Add ERC: AgentNFT Extension for ERC-721

ERCS/erc-7860.md

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+---
+eip: 7860
+title: AgentNFT Extension for ERC-721
+description: ERC-721 AgentNFT Extension, enabling on-chain identity for AI-powered entities
+author: AgentBall (@agentball)
+discussions-to: https://ethereum-magicians.org/t/erc-7860-agentnft-extension-for-erc-721/22502
+status: Draft
+type: Standards Track
+category: ERC
+created: 2025-01-10
+requires: 165, 721
+---
+
+
+## **Abstract**
+
+This EIP introduces an extension to [ERC-721](./eip-721.md) that enables NFTs to be associated with AI agents, including prompts and other agent settings. This extension allows a NFT token to store prompts and AI agent’s address, facilitating the establishment of an on-chain identity for AI-powered entities.
+
+## **Motivation**
+
+As artificial intelligence becomes increasingly integrated with blockchain technology, there is a growing need for standardized interfaces that enable NFTs to interact with AI systems. Current ERC-721 tokens lack native support for AI integration. However, ERC-721 tokens are non-fungible, transferable, capable of storing data, and compatible with extensions such as [ERC-6551](./eip-6551.md) wallets. These characteristics make ERC-721 a suitable standard for serving as an on-chain identity for AI agents.
+At present, prompts and other relevant information are often stored in the NFT token URI without a standardized format, making recognition and application challenging. This extension addresses these limitations by providing:
+
+1. A decentralized on-chain identity for AI agents – By associating AI agents with AgentNFTs, this extension enables them to interact with smart contracts in a highly composable manner.
+2. A transferable and non-custodial asset type – AgentNFTs function as liquid assets, facilitating ownership transfers while preserving on-chain value.
+3. An interface for storage and management of prompts and AI agent addresses – Each AgentNFT securely maintains its associated AI agent’s address and prompt data, ensuring consistency and interoperability.
+4. Prompts and other data can be encrypted for privacy while remaining verifiable for authenticity.
+
+## **Specification**
+
+The extension introduces the following interface:
+
+```
+/**
+ * @title IAgentNFT
+ * @dev Interface for ERC721 AgentNFT extension that adds prompt and agent management capabilities
+ * This extension allows NFTs to store and manage prompts and AI Agent's corresponding address
+ */
+interface IAgentNFT  /* is IERC165, IERC721 */ {
+    /**
+     * @dev Emitted when an address is updated for a AgentNFT
+     * @param tokenId The ID of the AgentNFT
+     * @param agent The new agent address
+     */
+    event AgentUpdated(uint256 indexed tokenId, address indexed agent);
+
+    /**
+     * @dev Emitted when a prompt is updated for a AgentNFT
+     * @param tokenId The ID of the AgentNFT
+     * @param prompt The new prompt string
+     */
+    event PromptUpdated(uint256 indexed tokenId, string prompt);
+
+    /**
+     * @dev Returns the current address corresponding to the AgentNFT. The address can be a wallet address or smart contract address. The AI Agent is represented by the AgentNFT of the given tokenId parameter
+     * @param tokenId The ID of the AgentNFT to query
+     * @return The address of the associated AI agent
+     */
+    function agent(uint256 tokenId) external view returns (address);
+
+    /**
+     * @dev Updates the address for an AgentNFT
+     * @param tokenId The ID of the AgentNFT to update
+     * @param newAgent The new agent address to assign
+     */
+    function updateAgent(uint256 tokenId, address newAgent) external;
+
+    /**
+     * @dev Returns the current prompt for a AgentNFT
+     * @param tokenId The ID of the AgentNFT to query
+     * @return The prompt string associated with the AgentNFT
+     */
+    function prompt(uint256 tokenId) external view returns (string memory);
+
+    /**
+     * @dev Updates the prompt for an AgentNFT
+     * @param tokenId The ID of the AgentNFT to update
+     * @param newPrompt The new prompt string to assign
+     */
+    function updatePrompt(uint256 tokenId, string memory newPrompt) external;
+}
+
+```
+
+## **Rationale**
+
+This interface is designed to be minimal yet flexible, ensuring compatibility with various use cases:
+
+1. On-Chain Agent Prompts – Prompts are a core asset of AI agents. By storing them within AgentNFTs, they become transferable, preserving their value and utility.
