I thought the hard part would be the scoring. Write clean YAML. Define expected behavior. Run agents. Compare scores. Catch regressions. Ship with confidence. That mental model lasted about one afternoon of real-agent field testing. The thing that broke was not the judge. It was not the rubric design. It was the realization that a scenario pack is only as honest as the path between your harness and a real, messy, third-party agent that imports ffmpeg at module scope, hardcodes gpt-...