pupila: Skill for Claude Code

Node.js Backend Patterns

Comprehensive guidance for building scalable, maintainable, and production-ready Node.js backend applications with modern frameworks, architectural patterns, and best practices.

When to Use This Skill

• Building REST APIs or GraphQL servers
• Creating microservices with Node.js
• Implementing authentication and authorization
• Designing scalable backend architectures
• Setting up middleware and error handling
• Integrating databases (SQL and NoSQL)
• Building real-time applications with WebSockets
• Implementing background job processing

Core Frameworks

Express.js - Minimalist Framework

Basic Setup:

import express, { Request, Response, NextFunction } from "express";
import helmet from "helmet";
import cors from "cors";
import compression from "compression";

const app = express();

// Security middleware
app.use(helmet());
app.use(cors({ origin: process.env.ALLOWED_ORIGINS?.split(",") }));
app.use(compression());

// Body parsing
app.use(express.json({ limit: "10mb" }));
app.use(express.urlencoded({ extended: true, limit: "10mb" }));

// Request logging
app.use((req: Request, res: Response, next: NextFunction) => {
  console.log(`${req.method} ${req.path}`);
  next();
});

const PORT = process.env.PORT || 3000;
app.listen(PORT, () => {
  console.log(`Server running on port ${PORT}`);
});

Fastify - High Performance Framework

Basic Setup:

import Fastify from "fastify";
import helmet from "@fastify/helmet";
import cors from "@fastify/cors";
import compress from "@fastify/compress";

const fastify = Fastify({
  logger: {
    level: process.env.LOG_LEVEL || "info",
    transport: {
      target: "pino-pretty",
      options: { colorize: true },
    },
  },
});

// Plugins
await fastify.register(helmet);
await fastify.register(cors, { origin: true });
await fastify.register(compress);

// Type-safe routes with schema validation
fastify.post<{
  Body: { name: string; email: string };
  Reply: { id: string; name: string };
}>(
  "/users",
  {
    schema: {
      body: {
        type: "object",
        required: ["name", "email"],
        properties: {
          name: { type: "string", minLength: 1 },
          email: { type: "string", format: "email" },
        },
      },
    },
  },
  async (request, reply) => {
    const { name, email } = request.body;
    return { id: "123", name };
  },
);

await fastify.listen({ port: 3000, host: "0.0.0.0" });