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name: auth-skill description: Authentication and authorization for real_deal platform including third-party login (WeChat, Apple, Google, GitHub, LinkedIn), OAuth/OIDC flows, account merging, session management, and security best practices. Use when implementing login systems, handling OAuth callbacks, managing user sessions, or working with identity providers.

Authentication & Authorization

Supported Identity Providers

Domestic (China)

• WeChat / WeChat Work
• DingTalk
• Alipay
• Weibo

International

• Apple
• Google
• GitHub
• LinkedIn
• Microsoft (Azure AD/Personal)

Extended

• Passkeys (WebAuthn)
• TOTP 2FA
• SMS one-tap login

OAuth/OIDC Flow (Code Flow + PKCE)

Initiation

1. User selects "Login with X"
2. Backend generates state and nonce
3. Frontend includes PKCE code_challenge
4. Redirect to provider

Callback

1. Verify state/nonce
2. Use code_verifier to exchange tokens
3. Extract user info from ID Token/userinfo endpoint
4. Minimal fields: email, avatar, nickname, unique ID

Account Binding

Automatic Binding:

• Same verified email triggers merge (with user confirmation)

Manual Binding:

• Users manage multiple providers in "Account & Security"
• Prevent duplicate accounts

WeChat/No Email:

• Use unionid/openid as unique key
• Prompt for email/phone when needed

Data Models

Core Models

• User - User profile
• UserIdentity - Provider linkage (provider/subject/verifiedEmail/linkedAt)
• Session - Active sessions
• RefreshToken - Hashed storage with revocation

Security Fields

• Hashed tokens stored in Redis/MongoDB
• Token rotation with revocation support
• Device fingerprinting (lightweight)

Session Management

Tokens

• Access Token: Short-lived (e.g., 15-60 minutes)
• Refresh Token: Rolling refresh mechanism
• Storage: Hashed in database, revocable

Cookies

• httpOnly / Secure / SameSite=Lax
• Session cookie for authenticated state
• CSRF protection

2FA

• Require for critical operations
• Optional for regular use

Security Best Practices

Request Validation

• CSRF tokens
• PKCE for all OAuth flows
• state and nonce parameters
• Rate limiting on login endpoints
• Login anomaly detection

Data Minimization

• Request only email/profile scopes
• Reject contact/friends list access
• Cache tokens/user info as needed
• Regular rotation and cleanup

Compliance

• GDPR/CCPA/PIPL support
• Consent management
• Audit logging
• Data export/deletion rights

Common Tasks

Add New Provider

1. Register application with provider
2. Add client ID/secret to environment variables
3. Implement OAuth flow handler
4. Update user account binding logic
5. Add UI login button

Account Merge

1. Detect matching verified emails
2. Prompt user for confirmation
3. Merge identities under single user
4. Migrate sessions and preferences

Session Cleanup

1. Implement token revocation on logout
2. Schedule cleanup of expired refresh tokens
3. Audit active sessions in user dashboard