Rebuilding what you know from the previous FAANG you worked at is expected on the whole.

What is douchey is presenting the whole thing as some sort of intense novelty and stroke of genius required in the age of agents when it's just doing what the other BigCo companies did to scale their monorepos already. Like a decade (or more) ago.

The reality it is when I first read the thing I was -- as a Xoogler -- like "Oh, yeah, so, like Piper & SrcFs and the stuff that Meta also does" and really didn't understand why they wouldn't have started with something off the shelf inside of vibe-conjuring a clone that they would then have to support

To me it speaks ill, again, of the engineering culture at Anthropic. "We do these things not because they are useful, but because they are novel."

Don't they have better things to do at Anthropic than building their own source control or rewriting Bun from scratch in another language? Like, y'know, basic site reliability? Or a coding harness that doesn't eat multiple GB of RAM?