[BUG] ESC key interrupts Claude response when canceling IME composition (Chinese input)

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

When Claude presents a Yes/No confirmation prompt, pressing ESC to cancel IME composition (e.g., dismissing a half-composed CJK character) simultaneously triggers Claude Code's interrupt shortcut, cutting off the interaction.

What Should Happen?

ESC should only cancel the IME composition. It should not interrupt Claude Code when an IME composition session is active.

Error Messages/Logs

Steps to Reproduce

1. Claude presents a Yes/No confirmation prompt (e.g., asking whether to proceed with an action)
2. User begins typing a response with additional description using a CJK input method (e.g., Traditional Chinese)
3. User triggers IME composition by typing CJK characters
4. User presses ESC to cancel the IME composition (to discard the half-composed character, without intending to interrupt Claude)
5. The interaction is interrupted — Claude Code treats ESC as a cancel/interrupt command instead of passing it to the IME

Claude Model

Sonnet (default)

Is this a regression?

No, this never worked

Last Working Version

_No response_

Claude Code Version

2.1.89

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Warp

Additional Information

Related to #15269 (ESC causing incomplete text submission, fixed 2026-02-06),
but distinct — the issue here is that ESC during active IME composition incorrectly interrupts the ongoing interaction (Yes/No question) rather than only canceling the IME composition.