The /copy command does not work in WSL

Describe the bug

/copy  fails under WSL2/WSLg with Failed to copy to clipboard: Error: clip.exe exited with code 1 .  But echo test | clip.exe  reliably works, including from the repository and with Unicode/large input. The bundled native clipboard module fails first because WSLg’s Wayland compositor lacks  ext-data-control / wlr-data-control ; forcing X11 by unsetting WAYLAND_DISPLAY  makes native clipboard copy work. The CLI’s  clip.exe  fallback appears to invoke  clip.exe  incorrectly, likely passing text as an argument instead of stdin.

Affected version

GitHub Copilot CLI 1.0.80.

Steps to reproduce the behavior

1. Launch WSL from Windows.
2. From WSL, start a copilot-cli session.
3. Send copilot a prompt and wait for a response.
4. Use the /copy command to copy the copilot response to the clipboard.
5. Observe the following error message:
   Failed to copy to clipboard: Error: clip.exe exited with code 1

Expected behavior

No new Copilot output, but the latest Copilot response gets copied to the clipboard a.k.a. copy/paste buffer, ready to paste elsewhere.

Additional context

My actual use-case is more deeply nested than this. I'm running Kubuntu 26.04 on a laptop, then launching a Windows VDI via Citrix Workspace. I run WSL from within the Windows VDI, and GitHub Copilot from within WSL.

まず、WSL2/WSLg で /copy を再現し、その clip.exe の呼び出しを、動作するコマンド echo test | clip.exe と比較します。CLI のクリップボードフォールバックとネイティブクリップボードの選択を追跡し、その後、最新の Copilot の応答が Unicode と大きな入力で正常にコピーされ、新しい出力を生成しないことを確認します。