~anthropic/claude-sonnet-latest → B (9:1)

Side B is a substantial, coherent refactor introducing an RPC batch API, room/thread scoping (ScopeId::Room replacing ThreadVisibility hack), and updates across server, CLI, types, and tests/integration scripts to match — real architectural work with passing test coverage. Side A merely adds unintegrated scaffolding (Dockerfile, fly.toml, deps.edn, and orphan .rs files not wired into any module), providing little demonstrable lasting value.