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

# Receipts

> Cryptographic receipts with Merkle Mountain Range proofs

# Receipts

Every AI inference in Lucid generates a **cryptographic receipt** — an immutable proof that the computation happened.

## What's in a Receipt?

| Field            | Description                                   |
| ---------------- | --------------------------------------------- |
| `id`             | Unique receipt identifier                     |
| `run_id`         | The inference run that generated this receipt |
| `input_hash`     | SHA-256 hash of the input                     |
| `output_hash`    | SHA-256 hash of the output                    |
| `model_passport` | Passport ID of the model used                 |
| `signature`      | Ed25519 signature from session signer         |
| `mmr_position`   | Position in the Merkle Mountain Range         |
| `epoch_id`       | The epoch this receipt belongs to             |

## Create & Verify

```typescript theme={null}
// Receipts are created automatically during inference
// You can also create them manually:
const receipt = await lucid.receipts.create({
  runId: "run_abc123",
  inputHash: "sha256:...",
  outputHash: "sha256:...",
  modelPassport: "passport_xyz"
});

// Verify a receipt
const verification = await lucid.receipts.verify(receipt.id);
console.log("Valid:", verification.valid);
console.log("Signature verified:", verification.signatureValid);
console.log("MMR proof verified:", verification.proofValid);
```

## Merkle Proof

Get the inclusion proof for a receipt:

```typescript theme={null}
const proof = await lucid.receipts.proof(receiptId);
console.log("Root:", proof.root);
console.log("Path:", proof.path);
console.log("Position:", proof.position);
```

## Verify by Hash

```typescript theme={null}
const result = await lucid.verify.byHash("sha256:abc123...");
```