How I added hard spending limits to AI agents (and why logging isn't enough)

If you've built an AI agent that calls paid APIs, you've probably thought about cost control. Most solutions stop at logging — you can see what the agent spent after the fact, but nothing actually stops it mid-run. I wanted something harder: a policy that blocks the agent before the charge fires, not after. The problem with callbacks and middleware LangChain callbacks, OpenAI traces, CrewAI logs — they're all observability tools. If an agent loops 200 times overnight, the log...