~x-ai/grok-latest → A (2:1)

A fixes a real indexing bug/inconsistency: rank-history `thread_post_index` becomes required 0-based (aligned with `/t/tag/N`), drops silent `unwrap_or(0)`/`+1` and the conditional link UI, and locks behavior with integration asserts. B is mostly a file split/inline of forum helpers plus an unrelated macOS sample script—useful structure/tooling, but little lasting product semantics versus A’s correctness change.