openai/gpt-chat-latest → B (4:1)

Side B fixes a correctness bug in the reducer by moving the zero-ratio guard before `ensure_item` and `voted_pairs.insert`, preventing ghost items and incorrectly recorded voted pairs, and updates the test to verify the corrected behavior. Side A adds broad theme persistence and room-aware URL handling across many files, but it is largely feature work and plumbing rather than a targeted correctness fix with the same lasting impact on core data integrity.