~x-ai/grok-latest → B (2:3)

B fixes a real correctness bug in core reducer logic: the zero-ratio guard ran after ensure_item and voted_pairs.insert, leaving ghost items and false voted-pair marks; moving the check before side effects permanently stops that corruption, with the unit test updated to match. A adds a useful RoomList RPC/CLI surface plus solid isolation tests, but it is additive API wiring over existing grants state rather than repairing flawed core behavior.