[BUG] Korean IME composition: jamo not displayed until syllable completion (Kitty + Gureumkim)

Environment

• Platform: macOS (darwin 25.0.0)
• Terminal: Kitty
• IME: Gureumkim (구름)
• Claude Code Version: 2.1.7

Problem

When typing Korean in Claude Code, individual jamo (자모) are not displayed during composition. Characters only appear after a complete syllable is formed.

Expected Behavior

Like native macOS apps and Gureumkim's normal behavior:

• Type ㄱ → see ㄱ
• Type ㄱ + ㅏ → see 가
• Type ㄱ + ㅏ + ㄴ → see 간

Actual Behavior

• Type ㄱ → nothing displayed
• Type ㄱ + ㅏ → nothing displayed
• Type ㄱ + ㅏ + ㄴ → 간 suddenly appears (or only after pressing space/enter)

This makes Korean input feel unnatural and hard to track what's being typed.

Related Issues

• #1547 - IME input causes performance issues
• #1553 - IME Composition Input Rendering Lag for Non-Latin Scripts
• #2620 - IME Composition Failure for Korean Character Input (closed as duplicate)
• #3045 - Investigation: Fixing IME Issues by Patching React Ink

Notes

This appears to be related to React Ink's TextInput component not properly handling IME pre-edit/composition state in terminal environments. The August 2025 IME fixes improved cursor positioning but the composition display issue persists.