Confidence in a demo is cheap because a demo runs once, on inputs you chose. Production runs a thousand times on inputs you didn't. The bridge between the two is an evaluation harness — the thing that lets you say "this works" and mean it.
Golden cases before clever prompts
Start by collecting real cases with known-correct outcomes: the messy PDF, the ambiguous form, the edge case that broke you last quarter. Run every workflow change against that set and measure pass rate. A prompt that feels better but drops your golden-case score is a regression, not an improvement.
Measure the failure mode, not just the pass rate
Two workflows with the same accuracy can be wildly different in production if one fails safely and the other fails silently. Track how it fails — does it escalate, or does it confidently emit garbage? A workflow that's 90% correct and 100% honest about the other 10% is safer than one that's 95% correct and hides its mistakes.