~x-ai/grok-latest → A (2:1)

A fixes real indexing semantics: rank-history thread_post_index aligns with 0-based /t/tag/N routes, drops the silent unwrap_or(0)/+1 skew, and locks it with RPC/HTML expect + integration asserts. B is worthwhile UI cleanup (SSR home compose like rooms, delete ExpandNewThreadForm and the extra toolbar), but it is path consolidation rather than a correctness/API fix.