Windows desktop regression: long plain-text paste freezes app and maximized UI becomes transparent

Summary

This issue is an additional reproduction and diagnostic supplement to #25709.

After updating the Codex Windows desktop app, I observed two regressions:

1. Pasting longer plain text into the conversation input can freeze the entire app. Short text and images can still be pasted normally. The freeze is intermittent: after reproducing it repeatedly, longer text could later be pasted successfully without changing the installed app version.
2. When the app window is maximized, the left sidebar, top bar, and bottom/status areas become transparent and show the desktop wallpaper.

Possible cause

The paste issue may be related to network conditions or synchronization of the TXT attachment automatically created for longer pasted text. This is only a hypothesis. A stalled or failed request should not make the entire desktop UI unresponsive.

Environment

• Windows 10 Enterprise, build 19044
• Codex package: OpenAI.Codex_26.527.7698.0_x64__2p2nqsd0c76g0
• Native Windows mode

The transparency issue also appears similar to #25754.