Record a failed run. The next five-minute check sends the alert with reason fail. The monitor's alert_repeat_sec controls repeated alerts; the default is 24 hours. Failing is not proof of life either: the clock keeps running. The ingest never sends e-mail and never calls out — it records alert_pending and the cron turns it into an alert with reason: "fail" within 5 minutes, under the same one-per-24h cap. Works by GET or POST.