technical-specification

name	technical-specification
description	Create detailed technical specifications, requirements documents, design documents, and system architecture specs. Use when writing technical specs, requirements docs, or design documents.

Technical Specification

Overview

Create comprehensive technical specifications that define system requirements, architecture, implementation details, and acceptance criteria for software projects.

When to Use

• Feature specifications
• System design documents
• Requirements documentation (PRD)
• Architecture decision records (ADR)
• Technical proposals
• RFC (Request for Comments)
• API design specs
• Database schema designs

Technical Specification Template

# Technical Specification: [Feature Name]

**Document Status:** Draft | Review | Approved | Implemented
**Version:** 1.0
**Author:** John Doe
**Date:** 2025-01-15
**Reviewers:** Jane Smith, Bob Johnson
**Last Updated:** 2025-01-15

## Executive Summary

Brief 2-3 sentence overview of what this spec covers and why it's being built.

**Problem:** What problem are we solving?
**Solution:** High-level description of the solution
**Impact:** Expected business/user impact

---

## 1. Background

### Context

Provide background on why this feature is needed:
- What's the current situation?
- What pain points exist?
- What's driving this change?

### Goals

- **Primary Goal:** Main objective of this feature
- **Secondary Goals:** Additional benefits
- **Success Metrics:** How we'll measure success
  - Metric 1: [Description] - Target: [Value]
  - Metric 2: [Description] - Target: [Value]

### Non-Goals

What this specification explicitly does NOT cover:
- Non-goal 1
- Non-goal 2
- Future considerations (out of scope for v1)

---

## 2. Requirements

### Functional Requirements

#### FR-1: User Authentication
**Priority:** P0 (Must Have)
**Description:** Users must be able to authenticate using email/password

**Acceptance Criteria:**
- [ ] User can register with email and password
- [ ] User can log in with credentials
- [ ] User receives email verification
- [ ] User can reset forgotten password
- [ ] Session expires after 7 days of inactivity

**Dependencies:** None

#### FR-2: Social Login
**Priority:** P1 (Should Have)
**Description:** Users can authenticate using OAuth providers

**Acceptance Criteria:**
- [ ] Support Google OAuth
- [ ] Support GitHub OAuth
- [ ] Link social accounts to existing accounts
- [ ] Unlink social accounts

**Dependencies:** FR-1

#### FR-3: Two-Factor Authentication
**Priority:** P2 (Nice to Have)
**Description:** Optional 2FA for enhanced security

**Acceptance Criteria:**
- [ ] Enable/disable 2FA in settings
- [ ] Support TOTP (Google Authenticator, Authy)
- [ ] Backup codes generation
- [ ] Recovery process if device is lost

**Dependencies:** FR-1

### Non-Functional Requirements

#### Performance
- **Response Time:** API endpoints < 200ms p95
- **Throughput:** Support 1000 requests/second
- **Database Queries:** < 50ms p95
- **Page Load:** First contentful paint < 1.5s

#### Scalability
- **Concurrent Users:** Support 100,000 simultaneous users
- **Data Growth:** Handle 10M user records
- **Horizontal Scaling:** Support 10 application instances

#### Security
- **Authentication:** JWT-based with refresh tokens
- **Password Hashing:** bcrypt with 12 rounds
- **Rate Limiting:** 100 requests/hour per IP
- **Data Encryption:** AES-256 at rest, TLS 1.3 in transit

#### Availability
- **Uptime:** 99.9% SLA
- **Recovery Time:** RTO < 4 hours, RPO < 1 hour
- **Backup:** Daily automated backups, 30-day retention

#### Compliance
- GDPR compliant (data export/deletion)
- SOC 2 Type II requirements
- PCI DSS (if handling payments)

---

## 3. System Architecture

### High-Level Architecture

┌─────────────┐ │ Client │ │ (React App) │ └──────┬──────┘ │ ▼ ┌─────────────┐ ┌──────────────┐ │ API Gateway │────▶│ Auth Service │ │ (Express) │ │ (Node.js) │ └──────┬──────┘ └──────┬───────┘ │ │ ▼ ▼ ┌─────────────┐ ┌──────────────┐ │User Service │ │ Database │ │ (Node.js) │────▶│ (PostgreSQL) │ └─────────────┘ └──────────────┘ │ ▼ ┌─────────────┐ │ Cache │ │ (Redis) │ └─────────────┘

