I built a gate that questions me, not the work. The challenge step pressure-tests a plan, and this one pressure-tests whether I understand it, because if the code is mine or the model's I still have to be able to stand behind it. There is no passive acceptance.
It runs before I approve a plan or a diff. It asks a few questions. If I cannot answer, the work is not ready to ship, even if the diff looks fine.
I made it a rule, not a suggestion. The weeks after this one are where I find out if I actually stop for it.