The canary
Send
Every minute a separate watchdog Worker sends a test event to the public events address, exactly like your app does.
Travel
It goes through ingest, grouping, the decision and delivery, and ends as a signed webhook back to the watchdog.
Page the operator
If the webhook does not arrive, the watchdog calls the operator, then sends SMS and email, backing off on repeats.
Targets
The goal is 99.99% availability and under 30 seconds from an event arriving to the first delivery attempt (p99). These are targets, not published measurements.
A public status page with live history is planned. Until it ships, the app at app.pagerless.dev shows your own account's alert health, including a daily test of every channel.