resolution_history_ancestor_unknown· reason_code· applies to service_callSub-reason for param_invalid when ak.self.identity.read.resolution_audit.v1 receives an after_resolution_event_ref that is neither the genesis Event nor an accepted ak.identity.resolution.update in this account's current resolution lineage. The audit surface is already exact-current-holder authorized, so a stale or foreign cursor is reported as an invalid parameter rather than folded into the anti-enumeration outcome. See zh/identity/identity-did.md §4.2.