mjunaidca/02-st-pdf-brain-ai-assistant ? reverse-engineered prompt

Build me a simple Streamlit web app where I can upload a PDF and chat with it using OpenAI’s Assistant API.

I want the app to feel like a clean, easy PDF helper, where a user can drop in a file, wait for it to be processed, then ask questions about the document in a chat style interface. If the same PDF is uploaded again, please check for an existing assistant or file first instead of creating duplicates. Keep the basic assistant and file management in one place, so it’s easy to follow and reuse later.

Please make the app work end to end, with a clear main screen, upload flow, chat area, and sensible status messages while the file and assistant are being created. If needed, look up the current OpenAI Assistant API docs online so the implementation matches the latest way it’s supposed to work.