principal_control_event_kind_forbidden· reason_code· applies to event_envelope, auth_decisionA Realm claiming ak.profile.principal_control_realm.v1 received a collaboration / media / content event kind outside its allowlist-only control-plane event policy. Reducers MUST reject instead of treating the Realm as ordinary collaboration history. See zh/models/realm-and-space.md §2.8.1 and artifacts/profiles/conformance-profiles.json#profile_requirements.