RuntimeError: Task attached to a different loop

Root cause

The FastAPI webhook dispatcher starts a background worker and creates its asyncio.Queue during app startup from a session-scoped pytest fixture. pytest-asyncio resets/replaces the event loop for the async test, so the request handler later awaits a queue Future bound to the stale startup loop.

Minimal fix

Change the FastAPI app/client fixtures in tests/conftest.py to be function-scoped, create the app inside the active test loop, and explicitly await lifespan startup before yielding the AsyncClient. Avoid constructing the dispatcher or starting background tasks at module import/session scope; shut them down during fixture teardown.