+2. Agent Information Authentication – On-chain information can be used for identification and authentication, enhancing transparency and trust.
+3. Efficient State Querying – The interface enables seamless tracking and updating of agent information, facilitating efficient state management.
+
+## **Backwards Compatibility**
+
+This extension is fully backwards compatible with ERC-721. 
+
+## **Reference Implementation**
+
+```solidity
+// SPDX-License-Identifier: MIT
+pragma solidity ^0.8.20;
+
+import { ERC721 } from "@openzeppelin/contracts/token/ERC721/ERC721.sol";
+import { Ownable } from "@openzeppelin/contracts/access/Ownable.sol";
+import { IAgentNFT } from "./IAgentNFT.sol";
+/**
+ * @title AgentNFT
+ * @dev Implementation of IAgentNFT, which adds prompt and agent management capabilities extension to ERC721
+ * This extension allows NFTs to store and manage prompts and AI Agent's corresponding address
+ */
+contract AgentNFT is ERC721, IAgentNFT, Ownable {
+    // Mapping from token ID to AI agent address
+    mapping(uint256 => address) private _agents;
+
+    // Mapping from token ID to prompt string
+    mapping(uint256 => string) private _prompts;
+
+    /**
+     * @dev Initializes the contract by setting a name and symbol to the AgentNFT collection
+     * @param name The name of the AgentNFT collection
+     * @param symbol The symbol of the AgentNFT collection
+     */
+    constructor(string memory name, string memory symbol) 
+        ERC721(name, symbol)
+        Ownable(msg.sender)
+    {}
+
+    /**
+     * @dev Safely mints a new AgentNFT
+     * @param to The address that will own the minted AgentNFT
+     * @param tokenId The AgentNFT id to mint
+     */
+    function safeMint(address to, uint256 tokenId) public onlyOwner {
+        _safeMint(to, tokenId);
+    }
+
+    /**
+     * @dev See {IAgentNFT}
+     * Requirements:
+     * - Token must exist
+     */
+    function agent(uint256 tokenId) public view override returns (address) {
+        require(ownerOf(tokenId) != address(0), "AgentNFT: token does not exist");
+        return _agents[tokenId];
+    }
+
+    /**
+     * @dev See {IAgentNFT-updateAgent}
+     * Requirements:
+     * - Caller must be token owner or approved
+     * - New agent address must not be zero address
+     */
+    function updateAgent(uint256 tokenId, address newAgent) public override {
+        require(ownerOf(tokenId) == msg.sender, 
+            "AgentNFT: caller is not owner nor approved");
+        require(newAgent != address(0), 
+            "AgentNFT: new agent is zero address");
+        _agents[tokenId] = newAgent;
+        emit AgentUpdated(tokenId, newAgent);
+    }
+
+    /**
+     * @dev See {IAgentNFT-prompt}
+     * Requirements:
+     * - Token must exist
+     */
+    function prompt(uint256 tokenId) public view override returns (string memory) {
+        return _prompts[tokenId];
+    }
+
+    /**
+     * @dev See {IAgentNFT-updatePrompt}
+     * Requirements:
+     * - Caller must be token owner, approved, or the assigned agent
+     * - New prompt must not be empty
+     */
+    function updatePrompt(uint256 tokenId, string memory newPrompt) public override {
+        require(
+            ownerOf(tokenId) == msg.sender || getApproved(tokenId) == msg.sender || isApprovedForAll(ownerOf(tokenId), msg.sender) || msg.sender == _agents[tokenId], 
+            "AgentNFT: caller is not owner, approved, or agent"
+        );
+        _prompts[tokenId] = newPrompt;
+        emit PromptUpdated(tokenId, newPrompt);
+    }
+} 
+```
+
+The reference implementation includes:
+
+1. Storage mappings for agents and prompts
+2. Events emission on state changes
+3. Input validation
+4. Full compatibility with ERC-721
+
+## **Security Considerations**
+
+1. Access Control
+    - Only token owners or approved operators should be able to update agents and prompts
+    - Implementations should validate agent addresses
+2. Storage Considerations
+    - Implementations should consider limiting prompt string length
+    - Data such as prompts can be encrypted for privacy, but need to be verifiable
+    - Gas costs for prompt storage and updates
+
+## **Copyright**
+
+Copyright and related rights waived via [CC0](../LICENSE.md).