attempts that failed for the last time and were given up on
attempts that failed and remain queued for another pass
operations that reached the bucket and succeeded
Optionalnotrue when there is no bucket bound at all, which is the free-tier default
rows the drain REFUSED to send, by scheme.
Reported rather than silently skipped. A queue row that cannot be mirrored is either a private file (correct, and this is the count that proves the rule is live) or a bug in whatever enqueued it, and a silent skip cannot tell those apart.
What one drain pass did, in the terms the meters care about.