Regression suite (LLM)
A regression suite is the standing set of evals that runs on every prompt change, model upgrade, or pipeline modification — designed to catch quality regressions on previously-working cases.
Regression suites are how production LLM teams in 2026 avoid the "fixed one bug, broke five" problem. Build a golden set of representative inputs covering the use cases your product depends on. On every prompt change, run the suite. Compare new scores vs baseline. Block merges on regressions past a configurable threshold. Tools: Braintrust, Langfuse, LangSmith, Inspect Evals, custom Python + pytest. The discipline is to grow the suite over time — every production bug becomes a new eval case.
When to use regression suite (llm)
- Any production LLM feature with evolving prompts or models.
- Multi-author prompt collaboration.
Common mistakes
- Suite too small or unrepresentative — passes won't predict production.
- No clear regression threshold — debates over every score change.
FAQ
What is regression suite (llm)?
A regression suite is the standing set of evals that runs on every prompt change, model upgrade, or pipeline modification — designed to catch quality regressions on previously-working cases.
When should I use regression suite (llm)?
Any production LLM feature with evolving prompts or models. Multi-author prompt collaboration.
What are the most common mistakes with regression suite (llm)?
Suite too small or unrepresentative — passes won't predict production. No clear regression threshold — debates over every score change.
Related terms
- Evals (LLM evaluations) — Evals are systematic tests that measure how well a language model or LLM-powered system performs on a defined task using a golden set of inputs and reference outputs.
- Evals-driven development — Evals-driven development is the discipline of writing the eval suite first, then iterating prompts and models against it — borrowing test-driven development for LLM work.
- Shadow deployment (LLM) — Shadow deployment runs a new model or prompt alongside the production one — receiving the same traffic but never showing output to users — to measure quality, latency, and cost before flipping live.
Last updated: 2026-06-01. Raw markdown: https://promtable.com/glossary/regression-suite.md.