End-to-end retrieval-augmented generation systems built on your actual data sources, PDFs, relational databases, REST APIs, websites, SharePoint, Confluence, and Notion, not a generic prototype that works on sample documents. Document ingestion handles format extraction (PyMuPDF, python-docx, HTML parsers with boilerplate removal) and then chunking strategy selection based on document structure: fixed-size windows for homogeneous text, paragraph-boundary splits for reports, hierarchical chunking (chunk + parent retrieval) for documents where individual chunks lack sufficient context. Embedding generation uses text-embedding-3-large or domain-specific fine-tuned models for high-accuracy retrieval; text-embedding-3-small for cost-sensitive, high-volume pipelines. Vector store indexing in Pinecone, Weaviate, pgvector, or Qdrant depending on your operational preferences and scale requirements. Hybrid search (dense vector + sparse BM25) with Reciprocal Rank Fusion merging, followed by cross-encoder re-ranking for the top-K candidates, consistently outperforms dense-only retrieval on real-world query sets. RAGAS four-dimension evaluation (Faithfulness, Answer Relevance, Context Precision, Context Recall) measured against a held-out query set before launch, retrieval quality is the primary driver of RAG output quality, and we evaluate it explicitly.