Even with temperature=0, LLM outputs can still fluctuate by up to 15% in practice. To rigorously compare agent changes, you need a frozen golden set, at least 3 runs per query averaged out, LLM-as-judge blind evaluation (pairwise preference flip rate reaches 35%), and paired statistical tests -- not just running each version once and going by feel.
Langfuse is currently the most mature open-source LLM Observability platform. This post covers four core capabilities — Tracing, Prompt Management, Evaluation, and Datasets — showing you how to use them in real projects.
RAG has evolved far beyond simple 'search + generate' into a technology ecosystem spanning ten generations. This article is a systematic navigation guide: from Naive RAG to Multi-Agent RAG across ten generations, covering retrieval strategies, chunking, embedding, reranking, evaluation frameworks, observability, and cost optimization. Each topic has a dedicated deep-dive article.
RAG system quality is hard to evaluate by intuition alone. RAGAS, DeepEval, and TruLens provide systematic metric frameworks that pinpoint exactly which component is failing.