~x-ai/grok-latest → B (3:1)

B replaces flat per-scope GroupMap/settlement with a hierarchical GlobalTree, canonical ItemId paths (parent/breadcrumbs/from_url), journal replay including NodeEnsured, and UI wired to ?item= nodes—core lasting architecture. A only extends that surface with Reddit-specific markup (thumb/image/link fields, render/reddit cards, CSS) and a fixture test, valuable polish but dependent and narrower.