Vietnamese text input renders with corrupted/doubled diacritical marks

Summary

When typing Vietnamese text in the terminal input on Windows, characters with compound Unicode diacritics (tone mark + vowel modifier) are rendered incorrectly. The base vowel, modifier, and tone mark appear as separate visible characters instead of a single composed glyph.

Expected Behavior

Vietnamese characters with compound diacritics render as single composed glyphs. For example:

• gặp displays as gặp
• lỗi displays as lỗi
• những displays as những

Actual Behavior

Characters with compound diacritics are split/doubled when typed. Examples of what appears on screen:

• gặp → rendered as gaạpaập
• lỗi → rendered as lôiỗi
• những → rendered as nhunữững
• cập nhật → rendered as câạp nhâật

Screenshot showing the bug:

Steps to reproduce the issue

1. Open command-code v0.27.0 in VS Code terminal on Windows 11
2. Switch input language to Vietnamese (Telex or VNI input method)
3. Type any Vietnamese sentence with compound diacritics, e.g.: gặp lỗi trong những bản cập nhật
4. Observe the rendered text in the input field

Command Code Version

v0.27.0

Operating System

Windows

Terminal/IDE

VSCode

Shell

PowerShell

Additional context

No response

报告中没有指出源文件或测试。首先在 Windows 11 上使用 PowerShell 和越南语 Telex 或 VNI 输入，在 VS Code 终端中重现该问题，然后跟踪终端输入渲染路径。对于列出的示例，越南语复合变音符号显示为单个组合字形，即视为完成。