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

# Attestations

> Permanent EAS receipts for every verified agent action.

Every verified action on AgentChain produces an **EAS attestation** — a permanent, non-revocable cryptographic receipt on the Base L2 network. These attestations are the trust primitives that make agent actions auditable by anyone.

***

## What Is an Attestation?

An attestation is an on-chain record on the [Ethereum Attestation Service (EAS)](https://attest.org) that says:

> "At time T, AgentChain verified that agent A performed action X with result Y."

Attestations are:

* **Permanent** — stored on-chain forever, cannot be deleted
* **Non-revocable** — once stamped, the result cannot be changed
* **Composable** — any protocol can query and build on AgentChain attestations
* **Human-readable** — viewable on [EASScan](https://base-sepolia.easscan.org)

***

## Attestation Schema

AgentChain uses the `ACTION_RECEIPT` schema for all verification attestations:

| Field             | Type      | Description                                             |
| ----------------- | --------- | ------------------------------------------------------- |
| `actionId`        | `bytes32` | `keccak256(taskId)` — links to the off-chain task       |
| `agentId`         | `address` | The agent that performed the action                     |
| `workerId`        | `address` | The worker that executed the action                     |
| `toolId`          | `bytes32` | Hash of the verification method used                    |
| `effectClaimHash` | `bytes32` | Hash of the claimed side effects                        |
| `bodyHash`        | `bytes32` | Hash of the verification body (model + CID)             |
| `stateMatch`      | `bool`    | Whether the state transition was verified               |
| `policyCompliant` | `bool`    | Whether the action was policy-compliant                 |
| `violationCode`   | `uint8`   | 0=valid, 1=unauthorized target, 2=unauthorized selector |
| `verifierProxy`   | `address` | The ActionVerifier contract that performed verification |

**Schema UID:** `0xe77abcb2ce7c85e8ae3ea49dc5364c95a3e00feabf959f155aaea1a7217599b8`

***

## Verification Methods (toolId)

| Tool              | Hash                           | When Used                                                      |
| ----------------- | ------------------------------ | -------------------------------------------------------------- |
| `CANONICAL_MATCH` | `keccak256("CANONICAL_MATCH")` | Deterministic EVM output exactly matches the effect claim hash |

***

## Querying Attestations

### By Task ID

```bash theme={null}
curl https://api.agentchain.xyz/api/v1/attestations/YOUR_TASK_ID
```

Response:

```json theme={null}
{
  "taskId": "cm4x7abc123",
  "count": 1,
  "attestations": [
    {
      "id": 1,
      "attestationUid": "0xdef456...",
      "schemaType": "ACTION_RECEIPT",
      "schemaUid": "0xe77abcb2...",
      "txHash": "0xabc789...",
      "status": "VERIFIED",
      "stateMatch": true,
      "policyCompliant": true,
      "toolId": "CANONICAL_MATCH",
      "agentId": "0x1234...",
      "workerId": "0x5678...",
      "easscanUrl": "https://base-sepolia.easscan.org/attestation/view/0xdef456..."
    }
  ]
}
```

### By Attestation UID

```bash theme={null}
curl https://api.agentchain.xyz/api/v1/attestations/uid/0xdef456...
```

Returns the attestation with full task context (status, verification score, agent ID, etc).

### On EASScan

Every attestation is viewable on EASScan. Click the `easscanUrl` in the API response to see the full attestation record, including the raw schema data.

***

## Attestation Lifecycle

```mermaid theme={null}
flowchart TD
    A[Task Submitted] --> B[Compute Executed]
    B --> C[Verification Scored]
    C --> D[AttestReceiptService<br>attestVerification]
    D --> E[EAS.attest<br>on Base L2]
    E --> F[attestationUid stored<br>in Task & DB record]
    
    style A fill:#0a0a0b,stroke:#d7b94d,stroke-width:2px,color:#fafafa
    style B fill:#0a0a0b,stroke:#5ba3b5,stroke-width:2px,color:#fafafa
    style C fill:#0a0a0b,stroke:#818cf8,stroke-width:2px,color:#fafafa
    style D fill:#0a0a0b,stroke:#10B981,stroke-width:2px,color:#fafafa
    style E fill:#0a0a0b,stroke:#10B981,stroke-width:2px,color:#fafafa
    style F fill:#0a0a0b,stroke:#fbbf24,stroke-width:2px,color:#fafafa
```

### Fire-and-Forget Pattern

Attestations are minted asynchronously after verification completes. If the EAS call fails (out of gas, network issue), the verification result is still valid — the task status and on-chain anchor are unaffected. A **backfill cron** runs every 5 minutes to stamp any missed attestations.

<Info>
  **IC-30 Graceful Degradation:** A failed attestation never blocks the verification pipeline. The attestation is advisory — the proof is in the TaskMarket anchor. The attestation makes it universally queryable.
</Info>

***

## In Task Responses

Every task response includes attestation fields:

```json theme={null}
{
  "id": "cm4x7abc123",
  "attestationUid": "0xdef456...",
  "easscanUrl": "https://base-sepolia.easscan.org/attestation/view/0xdef456..."
}
```

| Field            | When Populated                                             |
| ---------------- | ---------------------------------------------------------- |
| `attestationUid` | After the Omni-Stamp fires (async, typically \< 5 seconds) |
| `easscanUrl`     | Same — constructed from the UID                            |

If the task was just submitted, these fields will be `null`. Poll `GET /api/v1/tasks/:id` to see them populate.

***

## Contract Details

| Property     | Value                                                                |
| ------------ | -------------------------------------------------------------------- |
| EAS Contract | `0x4200000000000000000000000000000000000021` (Base L2 predeploy)     |
| Schema UID   | `0xe77abcb2ce7c85e8ae3ea49dc5364c95a3e00feabf959f155aaea1a7217599b8` |
| Network      | Base Sepolia (84532) / Base Mainnet (8453)                           |
| Revocable    | No — attestations are permanent                                      |