[BUG] Korean (Hangul) IME: last syllable dropped on space/punctuation in 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 typing Korean (Hangul) in the Claude Code input prompt, the last syllable in composition is dropped if
I press space or punctuation (., ,, etc.) immediately after.

## Environment

• OS: Pop!_OS (COSMIC desktop, Wayland session)
• Terminal: Ghostty
• IME: fcitx5 + fcitx5-hangul (WordCommit=False)

## Reproduction

1. Type 한글 in the Claude Code input prompt
2. Immediately press space
3. Result: 한 — the last syllable 글 is lost

## Workaround

• Press an arrow key (←/→) before space → input is preserved

## Suspected cause

• Arrow keys are multi-byte escape sequences (ESC [ A), giving fcitx5 time to commit the preedit before

the key is processed

• Space is a single byte, processed immediately by the TUI before the IME commit event arrives
• Likely a raw-mode input handling timing issue between Claude Code's TUI and the IME's preedit→commit

cycle

This does NOT happen in a regular bash shell within the same terminal — only inside Claude Code's input
prompt. Confirms the issue is specific to Claude Code's input handling, not the terminal or IME stack.

What Should Happen?

The full composed Korean text should be preserved when pressing space or punctuation immediately after
typing.

For example, typing 한글 followed by space should produce 한글 , not 한 .

The IME's commit event for the in-progress syllable should be processed before the following keystroke
(space/punctuation) is consumed by the input handler.

Error Messages/Logs

Steps to Reproduce

1. Open Claude Code in a terminal with fcitx5-hangul IME active (Hangul input mode on)
2. In the input prompt, type any Korean word — e.g., 한글 (key sequence: h a n g e u l)
3. Without pausing, press space (or ., ,)
4. Observe: the last syllable is missing — 한 instead of 한글

Note: The same input typed into a plain bash shell in the same terminal commits correctly. The bug only
manifests inside Claude Code's TUI input.

Claude Model

None

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.1.153 (Claude Code)

Platform

Other

Operating System

Other Linux

Terminal/Shell

Other

Additional Information

• IME stack: fcitx5 5.1.7 + fcitx5-hangul (WordCommit=False)
• Desktop session: COSMIC Wayland on Pop!_OS
• fcitx5 frontend used by Ghostty: wayland_v2 (confirmed via fcitx5-diagnose)

The arrow-key workaround strongly suggests this is a raw-mode input timing issue in Claude Code's TUI, not
an IME or terminal bug.