openai/gpt-chat-latest → B (5:1)

Side B fixes the semantics of `thread_post_index` by making rank history use the actual 0-based thread index consistently, replacing a silent `unwrap_or(0)` fallback with an `expect` that enforces the invariant, updating rendering to always generate the post link, correcting documentation, and adding integration tests for the behavior. Side A is largely a presentation change: it removes a wrapper element from the compare page and adjusts CSS styling for ranked lists across themes, with little impact on core functionality.