### Component Diagram

#### Frontend (React)
- **Login Page:** Email/password and social login
- **Registration Page:** User signup with validation
- **Settings Page:** Manage 2FA and connected accounts
- **Components:** Reusable auth components

#### Backend (Node.js/Express)
- **Auth Controller:** Handle authentication requests
- **User Controller:** Manage user data
- **Auth Middleware:** Validate JWT tokens
- **Rate Limiter:** Prevent abuse

#### Database (PostgreSQL)
- **users table:** User account data
- **sessions table:** Active sessions
- **oauth_connections table:** Social login links

#### Cache (Redis)
- Session storage
- Rate limit counters
- Temporary tokens (password reset, email verification)

---

## 4. Data Model

### Database Schema

```sql
-- Users table
CREATE TABLE users (
  id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
  email VARCHAR(255) UNIQUE NOT NULL,
  password_hash VARCHAR(255),
  email_verified BOOLEAN DEFAULT FALSE,
  two_factor_enabled BOOLEAN DEFAULT FALSE,
  two_factor_secret VARCHAR(32),
  created_at TIMESTAMP DEFAULT NOW(),
  updated_at TIMESTAMP DEFAULT NOW(),
  last_login_at TIMESTAMP
);

-- OAuth connections
CREATE TABLE oauth_connections (
  id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
  user_id UUID REFERENCES users(id) ON DELETE CASCADE,
  provider VARCHAR(50) NOT NULL, -- 'google', 'github'
  provider_user_id VARCHAR(255) NOT NULL,
  access_token TEXT,
  refresh_token TEXT,
  created_at TIMESTAMP DEFAULT NOW(),
  UNIQUE(provider, provider_user_id)
);

-- Sessions
CREATE TABLE sessions (
  id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
  user_id UUID REFERENCES users(id) ON DELETE CASCADE,
  token VARCHAR(255) UNIQUE NOT NULL,
  expires_at TIMESTAMP NOT NULL,
  created_at TIMESTAMP DEFAULT NOW(),
  ip_address INET,
  user_agent TEXT
);

-- Indexes
CREATE INDEX idx_users_email ON users(email);
CREATE INDEX idx_sessions_token ON sessions(token);
CREATE INDEX idx_sessions_user_id ON sessions(user_id);
CREATE INDEX idx_oauth_user_id ON oauth_connections(user_id);

API Data Models

interface User {
  id: string;
  email: string;
  emailVerified: boolean;
  twoFactorEnabled: boolean;
  createdAt: string;
  updatedAt: string;
  lastLoginAt?: string;
}

interface LoginRequest {
  email: string;
  password: string;
  twoFactorCode?: string;
}

interface LoginResponse {
  success: boolean;
  token: string;
  refreshToken: string;
  user: User;
  expiresIn: number;
}

interface RegisterRequest {
  email: string;
  password: string;
  confirmPassword: string;
}

---

5. API Design

Authentication Endpoints

POST /api/auth/register

Description: Register a new user account

Request:

{
  "email": "[e-mail]",
  "password": "SecurePass123!",
  "confirmPassword": "SecurePass123!"
}

Response (201):

{
  "success": true,
  "user": {
    "id": "550e8400-e29b-41d4-a716-446655440000",
    "email": "[e-mail]",
    "emailVerified": false
  },
  "message": "Verification email sent"
}

Errors:

• 400: Invalid email format
• 409: Email already exists
• 422: Password too weak

POST /api/auth/login

Description: Authenticate user and return JWT token

Request:

{
  "email": "[e-mail]",
  "password": "SecurePass123!",
  "twoFactorCode": "123456"
}

Response (200):

{
  "success": true,
  "token": "eyJhbGciOiJIUzI1NiIs...",
  "refreshToken": "eyJhbGciOiJIUzI1NiIs...",
  "user": {
    "id": "550e8400-e29b-41d4-a716-446655440000",
    "email": "[e-mail]"
  },
  "expiresIn": 3600
}

Errors:

• 401: Invalid credentials
• 403: Account locked
• 428: 2FA code required

Rate Limiting

Endpoint	Limit	Window
POST /api/auth/login	5 attempts	15 minutes
POST /api/auth/register	3 attempts	1 hour
POST /api/auth/reset-password	3 attempts	1 hour

---

6. Implementation Plan

Phase 1: Core Authentication (Week 1-2)

• Database schema setup
• User registration endpoint
• Email/password login
• JWT token generation
• Password hashing
• Basic frontend forms

Phase 2: Email Verification (Week 3)

• Email service integration
• Verification token generation
• Verification endpoint
• Email templates
• Resend verification email

Phase 3: Social Login (Week 4)

• OAuth integration (Google)
• OAuth integration (GitHub)
