VSCode panel: IME composition underline not visible (macOS Japanese)

Description

On macOS with Japanese IME (ローマ字入力), the composition underline (変換中の下線) is not displayed in the Claude Code panel input field.

Predictive conversion candidates also do not appear inline — you must press Space to trigger conversion.

Other VSCode areas (editor, terminal, search) display the IME underline correctly. This issue is isolated to the Claude Code panel's input field.

Environment

• macOS (Darwin 24.6.0)
• VSCode (latest)
• Claude Code extension (latest)
• Japanese IME (ローマ字入力, Live Conversion ON)

Steps to reproduce

1. Open Claude Code panel in VSCode
2. Switch to Japanese IME
3. Start typing in the input field
4. No composition underline appears during conversion

Expected behavior

Composition underline should be visible while typing, same as in VSCode editor and terminal.

Workaround

Using claude CLI in the integrated terminal works correctly.