[BUG] Enter key becomes completely unresponsive after mixing full-width IME characters with half-width text (Windows native app)

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?

On Windows, the Claude Code desktop app's input field sometimes becomes completely unresponsive to the Enter key after typing a sequence that mixes full-width (zenkaku) IME-composed characters — such as Japanese punctuation (、。) or full-width parentheses (（）) — with half-width (hankaku) alphanumeric characters. This does NOT happen in a web browser or in Notepad, only in the Claude Code desktop app.

Unlike other reported IME issues where Enter sends the prompt prematurely (e.g. #8405, #8455), in this case Enter does nothing at all — not once, not even after pressing it repeatedly. The only way to recover is to click elsewhere (e.g. click into the input field again, or click another UI element) to shift focus, which appears to force the stuck IME composition state to commit.

This may share underlying composition-handling code with the open Korean IME issue #83712, which shows a similar composition-state bug on Windows.

Environment: Windows 11, version 25H2, build 26200. IME: Microsoft IME (Japanese). Frequency: intermittent, not on every occurrence.

What Should Happen?

Enter should submit the message (or insert a newline, as appropriate) once IME composition is genuinely finished, without requiring a focus change to "unstick" the input.

Error Messages/Logs

Steps to Reproduce

1. Open the Claude Code desktop app on Windows
2. Switch to Japanese IME (Microsoft IME)
3. In the chat input, type the following, using IME conversion for the full-width characters:

１．
（）
WWW

(full-width "1.", empty full-width parentheses, then half-width "WWW")

1. Press Enter to submit
2. Result: Nothing happens. Repeated Enter presses have no effect.
3. Workaround: Clicking elsewhere in the UI (losing/regaining focus) commits the stuck state and the input becomes responsive again.

Claude Model

Sonnet (default)

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

2.1.220

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Other

Additional Information

Claude Code desktop app (native Windows app, launched from desktop shortcut)