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

Side A is a large mechanical refactor (REST endpoints collapsed into an RPC batch dispatcher) with lots of churn but no new correctness guarantee — it's mostly moving code around. Side B fixes a real, subtle bug (feed cutoff using wall-clock timestamps instead of durable append order, causing missed/duplicated posts under concurrent writes or clock rollback) and adds permission-aware multi-room visibility with targeted regression tests, delivering concrete lasting correctness value in a small, precise diff.