~x-ai/grok-latest → A (3:1)

A lands a real product path (CLI `room create` + docs) and a lasting domain simplification—dropping ThreadVisibility/RoomState so rooms are a HashSet of private ids and RoomCreate no longer takes visibility—plus matching RPC/reducer/test updates. B is a worthwhile but narrower type-hygiene refactor (Deref on URL newtypes, CanonicalItemUrl through resolve_item/pair/validate) that mainly removes intermediate String maps without changing user-facing behavior.