feat: add ESLint 9 configuration with TypeScript support

- Add eslint.config.js using new flat config format
- Configure @typescript-eslint/parser and plugin for TypeScript files
- Add separate config for vanilla JavaScript files (gateway/ui)
- Include Node.js and browser globals
- Enable strict rules: curly braces, no-eval, eqeqeq, etc.
- Configure TypeScript-specific rules (no-explicit-any, no-non-null-assertion)
- Add @typescript-eslint/parser and @typescript-eslint/eslint-plugin dependencies

eslint.config.js

@@ -0,0 +1,179 @@
+// 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',
+        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/**',
+    ],
+  },
+];

package.json

@@ -32,6 +32,8 @@
     "@types/react": "^19.0.0",
     "@types/turndown": "^5.0.0",
     "@types/ws": "^8.18.1",
+    "@typescript-eslint/eslint-plugin": "^8.55.0",
+    "@typescript-eslint/parser": "^8.55.0",
     "eslint": "^9.0.0",
     "tsx": "^4.0.0",
     "typescript": "^5.7.0",

pnpm-lock.yaml

@@ -102,6 +102,12 @@ importers:
       '@types/ws':
         specifier: ^8.18.1
         version: 8.18.1
+      '@typescript-eslint/eslint-plugin':
+        specifier: ^8.55.0
+        version: 8.55.0(@typescript-eslint/parser@8.55.0(eslint@9.39.2)(typescript@5.9.3))(eslint@9.39.2)(typescript@5.9.3)
+      '@typescript-eslint/parser':
+        specifier: ^8.55.0
+        version: 8.55.0(eslint@9.39.2)(typescript@5.9.3)
       eslint:
         specifier: ^9.0.0
         version: 9.39.2
@@ -991,6 +997,65 @@ packages:
   '@types/yauzl@2.10.3':
     resolution: {integrity: sha512-oJoftv0LSuaDZE3Le4DbKX+KS9G36NzOeSap90UIK0yMA/NhKJhqlSGtNDORNRaIbQfzjXDrQa0ytJ6mNRGz/Q==}
 
