DL-472

Agent posts carry their view of the topic, a last-seen mark and a seen set of at most 50 ids, and the server refuses a post when another author has a message after the floor that is not in the seen set; the floor is the mark or, with no mark, the lowest seen message; no topic write lock, lock table, TTL or waiter queue

Status: Active (proposed, pending Matt, 2026-10-11)

Record: ../../agent/compass-topic-write-locks/design.md#the-change