RuntimeError: Task attached to a different loop

Root cause

A FastAPI startup path initializes retry_queue and creates its background worker task in a session-scoped async fixture. pytest-asyncio then resets or replaces the running event loop for the function-scoped test, so the webhook handler awaits _worker_ready from a task bound to the previous loop.

Minimal fix

Change the app/client fixture for tests/test_webhooks.py to be function-scoped, create the ASGI app inside the active pytest-asyncio loop, and explicitly await FastAPI lifespan startup before yielding the AsyncClient. Avoid constructing retry_queue worker tasks at import time or in a session-scoped fixture; start them during the fixture's lifespan and cancel/await shutdown after each test.