What problem does it solve? Scoring LLM chat completions for quality in .NET requires navigating the Microsoft.Extensions.AI.Evaluation 10.8 API surface, judge model configuration, and undocumented wire behaviors that cause silent failures like null metrics and misrouted local models. ## Core Features & Use Cases - LLM-as-judge evaluation: Score responses with Relevance, Groundedness, Completeness, Coherence, Fluency, and Equivalence evaluators against OpenAI-compatible or local LM Studio judges. - Verified 10.8 API guidance: Correct client construction, EvaluationContext subclassing, temperature pinning via decorating IChatClient, and the tag-based response protocol evaluators actually send. - Local judge operations: LM Studio probing, reasoning-model traps, memory guardrails, silent model-fallback detection, and a judge-quality agreement method with an 80% known-good bar. - Use Case: A developer building a nightly trend-not-gate eval job for a .NET AI assistant uses this to wire a judge client, replay frozen fixtures through evaluators, and validate a local gemma judge before adoption. ## Quick Start Use the dotnet-ai-evaluation skill to set up a Microsoft.Extensions.AI.Evaluation judge that scores my chat completion responses for relevance and groundedness.