The problem is that you always need stronger AI to review weaker one, otherwise reviewed AI will eventually prompt-inject reviewing AI. Alternatively they could also both escalate and go off the rails while warring with each other.

You don't necessarily need a reviewer that's immune to prompt injection, you just need one that can express a panic state with conflicting/ambiguous material rather than going along with it, and you can treat that with a shutoff to be safe, or an operator review.

[dead]