Terminal output truncation/corruption on Windows with Korean text

Description

Terminal output is being truncated or corrupted when Claude Code CLI outputs text containing:

• Korean (Hangul) characters
• Unicode box-drawing characters (─, │, ┌, ┐, └, ┘)
• Mixed content with emojis

Environment

• OS: Windows 11
• Terminal: PowerShell
• Claude Code version: Latest
• Locale: Korean (ko_KR)

Symptoms

1. Lines are partially cut off (beginning of line missing)
2. Entire lines disappear and show as blank
3. Text alignment is broken in tables and diagrams
4. Issue worsens with Korean text + special characters

Example

Expected output:

┌─────────────────┐
│  테스트 박스    │
└─────────────────┘

Actual output:

┌─────────────────┐

                   ┘

Steps to Reproduce

1. Run Claude Code on Windows with PowerShell
2. Request output containing Korean text with ASCII diagrams or tables
3. Observe truncated/missing content

Attempted Fixes (No Effect)

• Set PYTHONIOENCODING=utf-8
• Set LANG=ko_KR.UTF-8
• Set COLUMNS=200
• Removed emojis from output

Suspected Cause

Wide character (CJK) width calculation issue in terminal rendering. Korean characters occupy 2 columns but may be calculated as 1.

---
🤖 Generated with Claude Code