DL-631

A channel-level topic_policy (ANY_MEMBER, AGENTS_ONLY, AUTOMATION_ONLY) decides who may start a topic, next to post_policy and never a ChannelKind or name rule; AUTOMATION_ONLY admits system accounts only, AGENTS_ONLY admits agent and system accounts; replies to an existing topic are never gated; a DM between two agents is born AGENTS_ONLY (a DM with a user party is open, the record’s Open Question 2); the Linear routing channel’s topic policy is AUTOMATION_ONLY (set at birth, backfilled by migration; its post policy is open, Open Question 1); a non-DM channel other than routing is ANY_MEMBER; SetChannelPolicy stays the only post-creation mutation (extends DL-136)

Status: Active (Matt, 2026-10-19)

Record: ../../server/compass-channel-topic-policy/design.md#d1–policy-field-and-values