OnChainRobin

[
  {
    "inputs": [],
    "stateMutability": "nonpayable",
    "type": "constructor"
  },
  {
    "inputs": [],
    "name": "ApprovalCallerNotOwnerNorApproved",
    "type": "error"
  },
  {
    "inputs": [],
    "name": "ApprovalQueryForNonexistentToken",
    "type": "error"
  },
  {
    "inputs": [],
    "name": "BalanceQueryForZeroAddress",
    "type": "error"
  },
  {
    "inputs": [
      {
        "internalType": "uint256",
        "name": "numerator",
        "type": "uint256"
      },
      {
        "internalType": "uint256",
        "name": "denominator",
        "type": "uint256"
      }
    ],
    "name": "ERC2981InvalidDefaultRoyalty",
    "type": "error"
  },
  {
    "inputs": [
      {
        "internalType": "address",
        "name": "receiver",
        "type": "address"
      }
    ],
    "name": "ERC2981InvalidDefaultRoyaltyReceiver",
    "type": "error"
  },
  {
    "inputs": [
      {
        "internalType": "uint256",
        "name": "tokenId",
        "type": "uint256"
      },
      {
        "internalType": "uint256",
        "name": "numerator",
        "type": "uint256"
      },
      {
        "internalType": "uint256",
        "name": "denominator",
        "type": "uint256"
      }
    ],
    "name": "ERC2981InvalidTokenRoyalty",
    "type": "error"
  },
  {
    "inputs": [
      {
        "internalType": "uint256",
        "name": "tokenId",
        "type": "uint256"
      },
      {
        "internalType": "address",
        "name": "receiver",
        "type": "address"
      }
    ],
    "name": "ERC2981InvalidTokenRoyaltyReceiver",
    "type": "error"
  },
  {
    "inputs": [],
    "name": "MintERC2309QuantityExceedsLimit",
    "type": "error"
  },
  {
    "inputs": [],
    "name": "MintToZeroAddress",
    "type": "error"
  },
  {
    "inputs": [],
    "name": "MintZeroQuantity",
    "type": "error"
  },
  {
    "inputs": [],
    "name": "NotCompatibleWithSpotMints",
    "type": "error"
  },
  {
    "inputs": [
      {
        "internalType": "address",
        "name": "owner",
        "type": "address"
      }
    ],
    "name": "OwnableInvalidOwner",
    "type": "error"
  },
  {
    "inputs": [
      {
        "internalType": "address",
        "name": "account",
        "type": "address"
      }
    ],
    "name": "OwnableUnauthorizedAccount",
    "type": "error"
  },
  {
    "inputs": [],
    "name": "OwnerQueryForNonexistentToken",
    "type": "error"
  },
  {
    "inputs": [],
    "name": "OwnershipNotInitializedForExtraData",
    "type": "error"
  },
  {
    "inputs": [],
    "name": "ReentrancyGuardReentrantCall",
    "type": "error"
  },
  {
    "inputs": [],
    "name": "SequentialMintExceedsLimit",
    "type": "error"
  },
  {
    "inputs": [],
    "name": "SequentialUpToTooSmall",
    "type": "error"
  },
  {
    "inputs": [],
    "name": "SpotMintTokenIdTooSmall",
    "type": "error"
  },
  {
    "inputs": [
      {
        "internalType": "uint256",
        "name": "value",
        "type": "uint256"
      },
      {
        "internalType": "uint256",
        "name": "length",
        "type": "uint256"
      }
    ],
    "name": "StringsInsufficientHexLength",
    "type": "error"
  },
  {
    "inputs": [],
    "name": "TokenAlreadyExists",
    "type": "error"
  },
  {
    "inputs": [],
    "name": "TransferCallerNotOwnerNorApproved",
    "type": "error"
  },
  {
    "inputs": [],
    "name": "TransferFromIncorrectOwner",
    "type": "error"
  },
  {
    "inputs": [],
    "name": "TransferToNonERC721ReceiverImplementer",
    "type": "error"
  },
  {
    "inputs": [],
    "name": "TransferToZeroAddress",
    "type": "error"
  },
  {
    "inputs": [],
    "name": "URIQueryForNonexistentToken",
    "type": "error"
  },
  {
    "anonymous": false,
    "inputs": [
      {
        "indexed": true,
        "internalType": "address",
        "name": "owner",
        "type": "address"
      },
      {
        "indexed": true,
        "internalType": "address",
        "name": "approved",
        "type": "address"
      },
      {
        "indexed": true,
        "internalType": "uint256",
        "name": "tokenId",
        "type": "uint256"
      }
    ],
    "name": "Approval",
    "type": "event"
  },
  {
    "anonymous": false,
    "inputs": [
      {
        "indexed": true,