• Account linking
• Frontend OAuth buttons

Phase 4: Security Features (Week 5)

• Two-factor authentication
• Password reset flow
• Rate limiting
• Session management
• Security headers

Phase 5: Testing & Polish (Week 6)

• Unit tests
• Integration tests
• E2E tests
• Security audit
• Performance testing
• Documentation

---

7. Testing Strategy

Unit Tests

• Password hashing/verification
• JWT token generation/validation
• Input validation
• Business logic

Coverage Target: 90%

Integration Tests

• API endpoint testing
• Database operations
• OAuth flow
• Email sending

Coverage Target: 80%

E2E Tests

• Complete registration flow
• Login with email/password
• Social login flow
• Password reset flow
• 2FA setup and verification

Coverage Target: Critical paths only

Performance Tests

• Load testing: 1000 concurrent logins
• Stress testing: Find breaking point
• Database query performance

---

8. Security Considerations

Threats

Threat	Mitigation
Brute force	Rate limiting, account lockout
SQL injection	Parameterized queries, ORM
XSS	Input sanitization, CSP headers
CSRF	CSRF tokens, SameSite cookies
Session hijacking	Secure cookies, HTTPS only
Password leaks	bcrypt hashing, password strength

Security Checklist

• HTTPS enforced
• Security headers configured
• Rate limiting implemented
• Input validation on all endpoints
• SQL injection prevention
• XSS prevention
• CSRF protection
• Secure password storage
• Audit logging

---

9. Monitoring & Observability

Metrics

• Authentication success rate
• Failed login attempts
• Average login time
• Active sessions
• 2FA adoption rate

Alerts

• Failed login rate > 10%
• Database connection errors
• Email sending failures
• Rate limit exceeded > 100 times/hour

Logging

// Log structure
{
  "timestamp": "2025-01-15T14:30:00Z",
  "level": "info",
  "event": "user_login",
  "userId": "550e8400-...",
  "ip": "192.168.1.1",
  "userAgent": "Mozilla/5.0...",
  "success": true,
  "duration": 125
}

---

10. Risks & Mitigation

Risk	Probability	Impact	Mitigation
OAuth provider downtime	Medium	High	Fallback to email login
Database migration issues	Low	High	Test thoroughly in staging
Performance under load	Medium	Medium	Load testing, caching
Security vulnerabilities	Low	Critical	Security audit, pen testing

---

11. Open Questions

1. Should we support passwordless authentication?
2. What's the session timeout policy?
3. Do we need magic link login?
4. Should we implement remember me functionality?

---

12. Alternatives Considered

Alternative 1: Use Auth0

Pros: Faster implementation, proven security Cons: Cost, vendor lock-in, less customization Decision: Build in-house for flexibility

Alternative 2: Session-based auth instead of JWT

Pros: Simpler revocation, less token size Cons: Harder to scale, CORS issues Decision: Use JWT for stateless scaling

---

13. Success Criteria

Launch Criteria

• All P0 requirements implemented
• Security audit passed
• Load testing passed (1000 concurrent users)
• Documentation complete
• 90% test coverage achieved

Post-Launch Metrics (Week 1)

• < 1% authentication error rate
• < 500ms average login time

• 95% user satisfaction (surveys)

• Zero security incidents

---

14. References

• OWASP Authentication Cheat Sheet
• JWT Best Practices
• OAuth 2.0 Spec
• Internal: Authentication RFC #123

## Best Practices

### ✅ DO
- Include acceptance criteria for each requirement
- Provide architecture diagrams
- Document API contracts
- Specify performance requirements
- List risks and mitigations
- Include implementation timeline
- Add success metrics
- Document security considerations
- Version your specs
- Get stakeholder review

### ❌ DON'T
- Be vague about requirements
- Skip non-functional requirements
- Forget about security
- Ignore alternatives
- Skip testing strategy
- Forget monitoring/observability
- Leave questions unanswered

## Resources

- [Google Design Docs](https://www.industrialempathy.com/posts/design-docs-at-google/)
- [RFC Template](https://github.com/philips/template-rfcs)
- [Architecture Decision Records](https://adr.github.io/)
- [Amazon Press Release / FAQ](https://www.productplan.com/glossary/working-backward-amazon-method/)