... Metrics tracked in AB test. So even if it's not explicitly encoded in the algo (or implicitly through some of the features plugged in), they'll pick the winning cell as long as it doesn't hurt Elon's metrics (I'm just parroting the comment you quoted).

It doesn't have to be in the algorithm for the systems to be tweaked to please Elon vanity metrics.

[I've been running lots of ML AB tests over the years, some in organizations of similar size & complexity as Twitter]

So many unnecessarily cynical takes here. Let's say you were in charge of a large legacy system that some segment of customers complain about it not working for them as well as other segments. How would you know whether their complaints are valid unless you measured it? You have to know first. So measure it.

I expect they're tracking the red team/blue team metrics because of the political shitstorm that's been the GOP's assertions they're being silenced by The Algorithm.

Ahh, the group of Elons.

I was wondering why I see so many tweets by him, and what his "Group's" impression quote is.

This is actually pretty hilarious.

The original code is a part of the home-mixer service, which is the "Main service used to construct and serve the Home Timeline."

I suspect the flag corresponds to weights not present in the repo.

Per original source, The code that was released today doesn't show the parts that actually alter the scores of Elon and other users. The part of the code referenced below just tracks Elon stats (from what I know). Employees removed most PII before the code was released.

Correct. It's a binary metric. Did the number go up, yes/no (kept job / not).

Interesting which "groups" they care about (e.g. mainstream political parties).

But who chooses the users to be metrics…