Merge pull request #2198 from AtCoder-NoviSteps/#2197

💥 Bump eslint-plugin-svelte from 2.46.1 to 3.9.2 (#2197)

Author: KATO-Hiro

eslint.config.mjs

@@ -4,19 +4,9 @@
 import typescriptEslint from '@typescript-eslint/eslint-plugin';
 import globals from 'globals';
 import tsParser from '@typescript-eslint/parser';
-import parser from 'svelte-eslint-parser';
-import path from 'node:path';
-import { fileURLToPath } from 'node:url';
+import svelteParser from 'svelte-eslint-parser';
+import sveltePlugin from 'eslint-plugin-svelte';
 import js from '@eslint/js';
-import { FlatCompat } from '@eslint/eslintrc';
-
-const __filename = fileURLToPath(import.meta.url);
-const __dirname = path.dirname(__filename);
-const compat = new FlatCompat({
-  baseDirectory: __dirname,
-  recommendedConfig: js.configs.recommended,
-  allConfig: js.configs.all,
-});
 
 export default [
   {
@@ -40,12 +30,11 @@ export default [
       'prisma/.fabbrica/index.ts',
     ],
   },
-  ...compat.extends(
-    'eslint:recommended',
-    'plugin:@typescript-eslint/recommended',
-    'plugin:svelte/recommended',
-    'prettier',
-  ),
+  // Base JS rules first
+  js.configs.recommended,
+  // Svelte rules override JS rules where appropriate (intentional)
+  // This allows Svelte-specific handling of rules like no-undef, no-unused-vars
+  ...sveltePlugin.configs['flat/recommended'],
   {
     plugins: {
       '@typescript-eslint': typescriptEslint,
@@ -55,6 +44,13 @@ export default [
       globals: {
         ...globals.browser,
         ...globals.node,
+        // Add Svelte 5 runes as global variables
+        $state: 'readonly',
+        $derived: 'readonly',
+        $effect: 'readonly',
+        $props: 'readonly',
+        $bindable: 'readonly',
+        $inspect: 'readonly',
       },
 
       parser: tsParser,
@@ -74,15 +70,25 @@ export default [
           'ts-ignore': false,
         },
       ],
+      // Add TypeScript ESLint rules manually
+      '@typescript-eslint/no-unused-vars': ['error', { argsIgnorePattern: '^_' }],
+      '@typescript-eslint/no-explicit-any': 'warn',
+      // Disable some strict Svelte rules that are too aggressive
+      'svelte/require-each-key': 'warn',
+      'svelte/no-useless-mustaches': 'warn',
+      'svelte/prefer-writable-derived': 'warn', // New in 3.6.0 - prefer $derived over $state+$effect
+      'svelte/valid-prop-names-in-kit-pages': 'warn', // Allow props other than data/errors in pages
+      'no-unused-vars': 'off', // Use TypeScript version instead
+      'no-undef': 'off', // TypeScript handles this
     },
   },
   {
     files: ['**/*.svelte'],
 
     languageOptions: {
-      parser: parser,
-      ecmaVersion: 5,
-      sourceType: 'script',
+      parser: svelteParser,
+      ecmaVersion: 'latest', // ES2023+ features support
+      sourceType: 'module', // ESM import/export support
 
       parserOptions: {
         parser: '@typescript-eslint/parser',

package.json

@@ -46,7 +46,7 @@
     "@vitest/ui": "3.2.4",
     "eslint": "9.29.0",
     "eslint-config-prettier": "10.1.5",
-    "eslint-plugin-svelte": "2.46.1",
+    "eslint-plugin-svelte": "3.9.2",
     "globals": "16.2.0",
     "husky": "9.1.7",
     "jsdom": "26.1.0",