Thai vowel "า" (U+0E32) not displaying in input field

Description

When typing Thai text in the Claude Code CLI input field, the Thai vowel "า" (sara aa, U+0E32) does not display. Other Thai combining characters also have display issues.

Environment

• OS: Linux (Ubuntu) / macOS
• Terminal: iTerm2
• Claude Code version: Latest

Steps to Reproduce

1. Open Claude Code CLI
2. Try to type Thai text containing "า" such as "กา" or "ทำ"
3. The vowel "า" is invisible while typing

Expected Behavior

Thai vowels should display correctly in the input field, similar to how they display in bash:

echo "กา ขา คา"  # displays correctly

Actual Behavior

• The consonant displays but the vowel "า" is invisible
• The characters are still sent correctly (output works fine)
• Only the input display is affected

Additional Context

• Bash echo commands display Thai correctly
• iTerm2 settings adjusted (UTF-8 encoding, various fonts tested including Noto Sans Mono)
• Issue appears to be with the input/readline library used by Claude Code
• This affects Thai language users' ability to see what they're typing