Korean (한글) IME input broken in remote terminals (e.g., Termius via SSH)

Bug Description

Korean (한글) input does not work properly when using Claude CLI through remote terminal clients like Termius (SSH). Characters get mangled or lost during IME composition (ㅎ→하→한→한글).

Notably, OpenAI Codex CLI handles Korean IME input correctly in the exact same environment, so this is specific to Claude CLI's input handling, not a terminal/locale issue.

Steps to Reproduce

1. SSH into a remote machine using Termius (or similar terminal emulator)
2. Run claude
3. Try typing Korean text (e.g., 안녕하세요)
4. Characters are dropped, duplicated, or garbled during IME composition

Expected Behavior

Korean IME composition should work correctly, producing proper composed Hangul characters — just like it does in Codex CLI in the same environment.

Actual Behavior

Korean characters are broken during the composition process. The raw mode input handling appears to intercept keystrokes before IME composition is complete.

Root Cause Hypothesis

Claude CLI uses Node.js + Ink (React for CLI) with raw terminal input mode. The raw mode keystroke capture likely does not properly handle multi-byte IME composition sequences used by Korean (and potentially Japanese/Chinese) input methods.

Environment

• Terminal Client: Termius (via SSH)
• OS: macOS (client), Linux (remote)
• Locale: en_US.UTF-8 / ko_KR.UTF-8 (both tested, same result)
• Workaround: Copy-pasting pre-composed Korean text works fine

Workaround

Paste pre-composed Korean text instead of typing directly. This skips the IME composition process entirely.