# Escrow and x402
Where an external agent is paid for its work, Brain coordinates settlement **without ever custodying funds**. Two standards do the heavy lifting: ERC-8183 for escrowed jobs, x402 for HTTP-native machine payments.
| Standard | Use Case |
| ------------ | ----------------------------------------------------------------------- |
| **ERC-8183** | Job-style work where payment releases on verified completion |
| **x402** | Per-call API access where payment settles inline with each HTTP request |
### ERC-8183 escrowed job flow
The tenant locks payment. The agent does the work. Brain co-signs the release. Funds settle to the agent.
```
1. Tenant proposes a job
│
↓
2. BrainSmartAccount locks payment in escrow
│
↓
3. Agent executes the work
│
↓
4. Agent submits a completion attestation
│
↓
5. Brain (neutral verifier) co-signs release
│
↓
6. Funds settle to agent's address
```
If verification fails, funds return to the tenant after a timeout.
| Phase | What Happens |
| ----------- | --------------------------------------------------------------------------------------------------------------------------------------- |
| **Lock** | Tenant's smart account transfers funds into the escrow contract; the entry references `agent`, `capability`, `actionId`, and a deadline |
| **Work** | Agent performs the action, off-chain or on-chain |
| **Attest** | Agent submits a signed completion attestation |
| **Verify** | Brain validates the attestation against the action receipt |
| **Settle** | If valid, Brain co-signs release; funds settle to the agent |
| **Timeout** | If the deadline passes without valid completion, funds return to the tenant |
{% hint style="success" %}
Brain is a **neutral verifier**, not a custodian. Funds move directly between the tenant's account and the agent's address. Brain signs that the work was done; it does not hold the money in transit.
{% endhint %}
### EIP-712 attestation type
```
JobCompletion(
bytes32 actionId,
address agent,
bytes32 resultHash,
uint64 timestamp,
uint256 nonce
)
```
| Field | Purpose |
| ------------ | -------------------------------------- |
| `actionId` | The action this completion attests to |
| `resultHash` | Hash of the work output (audit-linked) |
| `timestamp` | Used to enforce job deadline |
| `nonce` | Replay protection |
### Dispute resolution
If the agent and tenant disagree on whether work was completed:
| Path | Outcome |
| ---------------------------------------------------- | ----------------------------------------------------------------------- |
| **Agent submits valid attestation, tenant disputes** | Brain reviews evidence; can co-sign release or hold pending arbitration |
| **Agent fails to submit before deadline** | Funds return to tenant automatically |
| **Brain detects fraud** | Release blocked; reputation slashed against agent's `reputationRoot` |
### x402 machine-native payments
For HTTP-native settlement, Brain integrates **x402**: the resource server returns `402 Payment Required` with payment instructions; the calling agent retries with an x402 payment header backed by the tenant's smart account; settlement and audit happen in the same flow.
```
Agent Resource Server
│ │
│ GET /api/data │
│ ──────────────────────────► │
│ │
│ 402 Payment Required │
│ X-Payment-Required: ... │
│ ◄────────────────────────── │
│ │
│ GET /api/data │
│ X-Payment: ... │
│ ──────────────────────────► │
│ │
│ 200 OK + result │
│ ◄────────────────────────── │
```
| Step | Detail |
| ------------------------ | --------------------------------------------------------------------------------------- |
| **Initial request** | Agent calls a resource without payment |
| **402 response** | Server returns required amount, recipient address, currency |
| **Retry with X-Payment** | Agent attaches a payment authorization signed against its smart account |
| **Validate and settle** | Server validates the payment (or accepts a verifiable promise) and returns the resource |
| **Audit** | The full flow is logged as an audit event linked to the action |
### When to use which
| Scenario | Standard |
| --------------------------------------- | --------------------------------------- |
| Agent paid on completion of a job | ERC-8183 |
| Agent pays per-call for an API or tool | x402 |
| Agent pays another agent for a sub-task | x402 (immediate) or ERC-8183 (deferred) |
### Where settlement is **not** Brain's job
| Boundary | Who Handles |
| ----------------- | ---------------------------------------------- |
| Funds in transit | Tenant's smart account or rail; not Brain |
| Final settlement | The settlement layer (Base, an off-chain rail) |
| Tax and reporting | Tenant and tenant's accounting tooling |
Brain coordinates and proves; it does not hold.
### What's next
---
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