The onus should be on the instructor to make sure that the student ends up actually understanding and being able to code/solve problems that they pose without using coding agents.
Why? Because:
1. this is exactly what is going on in the real world. People are able to get AI to do whatever the hell they want, but the ones who just use it lazily end up with huge cognitive debts and codebases riddled with opaque bugs that they do not understand whatsoever. If we prevent students from confronting this temptation, then we are sort of coddling or shielding them from it, and not really preparing them to avoid pitfalls of this type.
2. you can actually learn a LOT by being given the answer, if you actually care to learn. i personally think it's pretty fucking lame to handicap a student's ability to learn in an attempt to prevent lazy abuse. isn't the whole point of a grade to measure how well you understand things? can't you have pop quizzes, assignments on a computer with no agent use, written tests, etc etc. to catch the lazy abusers? this is an unnecessary prevention of lazy abuse that unfairly handicaps learning