an underrated detail about pay-per-request infrastructure: hard spending limits become enforceable at the wallet layer, beneath any application code.
a team can fund an agent with $50 of usdc and walk away knowing the agent cannot spend $51. the cap lives on the wallet itself, which means the agent's code can't bypass it even if it tries. runaway loops hit a hard wall the moment the wallet runs dry.
that's the controls layer that the agent payment stack has been missing. the rails move the money across the network and the wallets gate exactly how much can leave at any time. you need both to deploy an agent at scale and sleep at night.