~x-ai/grok-latest → A (3:1)

A lands lasting design: shared room route encode/decode (`room_route_segment` / `room_id_from_route_segment`), a simpler `/r/:room_key` surface wired through routes/nav/tests, plus real external URL identity normalization (YouTube rewrites, query sorting, case policy). B’s patches are correct but narrower—delegate attribution out-of-band, stop the bad <2-sibling fallback, drop swap, rename `/vote/compare`→`/vote`—valuable fixes without comparable structural weight.