What problem does it solve? Adding a new page to a web app involves many easy-to-miss conventions: validated search params, breadcrumbs, error boundaries, loader prefetching, i18n segments, and SEO metadata. This Skill encodes all of those conventions so every new route follows the same URL contract and thin-shell architecture across the React (TanStack Router) and Astro workspaces. ## Core Features & Use Cases - Platform-aware routing: Detects whether you are working in packages/app/react or packages/app/astro and loads the matching child instructions and pattern registry. - React route generation: Creates TanStack Router file-based routes with createFileRoute, Zod-validated search params composed from SDK schemas, breadcrumbs via staticData, RouteError boundaries, and loader prefetching with ensureQueryData. - Astro route generation: Creates localized .astro pages under src/pages/[locale]/ with getStaticPaths, content collections, sitemap integration, and SEO metadata through BaseLayout. - Use Case: Ask to add a /customers list page and get a thin-shell route with validated pagination search params, a prefetch loader, breadcrumb, error component, and a regenerated route tree — with components owning their own data fetching. ## Quick Start Create a new route for the customers list page with search param validation and breadcrumbs in the React app.