relation_kind_contains_derived· reason_code· applies to event_envelope, schema_validationSub-reason for schema_violation when a direct ak.relation.create / update / delete targets a derived-projection contains shape (Space(board) -> Space(list) or Space(list) -> Strand). Truth sources are the space_parent and strand_position typed results written via ak.space.parent / ak.strand.move / ak.strand.reorder Events; only the non-derived object-composition contains form is directly writable. See zh/models/relation.md §3.2 and zh/models/realm-and-space.md §3.5-§3.6.