~anthropic/claude-sonnet-latest → A (3:2)

Side A is a focused, coherent change: it adds a working `room create` CLI command wired to a simplified server-side RoomCreate RPC, removes now-unneeded ThreadVisibility plumbing, and updates docs/tests consistently across cli/server/types. Side B is much larger but noisier and riskier — it introduces cookie-based auth, new routes, and a substantial UI refactor while also committing an unrelated, out-of-place 'plan2.md' AI-chat transcript file that adds no real value and pollutes the repo.