[Regression] CJK IME candidate selection broken — number keys intercepted, cannot select characters

Description

Chinese IME (Input Method Editor) candidate selection is broken in the Claude Code CLI prompt. When typing Chinese characters, the IME candidate window appears but pressing number keys (1-9) to select a candidate does not work — the key presses are intercepted by Claude Code's key dispatcher instead of being routed to the IME.

This is a regression

A previous version of Claude Code (cmux) handled CJK IME input correctly — users could see the candidate window and select characters with number keys. After updating, this functionality broke.

Related closed issues

• #50611 — IME composition on macOS routes committed text through key-action dispatcher (CLOSED)
• #22853 — Fix IME input for Vietnamese, Chinese, Japanese, Korean (CLOSED)
• #19207 — IME cursor position support for CJK input

These were closed but the problem has resurfaced, suggesting a regression.

Environment

• Claude Code version: 2.1.100
• macOS version: 26.3.1 (Build 25D2128)
• Terminal: cmux
• Input method: macOS built-in Chinese IME (Zhuyin / Bopomofo)
• Chip: Apple Silicon

Steps to reproduce

1. Switch to Chinese input method (e.g., Zhuyin)
2. Start typing in the Claude Code CLI prompt
3. IME candidate window appears with numbered candidates
4. Press a number key (e.g., 1) to select a character
5. Expected: The corresponding Chinese character is inserted
6. Actual: The number key is intercepted by Claude Code; no character is selected from the IME candidate list

Screenshot

The candidate window appears but selection does not work:

• The IME shows candidates numbered 1-9
• Pressing number keys does not select from the candidates

Impact

This is a blocking issue for CJK (Chinese/Japanese/Korean) users who rely on IME for daily input. The current workaround is to type in an external editor and paste, which significantly degrades the user experience.