Backend Hang Debug Purpose - Detect and resolve event-loop hangs where the FastAPI app stops responding (e.g., times out) due to synchronous executor shutdown in the SSE news stream. - Provide a repeatable triage flow using to capture live stacks and pinpoint blocking code. Scope - Backend: (news stream), (RSS workers), startup processes. - Tooling: for live stack dumps; with timeouts for smoke tests. Quick Triage 1. Reproduce hang : and ; note timeouts. 2. Process check : to confirm listener; to rule out FD leak. 3. Stack capture (inside backend venv): then (and worker pid if multiprocess).…