openai/gpt-chat-latest → B (3:2)

Side B adds a substantive new CLI capability (`room create`) end-to-end, wiring a new command through the client, RPC, server, and documentation so users can create private rooms directly. It also simplifies the room model by removing the unused visibility concept and replacing the room registry with a `HashSet` of room IDs, whereas Side A mixes one important bugfix (passing the delegate out-of-band and avoiding an incorrect fallback when too few sibling items exist) with mostly UX cleanup and route renaming.