import { defineConfig } from 'vite'
import tsConfigPaths from 'vite-tsconfig-paths'
import { tanstackStart } from '@tanstack/react-start/plugin/vite'
import viteReact from '@vitejs/plugin-react'

export default defineConfig({
  plugins: [
    tsConfigPaths(),
    tanstackStart(),
    viteReact(),  // MUST come AFTER tanstackStart
  ],
})

tsconfig.json gotcha

Do NOT enable verbatimModuleSyntax - it leaks server bundles into client bundles.

Server Functions

See references/server-functions.md for complete guide.

⚠️ Critical: Route loaders run on server for initial SSR, but run on CLIENT during navigation. Always wrap server code in createServerFn() to ensure it runs server-side.

When to use what (Cloudflare Workers):

Use Case	Solution
Server code in route loaders	`createServerFn()`
Server code from client event handlers	API routes (`server.handlers`) work best
Access Cloudflare bindings	`import { env } from 'cloudflare:workers'`

createServerFn - for loaders:

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

export const getData = createServerFn().handler(async () => {
  return { data: process.env.SECRET }  // Server-only
})

API routes - for client event handlers:

// routes/api/users.ts
export const Route = createFileRoute('/api/users')({
  server: {
    handlers: {
      POST: async ({ request }) => {
        const body = await request.json()
        return Response.json(await db.users.create(body))
      },
    },
  },
})

// In component: fetch('/api/users', { method: 'POST', body: JSON.stringify(data) })

Key APIs:

createServerFn() - Server-only functions for loaders
server.handlers - API routes for client event handlers
createMiddleware({ type: 'function' }) - Reusable middleware
@tanstack/react-start/server: getRequestHeaders(), setResponseHeader(), getCookies()

Routing

See references/routing.md for complete patterns.

File conventions in src/routes/:

Pattern	Route
`index.tsx`	`/`
`posts.$postId.tsx`	`/posts/:postId`
`_layout.tsx`	Layout (no URL)
`__root.tsx`	Root layout (required)

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

const getPost = createServerFn()
  .handler(async () => await db.post.findFirst())

export const Route = createFileRoute('/posts/$postId')({
  loader: ({ params }) => getPost({ data: params.postId }),
  component: () => {
    const post = Route.useLoaderData()
    return <h1>{post.title}</h1>
  },
})

Cloudflare Deployment

See references/cloudflare-deployment.md for complete guide.

pnpm add -D @cloudflare/vite-plugin wrangler

vite.config.ts - add cloudflare plugin:

import { cloudflare } from '@cloudflare/vite-plugin'
// Add to plugins: cloudflare({ viteEnvironment: { name: 'ssr' } })

wrangler.jsonc:

{
  "$schema": "./node_modules/wrangler/config-schema.json",
  "name": "my-app",
  "compatibility_date": "<CURRENT_DATE>",  // Use today's YYYY-MM-DD
  "compatibility_flags": ["nodejs_compat"],
  "main": "@tanstack/react-start/server-entry",
  "observability": { "enabled": true }
}

Access Cloudflare bindings in server functions:

import { env } from 'cloudflare:workers'
const value = await env.MY_KV.get('key')

Static Prerendering (v1.138.0+):

tanstackStart({ prerender: { enabled: true } })

TanStack Query Integration

See references/query-integration.md for SSR setup.

pnpm add @tanstack/react-query @tanstack/react-router-ssr-query

// Preload in loaders, consume with useSuspenseQuery
loader: ({ context }) => context.queryClient.ensureQueryData(myQueryOptions)

Better-Auth Integration

See references/better-auth.md for complete guide.

⚠️ Critical: Use createFileRoute with server.handlers, NOT the legacy createAPIFileRoute.

Mount the auth handler at /src/routes/api/auth/$.ts:

import { auth } from '@/lib/auth'
import { createFileRoute } from '@tanstack/react-router'

export const Route = createFileRoute('/api/auth/$')({
  server: {
    handlers: {
      GET: ({ request }) => auth.handler(request),
      POST: ({ request }) => auth.handler(request),
    },
  },
})

Auth config with tanstackStartCookies plugin:

import { betterAuth } from "better-auth"
import { tanstackStartCookies } from "better-auth/tanstack-start"

export const auth = betterAuth({
  // ...your config
  plugins: [tanstackStartCookies()] // MUST be last plugin
})

Protect routes with middleware:

import { createMiddleware } from "@tanstack/react-start"
import { getRequestHeaders } from "@tanstack/react-start/server"
import { auth } from "./auth"

export const authMiddleware = createMiddleware().server(
  async ({ next }) => {
    const session = await auth.api.getSession({ headers: getRequestHeaders() })
    if (!session) throw redirect({ to: "/login" })
    return next()
  }
)

// In route:
export const Route = createFileRoute('/dashboard')({
  server: { middleware: [authMiddleware] },
  component: Dashboard,
})

GitHub Actions Auto-Deploy

See references/github-actions-deploy.md for CI/CD setup with preview deployments.

tanstack-start

TanStack Start

Project Setup

Critical Configuration

vite.config.ts