[BUG] Korean text gets corrupted when copying (via /copy or selection) with new renderer enabled

Found 2 possible duplicate issues:

1. https://github.com/anthropics/claude-code/issues/42417
2. https://github.com/anthropics/claude-code/issues/42406

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Found 2 possible duplicate issues: 1. New renderer (CLAUDE_CODE_NO_FLICKER=1): Japanese text clipboard copy garbled on Windows (UTF-8 → CP932 mojibake via OSC 52) #42417 2. [[Bug] NO_FLICKER mode garbles Japanese text output on Windows #42406](https://github.com/anthropics/claude-code/issues/42406) This issue will be automatically closed as a duplicate in 3 days. If your issue is a duplicate, please close it and 👍 the existing issue instead To prevent auto-closure, add a comment or 👎 this comment 🤖 Generated with Claude Code

This suggests the issue is not limited to Japanese, but likely affects Unicode handling for multiple non-ASCII languages (e.g., Korean as well).

The problem does not occur when using the default renderer.

이슈 보고하러 왔는데 이미 올렸네요!

<img width="756" height="155" alt="Image" src="https://github.com/user-attachments/assets/d0439658-8c7a-43a5-8261-02ca269868d1" />

<img width="179" height="38" alt="Image" src="https://github.com/user-attachments/assets/88117566-dbd5-4f0e-b228-ab6f57c80d4a" />

Bug: Korean text copy from active Claude Code session produces garbled output (Windows)

Environment

• OS: Windows 11 Pro 10.0.26200
• Terminal codepage: 949 (CP949/EUC-KR)
• Claude Code version: Latest CLI
• Shell: bash (MSYS2/Git Bash)

Description

Korean (?쒓?) text displayed correctly on screen in the active Claude Code session gets garbled when copied to clipboard. This only happens when copying from the active session with flicker/streaming rendering enabled.

Steps to reproduce

1. Start Claude Code on Windows with codepage 949 (chcp ??949)
2. Ask a question that produces Korean text output
3. Copy Korean text from the active (streaming) session
4. Paste into any editor

Expected

.devflow/hooks/post-edit.sh - 주석 검사 훅 활성, 세션 중간에도 sh 수정만으로 즉시 반영

Actual

.devflow/hooks/post-edit.sh ??雅뚯눘苑?野??????뽮쉐, ?紐꾨^@?餓λ쵌而?癒?즲 sh ??륁젟?숇슣?앮에??⑸맩??獄쏆꼷??

Notes

• Copying Korean text from other pages or completed sessions works fine
• Only the active session with flicker rendering has this issue
• The garbled pattern is consistent with UTF-8 bytes being interpreted as EUC-KR (CP949)
• ASCII and mixed Korean/ASCII text may partially survive, pure Korean blocks are most affected

This issue has been automatically locked since it was closed and has not had any activity for 7 days. If you're experiencing a similar issue, please file a new issue and reference this one if it's relevant.