openai/gpt-chat-latest → B (3:2)

Side B consolidates base-URL generation into a shared util function, replaces multiple hardcoded host/environment checks across OAuth and callback flows with a single HOSTNAME-aware implementation, and updates the frontend to use window.location.origin, improving portability for custom hosts. Side A adds a useful UI enhancement by making pinned child-group icons submit the existing unpin flow and backs it with browser tests, but its impact is confined to a specific interaction rather than infrastructure used across many authentication and redirect paths.