Korean IME (한글) input broken in CLI prompt — characters decompose into individual jamo

Bug Description

Korean IME input in the Claude Code CLI prompt produces decomposed jamo (자모 분리 현상) instead of properly composed syllable blocks. For example, typing 한글 results in individual consonants and vowels appearing separately.

This issue does not occur in regular terminal shell input — only in the Claude Code prompt itself.

This is a Regression

Korean input was working correctly in Claude Code until today (2026-06-22). After a logout/login (with no software changes made by the user), Korean IME has been broken ever since. The user made no changes to the system.

Environment

• Claude Code version: 2.1.181
• macOS: 15.6.1 (Build 24G90)
• Terminal: Apple Terminal (TERM_PROGRAM=Apple_Terminal)
• TERM: xterm-256color
• LANG / LC_ALL: ko_KR.UTF-8
• Node.js: v24.2.0

Steps to Reproduce

1. Set system input source to Korean (두벌식)
2. Launch claude in Terminal
3. Type any Korean text at the prompt
4. Observe jamo decomposition (자모 분리)

Expected Behavior

Korean characters compose correctly into syllable blocks, as they did before today.

Actual Behavior

Individual consonants and vowels (자모) appear separately. The IME composition does not complete before keystrokes are forwarded to the input handler.

Workaround

Currently the only usable workaround is typing Korean in another application and pasting via Cmd+V.