NFT Marketplace Standard

See also: LP-4155, LP-6022

Abstract

This LP defines the canonical NFT marketplace infrastructure for the Lux Network, providing trading primitives for ERC-721 and ERC-1155 assets. The standard adopts two complementary protocols: Seaport (MIT license) as the primary order-book marketplace from OpenSea, and Sudoswap v2 (AGPL-3.0) as an automated market maker (AMM) for NFTs. Together these protocols enable auctions, fixed-price listings, collection offers, royalty enforcement, and liquidity pools for NFT trading on Lux C-Chain and compatible EVMs.

Activation

Parameter	Value
Flag string	lp2502-nft-marketplace-standard
Default in code	N/A
Deployment branch	N/A
Roll-out criteria	N/A
Back-off plan	N/A

Motivation

NFT marketplaces require battle-tested, audited infrastructure to ensure secure trading. Rather than building custom marketplace contracts, Lux adopts industry-standard protocols with proven security records:

1. Security: Seaport and Sudoswap have undergone extensive audits (OpenZeppelin, Trail of Bits, Spearbit, Cyfrin)
2. Interoperability: Standard order formats enable cross-marketplace liquidity aggregation
3. Feature Completeness: Auctions, offers, bundles, royalties, and AMM pools in unified infrastructure
4. Ecosystem Alignment: Zoo ecosystem NFT marketplace uses these same primitives
5. Developer Experience: Well-documented APIs with existing SDK and tooling support

Specification

Protocol Selection

Seaport (Primary Marketplace)

License: MIT Location: lib/seaport/ Version: 1.6

Seaport is the order-book marketplace protocol from OpenSea supporting:

• Basic Orders: Fixed-price listings and purchases
• Dutch Auctions: Descending price auctions
• English Auctions: Ascending price auctions with bid increments
• Collection Offers: Offers on any item in a collection
• Trait Offers: Offers on items with specific attributes
• Bundle Orders: Multiple NFTs in single transaction
• Partial Fills: Partial fulfillment of orders
• Conduits: Approval management for efficient transfers

Core Contracts:

lib/seaport/contracts/
├── Seaport.sol                    # Main marketplace contract
├── conduit/
│   ├── Conduit.sol               # Token transfer conduit
│   └── ConduitController.sol     # Conduit management
├── helpers/
│   ├── SeaportRouter.sol         # Multi-call router
│   ├── TransferHelper.sol        # Batch transfers
│   └── navigator/                # Order building helpers
│       └── SeaportNavigator.sol
├── zones/
│   ├── PausableZone.sol          # Pausable order zone
│   └── PausableZoneController.sol
└── helpers/order-validator/
    └── SeaportValidator.sol      # Order validation

Canonical Addresses (cross-chain):

Contract	Address
Seaport 1.6	0x0000000000000068F116a894984e2DB1123eB395
ConduitController	0x00000000F9490004C11Cef243f5400493c00Ad63
SeaportValidator	0x00e5F120f500006757E984F1DED400fc00370000
SeaportNavigator	0x0000f00000627D293Ab4Dfb40082001724dB006F

Sudoswap v2 (NFT AMM)

License: AGPL-3.0 Location: src/sudo2/ Version: 1.1

Sudoswap provides automated market making for NFTs with bonding curves:

• Liquidity Pools: Deposit NFTs + tokens to provide liquidity
• Bonding Curves: Linear, exponential, XYK, GDA pricing
• Property Checking: Filter by traits or token IDs
• Royalty Support: ERC-2981 and Manifold registry
• Settings: Project-controlled pool configurations
• ERC-1155 Support: Multi-token AMM pools

Core Contracts:

src/sudo2/src/
├── LSSVMPair.sol                 # Base pair contract
├── LSSVMPairFactory.sol          # Pair deployment factory
├── LSSVMRouter.sol               # Swap routing
├── VeryFastRouter.sol            # Optimized multi-swap router
├── RoyaltyEngine.sol             # On-chain royalty lookup
├── bonding-curves/
│   ├── LinearCurve.sol           # Linear price curve
│   ├── ExponentialCurve.sol      # Exponential price curve
│   ├── XykCurve.sol              # Constant product curve
│   └── GDACurve.sol              # Gradual Dutch Auction
├── erc721/
│   ├── LSSVMPairERC721.sol       # ERC-721 pairs
│   ├── LSSVMPairERC721ETH.sol    # 721<>ETH pairs
│   └── LSSVMPairERC721ERC20.sol  # 721<>ERC20 pairs
├── erc1155/
│   ├── LSSVMPairERC1155.sol      # ERC-1155 pairs
│   ├── LSSVMPairERC1155ETH.sol   # 1155<>ETH pairs
│   └── LSSVMPairERC1155ERC20.sol # 1155<>ERC20 pairs
├── property-checking/
│   ├── MerklePropertyChecker.sol # Merkle-based ID filtering
│   └── RangePropertyChecker.sol  # ID range filtering
└── settings/
    ├── StandardSettings.sol      # Configurable pool settings
    └── StandardSettingsFactory.sol

