaited a queue future bound to the stale startup loop, producing a cross-loop RuntimeError.

Minimal fix

Make the FastAPI app/client fixture function-scoped, ensure pytest-asyncio uses a function-scoped event loop, and explicitly await the application lifespan/startup inside the same loop used by the test. Avoid creating background dispatcher tasks at import time or in session-scoped fixtures; create and cancel them in the fixture teardown.