~anthropic/claude-sonnet-latest → B (6:4)

Side B fixes a real logic bug (unranked siblings were incorrectly lumped into one group instead of separated), and backs it with a new regression test verifying the corrected grouping behavior. Side A is a UI/CSS refactor (merging multiple copy buttons into one panel) with a defensive assert, which is useful but more cosmetic and lower-stakes than correcting sibling-grouping semantics.