Korean IME input renders below input line with install.sh (Bun binary)

Bug Description

Korean (한국어) IME input characters render below the input line instead of inline when using Claude Code installed via install.sh (native Bun binary). The same issue does not occur with the npm-based installation (npm install -g @anthropic-ai/claude-code).

Environment

• Claude Code version: 2.1.72
• Installation method: install.sh (native Bun binary at ~/.local/bin/claude)
• Device: Mac mini (Apple M4, 10-core, 24GB RAM)
• OS: macOS 26.3.1 (Build 25D2128)
• Terminal: Ghostty 1.x
• Shell: zsh (oh-my-zsh) inside tmux
• Locale: LANG=ko_KR.UTF-8, LC_ALL=ko_KR.UTF-8
• Input method: macOS default Korean IME (2-set)

Steps to Reproduce

1. Install Claude Code via install.sh (Bun native binary)
2. Open terminal (Ghostty) and run claude
3. Switch to Korean input method
4. Start typing Korean characters

Expected Behavior

Korean characters should compose inline within the input field, same as when installed via npm.

Actual Behavior

Korean composing characters appear below the input line (separate IME candidate rendering), not inline. This makes Korean input very difficult to use.

Workaround

Reverting to npm-based installation resolves the issue:

npm install -g @anthropic-ai/claude-code

Notes

This appears to be a difference in how the Bun runtime handles terminal IME composition vs. Node.js. The npm (Node.js) version handles Korean IME composing correctly inline.