[BUG] Panic on UTF-8 character boundary with Korean text

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?

Panic on UTF-8 character boundary with Korean text

What Should Happen?

• Reproduction method: Run claude in a directory with a markdown file containing Korean characters

Error Messages/Logs

- ERROR message: Panic on UTF-8 character boundary with Korean text

Steps to Reproduce

• Panic on UTF-8 character boundary with Korean text
• version: 2.0.75
• Reproduction method: Run claude in a directory with a markdown file containing Korean characters
• ERROR message: Panic on UTF-8 character boundary with Korean text
• OS: macOS 24.6.0

Claude Model

Sonnet (default)

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

2.0.75

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_