Honestly, at this point the best we have is to hope the whitehat AI scanning for issues is stronger than the blackhat AI.
I think you got it backwards. For your AI to succeed, it needs to poke a hole on all layers, not one in many layers. If an attacker pokes a hole in n-1 layers but the 1 layer remains untouched, the system's integrity is preserved.
Why do you think defense in depth is a basic concept?
Defense in depth says that simply compromising your application code shouldn't provide access to the physical hardware you're running on, and that's hopefully the case, but it doesn't mean your app is not hacked. It just hopefully means that a hack on your app code doesn't automatically give the attacker access to your entire company.
Many bugs live in all those layers that may undermine your ability to lock down inputs and outputs.
This is more fundamental than better input checking. Your compute substrate itself is flawed. Intelligence and speed is indeed the only thing between “safe” and “completely open”.
I fully agree it’s a good idea to be minimal etc but I don’t see it being sufficient in the long run.