Block a user
CSV / JSON export of check history
Uptime calendar heatmap (GitHub-style, per day)
Per-monitor detail page with full history and time-axis chart
--dry-run flag for start (run checks, no alerts)
validate subcommand (parse config, print summary, exit non-zero on errors)
Escalation policy (alert A immediately, alert B after N minutes still down)
Generic webhook alerter (configurable template body)
HTTP response header assertion
README with self-hosting guide (nginx config snippet)
Single-file output (inline all CSS)