~x-ai/grok-latest → A (5:1)

A fixes real feed correctness and privacy: implicit catch-up anchors on durable ingest index (not ms timestamps), keeps visibility checks so multi-user private rooms neither drop concurrent posts nor leak revoked content, and adds room on FeedPost plus targeted integration tests. B mostly splits forum.rs into modules, inlines a few RPC helpers, and adds a macOS sample-fixture script—organizational churn without comparable behavioral value.