Ctrl+V image paste in iTerm2 fails when macOS Korean IME (2-Set Korean) input source is active

Summary

Ctrl+V clipboard image paste in iTerm2 fails 100% of the time when the macOS Korean input source (2-Set Korean, built-in IME) is active, and works 100% of the time when the input source is English (ABC). The failure is silent — no error, nothing is inserted.

This may explain the "intermittent" (~50–60%) failure rate reported in #29365: whether paste succeeds depends on which input source happens to be active at that moment, which was not captured as a variable in that report.

Steps to reproduce

1. macOS with two input sources enabled: ABC (English) and 2-Set Korean (macOS built-in Korean IME).
2. Open iTerm2 and run claude.
3. Copy an image to the clipboard (e.g. Cmd+Shift+Ctrl+4 screenshot).
4. Switch the input source to 2-Set Korean (한/영 key).
5. Focus the Claude Code prompt and press Ctrl+V.

Actual: Nothing happens. No [Image #N] placeholder, no error message.

Expected: The image is attached as [Image #N], same as when the English input source is active.

Switching the input source back to ABC (English) and pressing Ctrl+V immediately works, with the same clipboard content, same session.

Notes

• Reproducible 100% of the time in both directions (Korean = always fails, English = always works).
• In Terminal.app, Ctrl+V image paste works regardless of input source, so this appears to be specific to how iTerm2 + the Korean IME deliver the Ctrl+V keystroke.
• iTerm2 "Applications in terminal may access clipboard" is enabled (/terminal-setup reports it as already configured).
• No key remapping tools installed (no Karabiner-Elements, no BetterTouchTool), default iTerm2 key mappings.
• Not running inside tmux.
• Likely related: #29365 (intermittent Ctrl+V image paste failures in iTerm2, closed as not planned).

Environment

• Claude Code: 2.1.201
• macOS: 26.5.2 (build 25F84)
• iTerm2: 3.6.11
• Input sources: ABC (English), 2-Set Korean (macOS built-in IME)