campusx-official/langchain-prompts ? reverse-engineered prompt

Build me a small Python app that helps me experiment with LangChain prompts and chat prompts in a simple way.

I want to be able to type in a user message, see how the prompt gets built, and try different prompt styles like a basic prompt, a chat prompt, and prompts that use chat history or placeholders. It should also let me change the temperature so I can see how the replies change.

Make it feel like a little teaching and testing tool, not a big production app. A simple interface is fine, as long as I can generate prompts, inspect the messages being sent, and save or load a sample chat history. If it helps, include a few ready made examples I can switch between.

Please keep it clean and easy to run, and use current LangChain docs online if anything has changed.