With ERC-8004 about to launch on the Ethereum mainnet, will it provide an optimal solution to the trust issue between on-chain AI Agents? As the x402 protocol is gradually implemented, AI Agents, authorized by users, are moving from proof-of-concept to practical implementation, considered a key technological attempt to foster an on-chain AI economy. However, a more fundamental question arises: How should users express and authorize their complex intentions to the AI ​​Agent? How does the AI ​​Agent choose the optimal payment method during execution? How can we verify that each payment action by the AI ​​Agent is genuinely authorized by the user? These questions, while seemingly reflecting the complexity of payment operations, fundamentally point to a more crucial premise: how to establish a trustworthy communication mechanism between "humans" and "AI Agents," and between "Agents" themselves. Against this backdrop, a protocol framework for AI Agent payments and collaboration is gradually taking shape. In September 2025, the AP2 (Agent Payments Protocol), spearheaded by Google, was released. This protocol aims to standardize the authorization, execution, and settlement processes of AI agents in payment scenarios, and through deep integration with the x402 protocol, provides an underlying channel for on-chain AI-native payments. However, a new problem arises: even if the authorization process and payment path are streamlined, how should AI agents verify each other's identity and trustworthiness when they begin to call, collaborate, and combine with one another? Currently, the number of AI systems and AI agents is exploding, and collaboration between cross-platform and cross-domain AI agents will become commonplace. If the trust issue between AI agents cannot be resolved, their communication and invocation will face potential security risks, ultimately hindering the expansion of the entire on-chain AI economy. ✜ The preview section has ended; the remaining hidden core content is here 👇 research.web3caff.com/archives...…