I woke up to a $400 OpenAI bill. Here's what I built to make sure it never happens again.

It was 2am when the email came in. "Your OpenAI usage has exceeded $400." An agent I'd been testing had hit a loop. It kept retrying a failed call, over and over, for six hours while I slept. By the time I saw it, the damage was done. I went looking for a tool that would let me set a hard daily limit per agent — something that would block the call before it ever reached OpenAI. I couldn't find one. So I built it. The problem with AI agents and money When you build with AI APIs, you're esse...