Pattern

Device health

Separate uptime, service health, data freshness and physical conditions so one green signal cannot hide another failure.

Decision flow

context→evidence→state→action→audit

Device online and camera streaming are separate states.
Show the last observed heartbeat as an absolute or relative time.
Label delayed, stale and offline transport states independently of health severity.

Show identity, connection, workload and recent device health.

Communicate device recency against a heartbeat expectation.

Show one device service state and diagnostic detail.

Label categorical operational status.