This is very cool!

If you're looking for a good test suite, I wonder if you might be able to adapt any of the tests available in XMage? They have a pretty extensive test suite (such as for copy effects [0]) and if you point your agent at their code, I wonder how many could be usefully adapted to your system?

[0] - https://github.com/magefree/mage/tree/master/Mage.Tests/src/...