saas-scaffolder – Design & UI skill for AI agents

SaaS Scaffolder

Tier: POWERFUL

Category: Product Team

Domain: Full-Stack Development / Project Bootstrapping

---

Input Format

Product: [name]
Description: [1-3 sentences]
Auth: nextauth | clerk | supabase
Database: neondb | supabase | planetscale
Payments: stripe | lemonsqueezy | none
Features: [comma-separated list]

---

File Tree Output

my-saas/
├── app/
│   ├── (auth)/
│   │   ├── login/page.tsx
│   │   ├── register/page.tsx
│   │   └── layout.tsx
│   ├── (dashboard)/
│   │   ├── dashboard/page.tsx
│   │   ├── settings/page.tsx
│   │   ├── billing/page.tsx
│   │   └── layout.tsx
│   ├── (marketing)/
│   │   ├── page.tsx
│   │   ├── pricing/page.tsx
│   │   └── layout.tsx
│   ├── api/
│   │   ├── auth/[...nextauth]/route.ts
│   │   ├── webhooks/stripe/route.ts
│   │   ├── billing/checkout/route.ts
│   │   └── billing/portal/route.ts
│   └── layout.tsx
├── components/
│   ├── ui/
│   ├── auth/
│   │   ├── login-form.tsx
│   │   └── register-form.tsx
│   ├── dashboard/
│   │   ├── sidebar.tsx
│   │   ├── header.tsx
│   │   └── stats-card.tsx
│   ├── marketing/
│   │   ├── hero.tsx
│   │   ├── features.tsx
│   │   ├── pricing.tsx
│   │   └── footer.tsx
│   └── billing/
│       ├── plan-card.tsx
│       └── usage-meter.tsx
├── lib/
│   ├── auth.ts
│   ├── db.ts
│   ├── stripe.ts
│   ├── validations.ts
│   └── utils.ts
├── db/
│   ├── schema.ts
│   └── migrations/
├── hooks/
│   ├── use-subscription.ts
│   └── use-user.ts
├── types/index.ts
├── middleware.ts
├── .env.example
├── drizzle.config.ts
└── next.config.ts

---

Key Component Patterns

Auth Config (NextAuth)

// lib/auth.ts
import { NextAuthOptions } from "next-auth"
import GoogleProvider from "next-auth/providers/google"
import { DrizzleAdapter } from "@auth/drizzle-adapter"
import { db } from "./db"

export const authOptions: NextAuthOptions = {
  adapter: DrizzleAdapter(db),
  providers: [
    GoogleProvider({
      clientId: process.env.GOOGLE_CLIENT_ID!,
      clientSecret: process.env.GOOGLE_CLIENT_SECRET!,
    }),
  ],
  callbacks: {
    session: async ({ session, user }) => ({
      ...session,
      user: {
        ...session.user,
        id: user.id,
        subscriptionStatus: user.subscriptionStatus,
      },
    }),
  },
  pages: { signIn: "/login" },
}

Database Schema (Drizzle + NeonDB)

// db/schema.ts
import { pgTable, text, timestamp, integer } from "drizzle-orm/pg-core"

export const users = pgTable("users", {
  id: text("id").primaryKey().$defaultFn(() => crypto.randomUUID()),
  name: text("name"),
  email: text("email").notNull().unique(),
  emailVerified: timestamp("emailVerified"),
  image: text("image"),
  stripeCustomerId: text("stripe_customer_id").unique(),
  stripeSubscriptionId: text("stripe_subscription_id"),
  stripePriceId: text("stripe_price_id"),
  stripeCurrentPeriodEnd: timestamp("stripe_current_period_end"),
  createdAt: timestamp("created_at").defaultNow().notNull(),
})

export const accounts = pgTable("accounts", {
  userId: text("user_id").notNull().references(() => users.id, { onDelete: "cascade" }),
  type: text("type").notNull(),
  provider: text("provider").notNull(),
  providerAccountId: text("provider_account_id").notNull(),
  refresh_token: text("refresh_token"),
  access_token: text("access_token"),
  expires_at: integer("expires_at"),
})

Stripe Checkout Route

// app/api/billing/checkout/route.ts
import { NextResponse } from "next/server"
import { getServerSession } from "next-auth"
import { authOptions } from "@/lib/auth"
import { stripe } from "@/lib/stripe"
import { db } from "@/lib/db"
import { users } from "@/db/schema"
import { eq } from "drizzle-orm"

export async function POST(req: Request) {
  const session = await getServerSession(authOptions)
  if (!session?.user) return NextResponse.json({ error: "Unauthorized" }, { status: 401 })

  const { priceId } = await req.json()
  const [user] = await db.select().from(users).where(eq(users.id, session.user.id))

  let customerId = user.stripeCustomerId
  if (!customerId) {
    const customer = await stripe.customers.create({ email: session.user.email! })
    customerId = customer.id
    await db.update(users).set({ stripeCustomerId: customerId }).where(eq(users.id, user.id))
  }

