[jdiff]

Anthropic's C compiler also had an incredible test suite available, and was trained on compiler codebases. It might have been built "from scratch" but compilers are incredibly well-trodden ground.

And to contrast, Cursor's browser explicitly reviewed Servo's architecture before setting out, and still wound up like that.

[sharifhsn]

The difference between using general knowledge and summaries and doing code-for-code rewrites cannot be understated. When creating `wedeo`, despite DIRECTLY reviewing FFmpeg's code, Claude would frequently make mistakes that would have to be fixed. I would constantly have it go and refer back to the ground truth FFmpeg source implementation. It did eventually work, but only after several rounds of reviews, and often dead-end investigations. Being able to directly inspect (and in some cases modify for extra debug output) FFmpeg at any given time was invaluable, and I doubt any rewrite would succeed without having that.