Fix IME composition Enter key sending message prematurely

[ji3g4m6zo6]

Summary

Fix an issue where pressing Enter during IME composition (e.g. Zhuyin/Bopomofo candidate selection) accidentally triggers message send before typing is finished.

Root cause

unified-input keydown handler sent on Enter without checking IME composition state.

Changes

• File: multi-panel/multi-panel.js
• Added composition state tracking:
  • compositionstart -> isInputComposing = true
  • compositionend -> isInputComposing = false
• Added IME guard before Enter-to-send:
  • isInputComposing || event.isComposing || event.keyCode === 229
• Keep original behavior for non-IME input:
  • Enter sends
  • Shift+Enter newline

Manual test

1. Use Zhuyin/Chinese IME in unified input.
2. Type phonetics to enter composing mode (underlined text).
3. Press Enter to select candidate.
4. Verify message is NOT sent during composition.
5. After composition ends, press Enter again.
6. Verify message is sent normally.

[Manho]

Thanks for the fix! I tested it locally with Zhuyin IME and it works correctly — Enter during composition no longer triggers send. 👍

A couple of suggestions before merging:

1. Move the IME guard inside the Enter check

Currently the guard returns early for all keydown events during IME composition. Right now that's fine since we only handle Enter, but it could silently break future keybindings (e.g. Escape). Suggest narrowing the scope:

inputTextarea.addEventListener('keydown', (e) => {
  if (e.key === 'Enter' && !e.shiftKey) {
    if (isInputComposing || e.isComposing) return;
    e.preventDefault();
    broadcastMessage(inputTextarea.value);
  }
});

2. Consider dropping e.keyCode === 229

Our content scripts (e.g. enter-behavior-chatgpt.js, enter-behavior-claude.js) only use event.isComposing for IME detection. keyCode === 229 is a legacy approach and may false-positive on some Android soft keyboards. For consistency, isInputComposing || e.isComposing should be sufficient.

Other than that, looks good — nice clean fix for a real pain point! 🎉

[ji3g4m6zo6]

Thanks for the review and suggestions — I’ve updated the PR accordingly.

What I changed

• Narrowed the IME guard scope to the Enter-to-send path only (no more early return for all keydown events).
• Removed e.keyCode === 229; now using isInputComposing || e.isComposing.

Verification

Re-tested with Zhuyin IME:

• Enter during composition selects candidates without sending
• Enter after composition ends sends normally
• Shift+Enter still inserts a newline

This keeps non-Enter keydown handling unblocked during composition.
Could you take another look when you have a moment? Thanks!

[Manho]

LGTM! Thanks for the update