RuntimeError: Task attached to a different loop

Root cause

Background retry worker and its asyncio.Queue were initialized during a session-scoped FastAPI startup fixture before pytest-asyncio reset the event loop for the test function. The webhook handler later awaited the queue from the function test loop, producing a cross-loop Future/Task RuntimeError.

Minimal fix

Make the FastAPI app/client fixture function-scoped so startup runs on the same loop as each async test, and explicitly await application lifespan startup before issuing requests. Avoid creating BackgroundTask/asyncio.Queue at import time or in a session-scoped fixture; initialize them inside the fixture/lifespan tied to the active pytest-asyncio event loop.