project-root/
├── eslint.config.mjs          # Single source of truth
├── .prettierrc                 # Unified formatting rules
├── package.json                # Root scripts only
├── .husky/pre-commit          # Git hooks
├── pnpm-workspace.yaml
├── frontend/
│   ├── package.json           # NO lint scripts
│   └── tsconfig.json
└── infrastructure/
    ├── package.json           # NO lint scripts
    └── tsconfig.json

import js from '@eslint/js';
import typescriptEslint from '@typescript-eslint/eslint-plugin';
import typescriptParser from '@typescript-eslint/parser';
import globals from 'globals';
import { fileURLToPath } from 'node:url';
import path from 'node:path';

const __dirname = path.dirname(fileURLToPath(import.meta.url));

const IGNORE_PATTERNS = [
  '**/node_modules/**',
  '**/dist/**',
  '**/build/**',
  '**/.next/**',
  '**/cdk.out/**',
  '**/*.d.ts',
  '**/*.config.js'
];

const SHARED_RULES = {
  'eol-last': ['error', 'always'],
  'no-console': ['warn', { allow: ['error', 'warn'] }],
  'no-unused-vars': 'off'
};

export default [
  // Global ignores
  { ignores: IGNORE_PATTERNS },

  // Frontend TypeScript
  {
    files: ['frontend/**/*.{ts,tsx}'],
    languageOptions: {
      parser: typescriptParser,
      parserOptions: {
        project: path.join(__dirname, 'frontend/tsconfig.json'),
        ecmaVersion: 'latest',
        sourceType: 'module'
      }
    },
    plugins: { '@typescript-eslint': typescriptEslint },
    rules: {
      ...SHARED_RULES,
      '@typescript-eslint/no-unused-vars': 'warn',
      '@typescript-eslint/no-explicit-any': 'error'
    }
  },

  // Infrastructure TypeScript
  {
    files: ['infrastructure/**/*.ts'],
    languageOptions: {
      parser: typescriptParser,
      parserOptions: {
        project: path.join(__dirname, 'infrastructure/tsconfig.json'),
        ecmaVersion: 'latest',
        sourceType: 'module'
      }
    },
    plugins: { '@typescript-eslint': typescriptEslint },
    rules: {
      ...SHARED_RULES,
      '@typescript-eslint/no-unused-vars': 'warn',
      '@typescript-eslint/no-explicit-any': 'error'
    }
  },

  // CLI scripts - allow console output
  {
    files: [
      'infrastructure/lib/cli/**/*.ts',
      'scripts/**/*.ts'
    ],
    rules: { 'no-console': 'off' }
  }
];

{
  "semi": true,
  "trailingComma": "all",
  "singleQuote": true,
  "printWidth": 100,
  "tabWidth": 2,
  "endOfLine": "auto"
}

{
  "scripts": {
    "lint": "eslint . --ext .ts,.tsx,.js,.jsx",
    "lint:fix": "eslint . --ext .ts,.tsx,.js,.jsx --fix",
    "format": "prettier --write \"**/*.{ts,tsx,js,jsx,json,md}\"",
    "format:check": "prettier --check \"**/*.{ts,tsx,js,jsx,json,md}\"",
    "prepare": "husky"
  },
  "lint-staged": {
    "**/*.{js,jsx,ts,tsx}": [
      "eslint --fix",
      "prettier --write --end-of-line auto"
    ],
    "*.{json,md,yml}": [
      "prettier --write --end-of-line auto"
    ]
  }
}

# .husky/pre-commit
pnpm exec lint-staged

pnpm add -D -w eslint \
  @typescript-eslint/parser \
  @typescript-eslint/eslint-plugin \
  typescript-eslint \
  @eslint/js \
  globals \
  prettier \
  eslint-config-prettier \
  husky \
  lint-staged

import nextPlugin from '@next/eslint-plugin-next';

{
  files: ['frontend/**/*.{ts,tsx}'],
  plugins: {
    '@next/next': nextPlugin,
    '@typescript-eslint': typescriptEslint
  },
  settings: {
    next: { rootDir: path.join(__dirname, 'frontend') }
  }
}

// frontend/eslint.config.mjs
import withNuxt from './.nuxt/eslint.config.mjs';
import { SHARED_RULES } from '../eslint.shared.mjs';

export default withNuxt({
  rules: { ...SHARED_RULES }
});

{
  files: ['infrastructure/lib/lambdas/**/*.ts'],
  rules: {
    'no-console': 'off',  // CloudWatch logs
    '@typescript-eslint/no-explicit-any': 'error'
  }
}

{
  files: ['scripts/**/*.ts', 'tools/**/*.ts'],
  rules: { 'no-console': 'off' }
}

// Tier 1: CLI Binaries
{
  files: ['infrastructure/lib/cli/bin/**/*.ts'],
  rules: { 'no-console': 'off' }
},

// Tier 2: Commands
{
  files: ['infrastructure/lib/cli/commands/**/*.ts'],
  rules: { 'no-console': 'off' }
},

// Tier 3: Domain Logic
{
  files: ['infrastructure/core/**/*.ts'],
  rules: { 'no-console': 'warn' }
}

git add .
git commit -m "feat: add feature"
# Automatically runs lint-staged on changed files

# Check formatting
pnpm format:check

# Fix all files
pnpm format

# Lint entire codebase
pnpm lint

# Auto-fix linting issues
pnpm lint:fix

# GitHub Actions
- run: pnpm install --frozen-lockfile
- run: pnpm lint
- run: pnpm format:check

// ✅ Correct order
{ files: ['**/*.ts'], rules: {...} },
{ files: ['frontend/**/*.ts'], rules: {...} },
{ files: ['frontend/lib/cli/**/*.ts'], rules: {...} }

// ❌ Wrong order - specific rules won't apply
{ files: ['frontend/lib/cli/**/*.ts'], rules: {...} },
{ files: ['**/*.ts'], rules: {...} }

# 1. Full codebase linting works
pnpm lint

# 2. Auto-fix works
pnpm lint:fix

# 3. Formatting works
pnpm format

# 4. Pre-commit hooks work
git add . && git commit -m "test"

# 5. No duplicate scripts in workspaces
grep -r '"lint":' */package.json
# Should ONLY show root package.json