Follow-up to the salvaged #80489 substring-fallback removal: the
structured 401/403 branch still exited with a bare return, leaving
_running True — dead listener, healthy-looking is_connected(), gateway
never told (the zombie half of the bug, OOF-156 class). It now sets a
non-retryable mattermost_auth_error with token guidance and notifies
the gateway fatal handler.
Also: pytest.importorskip for aiohttp in the verifier probe file
(module-level import crashed collection in envs without the optional
dep), and probe fixtures updated for the escalation attributes.
Independent-verifier boundary probes for commit fdd1a11ac5, covering
cases the implementer's regression tests did not exercise:
- WSServerHandshakeError(status=403) also stops the loop (only 401 tested)
- WSServerHandshakeError(status=500) does NOT stop the loop (structured
check must not over-match on type alone)
- transient error containing the word 'unauthorized' (not digit substring)
now retries correctly
- 5 consecutive transient errors all retry, not just the first
Verified these 2nd/4th tests fail against the pre-fix baseline commit
(01a1037d1e) and pass against the fix (fdd1a11ac5), confirming they
have real signal.
Teknium