        "internalType": "address",
        "name": "owner",
        "type": "address"
      },
      {
        "indexed": true,
        "internalType": "address",
        "name": "operator",
        "type": "address"
      },
      {
        "indexed": false,
        "internalType": "bool",
        "name": "approved",
        "type": "bool"
      }
    ],
    "name": "ApprovalForAll",
    "type": "event"
  },
  {
    "anonymous": false,
    "inputs": [
      {
        "indexed": false,
        "internalType": "string",
        "name": "newBaseURI",
        "type": "string"
      }
    ],
    "name": "BaseURIUpdated",
    "type": "event"
  },
  {
    "anonymous": false,
    "inputs": [
      {
        "indexed": true,
        "internalType": "uint256",
        "name": "fromTokenId",
        "type": "uint256"
      },
      {
        "indexed": false,
        "internalType": "uint256",
        "name": "toTokenId",
        "type": "uint256"
      },
      {
        "indexed": true,
        "internalType": "address",
        "name": "from",
        "type": "address"
      },
      {
        "indexed": true,
        "internalType": "address",
        "name": "to",
        "type": "address"
      }
    ],
    "name": "ConsecutiveTransfer",
    "type": "event"
  },
  {
    "anonymous": false,
    "inputs": [
      {
        "indexed": false,
        "internalType": "string",
        "name": "newContractURI",
        "type": "string"
      }
    ],
    "name": "ContractURIUpdated",
    "type": "event"
  },
  {
    "anonymous": false,
    "inputs": [
      {
        "indexed": true,
        "internalType": "address",
        "name": "previousOwner",
        "type": "address"
      },
      {
        "indexed": true,
        "internalType": "address",
        "name": "newOwner",
        "type": "address"
      }
    ],
    "name": "OwnershipTransferred",
    "type": "event"
  },
  {
    "anonymous": false,
    "inputs": [
      {
        "indexed": false,
        "internalType": "uint256",
        "name": "newPrice",
        "type": "uint256"
      }
    ],
    "name": "PriceUpdated",
    "type": "event"
  },
  {
    "anonymous": false,
    "inputs": [
      {
        "indexed": false,
        "internalType": "bool",
        "name": "isEnabled",
        "type": "bool"
      }
    ],
    "name": "PublicMintStateChanged",
    "type": "event"
  },
  {
    "anonymous": false,
    "inputs": [
      {
        "indexed": true,
        "internalType": "address",
        "name": "from",
        "type": "address"
      },
      {
        "indexed": true,
        "internalType": "address",
        "name": "to",
        "type": "address"
      },
      {
        "indexed": true,
        "internalType": "uint256",
        "name": "tokenId",
        "type": "uint256"
      }
    ],
    "name": "Transfer",
    "type": "event"
  },
  {
    "anonymous": false,
    "inputs": [
      {
        "indexed": true,
        "internalType": "address",
        "name": "to",
        "type": "address"
      },
      {
        "indexed": false,
        "internalType": "uint256",
        "name": "amount",
        "type": "uint256"
      }
    ],
    "name": "TreasuryMinted",
    "type": "event"
  },
  {
    "anonymous": false,
    "inputs": [
      {
        "indexed": true,
        "internalType": "address",
        "name": "owner",
        "type": "address"
      },
      {
        "indexed": false,
        "internalType": "uint256",
        "name": "amount",
        "type": "uint256"
      }
    ],
    "name": "Withdrawn",
    "type": "event"
  },
  {
    "inputs": [],
    "name": "MAX_PUBLIC_MINT",
    "outputs": [
      {
        "internalType": "uint256",
        "name": "",
        "type": "uint256"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [],
    "name": "MAX_SUPPLY",
    "outputs": [
      {
        "internalType": "uint256",
        "name": "",
        "type": "uint256"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [],
    "name": "MAX_TREASURY_MINT",
    "outputs": [
      {
        "internalType": "uint256",
        "name": "",
        "type": "uint256"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [
      {
        "internalType": "address",
        "name": "",
        "type": "address"
      }
    ],
    "name": "amountMinted",
    "outputs": [
      {
