npm install @tanstack/react-router @tanstack/router-devtools
npm install -D @tanstack/router-plugin

**Vite Config** (TanStackRouterVite MUST come before react()):
```typescript
// vite.config.ts
import { TanStackRouterVite } from '@tanstack/router-plugin/vite'

export default defineConfig({
  plugins: [TanStackRouterVite(), react()], // Order matters!
})

src/routes/
├── __root.tsx         → createRootRoute() with <Outlet />
├── index.tsx          → createFileRoute('/')
└── posts.$postId.tsx  → createFileRoute('/posts/$postId')

import { createRouter, RouterProvider } from '@tanstack/react-router'
import { routeTree } from './routeTree.gen' // Auto-generated by plugin

const router = createRouter({ routeTree })
<RouterProvider router={router} />

<Link to="/posts/$postId" params={{ postId: '123' }} />
<Link to="/invalid" /> // ❌ TypeScript error

export const Route = createFileRoute('/posts/$postId')({
  loader: async ({ params }) => ({ post: await fetchPost(params.postId) }),
  component: ({ useLoaderData }) => {
    const { post } = useLoaderData() // Fully typed!
    return <h1>{post.title}</h1>
  },
})

const postOpts = (id: string) => queryOptions({
  queryKey: ['posts', id],
  queryFn: () => fetchPost(id),
})

export const Route = createFileRoute('/posts/$postId')({
  loader: ({ context: { queryClient }, params }) =>
    queryClient.ensureQueryData(postOpts(params.postId)),
  component: () => {
    const { postId } = Route.useParams()
    const { data } = useQuery(postOpts(postId))
    return <h1>{data.title}</h1>
  },
})

import { tanstackRouter } from '@tanstack/router-plugin/vite'

export default defineConfig({
  plugins: [
    tanstackRouter({
      target: 'react',
      virtualRouteConfig: './routes.ts', // Point to your routes file
    }),
    react(),
  ],
})

import { rootRoute, route, index, layout, physical } from '@tanstack/virtual-file-routes'

export const routes = rootRoute('root.tsx', [
  index('home.tsx'),
  route('/posts', 'posts/posts.tsx', [
    index('posts/posts-home.tsx'),
    route('$postId', 'posts/posts-detail.tsx'),
  ]),
  layout('first', 'layout/first-layout.tsx', [
    route('/nested', 'nested.tsx'),
  ]),
  physical('/classic', 'file-based-subtree'), // Mix with file-based
])

import { z } from 'zod'

export const Route = createFileRoute('/products')({
  validateSearch: (search) => z.object({
    page: z.number().catch(1),
    filter: z.string().catch(''),
    sort: z.enum(['newest', 'oldest', 'price']).catch('newest'),
  }).parse(search),
})

import { zodValidator, fallback } from '@tanstack/zod-adapter'
import { z } from 'zod'

const searchSchema = z.object({
  query: z.string().min(1).max(100),
  page: fallback(z.number().int().positive(), 1),
  sortBy: z.enum(['name', 'date', 'relevance']).optional(),
})

export const Route = createFileRoute('/search')({
  validateSearch: zodValidator(searchSchema),
  // Type-safe: Route.useSearch() returns typed params
})

export const Route = createFileRoute('/posts/$postId')({
  loader: async ({ params }) => {
    const post = await fetchPost(params.postId)
    if (!post) throw new Error('Post not found')
    return { post }
  },
  errorComponent: ({ error, reset }) => (
    <div>
      <p>Error: {error.message}</p>
      <button onClick={reset}>Retry</button>
    </div>
  ),
})

const router = createRouter({
  routeTree,
  defaultErrorComponent: ({ error }) => (
    <div className="error-page">
      <h1>Something went wrong</h1>
      <p>{error.message}</p>
    </div>
  ),
})

export const Route = createFileRoute('/posts/$postId')({
  notFoundComponent: () => <div>Post not found</div>,
})

import { redirect } from '@tanstack/react-router'

export const Route = createFileRoute('/dashboard')({
  beforeLoad: async ({ context }) => {
    if (!context.auth.isAuthenticated) {
      throw redirect({
        to: '/login',
        search: { redirect: location.pathname }, // Save for post-login
      })
    }
  },
})

// routes/(authenticated)/route.tsx - protects all children
export const Route = createFileRoute('/(authenticated)')({
  beforeLoad: async ({ context }) => {
    if (!context.auth.isAuthenticated) {
      throw redirect({ to: '/login' })
    }
  },
})

// main.tsx - pass auth state to router
function App() {
  const auth = useAuth() // Your auth hook

  return (
    <RouterProvider
      router={router}
      context={{ auth }} // Available in beforeLoad
    />
  )
}

// Server function with input validation
export const myFn = createServerFn({ method: 'POST' })
  .inputValidator(z.object({
    name: z.string().min(2),
    age: z.number().min(18),
  }))
  .handler(async ({ data }) => data)

// Client: Workaround to parse stringified issues
try {
  await mutation.mutate({ data: invalidData })
} catch (error) {
  if (error.message.startsWith('[')) {
    const issues = JSON.parse(error.message)
    // Now can use structured error data
    issues.forEach(issue => {
      console.log(issue.path, issue.message)
    })
  }
}

// Route with param parsing
export const Route = createFileRoute('/posts/$postId')({
  params: {
    parse: (params) => ({
      postId: z.coerce.number().parse(params.postId),
    }),
  },
})

// Component: Use strict mode (default) for parsed params
function Component() {
  const { postId } = useParams() // ✓ Parsed as number
  // const { postId } = useParams({ strict: false }) // ✗ String!

