widgetplatform/widget-oa ? reverse-engineered prompt

Build me a lightweight chat widget for websites that connects to OpenAI Assistants.

I want a small embeddable widget with a floating button, a popup chat window, and a clean responsive design that works well on desktop and mobile. It should be easy to drop into a site with one script tag, and it should load the chat UI in an iframe so the widget can stay isolated from the rest of the page.

Please include a simple server for talking to the OpenAI API and handling chat history and feedback, plus a React app for the iframe target. I’d like the widget to be configurable with things like colors, button spacing, and display style, and it should support using either a hosted service or my own server if I want to self host it.

Use the existing project structure and make it work end to end, and look up current docs online if you need to.