I might have missed how to do it, since I am dumb and easily confused (and ever more so the older I get, more is the pity for me) BUT I didn't see a way to do e.g. "flow foo.js" and have it not check the other *.js files in there. That is annoying for several reasons. The fundamental issue for me in terms of UX is that I think the more fundamental UI is to require being given a set of paths-to-files to check. The "check all files implicitly automagically" is some weird nice-to-have in my book, and really not the right default at all. But of course it is all kinda subjective. Still... I'm pretty sure I'm right. ;-)