There are 3.5 serious open codebases of web browsers currently. Only two are full featured. It's not nothing, but it's very far from "source exists so it's easy to copy what they do".
But detailed specs exists for both HTML and JS and tests also exists and unlimited amount of test data. You can just try running webpage or program and also have reference implementations - it's much easier for agents to understand that. Also HTML they know super well from scraping whole internet but still impressive.
There are 3.5 serious open codebases of web browsers currently. Only two are full featured. It's not nothing, but it's very far from "source exists so it's easy to copy what they do".
But detailed specs exists for both HTML and JS and tests also exists and unlimited amount of test data. You can just try running webpage or program and also have reference implementations - it's much easier for agents to understand that. Also HTML they know super well from scraping whole internet but still impressive.