[BUG] Unicode Character Input Corruption in Claude Code Terminal

Environment

• Platform: Anthropic Max subscription
• Claude CLI version: 1.0.84 (Claude Code)
• Operating System: Windows 11
• Terminal: VS Code integrated terminal
• Node.js version: v22.17.0
• Locale: en_US.UTF-8

Bug Description

Claude Code terminal corrupts Unicode characters when typing directly in the interactive chat interface. ASCII characters work perfectly, but any Unicode characters (accented letters, non-Latin scripts, emojis) become garbled or display incorrectly.

Steps to Reproduce

1. Open Claude Code in VS Code terminal: claude
2. Try typing text with Unicode characters:

• Vietnamese: xin chào, tôi cần giúp đỡ
• French: café, résumé, naïve
• Spanish: niño, señor, mañana
• German: Müller, Größe, weiß

1. Observe character corruption/display issues

Expected Behavior

Unicode characters should display and be processed correctly, just like in regular terminal or VS Code editor.

Actual Behavior

• Unicode characters appear corrupted, as question marks, or as mojibake
• Input becomes unreadable for non-ASCII content
• Only ASCII/English characters work properly
• Issue affects all languages with diacritics and special characters

Additional Context

• Regular VS Code terminal handles Unicode perfectly
• Issue only occurs within Claude Code interactive session
• Problem persists after setting UTF-8 encoding in VS Code settings
• Affects international users across multiple languages
• Related to existing UTF-8 corruption issues: #1716, #2154, #3416