GitHub Copilot Productivity

# VS Code Copilot Shortcuts (macOS)
Tab                     # Accept current suggestion
Escape                  # Dismiss suggestion
Alt+]                   # Next suggestion
Alt+[                   # Previous suggestion
Cmd+I                   # Open inline chat
Ctrl+Shift+I            # Open Copilot Chat panel
Cmd+Shift+Alt+Enter     # Open Copilot completions panel (see all suggestions)

// Fetch user data from the API, handle loading and error states,
// and cache the result for 5 minutes using the stale-while-revalidate pattern
async function useUser(userId: string) {
  // Copilot generates the implementation based on the comment
}

// Define the types first - Copilot uses them for accurate suggestions
interface CartItem {
  id: string;
  name: string;
  price: number;
  quantity: number;
  discount?: number;
}

interface CartSummary {
  items: CartItem[];
  subtotal: number;
  tax: number;
  discount: number;
  total: number;
}

// Copilot now generates an accurate implementation because it understands the types
function calculateCartSummary(items: CartItem[], taxRate: number): CartSummary {
  // Tab to accept Copilot's suggestion
}

// Convert kebab-case to camelCase
// "hello-world" -> "helloWorld"
// "background-color" -> "backgroundColor"
// "border-top-left-radius" -> "borderTopLeftRadius"
function kebabToCamel(str: string): string {
  // Copilot generates accurate implementation from examples
}

// Good: Descriptive name gives Copilot context
function validateEmailAndReturnNormalized(email: string): string | null {
  // Copilot knows to validate AND normalize
}

// Less effective: Vague name
function processInput(data: string): string | null {
  // Copilot has less context about what to generate
}

# Chat slash commands in VS Code
/explain    # Explain the selected code
/fix        # Suggest a fix for the selected code
/tests      # Generate tests for the selected code
/doc        # Generate documentation for the selected code
/optimize   # Suggest performance improvements

# Chat participants
@workspace  # Ask about your entire project
@vscode     # Ask about VS Code settings and features
@terminal   # Ask about terminal commands

# Example prompts:
# "Write unit tests for the calculateCartSummary function using Vitest"
# "@workspace Where is the authentication middleware defined?"
# "/explain What does this regex do?"
# "/fix This function throws when the array is empty"
# "@terminal How do I find all files modified in the last 24 hours?"

# .github/copilot-instructions.md
## Project Context
This is a Next.js 15 application using the App Router, TypeScript, Tailwind CSS,
and Prisma ORM with PostgreSQL.

## Code Style
- Use functional components with TypeScript interfaces for props
- Use server components by default, add 'use client' only when needed
- Prefer named exports over default exports
- Use Zod for runtime validation of API inputs
- Use React Server Actions for form mutations

## Naming Conventions
- Components: PascalCase (UserProfile.tsx)
- Utilities: camelCase (formatDate.ts)
- API routes: REST conventions (GET, POST, PUT, DELETE)
- Database: snake_case for columns, PascalCase for Prisma models

## Testing
- Use Vitest for unit tests
- Use Playwright for E2E tests
- Tests go in __tests__ directories adjacent to the code they test

// Select a function and use /tests or Cmd+I with "write tests"
// Copilot generates comprehensive test suites:

import { describe, it, expect } from 'vitest';
import { calculateCartSummary } from './cart';

describe('calculateCartSummary', () => {
  it('calculates subtotal from item prices and quantities', () => {
    const items = [
      { id: '1', name: 'Widget', price: 10, quantity: 2 },
      { id: '2', name: 'Gadget', price: 25, quantity: 1 },
    ];
    const summary = calculateCartSummary(items, 0.1);
    expect(summary.subtotal).toBe(45);
  });

  it('applies discounts correctly', () => {
    const items = [
      { id: '1', name: 'Widget', price: 100, quantity: 1, discount: 20 },
    ];
    const summary = calculateCartSummary(items, 0.1);
    expect(summary.discount).toBe(20);
    expect(summary.total).toBeLessThan(100);
  });

  it('handles empty cart', () => {
    const summary = calculateCartSummary([], 0.1);
    expect(summary.total).toBe(0);
    expect(summary.items).toHaveLength(0);
  });
});