Drift is a gradual change in behavior, quality, or cost over time even when your code has not changed. It comes from provider model updates, shifting input distribution, or prompt changes. Detect it with evaluators on sampled production traffic and alert when scores slip.
Why it matters
A model can be "up" while quietly getting worse or more expensive. Drift is the slow failure that uptime monitoring misses entirely.
How it works
Drift comes from provider model updates, changing input distribution, or prompt edits. Detect it by running evaluators on sampled production traffic and watching scores over time.