Looks cool! Including the script in the project directory is the way, and I created on makesh[1] with that in mind. Since it's a submodule it can be easily pulled around with a repo and updated.
Glad to see people are finally going back to ahell scripts since they are very ergonomic and with a little portability in mind, they can be cross platform too.
It’s very simple so isn’t good for everything, but works well as a simple command runner.
[1] https://github.com/xonixx/makesure