I'm glad you wrote it up. Thanks! But I feel like the folks behind the HTML5 spec and the comprehensive test suite deserve the lion's share of the credit for this (very neat) achievement.
Most projects don't have a detailed spec at the outset. Decades of experience have shown that trying to build a detailed spec upfront does not work out well for a vast class of projects. And many projects don't even have a comprehensive test suite when they go into production!
Having a comprehensive spec and test suite is an absolute requirement, without it all you got is vibe-testing, LGTM feels. As shown by the OP, you can throw away the code and regenerate it back from tests and specs. Our old manual code is now the new machine code.
I completely agree. I hope I gave them enough credit in the blog post and the GitHub repo.