Records the post-review finding discovered during browser smoke-testing: the Admin-003 hub hardening was incomplete — the server-side Blazor HubConnection clients had no way to authenticate, so hub negotiate 401'd and four cluster pages threw unhandled 500s. Logged as Admin-013 (High, Error handling & resilience), Status Resolved, fixed by commitsf254539+8d5dbb4. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>