RAG & Search Engineering — Complete Reference Build production-grade retrieval systems with hybrid search , grounded generation , and measurable quality . This skill covers: - RAG : Chunking, contextual retrieval, grounding, adaptive/self-correcting systems - Search : BM25, vector search, hybrid fusion, ranking pipelines - Evaluation : recall@k, nDCG, MRR, groundedness metrics Modern Best Practices (Jan 2026) : - Separate retrieval quality from answer quality ; evaluate both (RAG: https://arxiv.org/abs/2005.11401). - Default to hybrid retrieval (sparse + dense) with reranking when precision m…