What problem does it solve? Building question-answering systems over private document collections requires wiring together document loaders, text splitters, embedding models, vector stores, and retrieval logic, which is error-prone without proven patterns. ## Core Features & Use Cases - Document Ingestion Pipelines: Load files, split them into token-aware chunks with overlap, embed them, and store them in an embedding store with metadata. - Retrieval Strategies: Configure content retrievers with score thresholds, hybrid vector-plus-keyword search, re-ranking, and hierarchical retrieval across summaries and chunks. - RAG-Enabled AI Services: Define LangChain4j AI service interfaces with system prompts and content retrievers for grounded, source-attributed answers. - Use Case: Build a company knowledge-base assistant in Spring Boot that ingests policy documents, retrieves relevant passages per question, and answers with citations while saying "I don't know" for out-of-scope queries. ## Quick Start Ask the agent to scaffold a Spring Boot RAG service using LangChain4j that ingests a folder of documents and answers questions over them.