I'm wondering if this is not handled better by readline or the shell, not the terminal emulator. Do you know if other terminal emulators do this?

I've tested alacritty, kitty, gnome-terminal and konsole and ctrl+backspace doesn't seem to work on any of them.
It does work in vscode, thanks to these default binds. They seem to be sending \u0017 for ctrl+backspace and \u001bd for ctrl+delete.

I will investigate if using \u0017 is better than the "alt+backspace" I'm currently sending. Also, I completely forgot about ctrl+delete, so I'll add that too.

I confirmed that this is handled by the readline library. I really don't want to add functionality that is duplicated by another layer of the shell. You should probably edit the readline configuration to get the behaviour you want in your shell. I think all you're doing here is mapping ctrl+backspace to Meta-Delete and having that handled by readline.

Do you mind if I close this PR?

Ah I see, yes I'll close the PR.
Thank you for your time.

Thanks for understanding. I hate turning away PRs, especially ones from people who have contributed successfully in the past, but I really want to keep the code as simple as I can.

I completely agree.
Don't worry at all about rejecting this PR. I just didn't know that readline can be configured, otherwise I wouldn't have done this code change. Thank you for helping me learn.