On Linux dual-stack sockets (IPV6_V6ONLY=0 default), an IPv4 loopback
connection arrives as ::ffff:127.0.0.1 and was 404'd by the literal set
check — silent outage of /debug/* when the proxy binds to :: or 0.0.0.0.
Replace the set-membership check with ipaddress.ip_address(host).is_loopback,
special-casing 'localhost' (not an IP literal) and treating ValueError
(malformed input) as non-loopback. The None sentinel for TestClient / UDS
sockets is preserved.
Unit 5 of the Codex-proxy resilience plan. Three always-on
/debug/* endpoints make "what is this process doing right now?"
a single curl away:
- GET /debug/tasks serializes asyncio.all_tasks() to name,
coro_qualname, stack_depth, done, and age_seconds (derived from
the WS session registry for Codex relay tasks, null otherwise).
Sorted by age desc. No frame locals, no request bodies, no
coroutine args.
- GET /debug/ws-sessions returns WebSocketSessionRegistry.snapshot().
- GET /debug/warmup returns WarmupRegistry.to_dict().
A FastAPI Depends(require_loopback) dependency 404s (not 403) any
non-loopback caller so debug routes stay invisible to external
scanners. Dependency chosen over middleware because the route set
is small and explicit Depends(...) makes the guard visible to
reviewers and easy to override in tests.
