openai/gpt-chat-latest → B (3:2)

Side B fixes a subtle correctness issue in feed catch-up by anchoring implicit feeds to durable ingest order instead of timestamps, preserving behavior under same-millisecond posts and clock rollback while enforcing permission-aware visibility. It also refactors duplicated feed-building logic into a shared function, adds room metadata to feed responses, and includes comprehensive integration tests for multi-user and private-room edge cases, whereas Side A adds substantial Reddit import functionality but is primarily a new feature rather than a core correctness improvement.