> This looping is a sort of "context-rot" -- the agent has the problem statement as part of it's input, and then a series of incorrect solutions.

While I agree, and also use your work around, I think it stands to reason this shouldn't be a problem. The context had the original problem statement along with several examples of what not to do and yet it keeps repeating those very things instead of coming up with a different solution. No human would keep trying one of the solutions included in the context that are marked as not valid.