+  '@typescript-eslint/eslint-plugin@8.55.0':
+    resolution: {integrity: sha512-1y/MVSz0NglV1ijHC8OT49mPJ4qhPYjiK08YUQVbIOyu+5k862LKUHFkpKHWu//zmr7hDR2rhwUm6gnCGNmGBQ==}
+    engines: {node: ^18.18.0 || ^20.9.0 || >=21.1.0}
+    peerDependencies:
+      '@typescript-eslint/parser': ^8.55.0
+      eslint: ^8.57.0 || ^9.0.0
+      typescript: '>=4.8.4 <6.0.0'
+
+  '@typescript-eslint/parser@8.55.0':
+    resolution: {integrity: sha512-4z2nCSBfVIMnbuu8uinj+f0o4qOeggYJLbjpPHka3KH1om7e+H9yLKTYgksTaHcGco+NClhhY2vyO3HsMH1RGw==}
+    engines: {node: ^18.18.0 || ^20.9.0 || >=21.1.0}
+    peerDependencies:
+      eslint: ^8.57.0 || ^9.0.0
+      typescript: '>=4.8.4 <6.0.0'
+
+  '@typescript-eslint/project-service@8.55.0':
+    resolution: {integrity: sha512-zRcVVPFUYWa3kNnjaZGXSu3xkKV1zXy8M4nO/pElzQhFweb7PPtluDLQtKArEOGmjXoRjnUZ29NjOiF0eCDkcQ==}
+    engines: {node: ^18.18.0 || ^20.9.0 || >=21.1.0}
+    peerDependencies:
+      typescript: '>=4.8.4 <6.0.0'
+
+  '@typescript-eslint/scope-manager@8.55.0':
+    resolution: {integrity: sha512-fVu5Omrd3jeqeQLiB9f1YsuK/iHFOwb04bCtY4BSCLgjNbOD33ZdV6KyEqplHr+IlpgT0QTZ/iJ+wT7hvTx49Q==}
+    engines: {node: ^18.18.0 || ^20.9.0 || >=21.1.0}
+
+  '@typescript-eslint/tsconfig-utils@8.55.0':
+    resolution: {integrity: sha512-1R9cXqY7RQd7WuqSN47PK9EDpgFUK3VqdmbYrvWJZYDd0cavROGn+74ktWBlmJ13NXUQKlZ/iAEQHI/V0kKe0Q==}
+    engines: {node: ^18.18.0 || ^20.9.0 || >=21.1.0}
+    peerDependencies:
+      typescript: '>=4.8.4 <6.0.0'
+
+  '@typescript-eslint/type-utils@8.55.0':
+    resolution: {integrity: sha512-x1iH2unH4qAt6I37I2CGlsNs+B9WGxurP2uyZLRz6UJoZWDBx9cJL1xVN/FiOmHEONEg6RIufdvyT0TEYIgC5g==}
+    engines: {node: ^18.18.0 || ^20.9.0 || >=21.1.0}
+    peerDependencies:
+      eslint: ^8.57.0 || ^9.0.0
+      typescript: '>=4.8.4 <6.0.0'
+
+  '@typescript-eslint/types@8.55.0':
+    resolution: {integrity: sha512-ujT0Je8GI5BJWi+/mMoR0wxwVEQaxM+pi30xuMiJETlX80OPovb2p9E8ss87gnSVtYXtJoU9U1Cowcr6w2FE0w==}
+    engines: {node: ^18.18.0 || ^20.9.0 || >=21.1.0}
+
+  '@typescript-eslint/typescript-estree@8.55.0':
+    resolution: {integrity: sha512-EwrH67bSWdx/3aRQhCoxDaHM+CrZjotc2UCCpEDVqfCE+7OjKAGWNY2HsCSTEVvWH2clYQK8pdeLp42EVs+xQw==}
+    engines: {node: ^18.18.0 || ^20.9.0 || >=21.1.0}
+    peerDependencies:
+      typescript: '>=4.8.4 <6.0.0'
+
+  '@typescript-eslint/utils@8.55.0':
+    resolution: {integrity: sha512-BqZEsnPGdYpgyEIkDC1BadNY8oMwckftxBT+C8W0g1iKPdeqKZBtTfnvcq0nf60u7MkjFO8RBvpRGZBPw4L2ow==}
+    engines: {node: ^18.18.0 || ^20.9.0 || >=21.1.0}
+    peerDependencies:
+      eslint: ^8.57.0 || ^9.0.0
+      typescript: '>=4.8.4 <6.0.0'
+
+  '@typescript-eslint/visitor-keys@8.55.0':
+    resolution: {integrity: sha512-AxNRwEie8Nn4eFS1FzDMJWIISMGoXMb037sgCBJ3UR6o0fQTzr2tqN9WT+DkWJPhIdQCfV7T6D387566VtnCJA==}
+    engines: {node: ^18.18.0 || ^20.9.0 || >=21.1.0}
+
   '@vitest/expect@3.2.4':
     resolution: {integrity: sha512-Io0yyORnB6sikFlt8QW5K7slY4OjqNX9jmJQ02QDda8lyM6B5oNgVWoSoKPac8/kgnCUzuHQKrSLtu/uOqqrig==}
 
@@ -1905,6 +1970,10 @@ packages:
     resolution: {integrity: sha512-hsBTNUqQTDwkWtcdYI2i06Y/nUBEsNEDJKjWdigLvegy8kDuJAS8uRlpkkcQpyEXL0Z/pjDy5HBmMjRCJ2gq+g==}
     engines: {node: '>= 4'}
 
