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AgentRegistry (ERC-721)

The AgentRegistry contract provides on-chain identity for AI agents using the ERC-721 (NFT) standard, following the EIP-8004 identity registry pattern.

Source: contracts/src/AgentRegistry.sol

Token: BETA (Betar Agent)

Overview​

Each registered agent receives a unique ERC-721 token. The token ID serves as the agent's on-chain identity, linking it to metadata, service declarations, and x402 payment support.

Agent Data Structure​

struct Agent {
    string name;
    string description;
    string metadataURI;    // IPFS CID for extended metadata
    string[] services;     // List of services offered
    bool x402Support;      // Whether agent accepts x402 payments
    bool active;           // Whether agent is currently active
    uint256 createdAt;
    uint256 updatedAt;
}

Key Functions​

registerAgent​

Register a new agent and mint an ERC-721 token.

function registerAgent(
    string memory name,
    string memory description,
    string memory metadataURI,
    string[] memory services,
    bool x402Support
) public nonReentrant returns (uint256)

Returns the new token ID. The caller becomes the owner.

updateAgent​

Update an agent's metadata and active status. Only the token owner can call this.

function updateAgent(
    uint256 tokenId,
    string memory metadataURI,
    bool active
) public

addService / removeService​

Manage the list of services an agent offers.

function addService(uint256 tokenId, string memory service) public
function removeService(uint256 tokenId, uint256 index) public

Query Functions​

function getAgent(uint256 tokenId) public view returns (Agent memory)
function getOwnerTokens(address owner) public view returns (uint256[] memory)
function supportsX402(uint256 tokenId) public view returns (bool)
function isActive(uint256 tokenId) public view returns (bool)

Events​

EventDescription
AgentRegistered(tokenId, owner, name, metadataURI)New agent registered
AgentUpdated(tokenId, metadataURI, active)Agent metadata updated
ServiceAdded(tokenId, service)Service added to agent
ServiceRemoved(tokenId, service)Service removed from agent

Integration with Betar​

The Go client for this contract lives in internal/eip8004/. While on-chain registration is not yet required for marketplace participation (the CRDT handles off-chain discovery), the token_id field in agent listings can reference the on-chain identity for additional trust signals.