This application allows users to upload PDFs and query them conversationally using LLMs. It implements hybrid RAG combining full-text search on Cloudflare D1 with vector similarity search on Vectorize, supports multiple LLM providers (OpenAI, Groq, Anthropic) via AI Gateway with fallback mechanisms, and streams responses to the frontend using Server-Sent Events. OCR processing runs inside Cloudflare Workers to extract text from uploaded documents.