fix: detect Next.js route groups as valid project structure

The project validator failed to recognize Next.js projects using route
groups (parenthesized directories like (app), (dashboard)). The
isTargetFile function did an exact directory match against potential
paths, missing layout files inside route group subdirectories.

Added route group pattern matching to isTargetFile so that paths like
app/(marketing)/layout.tsx match the potentialPath 'app'.

Fixes #2936

Author: mvanhorn

packages/utility/src/path.ts

@@ -84,7 +84,15 @@ export const isTargetFile = (
     }
 
     const dirName = normalize(path.dirname(targetFile));
-    return potentialPaths.some((p) => normalize(p) === dirName);
+    return potentialPaths.some((p) => {
+        const normalizedP = normalize(p);
+        if (normalizedP === dirName) return true;
+        // Support Next.js route groups: match files inside (group) subdirectories
+        // e.g., app/(marketing)/layout.tsx should match potentialPath 'app'
+        const parentDir = normalize(path.dirname(dirName));
+        const groupDir = path.basename(dirName);
+        return parentDir === normalizedP && /^\([^)]+\)$/.test(groupDir);
+    });
 };
 
 export const isRootLayoutFile = (

packages/utility/test/path.test.ts

@@ -190,4 +190,24 @@ describe('isTargetFile', () => {
         const targetFile = 'src/components/layout.tsx';
         expect(isRootLayoutFile(targetFile)).toBe(false);
     });
+
+    test('returns true for layout in a Next.js route group under app/', () => {
+        expect(isRootLayoutFile('app/(marketing)/layout.tsx')).toBe(true);
+    });
+
+    test('returns true for layout in a Next.js route group under src/app/', () => {
+        expect(isRootLayoutFile('src/app/(dashboard)/layout.tsx')).toBe(true);
+    });
+
+    test('returns true for layout in route group with jsx extension', () => {
+        expect(isRootLayoutFile('app/(app)/layout.jsx')).toBe(true);
+    });
+
+    test('returns false for layout nested deeper than one route group level', () => {
+        expect(isRootLayoutFile('app/(app)/nested/layout.tsx')).toBe(false);
+    });
+
+    test('returns false for layout in directory that looks like route group but is not', () => {
+        expect(isRootLayoutFile('app/marketing/layout.tsx')).toBe(false);
+    });
 });