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ADR-0048: ESLint for Code Quality

Status​

Accepted - 2025-01-26

Context​

TypeScript codebase needs consistent style, error prevention, and best practices enforcement.

Decision​

ESLint 9.x with TypeScript ESLint plugin.

Rationale​

  1. Industry Standard: Most popular JavaScript linter
  2. TypeScript Support: @typescript-eslint/parser
  3. Extensible: 300+ plugins available
  4. Auto-Fixable: Most issues fixable via --fix

Configuration​

// eslint.config.js (ESLint 9.x flat config)
import tseslint from '@typescript-eslint/eslint-plugin';
import tsparser from '@typescript-eslint/parser';

export default [
  {
    files: ['**/*.ts', '**/*.tsx'],
    languageOptions: {
      parser: tsparser,
      parserOptions: {
        project: './tsconfig.json',
      },
    },
    plugins: {
      '@typescript-eslint': tseslint,
    },
    rules: {
      // TypeScript
      '@typescript-eslint/no-explicit-any': 'error',
      '@typescript-eslint/no-unused-vars': ['error', { argsIgnorePattern: '^_' }],
      '@typescript-eslint/explicit-function-return-type': 'off',

      // Best Practices
      'no-console': ['warn', { allow: ['warn', 'error'] }],
      'prefer-const': 'error',
      'no-var': 'error',

      // Code Style (handled by Prettier)
      'indent': 'off',
      'quotes': 'off',
    },
  },
];

CI/CD Integration​

# GitHub Actions
pnpm lint  # Fails if errors

References​