Atomic Settlement
Atomic Settlement
Section titled “Atomic Settlement”bitCaster settles matched orders with the Cashu mint. It does not run a bilateral swap between two peers.
When you place an order, your wallet authorizes it with a PAY_TO_UNLOCK
capability. The matching engine checks this authorization when it admits the
order. It does not call the mint at this stage.
When orders match, the engine creates one or more fills. Each fillId
identifies one real fill. The engine can put one or more fills into an atomic
settlement group. Each groupId identifies that group. Do not use a groupId
as a fill identifier.
The engine submits one multi-party conversion for each settlement group. The mint completes the group as one operation. A group can use one of these conversion types:
- Complementary conversion. It exchanges compatible conditional-token and collateral positions.
- Mint conversion. It creates a complete conditional-token set as part of the conversion.
The NUT also defines merge conversion. bitCaster does not expose it in this release.
When the mint confirms a group, it returns exact result entries. Your wallet stores the submitted operation and the confirmed result. If the wallet stops or loses its connection, it can recover the exact operation and result later.
Cancellation and continuation
Section titled “Cancellation and continuation”Cancellation only retracts an order that still rests on the book. It does not
spend a PAY_TO_UNLOCK capability. It does not refund a capability.
After a partial fill, a residual order needs a new capability before it can rest on the book again.
What the engine can see
Section titled “What the engine can see”Your wallet sends the exact PAY_TO_UNLOCK proofs that authorize the order.
The engine sees those proofs and their secrets. It does not receive your wallet
seed, output blinding factors, refund key, or other wallet proofs.
The engine can use only the output choices that your wallet authorized. It cannot redirect the value or extend the authorization. If the engine does not settle, those authorized proofs remain unavailable until their refund becomes valid.
If submission is absent or uncertain, the wallet reconciles with the durable
engine and mint authority. A PAY_TO_UNLOCK capability can still refund after
its expiry under the NUT rules.
Further reading
Section titled “Further reading”See the technical settlement protocol for the lifecycle and trust boundary.