reflex-dev/reflex-chat ? reverse-engineered prompt

Build me a ChatGPT style web app in Python using Reflex that feels clean and easy to use. I want users to be able to start new chat sessions, switch between them, and delete them when they’re done. It should work nicely on desktop and mobile, and the whole app should be customizable without needing any web development knowledge.

Use an OpenAI API key from the environment, and make it simple to swap in a different language model later if needed. Please keep the interface friendly and modern, with the chat view front and center, plus a simple sidebar or menu for managing conversations. If anything in the current docs or current Reflex setup has changed, look up the latest guidance online and follow that.