openai/gpt-chat-latest → A (4:1)

Side A removes the now-redundant ExpandNewThreadForm UI action and its server handler, switching the public home page to server-render the same collapsed new-thread slot used on room pages. This simplifies the architecture by eliminating duplicate interaction paths and associated parsing/tests while preserving logged-in and logged-out behavior. Side B mainly deletes a dead zero-ratio guard and updates a test to reflect existing downstream handling, which is a smaller cleanup with less architectural impact.