fix: allow TS .svelte.ts modules

Author: paoloricciuti

.changeset/ready-lines-remain.md

@@ -0,0 +1,5 @@
+---
+'@sveltejs/mcp': patch
+---
+
+fix: allow TS `.svelte.ts` modules

packages/mcp-server/package.json

@@ -28,17 +28,18 @@
 		"svelte": "^5.39.2",
 		"svelte-eslint-parser": "^1.3.2",
 		"tmcp": "^1.13.0",
+		"ts-blank-space": "^0.6.2",
 		"typescript-eslint": "^8.44.0",
 		"valibot": "^1.1.0",
 		"vitest": "^3.2.4",
 		"zimmerframe": "^1.1.4"
 	},
 	"devDependencies": {
 		"@anthropic-ai/sdk": "^0.65.0",
-		"dotenv": "^17.2.3",
 		"@sveltejs/kit": "^2.42.2",
 		"@types/eslint-scope": "^8.3.2",
 		"@types/estree": "^1.0.8",
-		"@typescript-eslint/types": "^8.44.0"
+		"@typescript-eslint/types": "^8.44.0",
+		"dotenv": "^17.2.3"
 	}
 }

packages/mcp-server/src/mcp/autofixers/add-compile-issues.ts

@@ -1,11 +1,28 @@
-import { compile } from 'svelte/compiler';
+import { compile as compile_component, compileModule } from 'svelte/compiler';
+import { extname } from 'path';
+import ts from 'ts-blank-space';
 
 export function add_compile_issues(
 	content: { issues: string[]; suggestions: string[] },
 	code: string,
 	desired_svelte_version: number,
 	filename = 'Component.svelte',
 ) {
+	let compile = compile_component;
+	const extension = extname(filename);
+	if (extension !== '.svelte') {
+		compile = compileModule;
+		// compile module doesn't accept .ts files so we need to transpile them first with ts-blank-space
+		// a fast and lightweight typescript transpiler that can strips types replacing them with white spaces
+		// so the code positions are not affected
+		if (extension === '.ts') {
+			code = ts(code, (node) => {
+				content.issues.push(
+					`The provided file is a module but it contains invalid TypeScript code: ${node.getText()} at ${node.getStart()}`,
+				);
+			});
+		}
+	}
 	const compilation_result = compile(code, {
 		filename: filename || 'Component.svelte',
 		generate: false,

packages/mcp-server/src/mcp/autofixers/add-eslint-issues.ts

@@ -12,7 +12,7 @@ function base_config(svelte_config: Config): ESLint.Options['baseConfig'] {
 	return [
 		...svelte.configs.recommended,
 		{
-			files: ['*.svelte'],
+			files: ['*.svelte', '*.svelte.ts', '*.svelte.js'],
 			rules: {
 				'no-self-assign': 'warn',
 				'svelte/infinite-reactive-loop': 'warn',