~x-ai/grok-latest → B (4:1)

B introduces a lasting core design: ItemId as full canonical URLs plus a composable url_rules engine (Reddit/YouTube normalization, parents/breadcrumbs) wired through path_types, reddit mapping, projection, and tests. A only patches test doubles (regex split, getRequestBody, redirect length, null token) and minor Playwright selectors so E2E auth runs again—real but localized infrastructure fix.