A pact, step by step

An agent buys a document translation for at most 1 USDC. The seller is paid by the page: four pages were ordered.

The happy path

1. Terms. The agent requests the translation. The seller answers 402 Payment Required with its terms: the condition (“Portuguese, at least 4 pages”), the verifier that will judge, and the deadlines. The agent can read all of this before paying anything.
2. Open. The agent calls open on the pact contract. The contract checks the cap and the deadlines, checks that buyer and seller differ, moves 1 USDC into escrow, and records which verifier key will judge this pact. Only the condition’s hash is stored, so the terms can’t change afterwards.
3. Delivery. The seller sends the document with a signature over its exact bytes. Neither side can later pretend something else was delivered.
4. Verdict. The buyer sends the delivery to the verifier as evidence. The verifier reads it, applies deterministic rules and signs an attestation: here, ALLOW 0.75 USDC, because only 3 of 4 pages arrived. Anyone can submit the attestation to the contract; the signature is what counts.
5. Settle. The seller collects 0.75 USDC. In the same transaction, the contract returns 0.25 USDC to the agent.
6. Receipt. The outcome is hashed into a receipt and anchored on-chain with others in a batch, so the agent can later prove what it paid for.

If the verifier had said DENY, step 5 would be a release instead, and the agent would get the full 1 USDC back.

States

Every pact is in exactly one of these states, and ends in exactly one of the last two.

State	Means	How it gets there
Funded	The cap is in escrow, waiting for a verdict	open
Allowed	The verifier approved an amount; the seller can collect	record_verdict with ALLOW
Denied	The verifier rejected the delivery	record_verdict with DENY
Settled	The seller was paid; any remainder went back to the buyer	settle, or close_meter for metered pacts
Released	The whole cap went back to the buyer	release

In both final states, the amount paid to the seller plus the amount returned to the buyer equals the cap. The contract’s tests enforce this as one of eight invariants.

Deadlines and silence

A pact has two deadlines, both counted in ledgers. A Stellar ledger closes about every 5 seconds.

• Verdict deadline: the last ledger at which a verdict can be recorded.
• Settle deadline: the last ledger at which the seller can collect.

When the pact opens, the buyer and seller also agree on a silence policy: what happens if no verdict arrives by the verdict deadline.

Silence policy	If the verdict deadline passes with no verdict
Refund (the default)	Anyone can call release, and the buyer gets the whole cap back
Pay	The seller can collect, as if the delivery had been approved

The Kit’s default deadlines for translations are 120 ledgers (about 10 minutes) for the verdict and 720 ledgers (about an hour) to settle.

Every way a pact can end

What happens	Outcome
The delivery is right	ALLOW for the full cap; the seller settles
Only part was delivered	ALLOW for a smaller amount; the seller settles that, the rest returns
The delivery is wrong	DENY; anyone calls release, and the buyer gets everything back
The seller never delivers	No verdict arrives. Under Refund, anyone can release after the verdict deadline
The verifier goes offline	Same as above: the silence policy applies at the verdict deadline
The seller never collects	After the settle deadline, anyone can release, so the money isn’t stuck
Someone submits a second verdict	Rejected: a pact accepts exactly one
A verdict for another pact is replayed	Rejected: each attestation is bound to one pact and one condition

Nobody’s permission is needed to get money back: release can be called by anyone once its conditions are met, and it can only pay the buyer.