+  ignore@7.0.5:
+    resolution: {integrity: sha512-Hs59xBNfUIunMFgWAbGX5cq6893IbWg4KnrjbYwX3tx0ztorVgTDA6B2sxf8ejHJ4wz8BqGUMYlnzNBer5NvGg==}
+    engines: {node: '>= 4'}
+
   import-fresh@3.3.1:
     resolution: {integrity: sha512-TR3KfrTZTYLPB6jUjfx6MF9WcWrHL9su5TObK4ZkYgBdWKPOFoSoQIdEuTuR82pmtxH2spWG9h6etwfr1pLBqQ==}
     engines: {node: '>=6'}
@@ -2180,6 +2249,10 @@ packages:
     resolution: {integrity: sha512-lKwV/1brpG6mBUFHtb7NUmtABCb2WZZmm2wNiOA5hAb8VdCS4B3dtMWyvcoViccwAW/COERjXLt0zP1zXUN26g==}
     engines: {node: '>=10'}
 
+  minimatch@9.0.5:
+    resolution: {integrity: sha512-G6T0ZX48xgozx7587koeX9Ys2NYy6Gmv//P89sEte9V9whIapMNF4idKxnW2QtCcLiTWlb/wfCabAtAFWhhBow==}
+    engines: {node: '>=16 || 14 >=14.17'}
+
   minimist@1.2.8:
     resolution: {integrity: sha512-2yyAR8qBkN3YuheJanUpWC5U3bb5osDywNB8RzDVlDwDHbocAJveqqj1u8+SVD7jkWT4yvsHCpWqqWqAxb0zCA==}
 
@@ -2704,6 +2777,12 @@ packages:
   traverse@0.3.9:
     resolution: {integrity: sha512-iawgk0hLP3SxGKDfnDJf8wTz4p2qImnyihM5Hh/sGvQ3K37dPi/w8sRhdNIxYA1TwFwc5mDhIJq+O0RsvXBKdQ==}
 
+  ts-api-utils@2.4.0:
+    resolution: {integrity: sha512-3TaVTaAv2gTiMB35i3FiGJaRfwb3Pyn/j3m/bfAvGe8FB7CF6u+LMYqYlDh7reQf7UNvoTvdfAqHGmPGOSsPmA==}
+    engines: {node: '>=18.12'}
+    peerDependencies:
+      typescript: '>=4.8.4'
+
   ts-mixer@6.0.4:
     resolution: {integrity: sha512-ufKpbmrugz5Aou4wcr5Wc1UUFWOLhq+Fm6qa6P0w0K5Qw2yhaUoiWszhCVuNQyNwrlGiscHOmqYoAox1PtvgjA==}
 
@@ -4196,6 +4275,97 @@ snapshots:
       '@types/node': 22.19.7
     optional: true
 