Dependencies

Sudoswap v2 requires additional dependencies (configured in src/sudo2/foundry.toml):

Dependency	Import Path	Purpose
Manifold Royalty Registry	manifoldxyz/	ERC-2981 royalty lookup
PRB Math	@prb/math/	Fixed-point arithmetic
Solmate	solmate/	Gas-optimized ERC20
Clones With Immutable Args	clones-with-immutable-args/	Minimal proxy deployment

Standards Compliance

ERC-721 (Non-Fungible Tokens)

Both protocols fully support ERC-721:

• safeTransferFrom for secure transfers
• approve / setApprovalForAll for marketplace approvals
• ownerOf for ownership verification

ERC-1155 (Multi-Token Standard)

Both protocols support ERC-1155:

• safeTransferFrom / safeBatchTransferFrom
• balanceOf / balanceOfBatch
• setApprovalForAll
• Sudoswap ERC-1155 pools trade specific token IDs

ERC-2981 (Royalty Standard)

Royalty enforcement via:

• Native ERC-2981 royaltyInfo() queries
• Manifold Royalty Registry fallback
• Support for legacy royalty interfaces (Rarible, Foundation, SuperRare, ArtBlocks)

interface IERC2981 {
    function royaltyInfo(uint256 tokenId, uint256 salePrice)
        external view returns (address receiver, uint256 royaltyAmount);
}

Seaport Integration

Order Structure

struct OrderParameters {
    address offerer;
    address zone;
    OfferItem[] offer;
    ConsiderationItem[] consideration;
    OrderType orderType;
    uint256 startTime;
    uint256 endTime;
    bytes32 zoneHash;
    uint256 salt;
    bytes32 conduitKey;
    uint256 totalOriginalConsiderationItems;
}

struct OfferItem {
    ItemType itemType;          // NATIVE, ERC20, ERC721, ERC1155
    address token;
    uint256 identifierOrCriteria;
    uint256 startAmount;
    uint256 endAmount;
}

struct ConsiderationItem {
    ItemType itemType;
    address token;
    uint256 identifierOrCriteria;
    uint256 startAmount;
    uint256 endAmount;
    address payable recipient;
}

Order Types

Type	Description
FULL_OPEN	Anyone can fulfill
PARTIAL_OPEN	Partial fills allowed
FULL_RESTRICTED	Zone approval required
PARTIAL_RESTRICTED	Partial + zone restricted
CONTRACT	Contract-generated order

Conduit System

Conduits enable single-approval token transfers:

// User approves conduit once
IERC721(nft).setApprovalForAll(conduitAddress, true);

// All Seaport orders use same approval
// No per-order approvals needed

Sudoswap Adaptations

Pool Types

Type	Buy NFT	Sell NFT	Trading Fee
TOKEN	Yes	No	No
NFT	No	Yes	No
TRADE	Yes	Yes	Yes

Bonding Curves

Linear Curve:

newPrice = currentPrice + delta (buy)
newPrice = currentPrice - delta (sell)

Exponential Curve:

newPrice = currentPrice * (1 + delta/1e18) (buy)
newPrice = currentPrice / (1 + delta/1e18) (sell)

XYK Curve (Constant Product):

x * y = k
newPrice derived from reserves

GDA Curve (Gradual Dutch Auction):

Price decays over time until purchase
Resets on each sale

Property Checking

Pools can restrict tradeable NFTs:

interface IPropertyChecker {
    function hasProperties(
        uint256[] calldata ids,
        bytes calldata propertyData
    ) external view returns (bool);
}

Implementations:

• MerklePropertyChecker: Merkle proof of ID inclusion
• RangePropertyChecker: ID range verification

Gas Costs

Operation	Gas Cost
Create pool	~250,000
Swap (single NFT)	~150,000
Swap (5 NFTs)	~400,000
Add liquidity	~180,000
Remove liquidity	~120,000

Cross-Chain NFTs

Warp Messaging Integration

NFTs can be transferred cross-chain using LP-6022 Warp Messaging:

interface ICrossChainNFT {
    // Lock NFT on source chain
    function lockAndBridge(
        uint256 tokenId,
        bytes32 destinationChainId,
        address recipient
    ) external returns (bytes32 messageId);

