Conversational AI doesn’t fail in the lab. It fails in production. The moment real users arrive, the combinatorial explosion of language, ambiguity, and intent exposes a hard truth: traditional QA, flow-based design, and manual testing are structurally incapable of preparing AI systems for reality. What looks stable in staging quickly degrades under long-tail behavior, creating silent failure modes that directly impact revenue, trust, and compliance. This session examines why common product assumptions collapse in AI interfaces and why even leading companies struggle to maintain reliability at scale. It introduces Generated Simulation — a systematic approach to simulating user behavior at production scale — enabling teams to quantify risk, surface blind spots, and transform unpredictability into actionable product insight.