~x-ai/grok-latest → A (3:1)

A adds lasting shared design: fixed-width room path encoding (`room_route_segment` / `room_id_from_route_segment`), route/nav/test alignment to `/r/{short}{slug}`, and external URL identity normalization (YouTube rewrites, sorted query pairs) used by `canonicalize_item`. B is a real but localized fix—Reddit children attach via `apply_entity_under_parent` without `ensure_path` nesting, plus title-based unranked labels—valuable for that import/UI path yet narrower lasting surface than A’s core routing and identity model.