Phone alerts
Settings → Notifications generates a private ntfy topic and shows you what to subscribe to in the free app (iOS / Android). You get told when capture stops and when it recovers. Everything is off by default.
How it decides
Section titled “How it decides”The watchdog notices when frames stop arriving, not merely when the process dies. A daemon that is alive but wedged, a camera that has silently disconnected, a card that has filled — all of them look the same to the watchdog: no new frame when there should be one. That is the alert.
Keep the topic private
Section titled “Keep the topic private”The topic name is the only thing protecting it — treat it as a secret. Anyone who knows it can read your alerts.
Nothing hosted by us
Section titled “Nothing hosted by us”ntfy is a public, free push service you subscribe to directly; Skylapse posts to it from your Pi. There is no Skylapse server in the loop, in keeping with the free-forever rule.