When prompt engineering became an engineering problem

Once people started using these systems for real work, the failure modes got expensive. Hallucinations weren’t funny anymore; they were bugs. And the fixes started to look less like “clever prompts” and more like control systems: scope checks, intermediate classification steps, low-temperature consistency, and explicit permission to say “I don’t know.”

This is also where you start seeing the early shape of evals: not formal benchmark suites, but practical tests you rerun because you need to trust the output. Reliability became a product requirement, which meant prompt design became less about charisma and more about constraints, gates, and verification.

The shift here is simple: prompting stopped being a parlor trick and became an operational discipline.