# Nft Dynamic And Onchain > Dynamic & On-Chain NFTs - Skill: `nickgallick/nft-dynamic-and-onchain` (Agent Skill) - Install (CLI): `npx skillmds@latest add nickgallick/nft-dynamic-and-onchain` - Raw SKILL.md: https://api.skillmd.com/api/skills/nickgallick/nft-dynamic-and-onchain/raw - Safety review: pending (external: skill-scanner PASS, skillspector PASS) - Works with: Claude Code, Claude.ai, OpenAI Codex - Category: Coding & Dev Tools - Author: nickgallick (https://skillmd.com/u/nickgallick) - Updated: 2026-09-21 - Page: https://skillmd.com/skills/nickgallick/nft-dynamic-and-onchain --- # Dynamic & On-Chain NFTs ## On-Chain SVG NFT — Full Pattern ```solidity // SPDX-License-Identifier: MIT pragma solidity ^0.8.19; import "@openzeppelin/contracts/token/ERC721/ERC721.sol"; import "@openzeppelin/contracts/utils/Base64.sol"; import "@openzeppelin/contracts/utils/Strings.sol"; contract DynamicAgentNFT is ERC721 { using Strings for uint256; struct Agent { string name; uint256 elo; uint8 tier; // 0=Bronze 1=Silver 2=Gold 3=Diamond uint256 wins; uint256 losses; uint256 badges; // Bitmask of earned badge IDs } mapping(uint256 => Agent) public agents; uint256 private _nextId; address public immutable arena; // Only arena contract can update stats string[4] private TIER_NAMES = ["Bronze", "Silver", "Gold", "Diamond"]; string[4] private TIER_COLORS = ["CD7F32", "C0C0C0", "FFD700", "B9F2FF"]; string[4] private TIER_EMOJI = ["\xF0\x9F\xA5\x89", "\xF0\x9F\xA5\x88", "\xF0\x9F\x8F\x86", "\xF0\x9F\x92\x8E"]; event AgentEvolved(uint256 indexed tokenId, uint8 newTier); constructor(address _arena) ERC721("SpartaAgent", "AGENT") { arena = _arena; } function mint(address to, string calldata name) external returns (uint256) { uint256 id = _nextId++; agents[id] = Agent(name, 1000, 0, 0, 0, 0); _mint(to, id); return id; } // Called by arena contract after each challenge function updateStats(uint256 tokenId, bool won, uint256 eloChange) external { require(msg.sender == arena, "Only arena"); Agent storage a = agents[tokenId]; if (won) { a.wins++; a.elo += eloChange; } else { a.losses++; a.elo = a.elo > eloChange ? a.elo - eloChange : 0; } // Check tier upgrade uint8 newTier = _calculateTier(a.elo); if (newTier > a.tier) { a.tier = newTier; emit AgentEvolved(tokenId, newTier); } } function _calculateTier(uint256 elo) internal pure returns (uint8) { if (elo >= 2200) return 3; // Diamond if (elo >= 1800) return 2; // Gold if (elo >= 1400) return 1; // Silver return 0; // Bronze } // ─── Full on-chain metadata generation ─── function tokenURI(uint256 tokenId) public view override returns (string memory) { require(_exists(tokenId), "Nonexistent"); Agent memory a = agents[tokenId]; string memory svg = _buildSVG(a, tokenId); string memory attrs = _buildAttributes(a); string memory jsonRaw = string(abi.encodePacked( '{"name":"', a.name, ' #', tokenId.toString(), '",', '"description":"A Sparta Arena competitor.",', '"image":"data:image/svg+xml;base64,', Base64.encode(bytes(svg)), '",', '"attributes":', attrs, '}' )); return string(abi.encodePacked( "data:application/json;base64,", Base64.encode(bytes(jsonRaw)) )); } function _buildSVG(Agent memory a, uint256 tokenId) internal view returns (string memory) { string memory bg = TIER_COLORS[a.tier]; string memory tier = TIER_NAMES[a.tier]; string memory emoji = TIER_EMOJI[a.tier]; // Win rate bar width uint256 totalGames = a.wins + a.losses; uint256 winPct = totalGames > 0 ? (a.wins * 100 / totalGames) : 50; uint256 barWidth = winPct * 3; // max 300px return string(abi.encodePacked( '', // Background gradient '', '', '', '', '', // Agent name '', a.name, '', // Token ID '#', tokenId.toString(), '', // ELO (big center number) '', a.elo.toString(), '', 'ELO RATING', // Tier badge '', '', emoji, ' ', tier, '', // Win rate bar 'WIN RATE', '', '', // Stats '', 'W: ', a.wins.toString(), '', '', 'L: ', a.losses.toString(), '', '' )); } function _buildAttributes(Agent memory a) internal view returns (string memory) { return string(abi.encodePacked( '[', '{"trait_type":"Tier","value":"', TIER_NAMES[a.tier], '"},', '{"trait_type":"ELO","display_type":"number","value":', a.elo.toString(), '},', '{"trait_type":"Wins","display_type":"number","value":', a.wins.toString(), '},', '{"trait_type":"Losses","display_type":"number","value":', a.losses.toString(), '}', ']' )); } } ``` ## Soulbound Tokens (ERC-5192) ```solidity // ERC-5192: Minimal Soulbound Token interface IERC5192 { function locked(uint256 tokenId) external view returns (bool); event Locked(uint256 tokenId); event Unlocked(uint256 tokenId); // Not emitted for pure SBTs } contract SpartaBadge is ERC721, IERC5192 { // All tokens are soulbound — cannot be transferred function locked(uint256) external pure returns (bool) { return true; } function _beforeTokenTransfer( address from, address to, uint256 tokenId, uint256 batchSize ) internal override { // Allow minting (from == 0) but block all transfers require(from == address(0), "Soulbound: non-transferable"); super._beforeTokenTransfer(from, to, tokenId, batchSize); } } ``` ## Composable NFTs (ERC-6059) ```solidity // Parent NFT owns child NFTs // Transfer parent → all children move with it contract ComposableAgent is ERC721 { // tokenId → array of child NFT references mapping(uint256 => ChildNFT[]) public childAssets; struct ChildNFT { address contractAddress; uint256 tokenId; } // Attach a badge/item to an agent function attachChild( uint256 parentId, address childContract, uint256 childTokenId ) external { require(ownerOf(parentId) == msg.sender, "Not owner"); // Transfer child NFT from sender to THIS contract (parent holds children) IERC721(childContract).transferFrom(msg.sender, address(this), childTokenId); childAssets[parentId].push(ChildNFT(childContract, childTokenId)); } // When parent is transferred, children must go with it function _afterTokenTransfer(address, address to, uint256 tokenId, uint256) internal override { // Children are held by THIS contract — the new owner controls them via parent // (Full ERC-6059 implementation tracks owner via parent chain) } } ```