This is a real problem. I've heard similar stories from people running CI pipelines — a retry loop bug burns through your entire monthly Actions minutes budget in hours, and there's no built-in circuit breaker there either.

The approach of tracking usage locally and cutting off before you hit billing overages makes a lot more sense than trying to parse the billing API after the fact. Prevention over detection.

Could be cool to set per-worker limits in addition to the global ones.

Totally. When I first launched my project, I literally couldn't sleep at night, kept worrying that some bug in my code would spiral into a self-inflicted Denial of Wallet attack by morning. That fear is what pushed me to build the circuit breaker early on. Prevention over detection is spot on.