sameer542003/DocChat ? reverse-engineered prompt

Build me a web app where people can sign up, log in, upload a PDF, and then ask questions about that document in a chat style interface. The app should read the PDF, break it into pieces, store it, and use AI to answer only from what is actually in the file, with short source previews or citations so the user can trust the answer. I want each user to see only their own documents and chats, be able to open a document, ask follow up questions, view past messages, and delete a document if they want.

Please make it a simple full stack app with a React frontend and a Node and Express backend, using MongoDB for storage. It should support JWT login, file upload for PDFs, and keep the experience clean and easy to use. If you need to check current docs for any library or API details, look them up online and use the latest approach.