eslint.config.js

/**
 * ESLint configuration for Paperlyte
 *
 * Uses the new flat config format (ESLint 9+) with:
 * - JavaScript recommended rules
 * - TypeScript strict type checking
 * - React Hooks rules for proper hook usage
 * - React Refresh rules for HMR compatibility
 * - Prettier integration for code formatting
 *
 * @see https://eslint.org/docs/latest/use/configure/configuration-files
 */
import js from '@eslint/js'
import globals from 'globals'
import reactHooks from 'eslint-plugin-react-hooks'
import reactRefresh from 'eslint-plugin-react-refresh'
import tseslint from 'typescript-eslint'
import prettierConfig from 'eslint-config-prettier'
import { defineConfig, globalIgnores } from 'eslint/config'

export default defineConfig([
  // Ignore build output directory
  globalIgnores(['dist']),
  {
    // Apply to all TypeScript and TSX files
    files: ['**/*.{ts,tsx}'],

    // Extend recommended configurations
    extends: [
      // ESLint JavaScript recommended rules
      js.configs.recommended,
      // TypeScript ESLint recommended rules (includes type checking)
      tseslint.configs.recommended,
      // React Hooks rules (prevents common mistakes with hooks)
      reactHooks.configs.flat.recommended,
      // React Refresh rules (ensures components can be hot-reloaded)
      reactRefresh.configs.vite,
      // Prettier config (disables conflicting ESLint rules)
      prettierConfig,
    ],

    languageOptions: {
      // Use ES2020 features
      ecmaVersion: 2020,
      // Browser globals (window, document, etc.)
      globals: globals.browser,
    },

    rules: {
      // Production console statements should be routed through the `monitoring`
      // utility or guarded behind `import.meta.env.DEV`. `warn`/`error` are
      // allowed everywhere as genuine production diagnostics.
      'no-console': ['error', { allow: ['warn', 'error'] }],
    },
  },
  // Node.js globals for build-tool configs and server-side scripts.
  // These files run in Node, not the browser, so process/Buffer/__dirname etc.
  // must be available. The TS rules from the block above still apply via
  // flat-config merging; this block only supplements the globals.
  {
    files: ['*.config.ts', 'scripts/**/*.ts', 'netlify/functions/**/*.ts'],
    languageOptions: {
      globals: globals.node,
    },
    // CLI scripts and serverless functions legitimately log to stdout/stderr;
    // the no-console audit (HIGH-002) is scoped to browser-side production
    // source (src/**), not Node build tooling.
    rules: {
      'no-console': 'off',
    },
  },
  // Sanctioned logging locations: `monitoring` and `analytics/**` are the
  // centralized, designated places where `console.log` is permitted.
  {
    files: ['src/utils/monitoring.ts', 'src/analytics/**'],
    rules: {
      'no-console': ['error', { allow: ['warn', 'error', 'log', 'group', 'groupEnd'] }],
    },
  },
])