> Why is it still hard to take an existing fully concrete specification, and an existing test suite, and dump out a working feature-complete port of huge, old, and popular projects? Lots of stuff like this will even be in the training

We have a smaller version of that ability already:

- https://simonwillison.net/2025/Dec/15/porting-justhtml/

See also https://www.dbreunig.com/2026/01/08/a-software-library-with-...

I need to write these up properly, but I pulled a similar trick with an existing JavaScript test suite for https://github.com/simonw/micro-javascript and the official WebAssembly test suite for https://github.com/simonw/pwasm