Your Agent Failed at Step 7. The Bug Was at Step 3.
When a multi-step agent produces a confidently wrong answer, the step that threw the error is almost never the step that caused it. The real culprit is an earlier decision whose bad output only surfaced downstream, so you patch the symptom and the failure comes back next week. This is agent failure attribution, and here is how to find the decisive step with counterfactual replay instead of guessing.