Keybinding, remove from the start of the line up to cursor

[yw1ee]

Hi, I'm very beginner about ghossty and ANSI escape code. I'm trying to set a keybinding like this.

keybind = super+bakcspace=csi:1K

I read that CSI 1K means clear from cursor to beginning of the line. in here. But in my ghossty, it just prints 'K'. I try similar ways such as text:\x1b[1K or 'esc [1K' but not work. Can someone tell me what I miss?