The nine and a half foot error the agents caught themselves

On the Midtown Phoenix tower we built an agentic system to run architecture work. Agents handling shell, structure, MEP, envelope, and quality review, driving a large Revit model with more than twelve thousand elements in it. Deep inside that model, the review agents caught a nine and a half foot error in one structural bay, and a wrong setback, that together would have cost about two hundred fifty thousand dollars to fix if either had made it into a permit set. Nobody flagged it for them to find. They found it because the review pass was built to distrust the model instead of assume it, same discipline behind the blind pass rule we now run on every takeoff. A bay a few feet off does not look dramatic on a drawing. It looks like nothing until a foundation is poured around it. The whole project's schedule and budget rode on catching that kind of detail before concrete, not after.