        "internalType": "uint256",
        "name": "",
        "type": "uint256"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [
      {
        "internalType": "address",
        "name": "to",
        "type": "address"
      },
      {
        "internalType": "uint256",
        "name": "tokenId",
        "type": "uint256"
      }
    ],
    "name": "approve",
    "outputs": [],
    "stateMutability": "payable",
    "type": "function"
  },
  {
    "inputs": [
      {
        "internalType": "address",
        "name": "owner",
        "type": "address"
      }
    ],
    "name": "balanceOf",
    "outputs": [
      {
        "internalType": "uint256",
        "name": "",
        "type": "uint256"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [],
    "name": "baseURI",
    "outputs": [
      {
        "internalType": "string",
        "name": "",
        "type": "string"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [],
    "name": "contractURI",
    "outputs": [
      {
        "internalType": "string",
        "name": "",
        "type": "string"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [],
    "name": "contractURIString",
    "outputs": [
      {
        "internalType": "string",
        "name": "",
        "type": "string"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [
      {
        "internalType": "uint256",
        "name": "tokenId",
        "type": "uint256"
      }
    ],
    "name": "getApproved",
    "outputs": [
      {
        "internalType": "address",
        "name": "",
        "type": "address"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [
      {
        "internalType": "address",
        "name": "owner",
        "type": "address"
      },
      {
        "internalType": "address",
        "name": "operator",
        "type": "address"
      }
    ],
    "name": "isApprovedForAll",
    "outputs": [
      {
        "internalType": "bool",
        "name": "",
        "type": "bool"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [],
    "name": "mintPrice",
    "outputs": [
      {
        "internalType": "uint256",
        "name": "",
        "type": "uint256"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [],
    "name": "name",
    "outputs": [
      {
        "internalType": "string",
        "name": "",
        "type": "string"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [],
    "name": "owner",
    "outputs": [
      {
        "internalType": "address",
        "name": "",
        "type": "address"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [
      {
        "internalType": "uint256",
        "name": "tokenId",
        "type": "uint256"
      }
    ],
    "name": "ownerOf",
    "outputs": [
      {
        "internalType": "address",
        "name": "",
        "type": "address"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [
      {
        "internalType": "uint256",
        "name": "amount",
        "type": "uint256"
      }
    ],
    "name": "publicMint",
    "outputs": [],
    "stateMutability": "payable",
    "type": "function"
  },
  {
    "inputs": [],
    "name": "publicMintEnabled",
    "outputs": [
      {
        "internalType": "bool",
        "name": "",
        "type": "bool"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [],
    "name": "renounceOwnership",
    "outputs": [],
    "stateMutability": "nonpayable",
    "type": "function"
  },
  {
    "inputs": [
      {
        "internalType": "uint256",
        "name": "tokenId",
        "type": "uint256"
      },
      {
        "internalType": "uint256",
        "name": "salePrice",
        "type": "uint256"
      }
    ],
    "name": "royaltyInfo",
    "outputs": [
      {
        "internalType": "address",
        "name": "receiver",
        "type": "address"
      },
      {
        "internalType": "uint256",
        "name": "amount",
        "type": "uint256"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [
      {
        "internalType": "address",
        "name": "from",
        "type": "address"
      },
      {
        "internalType": "address",
        "name": "to",
        "type": "address"
      },
      {
        "internalType": "uint256",
        "name": "tokenId",
        "type": "uint256"
      }
    ],
    "name": "safeTransferFrom",
    "outputs": [],
