Image drag-and-drop broken in tmux (regression)

Description

Image drag-and-drop into the Claude Code CLI input area no longer works when running inside tmux. This was previously working.

Environment

• Claude Code: 2.1.114
• tmux: 3.6a (Homebrew, macOS)
• Terminal: Terminal.app
• macOS: Sequoia (Darwin 25.4.0)
• Hardware: Mac Studio M2 Ultra

Repro

1. Start a tmux session
2. Run claude inside a tmux pane
3. Drag an image file from Finder onto the CLI input area
4. macOS shows the green circle with "+" indicating a valid drop target
5. Expected: [Image 1] appears in the input area
6. Actual: Nothing happens — the drop is silently ignored

Works in

• Claude Code running in a direct Terminal.app tab (no tmux) — drag-and-drop works correctly, [Image 1] appears as expected

Notes

• tmux 3.6a is the latest version (no update available)
• This was working in a prior CC version inside tmux (exact version unknown)
• The drop target visual feedback (green +) comes from Terminal.app/macOS, suggesting the terminal accepts the event but CC's input handler doesn't receive the payload through tmux's PTY layer