AWS adds hard limits that stop spend outright

AWS added a way for account owners to cap spending outright, per its account-level spend limits page in the Accounts reference. The only existing control, AWS Budgets, notifies after spend crosses a threshold; it doesn't stop the bill. For an agent running with standing AWS credentials, that gap has been a blank check.

Before this, an agent calling paid services on its own could keep running past a Budgets alert, since nothing stopped the meter. A hard limit closes that gap without needing a human to read a notification in time.

What the docs don't spell out is behavior at the edges. It's unclear whether a limit blocks new API calls only, or also affects resources already running when the cap hits.

Anyone wiring this into an agent's AWS setup should test that behavior before trusting it as a kill switch. Set the limit ahead of the agent's first live run, before a surprise invoice forces the question.