[Windows] Computer Use turn-ended helper leaves persistent blank white desktop surface #32783

What happened

After Codex Desktop runs for a while, a large blank white borderless rectangle appears near the upper-left of the Windows desktop. It has no title bar or close control and cannot be dismissed normally.

Closing Codex/ChatGPT and its visible background processes does not remove the rectangle. It is not listed as a normal application window, which makes it appear to be an orphaned native capture/compositor surface rather than a regular app window.

The issue first appeared on Codex Desktop 26.707.3748.0. The client has since updated to 26.707.8479.0, but the already-orphaned surface remains. The active and newly bundled Computer Use helper are byte-for-byte identical:

• Computer Use package: @oai/sky 0.4.20
• codex-computer-use.exe SHA-256: F2B2F56FCD1699B0FA32DEC3214A56A1D36B937A2ECF58CC822AB4A904551E03

What I expected

The turn-ended notification/capture helper should exit without leaving any visible desktop surface. Any helper-created surface should be destroyed when the helper or Codex Desktop exits.

Steps to reproduce

1. On Windows 10 build 19044, enable the Codex Computer Use plugin.
2. Configure Codex's turn-ended notification to invoke codex-computer-use.exe with the turn-ended argument.
3. Use Codex Desktop for an extended session with multiple completed turns.
4. Observe that a blank white borderless rectangle eventually appears on the desktop.
5. Close Codex Desktop and its visible background processes.
6. Observe that the rectangle remains and offers no normal way to close it.

The appearance is intermittent rather than tied to one known prompt.

Additional context

• OS: Windows 10 IoT Enterprise LTSC, x64, build 19044.
• Disabling only the turn-ended notify command prevents further notifier invocations while leaving Computer Use available.
• The existing rectangle can survive process exit; removing it appears to require restarting the Windows graphics compositor or rebooting.
• No compositor reset or reboot was performed because other long-running work was active.
• The public Codex changelog does not identify a specific fix in the newer client builds, and the native helper binary is unchanged.
• A screenshot showing the rectangle is available if maintainers need it.

Possibly related:

• Windows Computer Use screenshot fails on Windows 10 22H2 when SetIsBorderRequired is called #25178 — Windows 10 Computer Use capture calls an API unsupported below build 20348
• Windows Desktop hangs/exits after turn-complete notification path #22655 — Windows turn-complete notification path hangs/exits
• Windows: Codex App UI renders as transparent/blank white content area #25236 — blank/transparent Windows UI
• Codex Desktop on Windows: rendering freezes/transparency when maximized #25513 — Windows DWM/rendering behavior