Code Patterns Reference

This skill contains comprehensive patterns for modern development. Reference files are organized by topic.

Quick Reference

Topic	Key Patterns	When to Use
API Design	REST, GraphQL, OpenAPI	Designing/implementing APIs
Testing	pytest, vitest, mocking	Writing tests
Docker	Multi-stage, Compose	Containerizing apps
CI/CD	GitHub Actions, pipelines	Setting up automation
Database	PostgreSQL, migrations	Database design
TypeScript	Types, generics, patterns	TS development
Python	async, patterns, uv	Python development
React/Next.js	Server Components, hooks	Frontend development

Reference Files

• api.md - REST, GraphQL, authentication, pagination
• testing.md - pytest, vitest, mocking, coverage
• docker.md - Dockerfiles, Compose, production
• ci-cd.md - GitHub Actions, deployment
• database.md - PostgreSQL, migrations, queries
• typescript.md - Types, generics, advanced patterns
• python.md - async, patterns, best practices
• react.md - Server Components, hooks, Next.js

---

API Design Quick Reference

REST Endpoints

GET    /resources         List
GET    /resources/{id}    Get one
POST   /resources         Create
PUT    /resources/{id}    Replace
PATCH  /resources/{id}    Update
DELETE /resources/{id}    Delete

HTTP Status Codes

Code	Meaning
200	OK
201	Created
204	No Content
400	Bad Request
401	Unauthorized
403	Forbidden
404	Not Found
422	Unprocessable
429	Rate Limited
500	Server Error

---

Testing Quick Reference

pytest

@pytest.fixture
def client():
    return TestClient(app)

def test_endpoint(client):
    response = client.get("/api/users")
    assert response.status_code == 200

vitest

import { describe, it, expect, vi } from 'vitest';

describe('Component', () => {
  it('should work', () => {
    expect(true).toBe(true);
  });
});

---

Docker Quick Reference

Multi-Stage Build

FROM node:20-alpine AS builder
WORKDIR /app
COPY package*.json ./
RUN npm ci
COPY . .
RUN npm run build

FROM node:20-alpine
COPY --from=builder /app/dist ./dist
USER node
CMD ["node", "dist/index.js"]

Compose

services:
  app:
    build: .
    ports:
      - "3000:3000"
    depends_on:
      db:
        condition: service_healthy
  db:
    image: postgres:16-alpine
    healthcheck:
      test: ["CMD", "pg_isready"]

---

CI/CD Quick Reference

GitHub Actions

name: CI
on: [push, pull_request]
jobs:
  test:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - uses: actions/setup-node@v4
      - run: npm ci
      - run: npm test

---

TypeScript Quick Reference

Utility Types

Partial<T>      // All properties optional
Required<T>     // All properties required
Pick<T, K>      // Select properties
Omit<T, K>      // Exclude properties
Record<K, V>    // Object with key type K, value type V

Generics

function first<T>(arr: T[]): T | undefined {
  return arr[0];
}

---

Python Quick Reference

Async

async def fetch_data():
    async with aiohttp.ClientSession() as session:
        async with session.get(url) as response:
            return await response.json()

Type Hints

def process(items: list[str]) -> dict[str, int]:
    return {item: len(item) for item in items}

---

React/Next.js Quick Reference

Server Component (default)

// app/page.tsx
async function Page() {
  const data = await fetch('...');
  return <div>{data}</div>;
}

Client Component

'use client';
import { useState } from 'react';

export function Counter() {
  const [count, setCount] = useState(0);
  return <button onClick={() => setCount(c => c + 1)}>{count}</button>;
}