DL-072
The durable delivery cursor is Server-owned: a contiguous low-water cursor plus a bounded above-cursor set per (agent_account_id, channel_id) on messages.seq (mirroring ControlAck’s acked_seq + applied_above), reconstructed from per-message acks, swept gap-aware on session start/reconnect; the per-(agent, channel) keying is ratified (Matt, 2026-07-29), amending RT-3’s “per-session” wording
Status: Active (Matt, 2026-07-29)