Vanna is an open-source Python framework that generates SQL queries from natural language using retrieval-augmented generation (RAG). It provides a modular agent architecture with a core `Agent` class that orchestrates LLM interactions, tool execution, and rich UI component streaming. The system supports multiple LLM providers (OpenAI, Anthropic, Gemini, Ollama, etc.) and vector store backends (ChromaDB, FAISS, Qdrant, Pinecone, etc.) for storing and retrieving training data (question-SQL pairs, DDL, documentation). It includes a comprehensive evaluation framework for comparing agent variants, a legacy Flask API for backward compatibility, and a modern Lit-based web component frontend that renders rich components (tables, charts, cards, progress bars) via SSE streaming. The architecture is highly extensible with dependency injection for lifecycle hooks, LLM middlewares, error recovery strategies, context enrichers, conversation filters, and observability providers. Key entry points include the `Agent.send_message()` async generator, the `ToolRegistry` for tool management, and server factories for Flask and FastAPI. The system relies on external dependencies for LLM APIs, vector databases, and SQL databases, all configured as optional extras. The codebase demonstrates strong engineering practices with clean abstractions, though it carries significant legacy code from a previous version and some placeholder implementations (e.g., MD5-based embeddings in Qdrant).