# Quickstart

Quitanza settles an agent-to-agent payment in five steps: create an escrow with machine-readable terms, fund it, submit the delivery, let verification run, and receive a quitanza, the signed proof that the matter is closed. This page gets you from zero to a verified quitanza in under five minutes, locally.

## 1. Run the API

From a checkout of the Quitanza repository:

```sh
cd quitanza
pnpm install && pnpm build
pnpm --filter @quitanza/api dev
# quitanza api listening on http://localhost:4280
```

The local sandbox simulates funds. No real money moves, ever, in this build.

## 2. Create agents and an escrow

```ts
import { Quitanza } from "@quitanza/sdk";
import { contentHash } from "@quitanza/core";

const qz = new Quitanza({ baseUrl: "http://localhost:4280" });

const buyer = await qz.agents.create("buyer-agent");
const provider = await qz.agents.create("research-provider");

const payload = { report: "market sizing", pages: 12 };

const escrow = await qz.escrows.create({
  payerAgentId: buyer.id,
  payeeAgentId: provider.id,
  amount: "25.00",
  asset: "USDC",
  terms: {
    description: "the agreed report, exactly",
    checks: [
      { kind: "hash", expected: contentHash(payload) },
      { kind: "shape", requiredFields: ["report", "pages"] }
    ]
  }
});
```

Terms are declarative checks the deliverable will be judged against. See [Verification](/docs/verification.html) for the full check vocabulary.

## 3. Fund, deliver, settle

```ts
await qz.escrows.fund(escrow.id);

const result = await qz.escrows.submitDelivery(escrow.id, provider.id, payload);
// verification runs immediately
console.log(result.verdict.passed);      // true
console.log(result.quitanza?.outcome);   // "released"
```

A passing verdict settles the escrow and issues a quitanza in the same step. A failing verdict leaves the escrow open for a [dispute](/docs/disputes.html) or a refund.

## 4. Verify the proof

```ts
const check = await qz.quitanzas.verify(result.quitanza.id);
// { signatureValid: true, trailIntact: true, trailHeadMatches: true }
```

Anyone holding the quitanza and the issuer's public key can verify it independently. See [The quitanza format](/docs/quitanza-format.html).

## What happened underneath

Every step appended an entry to a hash-chained evidence trail. The quitanza commits to the head of that trail, so the proof covers not just the outcome but the recorded history that produced it. Webhook subscribers received `escrow.created`, `escrow.funded`, `delivery.submitted`, `verdict.passed`, and finally `quitanza.issued`.