How I Cut My Claude Code Bill by 60% with a 200-Line Classifier

I love Claude Code. It's the best AI coding assistant I've used. But after a few weeks of heavy usage, I checked my API costs and nearly fell out of my chair. $247 in a month. Most of that was from simple prompts that didn't need Claude Sonnet. Things like "what does this function do?" or "read the file at src/main.py" or "add a test for this function." Basic stuff that any decent LLM can handle. So I built a router. It sits between Claude Code and the API, classifies each prompt in about 10ms, and sends simple stuff to cheaper models while keeping the complex work on Claude. After a month of using it, my bill dropped to $98. Same usage pattern. Same quality. 60% less money. Here's how it works and how you can do the same. The Problem: Every Prompt Costs the Same When you use Claude Code (or most AI coding tools), every single request hits the same expensive model. It doesn't matter if you're asking it to refactor a complex async system or just read a file. You pay full price. In my ca