[BUG] When typing Korean (or other IME-based languages) in Claude Code CLI, the intermediate composition characters appear outside the input prompt area before being committed.

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

To Reproduce
Steps to reproduce the behavior:

1. Launch Claude Code CLI
2. Start typing Korean characters using an IME (Input Method Editor)
3. Observe that the pre-composition characters render outside/above the intended input area
4. The final committed text appears correctly, but the composition process is visually broken

Expected behavior
IME composition characters should remain within the input prompt area during the entire typing process, similar to how they behave in standard terminal applications.

Environment

• OS: Linux mint 22.3
• Terminal: Default Terminal
• Claude Code version: 2.1.37
• IME: Korean

Additional context
This appears to be a known issue with terminal UI frameworks (Ink/React-based) and IME composition handling. The issue affects the user experience for CJK language users but doesn't prevent functionality - the final input is processed correctly.

What Should Happen?

IME composition characters should remain within the input prompt area during the entire typing process, similar to how they behave in standard terminal applications.

Error Messages/Logs

Steps to Reproduce

Steps to reproduce the behavior:

1. Launch Claude Code CLI
2. Start typing Korean characters using an IME (Input Method Editor)
3. Observe that the pre-composition characters render outside/above the intended input area
4. The final committed text appears correctly, but the composition process is visually broken

Claude Model

Not sure / Multiple models

Is this a regression?

No, this never worked

Last Working Version

_No response_

Claude Code Version

2.1.37

Platform

Anthropic API

Operating System

Ubuntu/Debian Linux

Terminal/Shell

Non-interactive/CI environment

Additional Information

_No response_