{
  "$id": "https://schema.nfh.global/RequestDigest/v2.0",
  "x-iri": "https://schema.nfh.global/RequestDigest/v2.0",
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "title": "Request Payload Digest",
  "description": "A cryptographic binding that explicitly ties a callback to the specific inbound request that triggered it. Establishes bilateral non-repudiation for the asynchronous leg of a Beckn interaction.  Use `lineage` (on `Context`) for cross-transaction causality.  Verification steps: 1. Recompute BLAKE2b-512 digest of the original request body; compare to `digest`. 2. Confirm `messageId` matches the `messageId` from the original request `Context`.",
  "type": "object",
  "required": [
    "digest"
  ],
  "properties": {
    "digest": {
      "type": "string",
      "pattern": "^BLAKE-512=[A-Za-z0-9+/]+=*$",
      "description": "BLAKE2b-512 hash of the parent request body, Base64-encoded with algorithm prefix. Format: `BLAKE-512={base64EncodedHash}`"
    }
  }
}