Is this substantially different than https://github.com/intellectronica/ruler? Or how would you differentiate?
But ... as the author and maintainer of Ruler I can tell you that I don't use it and I don't recommend using it (or this new tool).
In almost all cases it isn't necessary anymore - most agents support AGENTS.md (or at least a hack like `@AGENTS.md` in CLAUDE.md), and Agent Skills are the best way to customise agents and are available everywhere now.
There are some corner cases where using a tool like Ruler may still make sense, but if in doubt, you probably don't need it.
I would really like all AI agents coding tools to have the same config formats, but I feel like we are not there yet :/