> ## Documentation Index
> Fetch the complete documentation index at: https://docs.peaq.xyz/llms.txt
> Use this file to discover all available pages before exploring further.

# peaq ERC-8004 Escrow

This page is the **real-life example** of the [ERC-8004 agent lifecycle](/peaqchain/build/advanced-operations/erc-8004/intro) described in the introduction.

This flow lets a **buyer machine** (Unitree) and a **seller machine** (Drone) register identities on peaq, create and accept a service claim on peaq, fund the claim from Base (USDT locked in a Base escrow), and then release payment on Base while peaq is kept in sync via LayerZero messages.

<img src="https://mintcdn.com/peaq/cIsq0vkknB1zIHac/assets/img/claim-processing-pipeline.svg?fit=max&auto=format&n=cIsq0vkknB1zIHac&q=85&s=2a7d5212436e338d0c189a06ca4745b5" alt="Omnichain Escrow Purchase Flow" width="1936" height="3362" data-path="assets/img/claim-processing-pipeline.svg" />

## Actors & Contracts

### Actors

| Actor               | Role                              |
| ------------------- | --------------------------------- |
| **Unitree (Buyer)** | Purchases a service               |
| **Drone (Seller)**  | Provides the service              |
| **peaq Chain**      | Identity + claim + state tracking |
| **Base Chain**      | Holds USDT escrow and pays seller |
| **LayerZero**       | Transports cross-chain messages   |

### Key Components

**peaq**

* **Identity / registration** — `register(agent-card.json)` → creates machine/agent identity (`agent_id`)
* **ClaimRegistry** — creates/accepts claims, locks stakes, tracks status
* **PaymentReceiver** — receives LayerZero messages (`lzReceive`) and updates peaq state
* **TransactionRegistry** — records funding/release events (auditability)

**Base**

* **BaseEscrow** — locks USDT, releases USDT to seller, emits cross-chain messages

***

## Phase 1 — Identity registration on peaq

**Goal:** Both parties become on-chain actors on peaq.

1. **Unitree → peaq:** `register("unitree-agent-card.json")`\
   **peaq → Unitree:** `agent_id`
2. **Drone → peaq:** `register("drone-agent-card.json")`\
   **peaq → Drone:** `agent_id`

**Result:** Both buyer and seller have peaq identities and can participate in claims.

***

## Phase 2 — Create & accept claim on peaq

**Goal:** Create a service purchase intent on peaq and have the seller accept it with stake.

### Buyer (Unitree)

1. Ensure buyer has USDC on peaq for stake (mint if needed).
2. Approve staking: `approve(ClaimRegistry, stake)`.
3. Ensure buyer has USDT on Base (mint if needed).
4. Create the claim on peaq:\
   `create_purchase_claim(seller=Drone, service_id, amount, deadline)`\
   **peaq → Unitree:** `claim_id`
5. Share `claim_id` to Drone (off-chain / manual in this diagram).

### Seller (Drone)

6. Fetch details: `get_claim(claim_id)`.
7. Verify claim + seller address (local checks).
8. Ensure seller has USDC on peaq for stake (mint if needed).
9. Approve staking: `approve(ClaimRegistry, stake)`.
10. Accept claim: `accept_claim(claim_id)`\
    **peaq:** locks seller stake\
    **peaq → Drone:** status `Accepted`.

**Result:** Claim exists and is accepted; both sides can poll status on peaq.

***

## Phase 3 — Cross-chain funding (Base → peaq)

**Goal:** Lock funds in Base escrow and mark the claim as **Funded** on peaq via LayerZero.

1. **Unitree → peaq:** `get_claim(claim_id)` (to confirm deadline).
2. **Unitree → Base:** `approve(BaseEscrow, USDT amount)`.
3. **Unitree → Base:** `BaseEscrow.deposit(claim_id, amount, seller, deadline)`\
   **BaseEscrow:** locks USDT.
4. **Base → LayerZero:** sends cross-chain “funded” message.
5. **LayerZero → peaq:** delivers to PaymentReceiver.
6. **peaq.PaymentReceiver:** `lzReceive()`
   * updates TransactionRegistry
   * updates claim status → **Funded**.

**Result:** Funds are escrowed on Base; peaq reflects “Funded”.

***

## Phase 4 — Release payment on Base + finalize on peaq

**Goal:** Seller performs the service off-chain; buyer releases escrowed payment; peaq finalizes status and returns stakes.

1. **Drone:** Performs the real-world service (off-chain).
2. **Unitree → Base:** `BaseEscrow.release(claim_id)`\
   **BaseEscrow:** transfers USDT to Drone\
   **Base → Drone:** USDT received.
3. **Base → LayerZero:** sends “completed” message.
4. **LayerZero → peaq:** delivers completion to PaymentReceiver.
5. **peaq.PaymentReceiver:**
   * updates TransactionRegistry
   * updates claim status → **Completed**
   * returns stakes to buyer & seller.

**Result:** Payment settled on Base; peaq records completion and settles stakes.

***

## State machine (peaq claim status)

**Created → Accepted → Funded → Completed**

***

## What to poll / verify

* **Buyer & Seller** poll on peaq: `get_claim(claim_id)` to read status + deadline.
* **Funding truth** lives on Base: USDT is locked/released by BaseEscrow.
* **peaq** is the coordination ledger: identity, claim lifecycle, audit trail, stake settlement.
* **LayerZero** is the sync bridge: delivers funding + completion events to peaq.

***

## Outcome

A single claim ties together:

* **Identity + staking + lifecycle** on peaq
* **USDT custody + payout** on Base
* **Cross-chain state synchronization** via LayerZero

Transaction is complete when Base pays out and peaq marks **Completed** and returns stakes.

***

## Contract addresses

### peaq

| Contract             | Address                                      |
| -------------------- | -------------------------------------------- |
| Identity Registry    | `0x2154317da929098A033ac1ef869d6A8bB771A0e3` |
| Claim Registry       | `0x48E33cF40D427004313760F1E514A7488e8DF0Cc` |
| Transaction Registry | `0xe2C58c1A0d18E87F0cD0f658E2f2806c3458C374` |
| Mock USDC            | `0x0Ad7E419358a462649d2D53b5C2B25cDf85Ca009` |

### LayerZero (peaq)

| Contract         | Address                                      |
| ---------------- | -------------------------------------------- |
| Payment Receiver | `0x49850c56cf8AAF27Ee20f78753D6A4f7C73EBB81` |
| peaq LZ Endpoint | `0x6F475642a6e85809B1c36Fa62763669b1b48DD5B` |

### Base

| Contract         | Address                                      |
| ---------------- | -------------------------------------------- |
| Base Escrow      | `0x76C73B6a1A145b9D578c474efeBA83191dF5DCC3` |
| Base USDT        | `0x280BEeeD2EAb5F661d664C26B2A808cEdf70be2d` |
| Base LZ Endpoint | `0x1a44076050125825900e736c501f859c50fE728c` |