It's mysterious to me as well, but yeah after looking through the code briefly I think you define macros in the keydoggerrc file, and then keydogger watches the clipboard for triggers and responds accordingly. I love the idea, still a bit too much in the dark on the implementation to have an opinion though. Given the highly sensitive nature of the clipboard, I appreciate how small the app is because it's auditable.
You get it perfectly. Being auditable was one of the priority which is exactly why it's small.
Regarding the clipboard, it's a third party dependency. I looked into implementing Wayland clipboard myself but it is too deep Wayland. The only reason clipboard exists is because I cannot send non-printable characters using uinput.
OP: Cool project, thanks for sharing!