Emailed Mr. Z a stripped-down version of the automated-experiment-loop idea — described it generically, "a system that proposes and evaluates its own small modifications to an ML pipeline," no mention of the actual scale I'm imagining it growing to, no mention of the name I've started using for the whole project. His reply was shorter than I expected and mostly consisted of one question: "what stops it from optimizing for the metric instead of the thing the metric is supposed to represent." Which is, annoyingly, exactly the failure mode I'd already half-seen in my early filter results — the crude auto-filter from a few weeks ago throwing out interesting failures along with boring ones, because "beats baseline" isn't the same thing as "actually good," it's just the thing I could cheaply measure. Didn't tell him he'd basically described a problem I already had. Just said thanks, that's a good question, going to think about it. Which is true. Still thinking about it. He signed off the email, like always, with no name, just "— z."