~x-ai/grok-latest → B (2:1)

B restores lasting product capability: HttpOnly session cookies, /login|/logout, ACL-gated /r/{short}/{slug} room index and thread/post/expand routes, compose forms, and POST /post that reuses rpc_post_with_bearer—making private rooms usable in the browser. A is a solid but secondary refactor that moves canonicalize_* / CanonicalItemUrl into slug-types and swaps string helpers for GardenItemUrl/ForumThreadUrl newtypes without adding behavior.