[rgoulter]

> ...idempotent, or at least stateless...

Even for a Makefile, "start", "test", "install" are likely to be phony (and not literally refer to files with those names).

The execution of a "start" task defers the role of "has it already been done" to other places.

One way of describing "task runner" is "nicer UX for .phony targets".

[kstrauser]

That's all true, but understates the important of a nicer UX. I've spent lots of time over the years working around Makefiles' idiosyncrasies. It's so good at its intended purpose that it's tempting to use it for vaguely related tasks. Turns out it's not as good for doing those things it was never designed for. "Just" reimagines what make could look like if it were designed to be a task runner instead. That hits a sweet spot for many of us. It looks like the Makefiles we're used to, minus the pains in the neck we've tolerated from abusing make for our own purposes.