From 41f1ea4672fff9d0c10dab51e8d50127dca19d6c Mon Sep 17 00:00:00 2001
From: Sehoon Shon <sshon@google.com>
Date: Wed, 11 Mar 2026 14:22:10 -0400
Subject: [PATCH] fix(core): handle EISDIR in robustRealpath on Windows
 (#21984)

---
 packages/core/src/utils/paths.test.ts | 16 ++++++++++++++++
 packages/core/src/utils/paths.ts      |  9 +++++++--
 2 files changed, 23 insertions(+), 2 deletions(-)

diff --git a/packages/core/src/utils/paths.test.ts b/packages/core/src/utils/paths.test.ts
index 4563c0485b..590f3aab58 100644
--- a/packages/core/src/utils/paths.test.ts
+++ b/packages/core/src/utils/paths.test.ts
@@ -528,6 +528,22 @@ describe('resolveToRealPath', () => {
     expect(resolveToRealPath(input)).toBe(expected);
   });
 
+  it('should return decoded path even if fs.realpathSync fails with EISDIR', () => {
+    vi.spyOn(fs, 'realpathSync').mockImplementationOnce(() => {
+      const err = new Error(
+        'Illegal operation on a directory',
+      ) as NodeJS.ErrnoException;
+      err.code = 'EISDIR';
+      throw err;
+    });
+
+    const p = path.resolve('path', 'to', 'New Project');
+    const input = pathToFileURL(p).toString();
+    const expected = p;
+
+    expect(resolveToRealPath(input)).toBe(expected);
+  });
+
   it('should recursively resolve symlinks for non-existent child paths', () => {
     const parentPath = path.resolve('/some/parent/path');
     const resolvedParentPath = path.resolve('/resolved/parent/path');
diff --git a/packages/core/src/utils/paths.ts b/packages/core/src/utils/paths.ts
index 338d4017e5..12622fbf86 100644
--- a/packages/core/src/utils/paths.ts
+++ b/packages/core/src/utils/paths.ts
@@ -384,7 +384,12 @@ function robustRealpath(p: string, visited = new Set<string>()): string {
   try {
     return fs.realpathSync(p);
   } catch (e: unknown) {
-    if (e && typeof e === 'object' && 'code' in e && e.code === 'ENOENT') {
+    if (
+      e &&
+      typeof e === 'object' &&
+      'code' in e &&
+      (e.code === 'ENOENT' || e.code === 'EISDIR')
+    ) {
       try {
         const stat = fs.lstatSync(p);
         if (stat.isSymbolicLink()) {
@@ -400,7 +405,7 @@ function robustRealpath(p: string, visited = new Set<string>()): string {
             lstatError &&
             typeof lstatError === 'object' &&
             'code' in lstatError &&
-            lstatError.code === 'ENOENT'
+            (lstatError.code === 'ENOENT' || lstatError.code === 'EISDIR')
           )
         ) {
           throw lstatError;