Address round-1 review on #913 and the SonarCloud new_reliability_rating gate:
- credential_cleanup_task no longer catches the cancellation exception
(Sonar python:S7497). A task-group cancel must propagate for structured-
concurrency teardown; graceful shutdown still flows through shutdown_event,
so the sleep no longer needs a cancel/break.
- Parametrize the scanner self-heal tests over 401 AND 403 (handled
identically at both call sites) and add a test that a failing periodic
sweep is logged non-fatally and does not crash the task.
- Log the stored-user count before the startup sweep (operability signal),
add a debug line when the credential row was already gone, and document
the at-most-one extra-401 convergence in _remove_stale_credential.
Refs Deck #198.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Deleted/disabled Nextcloud users left their app_passwords row in storage,
so user_manager_task re-spawned their scanner every poll interval only to
401 again — an endless re-spawn/auth-failure loop (observed on
tenant-blackbox-demo: ~534 respawns/3h, matching the 60s poll interval).
- Delete the stored app password on a hard 401/403 in user_scanner_task
(both the pre-validation and in-scan-loop paths), breaking the re-spawn
loop at the source so the user-manager stops recreating the scanner.
- Add a periodic credential_cleanup_task backstop (hourly) that sweeps
cleanup_invalid_app_passwords for anything the per-scanner path misses.
- Run the startup cleanup for all deployment modes: drop the stale
`not oauth_enabled` guard so login_flow tenants (the cloud default) are
covered. NOTE: login_flow startup now makes one concurrent OCS
validation call per stored user before readiness.
Refs Deck #198.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