    // Mint wrapped NFT on destination
    function receiveAndMint(
        bytes32 sourceChainId,
        address originalCollection,
        uint256 tokenId,
        address recipient,
        bytes calldata warpProof
    ) external;
}

Supported Chains

Chain	Chain ID	Status
C-Chain	96369	Primary
Hanzo EVM	36963	Supported
Zoo EVM	200200	Supported
chains	Various	Via Warp

Zoo Ecosystem Integration

The Zoo NFT marketplace uses these same primitives:

~/work/zoo/contracts/
├── marketplace/
│   ├── ZooSeaport.sol        # Seaport wrapper with Zoo fees
│   ├── ZooSudoPool.sol       # Sudoswap pool factory
│   └── ZooRoyaltyEngine.sol  # Zoo-specific royalty handling

Zoo-Specific Features:

• ZOO token fee discounts
• Creator royalty enforcement (minimum 2.5%)
• Curated collection verification
• Community governance for marketplace parameters

Rationale

Why Seaport

1. Battle-tested: Processes billions in NFT volume on OpenSea
2. Flexible: Supports any order type (auctions, offers, bundles)
3. Gas-efficient: Single-approval conduit system
4. MIT License: Permissive for commercial use
5. Standards: EIP-712 signatures, ERC-2981 royalties

Why Sudoswap

1. Instant Liquidity: No waiting for buyers/sellers
2. Price Discovery: Automated pricing via bonding curves
3. LP Incentives: Earn trading fees by providing liquidity
4. Property Filtering: Trade only specific traits/IDs
5. AGPL-3.0: Ensures derivatives remain open source

Protocol Complementarity

Feature	Seaport	Sudoswap
Fixed-price listings	Yes	No
Auctions	Yes	No
Collection offers	Yes	No
Instant liquidity	No	Yes
Bonding curves	No	Yes
LP rewards	No	Yes
Bundle trades	Yes	Limited

Backwards Compatibility

This LP introduces new marketplace infrastructure without modifying existing token standards. Collections using ERC-721 or ERC-1155 work without modification.

Migration Path:

• Existing listings on other marketplaces remain valid
• Users approve Seaport conduit for new listings
• Sudoswap pools can be created for any collection
• Royalty settings from ERC-2981 are respected

Test Cases

Seaport Tests

describe("Seaport NFT Marketplace", () => {
    it("should execute basic order", async () => {
        const order = await createOrder({
            offerer: seller,
            offer: [{ itemType: 2, token: nft, identifier: 1 }],
            consideration: [{ itemType: 0, amount: parseEther("1") }]
        });

        await seaport.connect(buyer).fulfillOrder(order, { value: parseEther("1") });
        expect(await nft.ownerOf(1)).to.equal(buyer.address);
    });

    it("should execute dutch auction", async () => {
        const startPrice = parseEther("10");
        const endPrice = parseEther("1");

        const order = await createOrder({
            offer: [{ token: nft, identifier: 1, startAmount: 1, endAmount: 1 }],
            consideration: [{ amount: startPrice, endAmount: endPrice }],
            startTime: now,
            endTime: now + 86400
        });

        // Price decreases over time
        await time.increase(43200); // 50% through auction
        const midPrice = parseEther("5.5");
        await seaport.connect(buyer).fulfillOrder(order, { value: midPrice });
    });

    it("should enforce royalties", async () => {
        const royaltyRecipient = await nft.royaltyInfo(1, parseEther("1"));

        await seaport.connect(buyer).fulfillOrder(order, { value: parseEther("1") });

        expect(await ethers.provider.getBalance(royaltyRecipient)).to.be.gt(0);
    });
});

Sudoswap Tests

describe("Sudoswap NFT AMM", () => {
    it("should create liquidity pool", async () => {
        const pool = await factory.createPairERC721ETH(
            nft.address,
            linearCurve.address,
            parseEther("1"),    // spotPrice
            parseEther("0.1"),  // delta
            0,                  // fee
            [1, 2, 3],         // initialNFTIds
            { value: parseEther("10") }
        );

        expect(await nft.balanceOf(pool.address)).to.equal(3);
    });

    it("should swap NFT for ETH", async () => {
        const [quote, newSpotPrice, newDelta, fee] = await pool.getSellNFTQuote(1, 1);

        await nft.approve(pool.address, 4);
        await pool.swapNFTsForToken([4], quote, seller.address);

        expect(await nft.ownerOf(4)).to.equal(pool.address);
    });

    it("should swap ETH for NFT", async () => {
        const [quote, newSpotPrice, newDelta, fee] = await pool.getBuyNFTQuote(1, 1);

        await pool.swapTokenForAnyNFTs(
            1,
            quote,
            buyer.address,
            false,
            address(0),
            { value: quote }
        );
    });

    it("should enforce property checking", async () => {
        const merkleProof = generateProof([1, 2, 3]);
        await pool.setPropertyChecker(merkleChecker.address, merkleProof);

