[BUG] Word deletion doesn't work with non-latin alphabet

Environment

• Platform (select one):
• [x] Anthropic API
• [ ] AWS Bedrock
• [ ] Google Vertex AI
• [x] Other: Max Account
• Claude CLI version: 1.0.18 (Claude Code)
• Operating System: macOS 15.5
• Terminal: Tested in multiple terminals: Ghostty, vscode terminal, iTerm2, Terminal app

Bug Description

When text in Claude Code contains non-latin characters, word deletion (opt + delete) deletes the whole text, not just the word. If there is a mixture of non-latin and latin characters, the non-latin text will be deleted up to the first latin symbol.
The same issue occurs with word navigation (opt + ← / opt + →).

Steps to Reproduce

1. Type text using only non-latin characters (e.g., 'тестовый текст на русском языке'). I've tested with Cyrillic and Thai characters.
2. Navigate to the end of the text.
3. Press opt + delete.

Expected Behavior

Only the last word should be deleted.

Actual Behavior

The entire text is deleted.

Additional Context

https://github.com/user-attachments/assets/2e1ecb58-9f77-4b20-9b79-317bc5129203