Properly parse at-commands with narrow non-breaking spaces (#18677)

packages/cli/src/ui/hooks/atCommandProcessor.test.ts

@@ -319,6 +319,35 @@ describe('handleAtCommand', () => {
     );
   }, 10000);
 
+  it('should correctly handle file paths with narrow non-breaking space (NNBSP)', async () => {
+    const nnbsp = '\u202F';
+    const fileContent = 'NNBSP file content.';
+    const filePath = await createTestFile(
+      path.join(testRootDir, `my${nnbsp}file.txt`),
+      fileContent,
+    );
+    const relativePath = getRelativePath(filePath);
+    const query = `@${filePath}`;
+
+    const result = await handleAtCommand({
+      query,
+      config: mockConfig,
+      addItem: mockAddItem,
+      onDebugMessage: mockOnDebugMessage,
+      messageId: 129,
+      signal: abortController.signal,
+    });
+
+    expect(result.error).toBeUndefined();
+    expect(result.processedQuery).toEqual([
+      { text: `@${relativePath}` },
+      { text: '\n--- Content from referenced files ---' },
+      { text: `\nContent from @${relativePath}:\n` },
+      { text: fileContent },
+      { text: '\n--- End of content ---' },
+    ]);
+  });
+
   it('should handle multiple @file references', async () => {
     const content1 = 'Content file1';
     const file1Path = await createTestFile(