  // Or manually parse when using strict: false
  const params = useParams({ strict: false })
  const postId = Number(params.postId)
}

// ✗ Doesn't work: notFoundComponent on pathless layout
export const Route = createFileRoute('/(authenticated)')({
  beforeLoad: ({ context }) => {
    if (!context.auth) throw redirect({ to: '/login' })
  },
  notFoundComponent: () => <div>Protected 404</div>, // Not rendered!
})

// ✓ Works: Define on child routes instead
export const Route = createFileRoute('/(authenticated)/dashboard')({
  notFoundComponent: () => <div>Protected 404</div>,
})

export const Route = createFileRoute('/posts/$postId')({
  loader: async ({ params, abortController }) => {
    await fetch(`/api/posts/${params.postId}`, {
      signal: abortController.signal,
    })
  },
  errorComponent: ({ error, reset }) => {
    // Check for undefined error (aborted request)
    if (!error) {
      return null // Or show loading state
    }
    return <div>Error: {error.message}</div>
  },
})

// Temporary workaround: Comment out tanstackStart() for tests
// vite.config.ts
export default defineConfig({
  plugins: [
    // tanstackStart(), // Disable for tests
    react(),
  ],
  test: { environment: 'jsdom' },
})

// ✗ Wrong: void + throw crashes dev server
export const Route = createFileRoute('/posts')({
  loader: async () => {
    void fetch('/api/posts').then(r => {
      throw new Error('boom') // Crashes!
    })
  },
})

// ✓ Correct: Always await or catch
export const Route = createFileRoute('/posts')({
  loader: async () => {
    try {
      const data = await fetch('/api/posts')
      return data
    } catch (error) {
      throw error // Caught by errorComponent
    }
  },
})

// ✗ Wrong: Empty filter causes hang
tanstackStart({
  prerender: {
    enabled: true,
    filter: (route) => false, // No routes → hangs!
  },
})

// ✓ Correct: Ensure at least one route or disable
tanstackStart({
  prerender: {
    enabled: true,
    filter: (route) => route.path === '/' || route.path.startsWith('/posts'),
  },
})

// Or temporarily disable
tanstackStart({
  prerender: { enabled: false },
})

// vite.config.ts - Make preview server accessible in Docker
export default defineConfig({
  preview: {
    host: true, // Bind to 0.0.0.0 instead of localhost
  },
  plugins: [
    devtools(),
    // nitro({ preset: "bun" }), // Remove temporarily if issues persist
    tanstackStart(),
    react(),
  ],
})

// ✗ Wrong: loaderData may not be available yet
export const Route = createFileRoute('/posts/$postId')({
  loader: async ({ params }) => {
    const post = await fetchPost(params.postId)
    return { post }
  },
  head: ({ loaderData }) => ({
    meta: [
      { title: loaderData.post.title }, // May be undefined!
    ],
  }),
})

// ✓ Correct: Explicitly await if needed
export const Route = createFileRoute('/posts/$postId')({
  loader: async ({ params }) => {
    const post = await fetchPost(params.postId)
    return { post }
  },
  head: async ({ loaderData }) => {
    await loaderData // Ensure loaded
    return {
      meta: [{ title: loaderData.post.title }],
    }
  },
})

// Virtual routes: Use automatic code splitting
// vite.config.ts
tanstackRouter({
  target: 'react',
  virtualRouteConfig: './routes.ts',
  autoCodeSplitting: true, // Use automatic splitting
})

// Don't use createLazyFileRoute in virtual routes
// It will be replaced with createFileRoute automatically

// ✗ Wrong: NavigateOptions doesn't catch missing params
const options: NavigateOptions = {
  to: '/posts/$postId', // No TS error, but params required!
}

// ✓ Correct: Use useNavigate() return type
const navigate = useNavigate()
type NavigateFn = typeof navigate
// Now type-safe across all usages

// ✗ Wrong: Missing leading slash
export const Route = createFileRoute('about')({ /* ... */ })

// ✓ Correct: Always start with /
export const Route = createFileRoute('/about')({ /* ... */ })

import { cloudflare } from '@cloudflare/vite-plugin'

export default defineConfig({
  plugins: [TanStackRouterVite(), react(), cloudflare()],
})

// Worker: functions/api/posts.ts
export async function onRequestGet({ env }) {
  const { results } = await env.DB.prepare('SELECT * FROM posts').all()
  return Response.json(results)
}

// Router: src/routes/posts.tsx
export const Route = createFileRoute('/posts')({
  loader: async () => fetch('/api/posts').then(r => r.json()),
})