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{
  "dependencies": {
    "@tanstack/react-start": "^1.154.0",
    "@tanstack/react-router": "latest",
    "react": "^19.0.0",
    "react-dom": "^19.0.0"
  },
  "devDependencies": {
    "vite": "latest",
    "@cloudflare/vite-plugin": "latest",
    "wrangler": "latest"
  }
}

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import { defineConfig } from 'vite'
import { tanstackStart } from '@tanstack/react-start/plugin/vite'
import { cloudflare } from '@cloudflare/vite-plugin'

export default defineConfig({
  plugins: [
    tanstackStart(),
    cloudflare({
      viteEnvironment: { name: 'ssr' } // Required for Workers
    })
  ]
})

{
  "scripts": {
    "dev": "vite dev --port 3000",
    "build": "vite build",
    "start": "node .output/server/index.mjs"
  }
}

// Old (Vinxi)
import { createAPIFileRoute } from '@tanstack/start/api'

export const Route = createAPIFileRoute('/api/users')({
  GET: async () => {
    return { users: [] }
  }
})

// New (Vite)
import { createServerFileRoute } from '@tanstack/react-start/api'

export const Route = createServerFileRoute('/api/users').methods({
  GET: async () => {
    return { users: [] }
  }
})

name = "my-app"
compatibility_date = "2026-01-21"
compatibility_flags = ["nodejs_compat"] # REQUIRED

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import { defineConfig } from 'vite'
import { tanstackStart } from '@tanstack/react-start/plugin/vite'
import { cloudflare } from '@cloudflare/vite-plugin'

export default defineConfig({
  plugins: [
    tanstackStart(),
    cloudflare({
      viteEnvironment: { name: 'ssr' } // REQUIRED
    })
  ]
})

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Access bindings in server functions:

```typescript
import { createServerFn } from '@tanstack/react-start/server'

export const getUser = createServerFn()
  .handler(async ({ request }) => {
    const env = request.context.cloudflare.env

    // D1
    const result = await env.DB.prepare('SELECT * FROM users').all()

    // KV
    const value = await env.KV.get('key')

    // R2
    const object = await env.BUCKET.get('file.txt')

    return result.results
  })

export const Route = createFileRoute('/users')({
  loader: async () => {
    // This route queries D1
  },
  // Disable prerendering
  prerender: false
})

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3. **Conditional logic in loaders**:

```typescript
loader: async ({ context }) => {
  // Skip DB queries during prerender
  if (typeof context.cloudflare === 'undefined') {
    return { users: [] }
  }

  const result = await context.cloudflare.env.DB.prepare('SELECT * FROM users').all()
  return { users: result.results }
}

import { createServerFn } from '@tanstack/react-start/server'

export const getUsers = createServerFn()
  .handler(async ({ request }) => {
    const env = request.context.cloudflare.env
    const result = await env.DB.prepare('SELECT * FROM users').all()
    return result.results
  })

import { getUsers } from './server-functions'

function UserList() {
  const users = await getUsers()

  return (
    <ul>
      {users.map(user => <li key={user.id}>{user.name}</li>)}
    </ul>
  )
}

export const uploadFile = createServerFn()
  .handler(async ({ request }) => {
    // By the time this runs, the entire file is already in memory
    const formData = await request.formData()
    const file = formData.get('file') as File

    // Too late to check size - file already loaded!
    if (file.size > 10_000_000) {
      throw new Error("File too large")
    }
  })

function FileUpload() {
  const handleSubmit = async (e: FormEvent) => {
    const file = e.currentTarget.querySelector('input[type="file"]').files[0]

    if (file.size > 10_000_000) {
      alert("File too large")
      return
    }

    await uploadFile({ file })
  }

  return <form onSubmit={handleSubmit}>...</form>
}

const login = createServerFn<{ username: string, password: string }, User>()
  .handler(async ({ data, request }) => {
    const user = await authenticateUser(data)

    if (!user) {
      // Redirect returns void, but type says it returns User
      throw redirect({ to: '/login', status: 401 })
    }

    return user
  })

// In component
const result = await login({ username, password })
// result is undefined if redirected, User object otherwise
// Check before using!
if (result) {
  console.log(result.name)
}

// This FAILS - cookies not forwarded
const getData = createServerFn()
  .handler(async () => {
    const response = await fetch('https://api.example.com/user')
    // 401 Unauthorized - no cookies!
  })

import { createIsomorphicFn } from '@tanstack/react-start/server'

const getData = createIsomorphicFn()
  .handler(async () => {
    // Runs on client when possible, preserving cookies
    const response = await fetch('https://api.example.com/user')
    return response.json()
  })

import { createServerFn } from '@tanstack/react-start/server'
import { getRequestHeaders } from '@tanstack/react-start/server'

const getData = createServerFn()
  .handler(async () => {
    const headers = getRequestHeaders() // Get browser's original headers

    const response = await fetch('https://api.example.com/user', {
      headers: {
        'Cookie': headers.get('cookie') || '',
        'X-XSRF-TOKEN': headers.get('x-xsrf-token') || '',
        'Origin': headers.get('origin') || '',
      }
    })

    return response.json()
  })

import { betterAuth } from 'better-auth'
import { reactStartCookies } from 'better-auth/plugins'

export const auth = betterAuth({
  plugins: [
    reactStartCookies(), // Handles cookie setting for TanStack Start
  ],
  // ... other config
})

// prisma/schema.prisma
generator client {
  provider   = "prisma-client"
  output     = "../src/generated/prisma"
  engineType = "library"
  runtime    = "cloudflare" // or "workerd"
}

generator client {
  provider = "prisma-client-js"
  previewFeatures = ["driverAdapters"]
}

datasource db {
  provider = "postgresql"
  url      = env("DATABASE_URL")
}

import { PrismaClient } from '@prisma/client'
import { PrismaPg } from '@prisma/adapter-pg'
import { Pool } from 'pg'

export const getUser = createServerFn()
  .handler(async ({ request }) => {
    const env = request.context.cloudflare.env

    const pool = new Pool({ connectionString: env.HYPERDRIVE.connectionString })
    const adapter = new PrismaPg(pool)
    const prisma = new PrismaClient({ adapter })

    return prisma.user.findMany()
  })

export const getUsers = createServerFn()
  .handler(async ({ request }) => {
    const env = request.context.cloudflare.env
    const result = await env.DB.prepare('SELECT * FROM users').all()
    return result.results
  })

import { createMiddleware } from '@tanstack/react-start/server'

const middleware = createMiddleware().server(async (ctx) => {
  try {
    const r = await ctx.next()

    // Check for error in response object
    if ('error' in r && r.error) {
      throw r.error
    }

    return r
  } catch (error: any) {
    console.error("Middleware caught an error:", error)
    return new Response("An error occurred", { status: 500 })
  }
})

const result = await login({ username, password })

if (result) {
  // Safe to use result
  console.log(result.name)
}

// This condition is statically evaluated and dead code eliminated
if (process.env.NODE_ENV === 'production') {
  // Production-only code
} else {
  // Development-only code (removed in prod build)
}