8.9.7.2 - The API Wrapper: Python & FastAPI (Difficulty: Hero | Path: Lab)

Building the Middleware

Why do you need a wrapper?

• Log requests: Save what users are asking.
• Rate Limit: Stop one user from spamming 1000 requests.
• Format Prompts: Inject hidden system instructions before the user's message reaches the AI.

How to code it (The Cheatsheet)

You don't need to be a master coder. Use Claude or ChatGPT to write the boilerplate for you.

Prompt: \"Write a simple Python FastAPI app that has one endpoint `/chat`. It should accept a JSON body, check for a Bearer token in the header, and then forward the request to a local vLLM instance running at port 8000.\"

This will give you a `main.py` file. You run it, and suddenly you have a professional API that controls how your AI is used.