React Router

Add React Router v7 routing

Add $route to the Vite SPA using React Router v7 Data Mode: createBrowserRouter + RouterProvider, imported from react-router. TanStack Query keeps server-state ownership. Do not adopt Framework/SSR or bare Declarative Mode; Express remains the backend.

Step 1 — Detect the toolchain and ensure the dep

source "${CLAUDE_PROJECT_DIR}/.claude/lib/detect-toolchain.sh"

If missing, add react-router with the detected package manager. Do not add react-router-dom; v7 uses one package. Confirm major version 7.

Step 2 — Place routing inside the feature slices

Keep frontend routing in vertical slices, never in backend routes/.

• One composition root, e.g. app/router.tsx, calls createBrowserRouter and is rendered by <RouterProvider> at the app entry.
• Each feature exports its own route objects (e.g. features/invoice/invoice.routes.tsx) that the root composes. A feature owns its routes like it owns its components and hooks.

Step 3 — Define routes with lazy code-splitting

Apply ${CLAUDE_SKILL_DIR}/references/patterns.md sections "Router setup" and "Lazy routes".

• Use route objects with Component, nested children, index, and layout routes that render <Outlet/>.
• Split each feature's route with lazy so its bundle loads on navigation.

Step 4 — Keep TanStack Query the source of truth for server data

Apply the reference section "TanStack Query integration".

• Components keep fetching through their useQuery/useMutation hooks. Do not re-fetch the same server data inside a loader and return it as a parallel source of truth.
• If a route needs to prefetch, have its loader call queryClient.ensureQueryData(...) for the feature's existing query key, then let the component read it via the same useQuery (warm cache).
• Use action only for non-Query mutations or progressive-enhancement forms; otherwise mutate via the existing TanStack Query mutation hook and invalidate keys.

Step 5 — Parse URL and search params at the boundary

Apply the reference section "Typed params". Parse untrusted params and useSearchParams with zod. Reuse an existing feature contract when it fits.

Step 6 — Pending and error states

Surface pending state with useNavigation. Give routes an ErrorBoundary (ErrorBoundary/errorElement) using useRouteError.

Step 7 — Verify

source "${CLAUDE_PROJECT_DIR}/.claude/lib/detect-toolchain.sh"
run_typecheck

Checklist

• Data Mode only: createBrowserRouter + RouterProvider, imports from react-router (v7).
• No Framework/SSR adoption; Express stays the backend.
• Routes live in feature slices on the frontend, composed by one root; not under backend routes/.
• Server state still owned by TanStack Query; loaders at most prefetch into the query client.
• params/search params parsed with zod into typed values.
• Routes are lazy-split and have pending + error states.
• run_typecheck passes.