Lesson 1 · 9 min
Why evals are not optional
The gap between 'it works on my five examples' and production is where teams get burned. Why intuition fails at scale, what an eval actually is, and the minimum bar before you can trust your AI feature.
The confidence trap
Every AI feature passes the developer's demo. The developer wrote the prompts, knows the happy path, and tested on a handful of cases that happen to work. Then it ships.
In production the inputs are adversarial, ambiguous, multilingual, malformed, and never quite what you expected. The feature degrades. Complaints trickle in. Prompt tinkering begins — and because there's no eval suite, every 'fix' might be breaking something else.
This is the confidence trap: high subjective confidence, zero objective measurement.