MPCP Artifact Bundle

Overview

An artifact bundle is a canonical JSON format that packages complete MPCP payment verification data for exchange between systems. It standardizes how settlement verification inputs are packaged for:

• dispute resolution workflows
• deterministic protocol test vectors
• developer tooling and debugging
• audit trails and compliance

Bundle Format

The bundle is a JSON object with artifact-keyed fields.

Full settlement bundle (Trust Gateway and audits)

Field	Type	Required	Description
policyGrant	object	yes	Full PA-signed PolicyGrant
sba	object	yes	SignedBudgetAuthorization
settlement	object	yes	Executed settlement result (XRPL txHash + memo)

Merchant-minimal bundle (privacy)

Bundles MAY omit policyGrant when using gateway-only PolicyGrant presentation. Verifiers MUST follow SBA-only merchant context and MUST NOT claim PolicyGrant PA signature verification.

Optional fields

Field	Type	Description
ledgerAnchor	object	On-chain attestation (e.g. HCS anchorRef; XRPL grant liveness via Credentials per PolicyGrant)
policyGrantPublicKeyPem	string	PolicyGrant signing public key PEM — makes bundle self-contained
sbaPublicKeyPem	string	SBA signing public key PEM — makes bundle self-contained

When policyGrantPublicKeyPem and sbaPublicKeyPem are present, verification can run without the corresponding environment variables.

Example

{
  "policyGrant": {
    "grantId": "grant-1",
    "policyHash": "a1b2c3",
    "expiresAt": "2030-12-31T23:59:59Z",
    "allowedRails": ["xrpl"],
    "allowedAssets": [{ "kind": "IOU", "currency": "RLUSD", "issuer": "rIssuer" }],
    "budgetMinor": "50000",
    "budgetEscrowRef": "xrpl:escrow:rGateway:12345",
    "authorizedGateway": "rGateway...",
    "issuer": "did:web:operator.example.com",
    "issuerKeyId": "policy-auth-key-1",
    "signature": "..."
  },
  "sba": {
    "authorization": {
      "grantId": "grant-1",
      "maxAmountMinor": "780",
      "budgetScope": "SESSION",
      "allowedRails": ["xrpl"],
      "allowedAssets": [{ "kind": "IOU", "currency": "RLUSD", "issuer": "rIssuer" }]
    },
    "issuer": "did:web:fleet.example.com",
    "issuerKeyId": "budget-auth-key-1",
    "signature": "..."
  },
  "settlement": {
    "txHash": "ABC123...",
    "rail": "xrpl",
    "amount": "780",
    "asset": { "kind": "IOU", "currency": "RLUSD", "issuer": "rIssuer" },
    "destination": "rDestination",
    "grantId": "grant-1",
    "nowISO": "2026-01-15T12:00:00Z"
  },
  "policyGrantPublicKeyPem": "-----BEGIN PUBLIC KEY-----\n...",
  "sbaPublicKeyPem": "-----BEGIN PUBLIC KEY-----\n..."
}

Verifier Support

The MPCP CLI accepts artifact bundles as input:

mpcp verify settlement-bundle.json
mpcp verify settlement-bundle.json --append-log audit.jsonl

Schema

The bundle format is defined by artifactBundleSchema in src/schema/artifactBundle.ts. Each nested artifact conforms to its respective MPCP schema (PolicyGrant, SignedBudgetAuthorization, SettlementResult).

Note: ledgerAnchor is currently loosely typed (generic object) in the schema. It will be formalized with a strict schema in a later update.