DL-137
The pinned board is a server-side per-channel capped ordered POINTER set over existing topic-scoped messages: pinning references an existing message_id (validated to a topic of the channel, join through topics) and creates no Message, so DL-099’s single-write-path stands; edit = a normal topic-mandatory post + compare-and-swap repoint (redelivery is ordinary DL-071/072/073 delivery of a new message id, dedup-safe); board txns serialize on channels … FOR UPDATE (cap + repoint races); startup delivery is a session-start pin sweep beside the D2 cursor sweep dispatching current pins regardless of cursor position; edits land at turn-settle (never steer); explicitly distinct from DL-096’s client-local sidebar pins, and compatible with DL-054 (no centre/badge/read state). RIG-1723
Status: Active (Matt, 2026-07-31)