I got it working! I wrote a bunch of scripts to wrap Watchman and my workflow. It all behaved precisely to plan!
Except for one thing: our pre-commit hooks.
We have a thing for code quality, and so we have a HUGE set of Git hooks. The biggest are our pre-commit hooks, which check a whole slew of things. From brace style to cyclomatic complexity, they really give the code a deep look.
The problem is, our environment uses mod_perl. Mod_perl doesn’t ship with macOS, and doesn’t compile cleanly/easily, esp. if you’re using Perlbrew to run an old-ass Perl.
Some of our commit checks rely on Apache2:: stuff to run.
Sadface. Others, more experienced than I, ran into similar issues, and bailed, too.
So I gave up. For the time being, my workflow will remain shitty, impractical, and inefficient. There is probably a way. It’s just not low-hanging fruit.