outbox+NNNN verifiedimportant

The whole family is one mechanism and is recorded as one entry: outbox+0001 through outbox+1024, powers of two, TTLs from one second to about seventeen minutes. A wait of any length is assembled from steps, so 600 seconds is 512 + 64 + 16 + 8 — four hops. Their depth is the only visible sign of pending retries, because intermediate attempts are never published as results. A monitoring panel that shows the sending queue but not these is showing a node with less work than it has. They also carry no consumers by design — the broker moves messages on expiry, nothing reads them. So the "queue with messages and no consumers" rule that catches a dead engine does not apply here.