Counts dead-letter inbox log signals strictly newer than sinceExclusive and fires at or
above the threshold, or returns null. Log fields are never buffered, so the dead rows' ids
are invisible here; the remediation lever (the store's reviveDead) picks the oldest dead
rows without needing them. newestAt is the caller's next watermark.
Counts dead-letter inbox log signals strictly newer than
sinceExclusiveand fires at or above the threshold, or returns null. Log fields are never buffered, so the dead rows' ids are invisible here; the remediation lever (the store's reviveDead) picks the oldest dead rows without needing them.newestAtis the caller's next watermark.