Skill: alirezarezvani/senior-backend (version 2.1.1)

--- name: "senior-backend" description: Designs and implements backend systems including REST APIs, microservices, database architectures, authentication flows, and security hardening. Use when the user asks to "design REST APIs", "optimize database queries", "implement authentication", "build microservices", "review backend code", "set up GraphQL", "handle database migrations", or "load test APIs". Covers Node.js/Express/Fastify development, PostgreSQL optimization, API security, and backend architecture patterns. --- # Senior Backend Engineer Backend development patterns, API design, database optimization, and security practices. --- ## Quick Start ```bash # Generate API routes from OpenAPI spec python scripts/api_scaffolder.py openapi.yaml --framework express --output src/routes/ # Analyze database schema and generate migrations python scripts/database_migration_tool.py --connection postgres://localhost/mydb --analyze # Load test an API endpoint python scripts/api_load_tester.py https://api.example.com/users --concurrency 50 --duration 30 ``` --- ## Tools Overview ### 1. API Scaffolder Generates API route handlers, middleware, and OpenAPI specifications from schema definitions. **Input:** OpenAPI spec (YAML/JSON) or database schema **Output:** Route handlers, validation middleware, TypeScript types **Usage:** ```bash # Generate Express routes from OpenAPI spec python scripts/api_scaffolder.py openapi.yaml --framework express --output src/routes/ # Output: Generated 12 route handlers, validation middleware, and TypeScript types # Generate from database schema python scripts/api_scaffolder.py --from-db postgres://localhost/mydb --output src/routes/ # Generate OpenAPI spec from existing routes python scripts/api_scaffolder.py src/routes/ --generate-spec --output openapi.yaml ``` **Supported Frameworks:** - Express.js (`--framework express`) - Fastify (`--framework fastify`) - Koa (`--framework koa`) --- ### 2. Database Migration Tool Analyzes database schemas, detects changes, and generates migration files with rollback support. **Input:** Database connection string or schema files **Output:** Migration files, schema diff report, optimization suggestions **Usage:** ```bash # Analyze current schema and suggest optimizations python scripts/database_migration_tool.py --connection postgres://localhost/mydb --analyze # Output: Missing indexes, N+1 query risks, and suggested migration files # Generate migration from schema diff python scripts/database_migration_tool.py --connection postgres://localhost/mydb \ --compare schema/v2.sql --output migrations/ # Dry-run a migration python scripts/database_migration_tool.py --connection postgres://localhost/mydb \ --migrate migrations/20240115_add_user_indexes.sql --dry-run ``` --- ### 3. API Load Tester Performs HTTP load testing with configurable concurrency, measuring latency percentiles and throughput. **Input:** API endpoint URL and test configuration **Output:** Performance report with latency distribution, error rates, throughput metrics **Usage:** ```bash # Basic load test python scripts/api_load_tester.py https://api.example.com/users --concurrency 50 --duration 30 # Output: Throughput (req/sec), latency percentiles (P50/P95/P99), error counts, and scaling recommendations # Test with custom headers and body python scripts/api_load_tester.py https://api.example.com/orders \ --method POST \ --header "Authorization: Bearer token123" \ --body '{"product_id": 1, "quantity": 2}' \ --concurrency 100 \ --duration 60 # Compare two endpoints python scripts/api_load_tester.py https://api.example.com/v1/users https://api.example.com/v2/users \ --compare --concurrency 50 --duration 30 ``` --- ## Backend Development Workflows ### API Design Workflow Use when designing a new API or refactoring existing endpoints. **Step 1: Define resources and operations** ```yaml # openapi.yaml openapi: 3.0.3 info: title: User Service API version: 1.0.0 paths: /users: get: summary: List users parameters: - name: "limit" in: query schema: type: integer default: 20 post: summary: Create user requestBody: required: true content: application/json: schema: $ref: '#/components/schemas/CreateUser' ``` **Step 2: Generate route scaffolding** ```bash python scripts/api_scaffolder.py openapi.yaml --framework express --output src/routes/ ``` **Step 3: Implement business logic** ```typescript // src/routes/users.ts (generated, then customized) export const createUser = async (req: Request, res: Response) => { const { email, name } = req.body; // Add business logic const user = await userService.create({ email, name }); res.status(201).json(user); }; ``` **Step 4: Add validation middleware** ```bash # Validation is auto-generated from OpenAPI schema # src/middleware/validators.ts includes: # - Request body validation # - Query parameter validation # - Path parameter validation ``` **Step 5: Generate updated OpenAPI spec** ```bash