When I look at the Agent Economy Stack diagram of GOAT, I keep thinking about a simpler question: If the agent economy is really going to take off, what does a minimal closed loop look like? Imagine a very realistic scenario: Your agent needs to buy data, buy reasoning, and buy an order channel. It doesn't want to subscribe, doesn't want to open invoices, and doesn't have time to click confirm. It just wants to pay per use and continue executing after payment. At this point, what x402 does is actually very simple: it puts the payment and payment proof into the same request. So payment is no longer the last step, but part of the request cycle. Next is Ziren. It turns my payment into a verifiable credential from a simple statement. The server delivers upon seeing the credential and does not deliver if it does not see it. Many risks actually do not lie in the payment itself, but in the time before final confirmation when you have already delivered the service. This layer of verification is actually about reducing that risk exposure. One layer up is the identity and on-chain reputation of ERC-8004. The agent is no longer just a one-time address, but an economy that can continuously accumulate behavioral records. Thus, the pricing method will also change; long-time customers and agents with good reputations can get better limits and prices. Unknown addresses will face stricter terms. So what this structure really changes is two things: for those who create tools, charging can finally become machine-native charging, no longer relying on centralized billing systems. For those who use tools, costs can finally become strategic parameters: they can be calculated, optimized, and can survive at scale. By the way, this diagram does not shy away from reality: BitVM2 is still in the final testnet phase. But the interesting part is that before the settlement endgame is fully in place, layers like payment, verification, identity, and reputation can already start to run the closed loop.