Cross-Chain NFT Interoperability Guide

## ROLE
You are an NFT infrastructure architect who builds systems enabling NFTs to exist and function across multiple blockchains. You understand the unique challenges of non-fungible cross-chain transfers versus fungible tokens.

## OBJECTIVE
Design a cross-chain NFT system for [NFT PROJECT/MARKETPLACE] that allows NFTs to bridge between [CHAINS] while preserving [PRIORITY: metadata, provenance history, utility, marketplace listings].

## TASK

### Cross-Chain NFT Models
- Lock-and-mint: lock NFT on source, mint wrapped NFT on destination
- Burn-and-mint: destroy on source, recreate on destination (requires canonical control)
- Multi-home: NFT can exist on multiple chains simultaneously (different use cases)
- State channel: NFT stays on origin chain, state is reflected cross-chain
- Comparison: which model fits gaming NFTs vs art vs utility tokens

### Metadata Preservation
- On-chain metadata: ensure metadata is replicated or accessible cross-chain
- Off-chain metadata: IPFS/Arweave URIs work the same regardless of chain
- Dynamic metadata: if metadata changes, how do updates propagate cross-chain?
- Token standards: ERC-721 to ERC-721, ERC-721 to SPL-NFT, or cross-standard
- Royalty enforcement: ERC-2981 and chain-specific royalty standards
- Collection integrity: maintaining collection-level metadata and verification

### Provenance & History
- Transfer history: complete ownership history must be queryable cross-chain
- Bridge events: record when NFT moved between chains as provenance events
- Creator attribution: original creator address/chain must always be retrievable
- Authenticity verification: prove an NFT on chain B is the genuine article from chain A
- Indexing: cross-chain indexer that aggregates complete NFT lifecycle

### Utility Preservation
- Gaming utility: cross-chain NFTs that grant in-game benefits on multiple chains
- Access control: NFT-gated content/communities that work regardless of chain
- DeFi utility: NFTs as collateral across chains (lending, fractionalization)
- Staking: stake NFTs for rewards regardless of which chain they're on
- Composability: NFT bundles, equipment sets, or nested NFTs across chains

### Marketplace Integration
- Cross-chain listings: list NFT for sale on any chain's marketplace
- Unified collection pages: aggregate listings and floor prices across chains
- Payment flexibility: buy with native token of any supported chain
- Royalty enforcement: creator royalties paid regardless of sale chain
- API standards: consistent APIs for marketplaces to display cross-chain NFTs

### Implementation Guide
- Smart contracts: bridge contracts, wrapped NFT contracts, registry contracts
- Standards: ONFT (LayerZero), xNFT, or custom cross-chain NFT standard
- Testing: testnet deployment on all target chains with full flow testing
- Migration plan: existing NFT collections moving to cross-chain
- Documentation: integration guide for wallets, marketplaces, and dApps

## OUTPUT FORMAT
Cross-chain NFT system design with architecture, metadata handling specification, provenance tracking, marketplace integration guide, and deployment plan.

## CONSTRAINTS
- NFT uniqueness must be preserved: no duplicates across chains
- Gas costs for NFT bridging can be high: optimize and communicate costs clearly
- Not all NFTs benefit from cross-chain: evaluate whether it adds real value
- Marketplace fragmentation: cross-chain should consolidate, not fragment, liquidity
- Legal: NFT ownership rights may vary by jurisdiction when crossing chains