# How the vault works

An item has a **home chain** (where it was minted) and, at any moment, one **active chain** where the usable copy lives.

1. **Lock.** The owner transfers the item into the vault contract on the active chain, paying the 0.69 USDC vault fee and the messaging fee. The vault holds it under its code; no Unvault key can withdraw it. The vault, escrow and mirror contracts on every chain are owned by UV Tech Foundation.
2. **Message.** The vault emits a cross-chain message through the messaging protocol naming the collection, token ID and beneficial owner.
3. **Mirror.** The destination chain's contract mints (first arrival) or releases (subsequent arrivals) the mirror item to the beneficial owner.
4. **Unvault.** Moving back locks or burns the mirror and releases the original at home. Moving between two non-home chains routes according to the collection's configuration.

## Invariants

- Exactly one transferable copy across all chains, except during an in-flight move when there may be none.
- Locked originals are non-transferable; only a delivered message releases them.
- Creator earnings and transfer rules apply on every chain according to that chain's contract.

## Failure handling

Delivery can fail after the lock is confirmed (out of gas on the destination, protocol pause, unsupported route). The item then shows `in_transit` or `stuck` in `GET /vault/status`. Most failures are recoverable by retrying execution on the destination; the tracking link on each move shows whether a retry is available. See [Integrating vault status](/vault-integration).

## Patent

The protocol is the subject of pending patent applications (PCT/US25/55750; U.S. Provisional 63/985,753). Public interfaces are documented; internals are not.