We built our first multi-agent system by accident. We had a single agent handling document analysis for a client — extract data, validate it, write a summary, trigger a follow-up action. It worked in demos. In production, it hallucinated its way through the validation step roughly 15% of the time, because one context window was doing too much and losing the thread. The fix wasn't better prompting. It was splitting the work across agents that each had one job. That experience shaped how we thi...