You know that feeling when you ship an AI feature and realize your token bill is 3x what you estimated? Yeah, that was me last week. I have this thing called Agent-Max — it's a multi-platform growth agent that runs autonomous workflows: generating content, publishing to Bluesky, Medium, Twitter, Reddit. Sounds heavy, right? Every Monday it synthesizes a week of reading, scrapes engagement metrics, decides what to post and where. Seven platforms. Infinite LLM calls if you're not paying attention. Last Sunday I realized I had no idea what I was actually spending. I knew roughly — "somewhere between $5-20/week" — but roughly is how you end up with bill shock. So I built PromptFuel to solve the actual problem: measure what your app is doing, not what the docs say it should do. Here's what three days of auditing my own code taught me. 1. Your bottleneck isn't the model you picked, it's the prompt you didn't trim I assumed my biggest cost sink was the weekly reflection.…