Live checks, measured propagation, incidents.

Every 5 minutes a probe publishes a small change to a dedicated probe environment through the same path as the dashboard (draft edit, then publish). Listeners running on Cloudflare in the locations above each keep one live connection to the edge with a server key of that environment. A sample is the time from the database commit timestamp of the published revision to the moment the signed bundle was received over the live connection. The commit timestamp is taken by Postgres at the start of the publishing transaction, slightly before the commit itself, so samples include the time the publish transaction takes.

Not measured: customer networks and devices, browsers, the last mile to an application, SDK processing after receipt, and the fallback transports (server-sent events and polling) used when a live connection is not available. Revisions that a listener did not receive within 15 seconds produce no sample here and are counted separately by the probe; samples below 0 ms or above 60 seconds are discarded as invalid.

Clocks: the commit time comes from the database server's clock, the arrival time from the Cloudflare Workers clock. Both are synchronised independently, so an offset between them of a few milliseconds is part of every sample. The probes are few and fixed in location; percentiles over a short window rest on few samples.