~x-ai/grok-latest → A (2:1)

A lands durable core design: centralized room path encoding (`room_route_segment` / fixed-width short id), route and link call sites rewritten to one segment, plus real external URL identity normalization (YouTube rewrites, sorted query pairs) with tests—replacing scattered `split_once('/')` URL building. B is a solid vertical feature (Reddit broker, OAuth, rate-limit/dedup worker, parsers) that replaces a stub, but it is product-specific integration plus a scratch `todo` file, so it adds less lasting cross-cutting value than A’s URL/types foundation.