    "stateMutability": "payable",
    "type": "function"
  },
  {
    "inputs": [
      {
        "internalType": "address",
        "name": "from",
        "type": "address"
      },
      {
        "internalType": "address",
        "name": "to",
        "type": "address"
      },
      {
        "internalType": "uint256",
        "name": "tokenId",
        "type": "uint256"
      },
      {
        "internalType": "bytes",
        "name": "_data",
        "type": "bytes"
      }
    ],
    "name": "safeTransferFrom",
    "outputs": [],
    "stateMutability": "payable",
    "type": "function"
  },
  {
    "inputs": [
      {
        "internalType": "address",
        "name": "operator",
        "type": "address"
      },
      {
        "internalType": "bool",
        "name": "approved",
        "type": "bool"
      }
    ],
    "name": "setApprovalForAll",
    "outputs": [],
    "stateMutability": "nonpayable",
    "type": "function"
  },
  {
    "inputs": [
      {
        "internalType": "string",
        "name": "_newBaseURI",
        "type": "string"
      }
    ],
    "name": "setBaseURI",
    "outputs": [],
    "stateMutability": "nonpayable",
    "type": "function"
  },
  {
    "inputs": [
      {
        "internalType": "string",
        "name": "_newContractURI",
        "type": "string"
      }
    ],
    "name": "setContractURI",
    "outputs": [],
    "stateMutability": "nonpayable",
    "type": "function"
  },
  {
    "inputs": [
      {
        "internalType": "address",
        "name": "receiver",
        "type": "address"
      },
      {
        "internalType": "uint96",
        "name": "feeNumerator",
        "type": "uint96"
      }
    ],
    "name": "setDefaultRoyalty",
    "outputs": [],
    "stateMutability": "nonpayable",
    "type": "function"
  },
  {
    "inputs": [
      {
        "internalType": "uint256",
        "name": "_newPrice",
        "type": "uint256"
      }
    ],
    "name": "setMintPrice",
    "outputs": [],
    "stateMutability": "nonpayable",
    "type": "function"
  },
  {
    "inputs": [
      {
        "internalType": "bool",
        "name": "_state",
        "type": "bool"
      }
    ],
    "name": "setPublicMintState",
    "outputs": [],
    "stateMutability": "nonpayable",
    "type": "function"
  },
  {
    "inputs": [
      {
        "internalType": "bytes4",
        "name": "interfaceId",
        "type": "bytes4"
      }
    ],
    "name": "supportsInterface",
    "outputs": [
      {
        "internalType": "bool",
        "name": "",
        "type": "bool"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [],
    "name": "symbol",
    "outputs": [
      {
        "internalType": "string",
        "name": "",
        "type": "string"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [
      {
        "internalType": "uint256",
        "name": "tokenId",
        "type": "uint256"
      }
    ],
    "name": "tokenURI",
    "outputs": [
      {
        "internalType": "string",
        "name": "",
        "type": "string"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [],
    "name": "totalSupply",
    "outputs": [
      {
        "internalType": "uint256",
        "name": "result",
        "type": "uint256"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [
      {
        "internalType": "address",
        "name": "from",
        "type": "address"
      },
      {
        "internalType": "address",
        "name": "to",
        "type": "address"
      },
      {
        "internalType": "uint256",
        "name": "tokenId",
        "type": "uint256"
      }
    ],
    "name": "transferFrom",
    "outputs": [],
    "stateMutability": "payable",
    "type": "function"
  },
  {
    "inputs": [
      {
        "internalType": "address",
        "name": "newOwner",
        "type": "address"
      }
    ],
    "name": "transferOwnership",
    "outputs": [],
    "stateMutability": "nonpayable",
    "type": "function"
  },
  {
    "inputs": [
      {
        "internalType": "uint256",
        "name": "amount",
        "type": "uint256"
      }
    ],
    "name": "treasuryMint",
    "outputs": [],
    "stateMutability": "nonpayable",
    "type": "function"
  },
  {
    "inputs": [],
    "name": "withdraw",
    "outputs": [],
    "stateMutability": "nonpayable",
    "type": "function"
  }
]

