Stop Engineering Prompts: How an Eval-First Harness Let Us Ship 25 Algorithm Versions Autonomously

This article details the creation of an eval-first AI harness that enabled the autonomous shipment of 25 algorithm versions in 13 days. The methodology focuses on immutable test sets and independent reviews to ensure changes do not cause regressions. The author emphasizes that the harness, rather than just prompt engineering or full automation, was key to the pace and safety of development.