  const checkoutSession = await stripe.checkout.sessions.create({
    customer: customerId,
    mode: "subscription",
    payment_method_types: ["card"],
    line_items: [{ price: priceId, quantity: 1 }],
    success_url: `${process.env.NEXT_PUBLIC_APP_URL}/dashboard?upgraded=true`,
    cancel_url: `${process.env.NEXT_PUBLIC_APP_URL}/pricing`,
    subscription_data: { trial_period_days: 14 },
  })

  return NextResponse.json({ url: checkoutSession.url })
}

Middleware

// middleware.ts
import { withAuth } from "next-auth/middleware"
import { NextResponse } from "next/server"

export default withAuth(
  function middleware(req) {
    const token = req.nextauth.token
    if (req.nextUrl.pathname.startsWith("/dashboard") && !token) {
      return NextResponse.redirect(new URL("/login", req.url))
    }
  },
  { callbacks: { authorized: ({ token }) => !!token } }
)

export const config = {
  matcher: ["/dashboard/:path*", "/settings/:path*", "/billing/:path*"],
}

Environment Variables Template

# .env.example
NEXT_PUBLIC_APP_URL=http://localhost:3000
DATABASE_URL=postgresql://user:[email protected]/neondb?sslmode=require
NEXTAUTH_SECRET=generate-with-openssl-rand-base64-32
NEXTAUTH_URL=http://localhost:3000
GOOGLE_CLIENT_ID=
GOOGLE_CLIENT_SECRET=
STRIPE_SECRET_KEY=sk_test_...
STRIPE_WEBHOOK_SECRET=whsec_...
NEXT_PUBLIC_STRIPE_PUBLISHABLE_KEY=pk_test_...
STRIPE_PRO_PRICE_ID=price_...

---

Scaffold Checklist

The following phases must be completed in order. Validate at the end of each phase before proceeding.

Phase 1 — Foundation

• [ ] 1. Next.js initialized with TypeScript and App Router
• [ ] 2. Tailwind CSS configured with custom theme tokens
• [ ] 3. shadcn/ui installed and configured
• [ ] 4. ESLint + Prettier configured
• [ ] 5. .env.example created with all required variables

✅ Validate: Run npm run build — no TypeScript or lint errors should appear.

🔧 If build fails: Check tsconfig.json paths and that all shadcn/ui peer dependencies are installed.

Phase 2 — Database

• [ ] 6. Drizzle ORM installed and configured
• [ ] 7. Schema written (users, accounts, sessions, verification_tokens)
• [ ] 8. Initial migration generated and applied
• [ ] 9. DB client singleton exported from lib/db.ts
• [ ] 10. DB connection tested in local environment

✅ Validate: Run a simple db.select().from(users) in a test script — it should return an empty array without throwing.

🔧 If DB connection fails: Verify DATABASE_URL format includes ?sslmode=require for NeonDB/Supabase. Check that the migration has been applied with drizzle-kit push (dev) or drizzle-kit migrate (prod).

Phase 3 — Authentication

• [ ] 11. Auth provider installed (NextAuth / Clerk / Supabase)
• [ ] 12. OAuth provider configured (Google / GitHub)
• [ ] 13. Auth API route created
• [ ] 14. Session callback adds user ID and subscription status
• [ ] 15. Middleware protects dashboard routes
• [ ] 16. Login and register pages built with error states

✅ Validate: Sign in via OAuth, confirm session user has id and subscriptionStatus. Attempt to access /dashboard without a session — you should be redirected to /login.

🔧 If sign-out loops occur in production: Ensure NEXTAUTH_SECRET is set and consistent across deployments. Add declare module "next-auth" to extend session types if TypeScript errors appear.

Phase 4 — Payments

• [ ] 17. Stripe client initialized with TypeScript types
• [ ] 18. Checkout session route created
• [ ] 19. Customer portal route created
• [ ] 20. Stripe webhook handler with signature verification
• [ ] 21. Webhook updates user subscription status in DB idempotently

✅ Validate: Complete a Stripe test checkout using a 4242 4242 4242 4242 card. Confirm stripeSubscriptionId is written to the DB. Replay the checkout.session.completed webhook event and confirm idempotency (no duplicate DB writes).

🔧 If webhook signature fails: Use stripe listen --forward-to localhost:3000/api/webhooks/stripe locally — never hardcode the raw webhook secret. Verify STRIPE_WEBHOOK_SECRET matches the listener output.

Phase 5 — UI

• [ ] 22. Landing page with hero, features, pricing sections
• [ ] 23. Dashboard layout with sidebar and responsive header
• [ ] 24. Billing page showing current plan and upgrade options
• [ ] 25. Settings page with profile update form and success states

✅ Validate: Run npm run build for a final production build check. Navigate all routes manually and confirm no broken layouts, missing session data, or hydration errors.

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Reference Files

For

… (full content is in the download package)