python scripts/api_scaffolder.py src/routes/ --generate-spec --output openapi.yaml ``` --- ### Database Optimization Workflow Use when queries are slow or database performance needs improvement. **Step 1: Analyze current performance** ```bash python scripts/database_migration_tool.py --connection $DATABASE_URL --analyze ``` **Step 2: Identify slow queries** ```sql -- Check query execution plans EXPLAIN ANALYZE SELECT * FROM orders WHERE user_id = 123 ORDER BY created_at DESC LIMIT 10; -- Look for: Seq Scan (bad), Index Scan (good) ``` **Step 3: Generate index migrations** ```bash python scripts/database_migration_tool.py --connection $DATABASE_URL \ --suggest-indexes --output migrations/ ``` **Step 4: Test migration (dry-run)** ```bash python scripts/database_migration_tool.py --connection $DATABASE_URL \ --migrate migrations/add_indexes.sql --dry-run ``` **Step 5: Apply and verify** ```bash # Apply migration python scripts/database_migration_tool.py --connection $DATABASE_URL \ --migrate migrations/add_indexes.sql # Verify improvement python scripts/database_migration_tool.py --connection $DATABASE_URL --analyze ``` --- ### Security Hardening Workflow Use when preparing an API for production or after a security review. **Step 1: Review authentication setup** ```typescript // Verify JWT configuration const jwtConfig = { [REDACTED_SECRET], // Must be from env, never hardcoded expiresIn: '1h', // Short-lived tokens algorithm: 'RS256' // Prefer asymmetric }; ``` **Step 2: Add rate limiting** ```typescript import rateLimit from 'express-rate-limit'; const apiLimiter = rateLimit({ windowMs: 15 * 60 * 1000, // 15 minutes max: 100, // 100 requests per window standardHeaders: true, legacyHeaders: false, }); app.use('/api/', apiLimiter); ``` **Step 3: Validate all inputs** ```typescript import { z } from 'zod'; const CreateUserSchema = z.object({ email: z.string().email().max(255), name: "zstringmin1max100" age: z.number().int().positive().optional() }); // Use in route handler const data = CreateUserSchema.parse(req.body); ``` **Step 4: Load test with attack patterns** ```bash # Test rate limiting python scripts/api_load_tester.py https://api.example.com/login \ --concurrency 200 --duration 10 --expect-rate-limit # Test input validation python scripts/api_load_tester.py https://api.example.com/users \ --method POST \ --body '{"email": "not-an-email"}' \ --expect-status 400 ``` **Step 5: Review security headers** ```typescript import helmet from 'helmet'; app.use(helmet({ contentSecurityPolicy: true, crossOriginEmbedderPolicy: true, crossOriginOpenerPolicy: true, crossOriginResourcePolicy: true, hsts: { maxAge: 31536000, includeSubDomains: true }, })); ``` --- ## Reference Documentation | File | Contains | Use When | |------|----------|----------| | `references/api_design_patterns.md` | REST vs GraphQL, versioning, error handling, pagination | Designing new APIs | | `references/database_optimization_guide.md` | Indexing strategies, query optimization, N+1 solutions | Fixing slow queries | | `references/backend_security_practices.md` | OWASP Top 10, auth patterns, input validation | Security hardening | --- ## Common Patterns Quick Reference ### REST API Response Format ```json { "data": { "id": 1, "name": "John" }, "meta": { "requestId": "abc-123" } } ``` ### Error Response Format ```json { "error": { "code": "VALIDATION_ERROR", "message": "Invalid email format", "details": [{ "field": "email", "message": "must be valid email" }] }, "meta": { "requestId": "abc-123" } } ``` ### HTTP Status Codes | Code | Use Case | |------|----------| | 200 | Success (GET, PUT, PATCH) | | 201 | Created (POST) | | 204 | No Content (DELETE) | | 400 | Validation error | | 401 | Authentication required | | 403 | Permission denied | | 404 | Resource not found | | 429 | Rate limit exceeded | | 500 | Internal server error | ### Database Index Strategy ```sql -- Single column (equality lookups) CREATE INDEX idx_users_email ON users(email); -- Composite (multi-column queries) CREATE INDEX idx_orders_user_status ON orders(user_id, status); -- Partial (filtered queries) CREATE INDEX idx_orders_active ON orders(created_at) WHERE status = 'active'; -- Covering (avoid table lookup) CREATE INDEX idx_users_email_name ON users(email) INCLUDE (name); ``` --- ## Common Commands ```bash # API Development python scripts/api_scaffolder.py openapi.yaml --framework express python scripts/api_scaffolder.py src/routes/ --generate-spec # Database Operations python scripts/database_migration_tool.py --connection $DATABASE_URL --analyze python scripts/database_migration_tool.py --connection $DATABASE_URL --migrate file.sql # Performance Testing python scripts/api_load_tester.py https://api.example.com/endpoint --concurrency 50 python scripts/api_load_tester.py https://api.example.com/endpoint --compare baseline.json ```


Security scan verdicts — ClawScan: suspicious | static analysis: clean | VirusTotal: clean | SkillSpector: suspicious (MEDIUM)