Desktop app (Windows): Cannot switch between Plan/Build mode - no UI toggle and Tab key not working

[abMXY]

Description

版本：最新的 Windows 桌面端（NSIS 安装）
Tab 键无法在 Build/Plan 模式间切换
界面上也看不到任何模式切换按钮/指示器（文档说右下角应有指示器）
在 TUI 终端版中 Tab 切换正常，但桌面版完全找不到切换入口

Plugins

No response

OpenCode version

1.18.4

Steps to reproduce

No response

Screenshot and/or share link

No response

Operating System

No response

Terminal

No response

[github-actions]

This issue might be a duplicate of existing issues. Please check:

• [Bug] Desktop App v1.18.1 new layout hides agent (Plan/Build) switching UI #36997: Desktop App new layout hides Plan/Build switching UI, Tab key intercepted by webview — same symptoms on Windows desktop
• Build/Plan missing in 1.18.4 #38054: Build/Plan missing in v1.18.4 on Windows desktop — same version and OS
• Bug: Plan/Build mode toggle missing from chat UI after latest update #37070: Plan/Build mode toggle missing from chat UI after latest update — same core issue

Please review those issues and add any additional context there if applicable.