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This skill should be used 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". Use for Node.js/Express/Fastify development, PostgreSQL optimization, API security, and backend architecture patterns.
npx skill4agent add alirezarezvani/claude-skills senior-backend# 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# Generate Express routes from OpenAPI spec
python scripts/api_scaffolder.py openapi.yaml --framework express --output src/routes/
# Output:
# Generated 12 route handlers in src/routes/
# - GET /users (listUsers)
# - POST /users (createUser)
# - GET /users/{id} (getUser)
# - PUT /users/{id} (updateUser)
# - DELETE /users/{id} (deleteUser)
# ...
# Created validation middleware: src/middleware/validators.ts
# Created TypeScript types: src/types/api.ts
# 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--framework express--framework fastify--framework koa# Analyze current schema and suggest optimizations
python scripts/database_migration_tool.py --connection postgres://localhost/mydb --analyze
# Output:
# === Database Analysis Report ===
# Tables: 24
# Total rows: 1,247,832
#
# MISSING INDEXES (5 found):
# orders.user_id - 847ms avg query time, ADD INDEX recommended
# products.category_id - 234ms avg query time, ADD INDEX recommended
#
# N+1 QUERY RISKS (3 found):
# users -> orders relationship (no eager loading)
#
# SUGGESTED MIGRATIONS:
# 1. Add index on orders(user_id)
# 2. Add index on products(category_id)
# 3. Add composite index on order_items(order_id, product_id)
# Generate migration from schema diff
python scripts/database_migration_tool.py --connection postgres://localhost/mydb \
--compare schema/v2.sql --output migrations/
# Output:
# Generated migration: migrations/20240115_add_user_indexes.sql
# Generated rollback: migrations/20240115_add_user_indexes_rollback.sql
# Dry-run a migration
python scripts/database_migration_tool.py --connection postgres://localhost/mydb \
--migrate migrations/20240115_add_user_indexes.sql --dry-run# Basic load test
python scripts/api_load_tester.py https://api.example.com/users --concurrency 50 --duration 30
# Output:
# === Load Test Results ===
# Target: https://api.example.com/users
# Duration: 30s | Concurrency: 50
#
# THROUGHPUT:
# Total requests: 15,247
# Requests/sec: 508.2
# Successful: 15,102 (99.0%)
# Failed: 145 (1.0%)
#
# LATENCY (ms):
# Min: 12
# Avg: 89
# P50: 67
# P95: 198
# P99: 423
# Max: 1,247
#
# ERRORS:
# Connection timeout: 89
# HTTP 503: 56
#
# RECOMMENDATION: P99 latency (423ms) exceeds 200ms target.
# Consider: connection pooling, query optimization, or horizontal scaling.
# 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# 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'python scripts/api_scaffolder.py openapi.yaml --framework express --output src/routes/// 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);
};# Validation is auto-generated from OpenAPI schema
# src/middleware/validators.ts includes:
# - Request body validation
# - Query parameter validation
# - Path parameter validationpython scripts/api_scaffolder.py src/routes/ --generate-spec --output openapi.yamlpython scripts/database_migration_tool.py --connection $DATABASE_URL --analyze-- 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)python scripts/database_migration_tool.py --connection $DATABASE_URL \
--suggest-indexes --output migrations/python scripts/database_migration_tool.py --connection $DATABASE_URL \
--migrate migrations/add_indexes.sql --dry-run# 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// Verify JWT configuration
const jwtConfig = {
secret: process.env.JWT_SECRET, // Must be from env, never hardcoded
expiresIn: '1h', // Short-lived tokens
algorithm: 'RS256' // Prefer asymmetric
};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);import { z } from 'zod';
const CreateUserSchema = z.object({
email: z.string().email().max(255),
name: z.string().min(1).max(100),
age: z.number().int().positive().optional()
});
// Use in route handler
const data = CreateUserSchema.parse(req.body);# 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 400import helmet from 'helmet';
app.use(helmet({
contentSecurityPolicy: true,
crossOriginEmbedderPolicy: true,
crossOriginOpenerPolicy: true,
crossOriginResourcePolicy: true,
hsts: { maxAge: 31536000, includeSubDomains: true },
}));| File | Contains | Use When |
|---|---|---|
| REST vs GraphQL, versioning, error handling, pagination | Designing new APIs |
| Indexing strategies, query optimization, N+1 solutions | Fixing slow queries |
| OWASP Top 10, auth patterns, input validation | Security hardening |
{
"data": { "id": 1, "name": "John" },
"meta": { "requestId": "abc-123" }
}{
"error": {
"code": "VALIDATION_ERROR",
"message": "Invalid email format",
"details": [{ "field": "email", "message": "must be valid email" }]
},
"meta": { "requestId": "abc-123" }
}| 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 |
-- 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);# 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