CenterChain

Module

NFT

An overlay on the stock cosmossdk.io/x/nft keeper that adds the rules a real world asset needs: an issuer-scoped class id, a technical issuer, sequential token ids, immutable metadata and a lock other modules can escrow with.

On-chain name: nftrwa · Consensus version 1

Full documentation on docs.centerchain.org

What the module owns

  • A class id is {issuer}/{product_ref}. The first segment must be the signer's own bech32 address, both segments are printable ASCII, the separator appears exactly once and neither side may contain a slash.
  • A token id is {class_id}/{sequence}. The sequence is a per-class counter that starts at 1 and only ever increases, and the module assigns it rather than the sender choosing it.
  • token_metadata_immutable is fixed when the class is created. When it is set, MsgSetNFTMetadata fails with ErrImmutableTokenMetadata, but only after the sender is confirmed as the class issuer.
  • The lock is the escrow other modules use: the holder keeps ownership and nobody else can move or burn the token until it is released.

Key features

Issuer-scoped classes

Class id format {issuer}/{product_ref} prevents name squatting and ensures clear ownership.

Sequential token IDs

Module assigns sequential IDs per class. No ID collision, no manual assignment.

Immutable metadata

Per-class flag token_metadata_immutable. When true, metadata cannot be changed after creation.

Cross-module escrow (lock)

The lock mechanism lets other modules (NFT market, Income) escrow tokens without taking ownership.

Messages

  • MsgCreateClass -- Create a new NFT class with issuer, product reference, and metadata immutability flag.
  • MsgMintNFT -- Mint a new token in a class (issuer only). Module assigns sequential ID.
  • MsgBurnNFT -- Burn a token (holder or issuer).
  • MsgSetNFTMetadata -- Update token metadata (only if class is not immutable, and only by issuer).
  • MsgTransferNFT -- Transfer ownership to another account.
  • MsgLockNFT / MsgUnlockNFT -- Escrow/release a token for other modules (NFT market, Income).
  • MsgUpdateClassIssuer -- Transfer class issuance authority (gov only).

Queries

  • Class / Classes -- Fetch a single class or paginated list of classes.
  • NFT / NFTs -- Fetch a single token or paginated list of tokens in a class.
  • ClassOwner / NFTsByOwner -- Owner queries by address.
  • Params -- Module parameters (caps, etc.).

Caps and limits

  • Class ID segments: printable ASCII, no slashes in segments
  • Max class metadata size: per module config
  • Token metadata: per module config
  • Sequential IDs: start at 1, monotonic increase

Integration guide

Represent a position as a unique token

NFT docs

Sell an NFT on chain

NFT market docs

Where the rules live

The NFT module provides the asset layer. NFT market adds secondary trading; Income adds yield distribution. Both hook NFT burns: market refunds the seller deposit, Income releases the token's earmark.

How it worksAll modules