Workers heartbeat into Redis every 90s as RFC3339 timestamp values with a
3-min TTL. The dashboard surfaces liveness based on workers.last_seen_at,
but until now nothing populated that column — the "Live" badge was always
red.
New 60s job in the consumer reads each active worker's Redis heartbeat
value, parses the timestamp, and writes it to workers.last_seen_at. Runs
on its own interval (separate from the 5-min dead-worker detection job,
which does heavier reassignment work) so the UI sees fresh data within a
minute.
Matthew Meszaros
8ae7759964