chore: introduce ESLint with @antfu/eslint-config flat config

.github/workflows/ci.yml

@@ -31,6 +31,9 @@ jobs:
       - name: Type check
         run: npx tsc --noEmit
 
+      - name: Lint
+        run: npm run lint
+
       - name: Build
         run: npm run build
 

CONTRIBUTING.md

@@ -17,6 +17,7 @@
 
 # 4. Run a few checks
 npx tsc --noEmit
+npm run lint
 npx vitest run src/
 
 # 5. Link globally (optional, for testing `opencli` command)
@@ -94,7 +95,7 @@
       })()
     `);
 
     return data.slice(0, Number(limit)).map((item: any) => ({
       title: item.title,
       url: item.url,
       date: item.created_at,
@@ -130,7 +131,8 @@
 
 ## Code Style
 
-- **TypeScript strict mode** — avoid `any` where possible.
+- **ESLint** — enforced via [`@antfu/eslint-config`](https://github.com/antfu/eslint-config) (flat config). Run `npm run lint` to check, `npm run lint:fix` to auto-fix.
+- **TypeScript strict mode** — avoid `any` where possible (currently `warn`, will be tightened to `error`).
 - **ES Modules** — use `.js` extensions in imports (TypeScript output).
 - **Naming**: `kebab-case` for files, `camelCase` for variables/functions, `PascalCase` for types/classes.
 - **No default exports** — use named exports.
@@ -156,6 +158,7 @@
 3. Run the checks that apply:
    ```bash
    npx tsc --noEmit           # Type check
+   npm run lint               # ESLint
    npx vitest run src/        # Unit tests
    opencli validate           # YAML validation (if applicable)
    ```

eslint.config.js

@@ -0,0 +1,28 @@
+import antfu from '@antfu/eslint-config'
+
+export default antfu({
+  typescript: {
+    tsconfigPath: './tsconfig.json',
+  },
+  ignores: [
+    'dist/**',
+    'scripts/**',
+    '**/*.cjs',
+    // E2E/smoke tests and vitest.config.ts are outside tsconfig.json include path
+    'tests/**',
+    'vitest.config.ts',
+  ],
+  rules: {
+    // Phase 1: warn on any — tighten to error incrementally
+    '@typescript-eslint/no-explicit-any': 'warn',
+    '@typescript-eslint/no-unused-vars': ['error', { argsIgnorePattern: '^_' }],
+    // CLI tool needs console output
+    'no-console': 'off',
+  },
+}, {
+  // Disable opinionated jsonc sort-keys for config files
+  files: ['**/*.json', '**/*.jsonc'],
+  rules: {
+    'jsonc/sort-keys': 'off',
+  },
+})