Litho is an AI-driven documentation generation engine built in Rust. It accepts source code as input, leverages multiple LLM providers (OpenAI, Claude, DeepSeek, Mistral, OpenRouter) to analyze and understand the codebase structure, and outputs structured technical documentation following the C4 model format. The tool automatically extracts architecture patterns, components, and relationships from code to produce container diagrams, component diagrams, and code-level documentation without manual intervention.