Sure, so where does that state get stored in a pure "task runner" tool? Attempts to muck with this metaphor ("state is what is left behind when the tool is not

Sure, so where does that state get stored in a pure "task runner" tool? Attempts to muck with this metaphor ("state is what is left behind when the tool is not running") are among the worst mistakes made by build systems. It's a feature, not a bug, and everyone who believes otherwise ends up rediscovering it the hard way.