--- version: 4.1.0-fractal name: nft-standards-4741c70867d4 description: Implement NFT standards (ERC-721, ERC-1155) with proper metadata handling, minting strategies, and marketplace integration. Use when creating NFT contracts, building NFT marketplaces, or implementing digital asset systems. --- # NFT Standards Master ERC-721 and ERC-1155 NFT standards, metadata best practices, and advanced NFT features. ## Do not use this skill when - The task is unrelated to nft standards - You need a different domain or tool outside this scope ## Instructions - Clarify goals, constraints, and required inputs. - Apply relevant best practices and validate outcomes. - Provide actionable steps and verification. - If detailed examples are required, open `resources/implementation-playbook.md`. ## Use this skill when - Creating NFT collections (art, gaming, collectibles) - Implementing marketplace functionality - Building on-chain or off-chain metadata - Creating soulbound tokens (non-transferable) - Implementing royalties and revenue sharing - Developing dynamic/evolving NFTs ## ERC-721 (Non-Fungible Token Standard) ```solidity // SPDX-License-Identifier: MIT pragma solidity ^0.8.0; import "@openzeppelin/contracts/token/ERC721/extensions/ERC721URIStorage.sol"; import "@openzeppelin/contracts/token/ERC721/extensions/ERC721Enumerable.sol"; import "@openzeppelin/contracts/access/Ownable.sol"; import "@openzeppelin/contracts/utils/Counters.sol"; contract MyNFT is ERC721URIStorage, ERC721Enumerable, Ownable { using Counters for Counters.Counter; Counters.Counter private _tokenIds; uint256 public constant MAX_SUPPLY = 10000; uint256 public constant MINT_PRICE = 0.08 ether; uint256 public constant MAX_PER_MINT = 20; constructor() ERC721("MyNFT", "MNFT") {} function mint(uint256 quantity) external payable { require(quantity > 0 && quantity <= MAX_PER_MINT, "Invalid quantity"); require(_tokenIds.current() + quantity <= MAX_SUPPLY, "Exceeds max supply"); require(msg.value >= MINT_PRICE * quantity, "Insufficient payment"); for (uint256 i = 0; i < quantity; i++) { _tokenIds.increment(); uint256 newTokenId = _tokenIds.current(); _safeMint(msg.sender, newTokenId); _setTokenURI(newTokenId, generateTokenURI(newTokenId)); } } function generateTokenURI(uint256 tokenId) internal pure returns (string memory) { // Return IPFS URI or on-chain metadata return string(abi.encodePacked("ipfs://QmHash/", Strings.toString(tokenId), ".json")); } // Required overrides function _beforeTokenTransfer( address from, address to, uint256 tokenId, uint256 batchSize ) internal override(ERC721, ERC721Enumerable) { super._beforeTokenTransfer(from, to, tokenId, batchSize); } function _burn(uint256 tokenId) internal override(ERC721, ERC721URIStorage) { super._burn(tokenId); } function tokenURI(uint256 tokenId) public view override(ERC721, ERC721URIStorage) returns (string memory) { return super.tokenURI(tokenId); } function supportsInterface(bytes4 interfaceId) public view override(ERC721, ERC721Enumerable) returns (bool) { return super.supportsInterface(interfaceId); } function withdraw() external onlyOwner { payable(owner()).transfer(address(this).balance); } } ``` ## ERC-1155 (Multi-Token Standard) ```solidity // SPDX-License-Identifier: MIT pragma solidity ^0.8.0; import "@openzeppelin/contracts/token/ERC1155/ERC1155.sol"; import "@openzeppelin/contracts/access/Ownable.sol"; contract GameItems is ERC1155, Ownable { uint256 public constant SWORD = 1; uint256 public constant SHIELD = 2; uint256 public constant POTION = 3; mapping(uint256 => uint256) public tokenSupply; mapping(uint256 => uint256) public maxSupply; constructor() ERC1155("ipfs://QmBaseHash/{id}.json") { maxSupply[SWORD] = 1000; maxSupply[SHIELD] = 500; maxSupply[POTION] = 10000; } function mint( address to, uint256 id, uint256 amount ) external onlyOwner { require(tokenSupply[id] + amount <= maxSupply[id], "Exceeds max supply"); _mint(to, id, amount, ""); tokenSupply[id] += amount; } function mintBatch( address to, uint256[] memory ids, uint256[] memory amounts ) external onlyOwner { for (uint256 i = 0; i < ids.length; i++) { require(tokenSupply[ids[i]] + amounts[i] <= maxSupply[ids[i]], "Exceeds max supply"); tokenSupply[ids[i]] += amounts[i]; } _mintBatch(to, ids, amounts, ""); } function burn( address from, uint256 id, uint256 amount ) external { require(from == msg.sender || isApprovedForAll(from, msg.sender), "Not authorized"); _burn(from, id, amount); tokenSupply[id] -= amount; } } ``` ## Metadata Standards ## 🧠 Knowledge Modules (Fractal Skills) ### 1. [Off-Chain Metadata (IPFS)](./sub-skills/off-chain-metadata-ipfs.md) ### 2. [On-Chain Metadata](./sub-skills/on-chain-metadata.md) --- Source attribution: Dokhacgiakhoa Original project: https://github.com/Dokhacgiakhoa/antigravity-ide/blob/c4a059bbf7a8d6b2162071f0fbfe74053faa6d20/.agent/skills/nft-standards/SKILL.md License: MIT License information: https://opensource.org/license/mit Original upstream instructions; downloaded from Mega AI Hub. ## Upstream license notice MIT License Copyright (c) 2026 Dokhacgiakhoa Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions: The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software. THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. ================================================================================ UNIVERSAL ACKNOWLEDGEMENTS & REFERENCES ================================================================================ This project is authored and maintained by Dokhacgiakhoa. Antigravity IDE (Enhanced Edition) draws significant inspiration and inherits open-source knowledge from the following masters and repositories: 1. Antigravity Kit (Core Reference) - Original Author: vudovn - Link: https://github.com/vudovn/antigravity-kit 2. Antigravity Awesome Skills (Skill Metadata Reference) - Original Author: sickn33 - Link: https://github.com/sickn33/antigravity-awesome-skills 3. UI/UX Pro Max (Design Philosophy Reference) - Original Author: sickn33 - Link: https://github.com/sickn33/ui-ux-pro-max 4. Model Context Protocol (MCP) standards - Authors: Anthropic & Ecosystem Contributors - Link: https://modelcontextprotocol.io/ 5. High-Performance Web Standards - Inspiration: Vercel Engineering & Anthony Fu (antfu) 6. Strategic Knowledge Extraction - Inspiration: Fabric Patterns (danielmiessler) *Note: All trademarks and copyrights belong to their respective owners. The references above reflect research-level inspiration and antecedent contributions. These parties are not involved in the management of this repository.* # Mega AI Hub resource metadata Creator / publisher: Dokhacgiakhoa Original project: https://github.com/Dokhacgiakhoa/antigravity-ide/blob/c4a059bbf7a8d6b2162071f0fbfe74053faa6d20/.agent/skills/nft-standards/SKILL.md Attribution basis: Source repository record Fields of work: Design, Development & Engineering, Marketing Roles: Backend Developer, Frontend Developer, Growth Marketer, Product Marketer, UX Designer Specialties: Backend Tools: Openzeppelin Country applicability: Country not specified Classification basis: Source catalog labels Instruction SHA-256: 35849b25979c2476bda4a5baac281d6fee29896452a9949012327425f7dcf9e8