openai/gpt-chat-latest → A (3:2)

Side A fixes a concrete production reliability issue by requiring OAuth when credentials exist, adding token refresh-and-retry on 401/403 responses, improving error propagation instead of silently falling back, and adding targeted tests for error truncation. Side B is a broad URL/routing refactor that centralizes room path handling and adds URL normalization utilities, but much of the patch is mechanical call-site updates and route rewiring rather than addressing a specific correctness or availability problem.