Sigh, I finally need to write up why this is delusional.
TLDR: if you're rewriting the implementation of an API, with an honest-to-god cleanroom (which LLMs are not) *and* a decidedly different underpinning *and* have a good-faith reason to do it, then reuse of the API is probably fair use.
Luis Villa
> we decided that the codebase is not a derivative work that would require carrying forward the GPL license and have decided to release the code under the MIT instead.
oh someone wants to get sued.
blog.gitbutler.com
We used agents to port all of Git to library-first, memory-safe Rust and it passes the entire C Git test suite.