~x-ai/grok-latest → B (1:4)

B fixes real feed correctness and privacy: durable ingest-index anchors instead of millisecond timestamps, permission-aware multi-user room visibility, FeedPost.room, plus solid integration/CLI tests. A mostly adds a long future-refactor plan.md and a thin RouteContext wrapper over ThreadNav without finishing the ItemId migration, so it delivers far less lasting runtime value.