Regression testing (for LLMs)
LLM regression testing re-runs a suite of evals on every change so a prompt or model update can’t silently degrade quality.
Regression testing for LLM systems means running your eval suite automatically whenever a prompt, model, or retrieval component changes — and blocking the change if quality drops, just like a failing unit test blocks a merge.
It’s what keeps cost optimizations safe: you can downgrade a model on a route only because the regression suite proves quality held.
Wired into CI/CD, regression evals turn “did this change hurt quality?” into a question answered before deploy instead of after a customer notices.