# RESTful API with Authentication - Requirements

> Example Spec demonstrating API feature development

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**Version**: 1.42.0  
**Last Updated**: 2026-02-11  
**Spec Type**: Example - API Feature

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## Overview

This Spec demonstrates how to structure requirements for a RESTful API feature. We'll build a simple task management API with JWT authentication, covering common API patterns like CRUD operations, authentication, authorization, and error handling.

**Learning Points:**
- API endpoint design
- Authentication and authorization
- Request/response formats
- Error handling
- API versioning

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## User Stories

### US-1: User Registration
**As a** new user  
**I want to** register an account with email and password  
**So that** I can access the task management system

**Acceptance Criteria:**
- WHEN I POST to `/api/v1/auth/register` with valid email and password THEN I receive a success response with user ID
- WHEN I register with an existing email THEN I receive a 409 Conflict error
- WHEN I register with invalid email format THEN I receive a 400 Bad Request error
- WHEN I register with password < 8 characters THEN I receive a 400 Bad Request error

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### US-2: User Login
**As a** registered user  
**I want to** log in with my credentials  
**So that** I can access my tasks

**Acceptance Criteria:**
- WHEN I POST to `/api/v1/auth/login` with valid credentials THEN I receive a JWT token
- WHEN I login with invalid credentials THEN I receive a 401 Unauthorized error
- WHEN I login successfully THEN the token expires after 24 hours
- WHEN I use an expired token THEN I receive a 401 Unauthorized error

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### US-3: Create Task
**As an** authenticated user  
**I want to** create a new task  
**So that** I can track my work

**Acceptance Criteria:**
- WHEN I POST to `/api/v1/tasks` with valid token and task data THEN I receive the created task with ID
- WHEN I create a task without authentication THEN I receive a 401 Unauthorized error
- WHEN I create a task with missing required fields THEN I receive a 400 Bad Request error
- WHEN I create a task successfully THEN it's associated with my user ID

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### US-4: List Tasks
**As an** authenticated user  
**I want to** view all my tasks  
**So that** I can see what I need to do

**Acceptance Criteria:**
- WHEN I GET `/api/v1/tasks` with valid token THEN I receive a list of my tasks
- WHEN I list tasks without authentication THEN I receive a 401 Unauthorized error
- WHEN I have no tasks THEN I receive an empty array
- WHEN I have multiple tasks THEN they are sorted by creation date (newest first)

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### US-5: Update Task
**As an** authenticated user  
**I want to** update a task's details  
**So that** I can modify task information

**Acceptance Criteria:**
- WHEN I PUT `/api/v1/tasks/:id` with valid token and data THEN the task is updated
- WHEN I update another user's task THEN I receive a 403 Forbidden error
- WHEN I update a non-existent task THEN I receive a 404 Not Found error
- WHEN I update with invalid data THEN I receive a 400 Bad Request error

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### US-6: Delete Task
**As an** authenticated user  
**I want to** delete a task  
**So that** I can remove completed or unwanted tasks

**Acceptance Criteria:**
- WHEN I DELETE `/api/v1/tasks/:id` with valid token THEN the task is deleted
- WHEN I delete another user's task THEN I receive a 403 Forbidden error
- WHEN I delete a non-existent task THEN I receive a 404 Not Found error
- WHEN I delete successfully THEN I receive a 204 No Content response

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## Functional Requirements

### FR-1: Authentication System
The system must provide JWT-based authentication for API access.

**Details:**
- Support user registration with email and password
- Support user login with credentials
- Generate JWT tokens with 24-hour expiration
- Validate JWT tokens on protected endpoints
- Hash passwords using bcrypt (10 rounds)

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### FR-2: Task CRUD Operations
The system must provide complete CRUD operations for tasks.

**Details:**
- Create: POST `/api/v1/tasks`
- Read (list): GET `/api/v1/tasks`
- Read (single): GET `/api/v1/tasks/:id`
- Update: PUT `/api/v1/tasks/:id`
- Delete: DELETE `/api/v1/tasks/:id`

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### FR-3: Authorization
The system must enforce user-level authorization for task operations.

**Details:**
- Users can only access their own tasks
- Users cannot view, update, or delete other users' tasks
- Return 403 Forbidden for unauthorized access attempts

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### FR-4: Input Validation
The system must validate all input data before processing.

