#808 Bug Report: CLI tools incorrectly handle Vietnamese input (backspace / diacritics)

[Anonymous]

When using Unikey with certain command‑line interfaces (e.g., Claude Code CLI), Vietnamese text input does not work correctly. Specifically:

Issue: When typing Vietnamese text (e.g., with diacritics like á, ô, ỗ, etc.), the backspace key removes the accent/diacritic incorrectly, resulting in missing or corrupted Vietnamese text.
Behavior: Instead of deleting the last character properly, the CLI loses the accent or deletes the wrong part of the composed Vietnamese syllable.
This occurs when using Unikey as the IME, especially in environments where input is processed character by character (e.g., Node.js CLI tools, terminals, etc.).
The problem seems related to how Unicode composing characters and backspace are communicated to the application — backspace is not interpreted properly, leading to lost accents.

Steps to Reproduce (example):

Enable Unikey Vietnamese keyboard input (Unicode).
Open a command‑line interface (e.g., PowerShell, Bash, Node CLI).
Start typing a Vietnamese word with diacritics (e.g., hòa, nguyễn, cộng).
Press backspace — the accent/diacritic is lost or mis‑deleted instead of removing the last character.

Actual Result:
Vietnamese letters lose their diacritics or become incorrect when pressing backspace in CLI environments.

Expected Result:
Backspace should remove the last character/combining mark properly so Vietnamese text behaves normally.