create-auth-skill
Create Auth Skill
Guide for adding authentication to TypeScript/JavaScript applications using Better Auth.
For code examples and syntax, see better-auth.com/docs.
Phase 1: Planning (REQUIRED before implementation)
Before writing any code, gather requirements by scanning the project and asking the user structured questions. This ensures the implementation matches their needs.
Step 1: Scan the project
Analyze the codebase to auto-detect:
- Framework — Look for
next.config,svelte.config,nuxt.config,astro.config,vite.config, or Express/Hono entry files. - Database/ORM — Look for
prisma/schema.prisma,drizzle.config,package.jsondeps (pg,mysql2,better-sqlite3,mongoose,mongodb). - Existing auth — Look for existing auth libraries (
next-auth,lucia,clerk,supabase/auth,firebase/auth) inpackage.jsonor imports. - Package manager — Check for
pnpm-lock.yaml,yarn.lock,bun.lockb, orpackage-lock.json.
Use what you find to pre-fill defaults and skip questions you can already answer.
Step 2: Ask planning questions
Use the AskQuestion tool to ask the user all applicable questions in a single call. Skip any question you already have a confident answer for from the scan. Group them under a title like "Auth Setup Planning".
Questions to ask:
-
Project type (skip if detected)
- Prompt: "What type of project is this?"
- Options: New project from scratch | Adding auth to existing project | Migrating from another auth library
-
Framework (skip if detected)
- Prompt: "Which framework are you using?"
- Options: Next.js (App Router) | Next.js (Pages Router) | SvelteKit | Nuxt | Astro | Express | Hono | SolidStart | Other
-
Database & ORM (skip if detected)
- Prompt: "Which database setup will you use?"
- Options: PostgreSQL (Prisma) | PostgreSQL (Drizzle) | PostgreSQL (pg driver) | MySQL (Prisma) | MySQL (Drizzle) | MySQL (mysql2 driver) | SQLite (Prisma) | SQLite (Drizzle) | SQLite (better-sqlite3 driver) | MongoDB (Mongoose) | MongoDB (native driver)
-
Authentication methods (always ask, allow multiple)
- Prompt: "Which sign-in methods do you need?"
- Options: Email & password | Social OAuth (Google, GitHub, etc.) | Magic link (passwordless email) | Passkey (WebAuthn) | Phone number
allow_multiple: true
-
Social providers (only if they selected Social OAuth above — ask in a follow-up call)
- Prompt: "Which social providers do you need?"
- Options: Google | GitHub | Apple | Microsoft | Discord | Twitter/X
allow_multiple: true
-
Email verification (only if Email & password was selected above — ask in a follow-up call)
- Prompt: "Do you want to require email verification?"
- Options: Yes | No
-
Email provider (only if email verification is Yes, or if Password reset is selected in features — ask in a follow-up call)
- Prompt: "How do you want to send emails?"
- Options: Resend | Mock it for now (console.log)
-
Features & plugins (always ask, allow multiple)
- Prompt: "Which additional features do you need?"
- Options: Two-factor authentication (2FA) | Organizations / teams | Admin dashboard | API bearer tokens | Password reset | None of these
allow_multiple: true
-
Auth pages (always ask, allow multiple — pre-select based on earlier answers)
- Prompt: "Which auth pages do you need?"
- Options vary based on previous answers:
- Always available: Sign in | Sign up
- If Email & password selected: Forgot password | Reset password
- If email verification enabled: Email verification
allow_multiple: true
-
Auth UI style (always ask)
- Prompt: "What style do you want for the auth pages? Pick one or describe your own."
- Options: Minimal & clean | Centered card with background | Split layout (form + hero image) | Floating / glassmorphism | Other (I'll describe)
Step 3: Summarize the plan
After collecting answers, present a concise implementation plan as a markdown checklist. Example:
## Auth Implementation Plan
- **Framework:** Next.js (App Router)
- **Database:** PostgreSQL via Prisma
- **Auth methods:** Email/password, Google OAuth, GitHub OAuth
- **Plugins:** 2FA, Organizations, Email verification
- **UI:** Custom forms
### Steps
1. Install `better-auth` and `@better-auth/cli`
2. Create `lib/auth.ts` with server config
3. Create `lib/auth-client.ts` with React client
4. Set up route handler at `app/api/auth/[...all]/route.ts`
5. Configure Prisma adapter and generate schema
6. Add Google & GitHub OAuth providers
7. Enable `twoFactor` and `organization` plugins
8. Set up email verification handler
9. Run migrations
10. Create sign-in / sign-up pages
Ask the user to confirm the plan before proceeding to Phase 2.
Phase 2: Implementation
Only proceed here after the user confirms the plan from Phase 1.
Follow the decision tree below, guided by the answers collected above.
Is this a new/empty project?
├─ YES → New project setup
│ 1. Install better-auth (+ scoped packages per plan)
│ 2. Create auth.ts with all planned config
│ 3. Create auth-client.ts with framework client
│ 4. Set up route handler
│ 5. Set up environment variables
│ 6. Run CLI migrate/generate
│ 7. Add plugins from plan
│ 8. Create auth UI pages
│
├─ MIGRATING → Migration from existing auth
│ 1. Audit current auth for gaps
│ 2. Plan incremental migration
│ 3. Install better-auth alongside existing auth
│ 4. Migrate routes, then session logic, then UI
│ 5. Remove old auth library
│ 6. See migration guides in docs
│
└─ ADDING → Add auth to existing project
1. Analyze project structure
2. Install better-auth
3. Create auth config matching plan
4. Add route handler
5. Run schema migrations
6. Integrate into existing pages
7. Add planned plugins and features
At the end of implementation, guide users thoroughly on remaining next steps (e.g., setting up OAuth app credentials, deploying env vars, testing flows).