+  '@typescript-eslint/eslint-plugin@8.55.0(@typescript-eslint/parser@8.55.0(eslint@9.39.2)(typescript@5.9.3))(eslint@9.39.2)(typescript@5.9.3)':
+    dependencies:
+      '@eslint-community/regexpp': 4.12.2
+      '@typescript-eslint/parser': 8.55.0(eslint@9.39.2)(typescript@5.9.3)
+      '@typescript-eslint/scope-manager': 8.55.0
+      '@typescript-eslint/type-utils': 8.55.0(eslint@9.39.2)(typescript@5.9.3)
+      '@typescript-eslint/utils': 8.55.0(eslint@9.39.2)(typescript@5.9.3)
+      '@typescript-eslint/visitor-keys': 8.55.0
+      eslint: 9.39.2
+      ignore: 7.0.5
+      natural-compare: 1.4.0
+      ts-api-utils: 2.4.0(typescript@5.9.3)
+      typescript: 5.9.3
+    transitivePeerDependencies:
+      - supports-color
+
+  '@typescript-eslint/parser@8.55.0(eslint@9.39.2)(typescript@5.9.3)':
+    dependencies:
+      '@typescript-eslint/scope-manager': 8.55.0
+      '@typescript-eslint/types': 8.55.0
+      '@typescript-eslint/typescript-estree': 8.55.0(typescript@5.9.3)
+      '@typescript-eslint/visitor-keys': 8.55.0
+      debug: 4.4.3
+      eslint: 9.39.2
+      typescript: 5.9.3
+    transitivePeerDependencies:
+      - supports-color
+
+  '@typescript-eslint/project-service@8.55.0(typescript@5.9.3)':
+    dependencies:
+      '@typescript-eslint/tsconfig-utils': 8.55.0(typescript@5.9.3)
+      '@typescript-eslint/types': 8.55.0
+      debug: 4.4.3
+      typescript: 5.9.3
+    transitivePeerDependencies:
+      - supports-color
+
+  '@typescript-eslint/scope-manager@8.55.0':
+    dependencies:
+      '@typescript-eslint/types': 8.55.0
+      '@typescript-eslint/visitor-keys': 8.55.0
+
+  '@typescript-eslint/tsconfig-utils@8.55.0(typescript@5.9.3)':
+    dependencies:
+      typescript: 5.9.3
+
+  '@typescript-eslint/type-utils@8.55.0(eslint@9.39.2)(typescript@5.9.3)':
+    dependencies:
+      '@typescript-eslint/types': 8.55.0
+      '@typescript-eslint/typescript-estree': 8.55.0(typescript@5.9.3)
+      '@typescript-eslint/utils': 8.55.0(eslint@9.39.2)(typescript@5.9.3)
+      debug: 4.4.3
+      eslint: 9.39.2
+      ts-api-utils: 2.4.0(typescript@5.9.3)
+      typescript: 5.9.3
+    transitivePeerDependencies:
+      - supports-color
+
+  '@typescript-eslint/types@8.55.0': {}
+
+  '@typescript-eslint/typescript-estree@8.55.0(typescript@5.9.3)':
+    dependencies:
+      '@typescript-eslint/project-service': 8.55.0(typescript@5.9.3)
+      '@typescript-eslint/tsconfig-utils': 8.55.0(typescript@5.9.3)
+      '@typescript-eslint/types': 8.55.0
+      '@typescript-eslint/visitor-keys': 8.55.0
+      debug: 4.4.3
+      minimatch: 9.0.5
+      semver: 7.7.3
+      tinyglobby: 0.2.15
+      ts-api-utils: 2.4.0(typescript@5.9.3)
+      typescript: 5.9.3
+    transitivePeerDependencies:
+      - supports-color
+
+  '@typescript-eslint/utils@8.55.0(eslint@9.39.2)(typescript@5.9.3)':
+    dependencies:
+      '@eslint-community/eslint-utils': 4.9.1(eslint@9.39.2)
+      '@typescript-eslint/scope-manager': 8.55.0
+      '@typescript-eslint/types': 8.55.0
+      '@typescript-eslint/typescript-estree': 8.55.0(typescript@5.9.3)
+      eslint: 9.39.2
+      typescript: 5.9.3
+    transitivePeerDependencies:
+      - supports-color
+
+  '@typescript-eslint/visitor-keys@8.55.0':
+    dependencies:
+      '@typescript-eslint/types': 8.55.0
+      eslint-visitor-keys: 4.2.1
+
   '@vitest/expect@3.2.4':
     dependencies:
       '@types/chai': 5.2.3
@@ -4459,7 +4629,6 @@ snapshots:
   brace-expansion@2.0.2:
     dependencies:
       balanced-match: 1.0.2
-    optional: true
 
   buffer-crc32@0.2.13: {}
 
@@ -5250,6 +5419,8 @@ snapshots:
 
   ignore@5.3.2: {}
 
+  ignore@7.0.5: {}
+
   import-fresh@3.3.1:
     dependencies:
       parent-module: 1.0.1
@@ -5504,6 +5675,10 @@ snapshots:
       brace-expansion: 2.0.2
     optional: true
 
+  minimatch@9.0.5:
+    dependencies:
+      brace-expansion: 2.0.2
+
   minimist@1.2.8: {}
 
   mitt@3.0.1: {}
@@ -6132,6 +6307,10 @@ snapshots:
   traverse@0.3.9:
     optional: true
 
+  ts-api-utils@2.4.0(typescript@5.9.3):
+    dependencies:
+      typescript: 5.9.3
+
   ts-mixer@6.0.4: {}
 
   tslib@2.8.1: {}