See swaywm/sway#5299 (comment)

Would it be possible to have Peek automatically start the render after capture, saving it using the default filepath it already uses?

When wl-copy is sent a signal to terminate it, it should clean up the temp buffer files instead of leaving them around.

This is a very simple shell protocol only allowing for fullscreen surfaces. You can find a very basic implementation here: https://github.com/swaywm/wlroots/blob/master/examples/fullscreen-shell.c

• commands to move a window up and down the stack
• commands to spawn a window in a location next or previous to the currently focused window in the stack where the window to spawn is given as an argument.