Installation
Core: npm install better-auth
Scoped packages (as needed):
| Package | Use case |
|---|---|
@better-auth/passkey |
WebAuthn/Passkey auth |
@better-auth/sso |
SAML/OIDC enterprise SSO |
@better-auth/stripe |
Stripe payments |
@better-auth/scim |
SCIM user provisioning |
@better-auth/expo |
React Native/Expo |
Environment Variables
BETTER_AUTH_SECRET=<32+ chars, generate with: openssl rand -base64 32>
BETTER_AUTH_URL=http://localhost:3000
DATABASE_URL=<your database connection string>
Add OAuth secrets as needed: GITHUB_CLIENT_ID, GITHUB_CLIENT_SECRET, GOOGLE_CLIENT_ID, etc.
Server Config (auth.ts)
Location: lib/auth.ts or src/lib/auth.ts
Minimal config needs:
database- Connection or adapteremailAndPassword: { enabled: true }- For email/password auth
Standard config adds:
socialProviders- OAuth providers (google, github, etc.)emailVerification.sendVerificationEmail- Email verification handleremailAndPassword.sendResetPassword- Password reset handler
Full config adds:
plugins- Array of feature pluginssession- Expiry, cookie cache settingsaccount.accountLinking- Multi-provider linkingrateLimit- Rate limiting config
Export types: export type Session = typeof auth.$Infer.Session
Client Config (auth-client.ts)
Import by framework:
| Framework | Import |
|---|---|
| React/Next.js | better-auth/react |
| Vue | better-auth/vue |
| Svelte | better-auth/svelte |
| Solid | better-auth/solid |
| Vanilla JS | better-auth/client |
Client plugins go in createAuthClient({ plugins: [...] }).
Common exports: signIn, signUp, signOut, useSession, getSession
Route Handler Setup
| Framework | File | Handler |
|---|---|---|
| Next.js App Router | app/api/auth/[...all]/route.ts |
toNextJsHandler(auth) → export { GET, POST } |
| Next.js Pages | pages/api/auth/[...all].ts |
toNextJsHandler(auth) → default export |
| Express | Any file | app.all("/api/auth/*", toNodeHandler(auth)) |
| SvelteKit | src/hooks.server.ts |
svelteKitHandler(auth) |
| SolidStart | Route file | solidStartHandler(auth) |
| Hono | Route file | auth.handler(c.req.raw) |
Next.js Server Components: Add nextCookies() plugin to auth config.
Database Migrations
| Adapter | Command |
|---|---|
| Built-in Kysely | npx @better-auth/cli@latest migrate (applies directly) |
| Prisma | npx @better-auth/cli@latest generate --output prisma/schema.prisma then npx prisma migrate dev |
| Drizzle | npx @better-auth/cli@latest generate --output src/db/auth-schema.ts then npx drizzle-kit push |
Re-run after adding plugins.
Database Adapters
| Database | Setup |
|---|---|
| SQLite | Pass better-sqlite3 or bun:sqlite instance directly |
| PostgreSQL | Pass pg.Pool instance directly |
| MySQL | Pass mysql2 pool directly |
| Prisma | prismaAdapter(prisma, { provider: "postgresql" }) from better-auth/adapters/prisma |
| Drizzle | drizzleAdapter(db, { provider: "pg" }) from better-auth/adapters/drizzle |
| MongoDB | mongodbAdapter(db) from better-auth/adapters/mongodb |
Common Plugins
| Plugin | Server Import | Client Import | Purpose |
|---|---|---|---|
twoFactor |
better-auth/plugins |
twoFactorClient |
2FA with TOTP/OTP |
organization |
better-auth/plugins |
organizationClient |
Teams/orgs |
admin |
better-auth/plugins |
adminClient |
User management |
bearer |
better-auth/plugins |
- | API token auth |
openAPI |
better-auth/plugins |
- | API docs |
passkey |
@better-auth/passkey |
passkeyClient |
WebAuthn |
sso |
@better-auth/sso |
- | Enterprise SSO |
Plugin pattern: Server plugin + client plugin + run migrations.
Auth UI Implementation
Sign in flow:
signIn.email({ email, password })orsignIn.social({ provider, callbackURL })- Handle
errorin response - Redirect on success
Session check (client): useSession() hook returns { data: session, isPending }
Session check (server): auth.api.getSession({ headers: await headers() })
Protected routes: Check session, redirect to /sign-in if null.
Security Checklist
-
BETTER_AUTH_SECRETset (32+ chars) -
advanced.useSecureCookies: truein production -
trustedOriginsconfigured - Rate limits enabled
- Email verification enabled
- Password reset implemented
- 2FA for sensitive apps
- CSRF protection NOT disabled
-
account.accountLinkingreviewed
Troubleshooting
| Issue | Fix |
|---|---|
| "Secret not set" | Add BETTER_AUTH_SECRET env var |
| "Invalid Origin" | Add domain to trustedOrigins |
| Cookies not setting | Check baseURL matches domain; enable secure cookies in prod |
| OAuth callback errors | Verify redirect URIs in provider dashboard |
| Type errors after adding plugin | Re-run CLI generate/migrate |