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.24;

import "erc721a/contracts/ERC721A.sol";
import "@openzeppelin/contracts/access/Ownable.sol";
import "@openzeppelin/contracts/token/common/ERC2981.sol";
import "@openzeppelin/contracts/utils/ReentrancyGuard.sol";
import "@openzeppelin/contracts/utils/Strings.sol";
import "@openzeppelin/contracts/utils/Base64.sol";

/**
 * @title OnChainRobin (OCR)
 * @notice Fully On-Chain NFT Collection for Robinhood Chain.
 * @dev Implements ERC721A, ERC2981 (Royalties), and fully on-chain deterministic SVG generation.
 */
contract OnChainRobin is ERC721A, ERC2981, Ownable, ReentrancyGuard {
    using Strings for uint256;

    // --- State Variables ---
    uint256 public constant MAX_SUPPLY = 5999;
    uint256 public constant MAX_PUBLIC_MINT = 5;
    uint256 public constant MAX_TREASURY_MINT = 99;

    uint256 public mintPrice = 0.001 ether;
    bool public publicMintEnabled = false;

    // Optional URIs if external fallback is ever required
    string public baseURI;
    string public contractURIString;

    mapping(address => uint256) public amountMinted;

    // --- Events ---
    event TreasuryMinted(address indexed to, uint256 amount);
    event PublicMintStateChanged(bool isEnabled);
    event PriceUpdated(uint256 newPrice);
    event Withdrawn(address indexed owner, uint256 amount);
    event BaseURIUpdated(string newBaseURI);
    event ContractURIUpdated(string newContractURI);

    // --- Constructor ---
    constructor() ERC721A("onChainRobin", "OCR") Ownable(msg.sender) {
        // Set default royalty to 3% (300 basis points)
        _setDefaultRoyalty(msg.sender, 300);
    }

    // --- Minting Functions ---

    /**
     * @notice Treasury mint for the owner (Max 99 per tx).
     * @param amount Number of NFTs to mint.
     */
    function treasuryMint(uint256 amount) external onlyOwner {
        require(amount > 0, "Amount must be greater than 0");
        require(amount <= MAX_TREASURY_MINT, "Exceeds max treasury mint per tx");
        require(_totalMinted() + amount <= MAX_SUPPLY, "Exceeds max supply");

        _mint(msg.sender, amount);
        emit TreasuryMinted(msg.sender, amount);
    }

    /**
     * @notice Public mint function.
     * @param amount Number of NFTs to mint.
     */
    function publicMint(uint256 amount) external payable nonReentrant {
        require(publicMintEnabled, "Public mint is disabled");
        require(amount > 0, "Amount must be greater than 0");
        require(amountMinted[msg.sender] + amount <= MAX_PUBLIC_MINT, "Exceeds wallet limit");
        require(_totalMinted() + amount <= MAX_SUPPLY, "Exceeds max supply");
        require(msg.value == mintPrice * amount, "Incorrect ETH payment");

        amountMinted[msg.sender] += amount;
        _mint(msg.sender, amount);
    }

    // --- Admin Functions ---

    /**
     * @notice Enables or disables the public mint.
     * @param _state True to enable, false to disable.
     */
    function setPublicMintState(bool _state) external onlyOwner {
        publicMintEnabled = _state;
        emit PublicMintStateChanged(_state);
    }

    /**
     * @notice Updates the public mint price.
     * @param _newPrice New price in wei.
     */
    function setMintPrice(uint256 _newPrice) external onlyOwner {
        mintPrice = _newPrice;
        emit PriceUpdated(_newPrice);
    }

    /**
     * @notice Updates the ERC2981 royalty configuration.
     * @param receiver Address to receive royalties.
     * @param feeNumerator Royalty percentage in basis points (e.g., 300 = 3%).
     */
    function setDefaultRoyalty(address receiver, uint96 feeNumerator) external onlyOwner {
        _setDefaultRoyalty(receiver, feeNumerator);
    }

    /**
     * @notice Sets a fallback base URI.
     * @param _newBaseURI New base URI string.
     */
    function setBaseURI(string calldata _newBaseURI) external onlyOwner {
        baseURI = _newBaseURI;
        emit BaseURIUpdated(_newBaseURI);
    }

