fix: avoid duplicate App definitions in Sandpack preview (v0.3.1)

package.json

@@ -1,6 +1,6 @@
 {
   "name": "artifact-cli",
-  "version": "0.3.0",
+  "version": "0.3.1",
   "description": "CLI tool for previewing React components in isolated sandboxes using Sandpack",
   "module": "index.ts",
   "type": "module",

src/infrastructure/templates/sandpackTemplate.ts

@@ -4,11 +4,13 @@ export function generateSandpackHtml(analysis: ComponentAnalysis): string {
   // Build files object for Sandpack
   const files: Record<string, string> = {};
 
-  // Main component file
-  files["/App.tsx"] = generateAppWrapper(analysis);
-
-  // Original component
-  files["/Component.tsx"] = analysis.code;
+  if (shouldUseDirectAppEntry(analysis)) {
+    // User code is already a root App component — use it directly to avoid duplicate App definitions
+    files["/App.tsx"] = analysis.code;
+  } else {
+    files["/App.tsx"] = generateAppWrapper(analysis);
+    files["/Component.tsx"] = analysis.code;
+  }
 
   // Local imports
   for (const localImport of analysis.localImports) {
@@ -354,14 +356,20 @@ export function generateSandpackHtml(analysis: ComponentAnalysis): string {
 </html>`;
 }
 
+function shouldUseDirectAppEntry(analysis: ComponentAnalysis): boolean {
+  return analysis.componentName === "App";
+}
+
 function generateAppWrapper(analysis: ComponentAnalysis): string {
+  const { componentName } = analysis;
+
   return `import React from 'react';
-import ${analysis.componentName} from './Component';
+import ${componentName} from './Component';
 
 export default function App() {
   return (
     <div>
-      <${analysis.componentName} />
+      <${componentName} />
     </div>
   );
 }