flynn/eslint.config.js

// ESLint 9+ flat config
// TypeScript configuration

import tsParser from '@typescript-eslint/parser';
import tsPlugin from '@typescript-eslint/eslint-plugin';

export default [
  {
    // TypeScript files
    files: ['**/*.{ts,tsx}'],
    languageOptions: {
      parser: tsParser,
      parserOptions: {
        ecmaVersion: 2022,
        sourceType: 'module',
        project: './tsconfig.json',
      },
      globals: {
        // Node.js globals
        process: 'readonly',
        console: 'readonly',
        Buffer: 'readonly',
        __dirname: 'readonly',
        __filename: 'readonly',
        global: 'readonly',
        module: 'readonly',
        require: 'readonly',
        exports: 'writable',
        // Common test globals
        describe: 'readonly',
        it: 'readonly',
        test: 'readonly',
        expect: 'readonly',
        beforeEach: 'readonly',
        afterEach: 'readonly',
        beforeAll: 'readonly',
        afterAll: 'readonly',
        vi: 'readonly',
      },
    },
    plugins: {
      '@typescript-eslint': tsPlugin,
    },
    rules: {
      // Possible errors
      'no-console': 'off', // Allow console in Node.js
      'no-debugger': 'warn',
      'no-dupe-keys': 'error',
      'no-duplicate-case': 'error',
      'no-empty': ['error', { allowEmptyCatch: true }],
      'no-ex-assign': 'error',
      'no-extra-boolean-cast': 'error',
      'no-func-assign': 'error',
      'no-irregular-whitespace': 'error',
      'no-unreachable': 'error',
      'valid-typeof': 'error',

      // Best practices
      'curly': ['error', 'all'],
      'eqeqeq': ['error', 'always', { null: 'ignore' }],
      'no-eval': 'error',
      'no-implied-eval': 'error',
      'no-return-await': 'off', // Disabled in favor of TS version
      '@typescript-eslint/return-await': 'error',
      'no-throw-literal': 'error',
      'no-unused-expressions': 'error',
      'no-useless-concat': 'error',
      'no-useless-return': 'error',
      'prefer-promise-reject-errors': 'error',

      // Variables - use TypeScript versions
      'no-undef': 'off', // TypeScript handles this
      'no-unused-vars': 'off', // Use TypeScript version
      '@typescript-eslint/no-unused-vars': ['warn', {
        argsIgnorePattern: '^_',
        varsIgnorePattern: '^_',
        caughtErrorsIgnorePattern: '^_',
      }],

      // TypeScript specific
      '@typescript-eslint/no-explicit-any': 'warn',
      '@typescript-eslint/no-non-null-assertion': 'warn',
      '@typescript-eslint/explicit-function-return-type': 'off',
      '@typescript-eslint/explicit-module-boundary-types': 'off',

      // Stylistic (basic only, prefer Prettier for formatting)
      'indent': ['error', 2, { SwitchCase: 1 }],
      'quotes': ['error', 'single', { avoidEscape: true }],
      'semi': ['error', 'always'],
      'comma-dangle': ['error', 'always-multiline'],
      'no-trailing-spaces': 'error',
      'eol-last': ['error', 'always'],
    },
  },
  {
    // JavaScript files (no TypeScript parser)
    files: ['**/*.{js,mjs,cjs}'],
    languageOptions: {
      ecmaVersion: 2022,
      sourceType: 'module',
      globals: {
        // Node.js globals
        process: 'readonly',
        console: 'readonly',
        Buffer: 'readonly',
        __dirname: 'readonly',
        __filename: 'readonly',
        global: 'readonly',
        module: 'readonly',
        require: 'readonly',
        exports: 'writable',
        // Browser globals (for gateway/ui)
        window: 'readonly',
        document: 'readonly',
        fetch: 'readonly',
        WebSocket: 'readonly',
        location: 'readonly',
        URLSearchParams: 'readonly',
        FileReader: 'readonly',
        navigator: 'readonly',
        alert: 'readonly',
        confirm: 'readonly',
        setTimeout: 'readonly',
        setInterval: 'readonly',
        clearTimeout: 'readonly',
        clearInterval: 'readonly',
      },
    },
    rules: {
      // Possible errors
      'no-console': 'off',
      'no-debugger': 'warn',
      'no-dupe-keys': 'error',
      'no-duplicate-case': 'error',
      'no-empty': ['error', { allowEmptyCatch: true }],
      'no-ex-assign': 'error',
      'no-extra-boolean-cast': 'error',
      'no-func-assign': 'error',
      'no-irregular-whitespace': 'error',
      'no-unreachable': 'error',
      'valid-typeof': 'error',

      // Best practices
      'curly': ['error', 'all'],
      'eqeqeq': ['error', 'always', { null: 'ignore' }],
      'no-eval': 'error',
      'no-implied-eval': 'error',
      'no-throw-literal': 'error',
      'no-unused-expressions': 'error',
      'no-useless-concat': 'error',
      'no-useless-return': 'error',

      // Variables
      'no-undef': 'error',
      'no-unused-vars': ['warn', {
        argsIgnorePattern: '^_',
        varsIgnorePattern: '^_',
        caughtErrorsIgnorePattern: '^_',
      }],

      // Stylistic
      'indent': ['error', 2, { SwitchCase: 1 }],
      'quotes': ['error', 'single', { avoidEscape: true }],
      'semi': ['error', 'always'],
      'comma-dangle': ['error', 'always-multiline'],
      'no-trailing-spaces': 'error',
      'eol-last': ['error', 'always'],
    },
  },
  {
    // Ignore patterns
    ignores: [
      'dist/**',
      'node_modules/**',
      '**/*.d.ts',
      'coverage/**',
      '.pnpm-store/**',
    ],
  },
];