openai/gpt-chat-latest → B (4:1)

Side B introduces a substantial architectural improvement by adding a settlement worker that batches vote processing, persists events before applying them, warms and serves cached rankings, and switches the UI to read cached rankings under a read lock. Although it also removes demo-counter code, the enduring value comes from the new settlement pipeline and ranking-cache API (`SettlementClient`, `warm_ranking_cache`, `ranked_items_cached`), whereas Side A is a focused bug fix that correctly moves the zero-ratio guard before `ensure_item` and `voted_pairs` updates to prevent ghost items and stale voted-pair state.