NFT marketplace behavior

The Universe Marketplace v1 exposes four isolated protocol authorities: arc20, atomicals_nft, realms, and subrealms. They share one durable transaction engine, and every route, cursor, idempotency scope, listing, offer, order, reservation, browse query, and status count is scoped to one protocol.

What the generic NFT lane accepts

An authoritative compact Atomical ID, with quantityAtomic always exposed as 1.

It rejects realm, subrealm, FT, container, and item subtypes. Those either belong to another lane or are not supported.

What must agree before collateral is accepted

For a non-fungible asset the authority requires independent views to agree:

• Bitcoin Core reports a confirmed, live output with the exact value and owner script, and a mature coinbase where applicable.
• The Atomicals provider reports exactly that location, script, and value.
• The height and hash on both the Bitcoin side and the Atomicals side stay unchanged across the verification bracket.

If any view disagrees, or the chain position moves mid-check, the request fails closed.

What is always rejected

• Mixed collateral, meaning an output carrying more than the selected asset.
• Spent outputs.
• Checkpoint drift between verification and execution.
• Ambiguous balances.
• Atomicals operations inside the settlement transaction.
• Burns.
• Output assignments that do not move the exact selected Atomical.

Ownership proof

Owner actions require a short lived owner session, issued only after a BIP-322 simple proof for P2WPKH or key-path P2TR. Proof is separate from signing the settlement transaction.

Lifecycle

Listing, reservation, purchase preparation, signed validation, broadcast, and settlement are distinct steps with their own routes and idempotency scope. See Marketplace v1 for the complete contract.