**Details:**
- Email: Valid email format, max 255 characters
- Password: Minimum 8 characters, max 128 characters
- Task title: Required, max 200 characters
- Task description: Optional, max 2000 characters
- Task status: Enum (pending, in_progress, completed)

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### FR-5: Error Handling
The system must provide consistent error responses.

**Details:**
- Use standard HTTP status codes
- Return JSON error responses with message and error code
- Include validation errors with field-specific messages
- Log errors for debugging

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### FR-6: API Versioning
The system must support API versioning for future compatibility.

**Details:**
- All endpoints prefixed with `/api/v1/`
- Version included in URL path
- Support for future versions without breaking existing clients

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## Non-Functional Requirements

### NFR-1: Performance
- API response time < 200ms for 95% of requests
- Support 100 concurrent users
- Database queries optimized with indexes

### NFR-2: Security
- Passwords hashed with bcrypt
- JWT tokens signed with secret key
- HTTPS required in production
- Rate limiting: 100 requests per minute per IP
- Input sanitization to prevent injection attacks

### NFR-3: Reliability
- 99.9% uptime
- Graceful error handling (no crashes)
- Database transactions for data consistency

### NFR-4: Maintainability
- RESTful API design principles
- Consistent naming conventions
- Comprehensive API documentation
- Unit test coverage > 80%

### NFR-5: Scalability
- Stateless API design (horizontal scaling)
- Database connection pooling
- Caching for frequently accessed data

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## API Endpoints Summary

| Method | Endpoint | Auth Required | Description |
|--------|----------|---------------|-------------|
| POST | `/api/v1/auth/register` | No | Register new user |
| POST | `/api/v1/auth/login` | No | Login user |
| POST | `/api/v1/tasks` | Yes | Create task |
| GET | `/api/v1/tasks` | Yes | List all user's tasks |
| GET | `/api/v1/tasks/:id` | Yes | Get single task |
| PUT | `/api/v1/tasks/:id` | Yes | Update task |
| DELETE | `/api/v1/tasks/:id` | Yes | Delete task |

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## Data Models

### User
```json
{
  "id": "uuid",
  "email": "string (unique)",
  "password": "string (hashed)",
  "createdAt": "timestamp",
  "updatedAt": "timestamp"
}
```

### Task
```json
{
  "id": "uuid",
  "userId": "uuid (foreign key)",
  "title": "string",
  "description": "string (optional)",
  "status": "enum (pending, in_progress, completed)",
  "createdAt": "timestamp",
  "updatedAt": "timestamp"
}
```

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## Error Response Format

```json
{
  "error": {
    "code": "ERROR_CODE",
    "message": "Human-readable error message",
    "details": {
      "field": "Specific field error (for validation)"
    }
  }
}
```

**Error Codes:**
- `INVALID_INPUT` - Validation error
- `UNAUTHORIZED` - Authentication required
- `FORBIDDEN` - Insufficient permissions
- `NOT_FOUND` - Resource not found
- `CONFLICT` - Resource already exists
- `INTERNAL_ERROR` - Server error

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## Out of Scope

The following are explicitly out of scope for this Spec:

- ❌ Password reset functionality
- ❌ Email verification
- ❌ OAuth/social login
- ❌ Task sharing between users
- ❌ Task categories or tags
- ❌ File attachments
- ❌ Real-time notifications
- ❌ Admin panel

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## Dependencies

- **Node.js** 14+ - Runtime environment
- **Express.js** 4.x - Web framework
- **PostgreSQL** 13+ - Database
- **jsonwebtoken** - JWT implementation
- **bcrypt** - Password hashing
- **express-validator** - Input validation

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## Success Criteria

This feature is considered complete when:

1. ✅ All 7 API endpoints are implemented and working
2. ✅ All acceptance criteria pass
3. ✅ Unit test coverage > 80%
4. ✅ Integration tests cover all endpoints
5. ✅ API documentation is complete
6. ✅ Security requirements are met
7. ✅ Performance requirements are met

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## Related Documentation

- [Design Document](design.md) - Technical design and architecture
- [Tasks Document](tasks.md) - Implementation plan
- [API Documentation Guide](../../spec-workflow.md) - How to document APIs

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**Version**: 1.42.0  
**Last Updated**: 2026-02-11  
**Status**: Example Spec