PHP, TypeScript, vibe coded and public. One ran up over $420k in API-priced tokens. Here’s what I found poking at php-rust.

There’s a new genre of open-source project: take a whole programming language, rebuild it in Rust, and let AI agents write nearly all of it. The TypeScript compiler has one. PHP has one. More keep showing up. They’re public, they’re huge, and at least one of them is actually fast.

I spent a day reading about them and I still can’t work out what they’re for. So this is me thinking out loud.

How I got pulled in

It started with this post from @rustaceans_rs . I clicked. Then I kept clicking. TypeScript in Rust. PHP in Rust. Other “X, but Rust” projects. As far as I can tell, all vibe coded: the humans steer, the agents type. The ts-rust README says it with a straight face: “I’ve never read a line of this code.”

The receipts

ts-rust is Theo’s port of Microsoft’s native TypeScript compiler (the Go one) to Rust. From its README:

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