P1 SHIPPED 704585b (site + list level, served-verified with seat tokens: my-* sites 403 for other seats and anonymous LAN, 200 owner/loopback; query_my_memory trimmed; mutation-checked). P2: item-level HasUniqueRoleAssignments + RoleAssignments on the row; list settings ReadSecurity (1 all / 2 own) and WriteSecurity (1 all / 2 own / 4 none) on DeclareList (XSD) and manifest List; one row rule shared by CAML LoadRows and ApplyPartyScope; fold DeleteListItem's own-row Refusal into WriteSecurity=2. Also close the untrimmed doors: tool_search + /search, tool_xquery, /agency query routes, recycle bin below site level.