[BUG] Claude Desktop: IME composition Enter key triggers submission in Plan feedback input field

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?

In Claude Desktop's Plan feature, when providing feedback in the plan feedback input field, pressing Enter to confirm IME (Input Method Editor) conversion incorrectly triggers message submission. This makes it nearly impossible to type Japanese (and likely other CJK languages) in the plan feedback field.

Steps to Reproduce

1. Open Claude Desktop on macOS
2. Start a conversation that triggers the Plan feature
3. When the plan is presented, focus on the feedback input field
4. Switch to Japanese IME input
5. Type a Japanese phrase that requires conversion (e.g., type "nihongo" to convert to 「日本語」)
6. Press Enter to confirm the IME conversion

Expected Behavior

The Enter key should only confirm the IME conversion candidate. The feedback message should not be submitted until after composition is complete and the user presses Enter again.

Actual Behavior

The Enter key immediately submits the feedback, sending an incomplete or partially converted message.

Note

Similar IME issues have been reported for Claude Code in VS Code (#8405, #8423, #8498), but this issue is specific to the Claude Desktop app's Plan feedback input field. The root cause is likely the same — compositionstart/compositionend events are not being properly handled to suppress Enter key submission during active IME composition.

Environment

• Platform: macOS
• App: Claude Desktop