# Task: Build User Authentication API

**Created**: 2025-11-13
**Owner**: Backend Team
**Priority**: High
**Type**: Feature

**Assigned Agent(s)**: Backend-focused workflow with security review
**Suggested Workflow**: `backend-only` (enhanced with security-specialist*)

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## Objective

Design and implement a secure user authentication system with JWT tokens, refresh tokens, email verification, and password reset functionality. The API must support role-based access control (RBAC) and integrate with our existing Next.js frontend.

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## Requirements

### Functional Requirements
- User registration with email verification
- Login with email/password
- JWT access tokens (15 min expiry)
- Refresh tokens (7 day expiry)
- Password reset via email
- Email verification on signup
- Role-based access control (admin, user, guest)
- Session management
- Logout (invalidate tokens)
- Rate limiting on auth endpoints

### Non-Functional Requirements
- **Performance**: Auth endpoints respond < 200ms
- **Scalability**: Handle 1000 concurrent users
- **Security**: Passwords hashed with bcrypt (10 rounds), tokens signed with RSA
- **Reliability**: 99.9% uptime
- **Compliance**: GDPR compliant, no PII in logs

### Technical Requirements
- **Framework**: Node.js 20+ with Express or Fastify
- **Language**: TypeScript 5.x
- **Database**: PostgreSQL with user/session tables
- **Authentication**: JWT with RS256 signing
- **Email**: SendGrid for transactional emails
- **Validation**: Zod for input validation
- **Testing**: Jest unit tests + Supertest integration tests

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## Context

### Background
Our current auth system is basic email/password without refresh tokens or email verification. We've had security concerns and need a production-grade solution before scaling to 10K users.

### Assumptions
- Users will use email/password (no OAuth for MVP)
- Email delivery is reliable (99% delivery rate)
- Users have access to their email for verification
- Frontend can handle JWT storage in httpOnly cookies

### Constraints
- **Time**: Must complete by November 30
- **Budget**: Use existing SendGrid plan (10K emails/month)
- **Technical**: Must work with existing PostgreSQL instance
- **Security**: Follow OWASP authentication guidelines

### Dependencies
- PostgreSQL database setup (complete)
- SendGrid API key (pending)
- Frontend ready to consume API (in progress)

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## Acceptance Criteria

- [ ] User can register with email/password
- [ ] Verification email sent on registration
- [ ] User can login after email verification
- [ ] JWT access token issued on login (15 min expiry)
- [ ] Refresh token issued (7 day expiry, httpOnly cookie)
- [ ] Password reset email sent on request
- [ ] User can reset password via email link
- [ ] Tokens can be refreshed before expiry
- [ ] Logout invalidates refresh token
- [ ] Rate limiting prevents brute force (5 attempts/min)
- [ ] Passwords hashed with bcrypt (10 rounds)
- [ ] RBAC enforced on protected routes
- [ ] All endpoints have input validation
- [ ] API returns proper HTTP status codes
- [ ] Errors don't leak sensitive information
- [ ] Unit test coverage > 85%
- [ ] Integration tests cover all flows

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## Scope

### In Scope
- User registration/login
- Email verification
- Password reset
- JWT token issuance
- Refresh token rotation
- RBAC middleware
- Rate limiting
- Input validation
- Error handling

### Out of Scope
- OAuth (Google, GitHub) - future release
- Two-factor authentication - future release
- Social login - not planned
- Magic links - future release
- Account deletion - separate task

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## Resources

### Documentation
- OWASP Auth Cheat Sheet: https://cheatsheetseries.owasp.org/
- JWT Best Practices: https://tools.ietf.org/html/rfc8725
- SendGrid API Docs: https://docs.sendgrid.com/

### Examples
- Reference implementation: github.com/example/auth-api
- Security patterns: docs/security-patterns.md

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## Deliverables

### Code
- [ ] `src/routes/auth.ts` - Auth routes
- [ ] `src/controllers/auth.controller.ts` - Auth logic
- [ ] `src/middleware/auth.middleware.ts` - JWT verification
- [ ] `src/middleware/rbac.middleware.ts` - Role checking
- [ ] `src/services/token.service.ts` - Token generation/verification
- [ ] `src/services/email.service.ts` - Email sending
- [ ] `src/models/user.model.ts` - User model
- [ ] `src/models/session.model.ts` - Session model

### Database
- [ ] Migration: Create users table
- [ ] Migration: Create sessions table
- [ ] Indexes for email lookups
- [ ] Indexes for session queries

### Tests
- [ ] Unit tests for auth controller
- [ ] Unit tests for token service
- [ ] Integration tests for registration flow
- [ ] Integration tests for login flow
- [ ] Integration tests for password reset
- [ ] Security tests (SQL injection, XSS)

### Documentation
- [ ] API documentation (OpenAPI/Swagger)
- [ ] Authentication flow diagrams
- [ ] Security considerations document
- [ ] Deployment guide

### Configuration
- [ ] Environment variables (.env.example)
- [ ] Database connection config
- [ ] SendGrid integration
- [ ] JWT key generation script

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## Success Metrics

- **Response Time**: < 200ms for all auth endpoints
- **Error Rate**: < 0.1% for auth operations
- **Security**: Zero critical vulnerabilities
- **Test Coverage**: > 85%
- **Email Delivery**: > 99%

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## Workflow

**Suggested agent sequence**:

1. **backend-architect** - Design API architecture, error taxonomy
2. **database-architect** - Design user/session schema with indexes
3. **python-expert** - Create database migration scripts
4. **frontend-developer** - Update frontend for new auth flow
5. **qc-automation-expert** - Create comprehensive test suite
6. **api-documenter** - Generate OpenAPI specification
7. **deployment-integration-expert** - Configure deployment

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## Risk Assessment

| Risk | Impact | Likelihood | Mitigation |
|------|--------|------------|------------|
| SendGrid rate limits exceeded | High | Low | Monitor usage, have backup provider |
| Token compromise | Critical | Low | Use RS256, rotate keys regularly |
| Brute force attacks | High | Medium | Rate limiting, account lockout |
| Email deliverability issues | Medium | Medium | Use verified sender, monitor bounces |

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## Timeline

**Estimated Duration**: 8 days

### Phase 1: Design (Day 1-2)
- API architecture
- Database schema
- Security review

### Phase 2: Implementation (Day 3-6)
- Core auth endpoints
- Token management
- Email integration
- RBAC middleware

### Phase 3: Testing (Day 7)
- Unit and integration tests
- Security testing
- Load testing

### Phase 4: Documentation & Deployment (Day 8)
- API documentation
- Deploy to staging
- Security audit

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## Security Considerations

### Password Storage
- Use bcrypt with 10 rounds (configurable)
- Never log passwords
- Enforce minimum complexity (8 chars, mix of types)

### Token Management
- Access tokens: 15 min expiry
- Refresh tokens: 7 day expiry, rotate on use
- Sign with RS256 (not HS256)
- Store refresh tokens hashed in database

### Rate Limiting
- Login: 5 attempts per 15 min per IP
- Registration: 3 per hour per IP
- Password reset: 3 per hour per email

### Email Security
- Use verified sender domain
- Include expiring tokens in links (1 hour)
- No sensitive data in email body

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## Notes

- Must pass security review before production
- Consider adding honeypot fields to prevent bots
- Monitor failed login attempts for patterns
- Plan for future OAuth integration
- Document all security decisions

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## Approval

**Approved By**: CTO
**Date**: 2025-11-13
**Sign-off**: ✅ Approved with security review

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**Version**: 1.0.0
**Status**: Approved
