~x-ai/grok-latest → B (3:4)

B replaces fragile timestamp cutoffs with durable ingest-order anchors and correct permission filtering in rpc_feed, fixing missed concurrent posts, clock-rollback gaps, and private-room leaks (including room on FeedPost). A is a real multi-user vote fix by dropping shared browser sentinel delegates for Option::None, but it is a narrower auth/UI binding cleanup than B’s core feed correctness and visibility hardening.