Alerts
A background sweep runs every 5 minutes, and once on startup, and checks three conditions:
- Low battery for every Device, with a 5-point hysteresis so it does not flap right at the threshold.
- Offline for every Device that has not polled for longer than its refresh rate times a multiplier. Skipped while the Device sleeps under Sleep Mode, and for a grace period after it wakes.
- Data Source fetch failing for every fetch-mode Data Source of a Poll Plugin whose consecutive scheduled failures reach a threshold.
Each condition opens an Alert the first time it is seen and resolves it the first time it clears. The Alerts page shows every active Alert plus anything resolved in the last 7 days.
Notifications through Apprise
Delivery goes through an apprise-api sidecar, which supports dozens of notification channels. Set KUROSHIRO_APPRISE_URL to enable it; without it, Alerts still open and resolve, they just are not delivered. Instance Settings has a Send a Test Notification button that exercises the real delivery path.
Thresholds and Retention
The low battery percentage, offline multiplier and fetch failure count come from environment variables, and each one can be overridden in Instance Settings without a restart. A daily Retention job prunes resolved Alerts and Device Log entries older than their Retention age; active Alerts are never touched.
The design decisions behind Alerts are recorded in ADR-0022, ADR-0025 and ADR-0027.