openai/gpt-chat-latest → B (3:2)

Side B refactors feed generation into a shared `rpc_feed` path and fixes a subtle correctness issue by anchoring implicit catch-up to durable ingest order instead of timestamps, while also enforcing visibility filtering and exposing room metadata in feed responses. Its integration tests cover timestamp collisions and private-room permission changes, whereas Side A primarily removes browser sentinel delegates by making pending-session agents optional to fix multi-user browser voting and simplify attribution.