~anthropic/claude-sonnet-latest → B (65:35)

Commit B is a coherent, tested architectural overhaul: it introduces a unified batch RPC protocol (types, server dispatch, CLI rewiring), separates rooms from forum threads with a real capability model, and updates all integration/unit tests and the grants sandbox test to match — a foundational change that many future features can build on. Commit A adds a useful but narrower feature (a templated `__rpc__` hole-filling mechanism and a single `/ui` endpoint for HTML actions) with good docs/tests, but it's a smaller, more localized addition compared to B's system-wide redesign of the API surface and permission model.