ferix: Skill for Claude Code

Create Auth Skill

Guide for adding authentication to TypeScript/JavaScript applications using Better Auth.

For code examples and syntax, see better-auth.com/docs.

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Decision Tree

Is this a new/empty project?
├─ YES → New project setup
│   1. Identify framework
│   2. Choose database
│   3. Install better-auth
│   4. Create auth.ts + auth-client.ts
│   5. Set up route handler
│   6. Run CLI migrate/generate
│   7. Add features via plugins
│
└─ NO → Does project have existing auth?
    ├─ YES → Migration/enhancement
    │   • Audit current auth for gaps
    │   • Plan incremental migration
    │   • See migration guides in docs
    │
    └─ NO → Add auth to existing project
        1. Analyze project structure
        2. Install better-auth
        3. Create auth config
        4. Add route handler
        5. Run schema migrations
        6. Integrate into existing pages

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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

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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.

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Server Config (auth.ts)

Location: lib/auth.ts or src/lib/auth.ts

Minimal config needs:

• database - Connection or adapter
• emailAndPassword: { enabled: true } - For email/password auth

Standard config adds:

• socialProviders - OAuth providers (google, github, etc.)
• emailVerification.sendVerificationEmail - Email verification handler
• emailAndPassword.sendResetPassword - Password reset handler