Better Auth

What it does

When your agent uses it

• Setting up Better Auth with NestJS backend
• Integrating Next.js App Router frontend
• Configuring Drizzle ORM schema
• Implementing social login (GitHub

Example prompts

• “Use the better-auth skill to provide Better Auth integration patterns for NestJS backend and Next.js frontend with Drizzle ORM and PostgreSQL”
• “/better-auth”

Requirements

• Node.js
• A credential in AUTH_GITHUB_CLIENT_SECRET
• A credential in BETTER_AUTH_SECRET
• Pre-approved tools (allowed-tools): Read, Write, Edit, Glob, Grep, Bash

Workflow steps

4 steps, taken from the step headings in SKILL.md.

1. 1Database Setup
2. 2Backend Setup (NestJS)
3. 3Frontend Setup (Next.js)
4. 4Advanced Features

What it can do on your machine

Read from SKILL.md and the folder at commit fe73fb3. It shows what the files ask for, not the result of running them.

• Tool permissions

  Pre-approves these tools, so the agent can use them without asking each time:

  • Read
  • Write
  • Edit
  • Glob
  • Grep
  • Bash

  From allowed-tools in the SKILL.md frontmatter.

• Runs code

  Ships script files (TypeScript, from the files we listed), which the agent can run.

  Shell commands in SKILL.md call:

  • npm
  • npx
  • psql
  • openssl

  From the folder's file list and the shell code blocks in SKILL.md.

• Network

  Links to these hosts (documentation or services it may open):

  • better-auth.com
  • orm.drizzle.team
  • docs.nestjs.com
  • nextjs.org

  From URLs in SKILL.md, links to its own repository left out.

• Credentials

  Names these keys or tokens, usually read from environment variables:

  • BETTER_AUTH_SECRET
  • AUTH_GITHUB_CLIENT_SECRET

  From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Better Auth loads about 2.4k tokens when it runs, and up to ~23k if it reads all its reference files. Until then it costs about 118 tokens; SKILL.md has 641 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it

~118

When it runs · the whole SKILL.md, loaded when a task matches

~2.4k

With references · SKILL.md plus every file in references/, read only if the agent opens them

~23k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

• NoteMentions a .env fileSKILL.md:252

  nment Variables**: Store all secrets in `.env`, add to `.gitignore`

• NoteMentions a .env fileSKILL.md:265

  - **Never commit secrets**: Add `.env` to `.gitignore`; never commit OAuth secrets or DB credentials

• NotePre-approves every shell command (allowed-tools: Bash)SKILL.md

  allowed-tools: Read, Write, Edit, Glob, Grep, Bash

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from giuseppe-trisciuoglio/developer-kit at commit fe73fb3, republished under its MIT licence (© giuseppe-trisciuoglio). 641 words, ~2,380 tokens.

name

better-auth

description

Provides Better Auth integration patterns for NestJS backend and Next.js frontend with Drizzle ORM and PostgreSQL. Use when setting up Better Auth with NestJS backend, integrating Next.js App Router frontend, configuring Drizzle ORM schema, implementing social login (GitHub, Google), adding plugins (2FA, Organization, SSO, Magic Link, Passkey), implementing email/password authentication with session management, or creating protected routes and middleware.

allowed-tools

Read, Write, Edit, Glob, Grep, Bash

# Backend (NestJS)
npm install better-auth @auth/drizzle-adapter drizzle-orm pg
npm install -D drizzle-kit

# Frontend (Next.js)
npm install better-auth

// app/dashboard/page.tsx
import { auth } from '@/lib/auth';
import { redirect } from 'next/navigation';

export default async function DashboardPage() {
  const session = await auth();

  if (!session) {
    redirect('/sign-in');
  }

  return (
    <div>
      <h1>Welcome, {session.user.name}</h1>
      <p>Email: {session.user.email}</p>
    </div>
  );
}

// Server: Configure 2FA with OTP sending
export const auth = betterAuth({
  plugins: [
    twoFactor({
      issuer: 'MyApp',
      otpOptions: {
        async sendOTP({ user, otp }, ctx) {
          await sendEmail({
            to: user.email,
            subject: 'Your verification code',
            body: `Code: ${otp}`
          });
        }
      }
    })
  ]
});

// Client: Verify TOTP and trust device
const verify2FA = async (code: string) => {
  const { data } = await authClient.twoFactor.verifyTotp({
    code,
    trustDevice: true  // Device trusted for 30 days
  });

  if (data) {
    router.push('/dashboard');
  }
};

// Server
import { passkey } from '@better-auth/passkey';
export const auth = betterAuth({
  plugins: [
    passkey({
      rpID: 'example.com',
      rpName: 'My App',
    })
  ]
});

// Client: Register passkey
const registerPasskey = async () => {
  const { data } = await authClient.passkey.register({
    name: 'My Device'
  });
};

// Client: Sign in with autofill
const signInWithPasskey = async () => {
  await authClient.signIn.passkey({
    autoFill: true,  // Browser suggests passkey
  });
};

© giuseppe-trisciuoglio, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

SKILL.md and 24 other files (references, assets) in plugins/developer-kit-typescript/skills/better-auth of giuseppe-trisciuoglio/developer-kit.

• SKILL.md
• assets/env.example
• assets/nestjs/auth.controller.ts
• assets/nestjs/auth.guard.ts
• assets/nestjs/auth.module.ts
• assets/nestjs/auth.schema.ts
• assets/nestjs/auth.service.ts
• assets/nestjs/database.module.ts
• assets/nestjs/database.service.ts
• assets/nextjs/auth-client.ts
• assets/nextjs/auth-route.ts
• assets/nextjs/dashboard-page.tsx
• assets/nextjs/middleware.ts
• assets/nextjs/sign-in-page.tsx
• assets/nextjs/use-session.ts
• references/best-practices.md
• references/examples.md
• … and 8 more

Open the folder on GitHubat commit fe73fb3