diff --git a/src/main/window/createMainWindow.test.ts b/src/main/window/createMainWindow.test.ts
index 8a61f157584..81e30ee4ea9 100644
--- a/src/main/window/createMainWindow.test.ts
+++ b/src/main/window/createMainWindow.test.ts
@@ -147,6 +147,12 @@ describe('createMainWindow', () => {
     expect(browserWindowInstance.loadURL).not.toHaveBeenCalled()
   })
 
+  it('keeps the browser close-policy marker absolute under Windows URL rules', () => {
+    expect(fileURLToPath(BROWSER_WINDOW_CLOSE_ALLOWED_PRELOAD, { windows: true })).toBe(
+      'C:\\__orca_window_close_allowed__'
+    )
+  })
+
   it('enables renderer sandboxing and opens external links safely', () => {
     const windowHandlers: Record<string, (...args: any[]) => void> = {}
     const webContents = {
diff --git a/src/shared/browser-window-close-policy.ts b/src/shared/browser-window-close-policy.ts
index 2ea28169ee7..93c37e18a48 100644
--- a/src/shared/browser-window-close-policy.ts
+++ b/src/shared/browser-window-close-policy.ts
@@ -1,2 +1,2 @@
-// Why: this marker carries the CLI's explicit close policy across <webview> attach before the guest exists.
-export const BROWSER_WINDOW_CLOSE_ALLOWED_PRELOAD = 'file:///__orca_window_close_allowed__'
+// Why: the synthetic drive keeps this marker absolute under Windows file-URL rules; main removes it before guest load.
+export const BROWSER_WINDOW_CLOSE_ALLOWED_PRELOAD = 'file:///C:/__orca_window_close_allowed__'