# Authentication & Authorization Implementation Patterns
Build secure, scalable authentication and authorization systems using industry-standard patterns and modern best practices.
## Use this skill when
- Implementing user authentication systems
- Securing REST or GraphQL APIs
- Adding OAuth2/social login or SSO
- Designing session management or RBAC
- Debugging authentication or authorization issues
## Do not use this skill when
- You only need UI copy or login page styling
- The task is infrastructure-only without identity concerns
- You cannot change auth policies or credential storage
## Instructions
- Define users, tenants, flows, and threat model constraints.
- Choose auth strategy (session, JWT, OIDC) and token lifecycle.
- Design authorization model and policy enforcement points.
- Plan secrets storage, rotation, logging, and audit requirements.
- If detailed examples are required, open `resources/implementation-playbook.md`.
## Safety
- Never log secrets, tokens, or credentials.
- Enforce least privilege and secure storage for keys.
## Resources
- `resources/implementation-playbook.md` for detailed patterns and examples.