API Design & Documentation

Generate a complete OpenAPI 3.1 specification in YAML for a [API NAME] REST API. Endpoints to document: [LIST ENDPOINTS, e.g., GET /users, POST /users, GET /users/{id}, PUT /users/{id}, DELETE /users/{id}]. For each endpoint include: summary, description, operationId, tags, parameters (path, query, header), request body schema, response schemas (200, 201, 400, 401, 403, 404, 422, 500), and security requirements. Include: info section (title, version, description), servers array, reusable components (schemas, responses, parameters, securitySchemes), and JWT bearer auth security scheme. Full valid YAML.

Design a GraphQL schema for a [DOMAIN: e-commerce/social platform/SaaS/marketplace] application. Include: 1) Core types with all fields and descriptions, 2) Query type: list queries (with pagination using cursor-based connection pattern), single item queries, and search, 3) Mutation type: create, update, delete mutations with input types and payload types, 4) Subscription type: real-time events for key state changes, 5) Enums for status fields, 6) Interfaces for shared fields, 7) Error handling: union return types with error variants, 8) Directives: @deprecated with reason. Full SDL (Schema Definition Language) format with descriptions on all types and fields.

Design a consistent error response standard for a REST API following RFC 7807 (Problem Details). Include: 1) Base error response schema (type, title, status, detail, instance, traceId), 2) Validation error extension (errors array with field, code, message), 3) HTTP status code decision tree (when to use 400 vs 422 vs 409 vs 404 etc.), 4) Error catalog: 20 common API errors with code, HTTP status, title, and description, 5) TypeScript interface for the error response, 6) Express middleware to produce consistent errors, 7) Client-side error handling pattern. Include examples for each error type.