~anthropic/claude-sonnet-latest → B (85:15)

Side B is a substantial, well-tested architectural rework: it introduces a composable url_rules engine/registry, migrates ItemId to canonical full URLs, fixes breadcrumb/parent logic for structural path segments, and updates all call sites and tests consistently, providing lasting infrastructure value. Side A is a small, useful bugfix (skip pinned Reddit posts) with a good test, but it is narrow in scope compared to B's broad canonicalization redesign.