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

Side B is a substantial feature commit introducing a hierarchical ItemId/fractal-tree model (parent/child, breadcrumbs, URL canonicalization), rewiring state/journal/reducer/UI to use it, replacing the flat scope-based GroupMap, with new tests and CSS support—clearly lasting architectural work. Side A is a small, focused refactor (Deque -> List with query-time capping) that removes a write-amplifying trim step, which is a solid but narrow correctness/perf improvement compared to B's broad structural redesign.