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Evaluation
Eval / Evaluation harness
A test suite for AI applications. The most important piece of infrastructure to build first.
An eval harness scores your AI system's outputs against a known dataset on every change. It has four parts: a dataset of inputs that mirrors real production traffic, a scoring mechanism per input (deterministic, LLM-as-judge, or human review), a reporting layer non-engineers can read, and CI integration that blocks shipping regressions. Tools like LangSmith, Braintrust, and Phoenix make this dramatically easier than rolling your own.
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