        // Only IDs 1, 2, 3 can be traded
        await expect(
            pool.swapNFTsForToken([5], quote, seller.address)
        ).to.be.revertedWith("PropertyCheckFailed");
    });
});

Reference Implementation

Lux Standard Library

Seaport: lib/seaport/

• Full OpenSea Seaport 1.6 deployment
• Includes conduits, zones, validators, helpers

Sudoswap: src/sudo2/

• Complete Sudoswap v2 with bonding curves
• ERC-721 and ERC-1155 pool support
• Royalty engine with Manifold integration

Deployment Commands

# Build contracts
cd ~/work/lux/standard
forge build

# Run Sudoswap tests (requires dependencies)
cd src/sudo2
forge test

# Deploy Seaport (uses canonical addresses)
forge script script/DeploySeaport.s.sol --broadcast

Integration Example

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.20;

import {ConsiderationInterface} from "seaport/contracts/interfaces/ConsiderationInterface.sol";
import {LSSVMPairFactory} from "./sudo2/src/LSSVMPairFactory.sol";

contract NFTMarketplace {
    ConsiderationInterface public immutable seaport;
    LSSVMPairFactory public immutable sudoFactory;

    constructor(address _seaport, address _sudoFactory) {
        seaport = ConsiderationInterface(_seaport);
        sudoFactory = LSSVMPairFactory(_sudoFactory);
    }

    // List NFT via Seaport
    function listNFT(
        address nft,
        uint256 tokenId,
        uint256 price
    ) external returns (bytes32 orderHash) {
        // Create and sign Seaport order
        // ...
    }

    // Create Sudoswap pool
    function createPool(
        address nft,
        uint256[] calldata tokenIds,
        uint256 spotPrice
    ) external payable returns (address pool) {
        pool = sudoFactory.createPairERC721ETH(
            IERC721(nft),
            linearCurve,
            spotPrice,
            0.05e18,  // 5% delta
            0,        // no fee
            tokenIds
        );
    }
}

Security Considerations

Seaport Security

1. Signature Validation: EIP-712 typed data signatures prevent replay attacks
2. Zone Restrictions: Pausable zones enable emergency stops
3. Conduit Isolation: Separate conduits isolate approval risks
4. Order Cancellation: Users can cancel orders on-chain
5. Audits: OpenZeppelin, Trail of Bits (multiple rounds)

Sudoswap Security

1. Reentrancy Protection: All swap functions use reentrancy guards
2. Overflow Protection: Solidity 0.8.x + PRB Math for safe arithmetic
3. Royalty Caps: Maximum royalty percentage enforced
4. Owner Controls: Pool owners can pause or migrate
5. Audits: Spearbit, Cyfrin, Narya (see v2-audits repo)

Cross-Chain Risks

1. Warp Message Verification: Always verify BLS aggregate signatures
2. Wrapped NFT Trust: Wrapped NFTs rely on bridge security
3. Finality: Wait for quantum finality on Q-Chain for high-value transfers
4. Metadata Sync: Off-chain metadata may lag cross-chain transfers

Economic Attacks

1. Wash Trading: Monitor for suspicious LP activity
2. Price Manipulation: Use time-weighted prices for oracles
3. Front-Running: Consider private mempools for high-value trades
4. Royalty Evasion: Off-chain royalty enforcement may be bypassed

Economic Impact

Fee Structure

Component	Seaport	Sudoswap
Protocol Fee	Configurable	0.5% default
Creator Royalty	ERC-2981	ERC-2981
LP Fee	N/A	Pool-configurable
Gas	~150k per trade	~150k per swap

Liquidity Benefits

• Sudoswap pools provide instant exit liquidity
• No listing fees for pool deposits
• LP providers earn trading fees
• Price discovery improves market efficiency

Open Questions

1. Royalty Enforcement: Should protocol enforce minimum royalties?
2. Cross-Chain Listings: Can Seaport orders span multiple chains?
3. Curve Governance: Who approves new bonding curve implementations?
4. Zoo Integration: Standardize Zoo marketplace fee handling?

References

1. Seaport Documentation
2. Seaport GitHub
3. Sudoswap Documentation
4. Sudoswap v2 Audits
5. ERC-721: Non-Fungible Token Standard
6. ERC-1155: Multi Token Standard
7. ERC-2981: NFT Royalty Standard
8. Manifold Royalty Registry
9. LP-6022
10. LP-4155

Copyright

Copyright and related rights waived via CC0.