AT Protocol (Bluesky) authentication library with:
- Rust token verification library
- Node.js OAuth gateway server
- TypeScript/React frontend utilities

Security Features:
- HMAC-SHA256 with constant-time comparison
- Rate limiting (IP-based)
- CSRF protection via nonces
- Secure token transport (URL fragments)
- Input validation for DIDs, handles, and OAuth state
- Sanitized error responses

See SECURITY.md for security practices and reporting.