Define API Contract Between Backend and Frontend

Feature: $ARGUMENTS

Task: Create detailed API contract specification for backend/frontend coordination

1. Define RESTful endpoints:

   Base URL: /api/v1/{feature}
   
   Endpoints:
   - GET /api/v1/{features}
     Query params: page, size, sort, filter
     Response: Page<{Feature}Response>
   
   - GET /api/v1/{features}/{id}
     Path param: id (Long)
     Response: {Feature}Response
   
   - POST /api/v1/{features}
     Body: {Feature}Request
     Response: {Feature}Response (201 Created)
   
   - PUT /api/v1/{features}/{id}
     Path param: id (Long)
     Body: {Feature}Request
     Response: {Feature}Response
   
   - DELETE /api/v1/{features}/{id}
     Path param: id (Long)
     Response: 204 No Content
   

2. Define request/response DTOs:

   // Request DTO (for POST/PUT)
   interface {Feature}Request {
     name: string;        // min: 2, max: 100
     description?: string; // max: 1000
     // Add domain-specific fields
   }
   
   // Response DTO (for GET)
   interface {Feature}Response {
     id: number;
     name: string;
     description?: string;
     createdAt: string;   // ISO 8601
     updatedAt: string;   // ISO 8601
     // Add computed fields
   }
   
   // Page response wrapper
   interface Page<T> {
     content: T[];
     totalElements: number;
     totalPages: number;
     size: number;
     number: number;
   }
   

3. Define error responses:

   {
     "timestamp": "2024-01-20T10:30:00Z",
     "status": 400,
     "error": "Bad Request",
     "message": "Validation failed",
     "path": "/api/v1/{features}",
     "errors": [
       {
         "field": "name",
         "message": "Name is required"
       }
     ]
   }
   

4. Define validation rules:

   • Backend: Bean Validation annotations
   • Frontend: Matching Zod schemas

   name: required, 2-100 chars
   description: optional, max 1000 chars
   email: valid email format
   date: ISO 8601 format
   

5. Define status codes:

   • 200: OK (GET, PUT)
   • 201: Created (POST)
   • 204: No Content (DELETE)
   • 400: Bad Request (validation)
   • 404: Not Found
   • 409: Conflict (duplicate)
   • 500: Internal Server Error

6. Integration requirements:

   • CORS: Allow frontend origin
   • Content-Type: application/json
   • Authentication: Bearer token (if needed)
   • Pagination: Spring Pageable format
   • Sorting: field,direction (e.g., "name,asc")

7. Backend implementation notes:

   // Entity fields match response DTO
   // Use MapStruct for DTO mapping
   // Repository method naming conventions
   // Service layer validation
   

8. Frontend implementation notes:

   // Zod schemas match validation rules
   // API client with base configuration
   // TanStack Query hooks
   // Error handling utilities
   

Save this contract as: PRPs/working-memory/{feature-name}/contracts/{feature}-api-contract.md

Share this file between backend and frontend teams for alignment.