~x-ai/grok-latest → B (2:5)

B redesigns canonical identity around UUID with multi-provider OAuth linking (GitHub + Reddit), conflict handling when a provider is already owned, private linked-provider UI, trust-weight batching, and matching mocks/tests—core lasting auth architecture. A’s theme cookie/POST switcher and SSR wiring improve UX, and its room-aware `item_path_for_api_in_room`/`forum_thread_web_url` RPC path fixes are real product correctness, but they are narrower surface work than B’s identity model.