    /**
     * @notice Sets the contract-level metadata URI.
     * @param _newContractURI New contract URI string.
     */
    function setContractURI(string calldata _newContractURI) external onlyOwner {
        contractURIString = _newContractURI;
        emit ContractURIUpdated(_newContractURI);
    }

    /**
     * @notice Safely withdraws the entire ETH balance of the contract.
     * Uses the recommended call pattern and ReentrancyGuard.
     */
    function withdraw() external onlyOwner nonReentrant {
        uint256 balance = address(this).balance;
        require(balance > 0, "No ETH to withdraw");

        (bool success, ) = msg.sender.call{value: balance}("");
        require(success, "Withdraw failed");

        emit Withdrawn(msg.sender, balance);
    }

    // --- On-Chain SVG & Metadata Generation ---

    /**
     * @notice Generates deterministic symmetric pixel art SVG based on Token ID.
     * @param tokenId The token ID to generate art for.
     * @return Base64 encoded SVG string.
     */
    function generateSVG(uint256 tokenId) internal pure returns (string memory) {
        // Derive a deterministic seed solely from the Token ID
        uint256 seed = uint256(keccak256(abi.encodePacked("OCR_SEED", tokenId)));

        string memory svg = "<svg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 16 16' shape-rendering='crispEdges'><rect width='16' height='16' fill='#DFFF00'/>";

        // Generate an 8x16 grid and mirror it horizontally to create 16x16 symmetric pixel art
        for (uint8 y = 0; y < 16; y++) {
            for (uint8 x = 0; x < 8; x++) {
                uint256 bitIndex = y * 8 + x;
                if ((seed >> bitIndex) & 1 == 1) {
                    string memory yStr = uint256(y).toString();
                    
                    // Left side pixel
                    svg = string.concat(
                        svg,
                        "<rect x='", uint256(x).toString(), "' y='", yStr, "' width='1' height='1' fill='#000'/>"
                    );
                    // Right side mirrored pixel
                    svg = string.concat(
                        svg,
                        "<rect x='", uint256(15 - x).toString(), "' y='", yStr, "' width='1' height='1' fill='#000'/>"
                    );
                }
            }
        }
        svg = string.concat(svg, "</svg>");
        return svg;
    }

    /**
     * @notice Returns the fully on-chain generated metadata for a given token.
     */
    function tokenURI(uint256 tokenId) public view virtual override returns (string memory) {
        if (!_exists(tokenId)) revert URIQueryForNonexistentToken();

        // If a base URI is set, it overrides the on-chain metadata
        if (bytes(baseURI).length > 0) {
            return string.concat(baseURI, tokenId.toString());
        }

        string memory svg = generateSVG(tokenId);
        uint256 seed = uint256(keccak256(abi.encodePacked("OCR_SEED", tokenId)));

        string memory json = Base64.encode(
            bytes(
                string.concat(
                    '{"name": "onChainRobin #', tokenId.toString(), '", ',
                    '"description": "100% Fully On-Chain Deterministic Pixel Art on the Robinhood Chain.", ',
                    '"attributes": [',
                    '{"trait_type": "Background", "value": "Electric Lime"}, ',
                    '{"trait_type": "Pixel Style", "value": "Symmetric"}, ',
                    '{"trait_type": "Seed", "value": "0x', Strings.toHexString(uint160(seed >> 96)), '"}, ',
                    '{"trait_type": "Renderer", "value": "On-Chain SVG"}',
                    '], ',
                    '"image": "data:image/svg+xml;base64,', Base64.encode(bytes(svg)), '"}'
                )
            )
        );

        return string.concat("data:application/json;base64,", json);
    }

    /**
     * @notice Contract-level metadata for marketplaces (e.g., OpenSea).
     */
    function contractURI() external view returns (string memory) {
        return contractURIString;
    }

    // --- Overrides ---

    /**
     * @dev Resolves override conflict between ERC721A and ERC2981.
     */
    function supportsInterface(bytes4 interfaceId) public view virtual override(ERC721A, ERC2981) returns (bool) {
        return super.supportsInterface(interfaceId);
    }

    /**
     * @dev Start token IDs at 1.
     */
    function _startTokenId() internal view virtual override returns (uint256) {
        return 1;
    }
}