~x-ai/grok-latest → B (1:3)

Side B delivers the foundational room web UI: session cookies and optional_principal auth, /login|/logout, ThreadNav, room_page/room_thread_* routes with ACL checks, compose/new-thread forms, and home wiring—core lasting product surface. Side A is a solid follow-on (form_template $form holes, HtmlUiAction, shared run_* helpers, progressive + morph via POST /ui) but assumes and refines that earlier surface rather than establishing it.