macOS: Backspace on image attachment token deletes char-by-char instead of whole token

[idanshimon]

Summary

On macOS, pressing Backspace on an image attachment token (e.g. [📎 copilot-image-14c299.png]) in the input removes one character at a time. On Windows, pressing Backspace removes the entire token at once — a much better UX.

Steps to Reproduce

1. macOS only
2. Copy an image to clipboard (e.g. screencapture -c /dev/null)
3. In the Copilot CLI, press Ctrl+V to attach the image (or use the Windows-native behavior)
4. Press Backspace once

Expected: Entire token [📎 copilot-image-xxxxx.png] is removed
Actual: One character is removed from the end of the token

Root Cause

On macOS, Backspace sends \x7f (DEL, ASCII 127). The CLI's token-boundary deletion logic appears to only activate on Windows-specific key sequences, not on the \x7f byte macOS terminals emit.

Related

• Issue macOS: Ctrl+V / Cmd+V does not paste clipboard images (terminal emulator limitation) #3104 — macOS image paste (the feature that surfaces this limitation)
• Community patch: https://github.com/idanshimon/copilot-cli-image-paste