fix(filesystem): let a list_directory_with_sizes stat failure reach the caller

src/filesystem/__tests__/structured-content.test.ts

@@ -96,6 +96,24 @@ describe('structuredContent schema compliance', () => {
       // The content should contain directory listing info
       expect(structuredContent.content).toContain('[FILE]');
     });
+
+    // A dangling symlink is listed by readdir but `fs.stat` cannot resolve it,
+    // so this is the real path to a failing stat. Reporting the entry as size 0
+    // makes it indistinguishable from an empty file -- `formatSize` renders both
+    // as "0 B" -- and adds a fabricated 0 to the combined size.
+    it('should reject when an entry cannot be stat-ed rather than report it as 0 bytes', async () => {
+      await fs.symlink(path.join(testDir, 'no-such-target'), path.join(testDir, 'dangling'));
+
+      const result = await client.callTool({
+        name: 'list_directory_with_sizes',
+        arguments: { path: testDir }
+      });
+
+      expect(result.isError).toBe(true);
+      const content = (result.content as Array<{ type: string; text: string }>).map(c => c.text).join('\n');
+      expect(content).toMatch(/ENOENT|dangling/);
+      expect(content).not.toMatch(/dangling\s+0 B/);
+    });
   });
 
   describe('move_file', () => {

src/filesystem/index.ts

@@ -485,25 +485,21 @@ server.registerTool(
     const entries = await fs.readdir(validPath, { withFileTypes: true });
 
     // Get detailed information for each entry
+    //
+    // A stat that fails is not an entry of size 0: `formatSize` renders that
+    // as "0 B", so an unreadable file and an empty one come out identical, and
+    // the entry's 0 is added to the combined size below. Let it reject, the
+    // way `list_directory` and `directory_tree` already let `readdir` reject.
     const detailedEntries = await Promise.all(
       entries.map(async (entry) => {
         const entryPath = path.join(validPath, entry.name);
-        try {
-          const stats = await fs.stat(entryPath);
-          return {
-            name: entry.name,
-            isDirectory: entry.isDirectory(),
-            size: stats.size,
-            mtime: stats.mtime
-          };
-        } catch (error) {
-          return {
-            name: entry.name,
-            isDirectory: entry.isDirectory(),
-            size: 0,
-            mtime: new Date(0)
-          };
-        }
+        const stats = await fs.stat(entryPath);
+        return {
+          name: entry.name,
+          isDirectory: entry.isDirectory(),
+          size: stats.size,
+          mtime: stats.mtime
+        };
       })
     );