The demo ran flawlessly for three weeks. Every test input parsed clean, every output routed correctly, and I thought we had a reliable system.
Then a supplier sent a confirmation email with an empty subject line.
The agent, which was supposed to extract order references and route them into a queue, got a null where it expected a string. It didn't crash. That would have been better. Instead it generated a plausible-looking order reference, routed it, and the downstream system processed it like it was real. Nobody caught it for four hours.
That is the demo problem: demos use inputs that look like what you expect. Production does not.
What the demo hid
