{
  "tool_id": "art-564-ucp-checkout-payload-lint",
  "tool_version": "1.0.0",
  "display_name": "UCP Checkout Payload Lint",
  "mcp_name": "lint_ucp_checkout_payload",
  "mandate_type": "compliance_mandate",
  "wave": 92,
  "gpu": false,
  "url": "https://ainumbers.co/chaingraph/art-564-ucp-checkout-payload-lint.html",
  "description": "Deterministic, verify-only structural lint of a caller-supplied Universal Commerce Protocol (UCP; Google + Shopify, announced NRF 2026-01-11, Apache-2.0 spec on GitHub) checkout resource against the schema pinned at tag v2026-04-08 of github.com/Universal-Commerce-Protocol/ucp. Checks the resource-level required[] field set, the status enum, ISO 4217 currency form, integer minor-unit amounts, and the exactly-one-subtotal / exactly-one-total cardinality rule on totals[]. Verdict CONFORMANT | NONCONFORMANT | UNKNOWN_VERSION: a payload declaring a UCP version outside the pinned allowlist is capped at UNKNOWN_VERSION regardless of otherwise-clean structure, never upgraded to CONFORMANT for a version this kernel has no pinned rules for. Never contacts a UCP or ACP endpoint and never fetches a live spec version -- the caller supplies the payload. UCP composes with AP2 rather than competing with it; part of the agentic-commerce-convergence chain alongside art-12 (ACP checkout conformance) and art-01 (AP2 mandate-chain validator).",
  "input_schema_ref": "chaingraph/art-564-ucp-checkout-payload-lint.html#manifest",
  "consumes": [],
  "feeds": [],
  "status": "live",
  "conformance_fixtures": true,
  "compute_capability": "server",
  "compute_images": [
    {"system":"sha256-source","image_id":"sha256:828c4890e7f551a049a00ccacf21c33350300f9b10d047e2d05904d0f97e5c62","valid_from":"2026-08-06"},
    {"system":"risc0","image_id":"sha256:a1a0bc89b5b1febaeda3519f6dbade0fa5ac16beeb143c4e1b01689573567bc6","valid_from":"2026-08-07"}
  ],
  "export_capability": [
    "json"
  ],
  "compute_proof_ready": "ready",
  "compute_proof": {
    "type": "ZkVmReceipt",
    "system": "risc0",
    "receiptFormat": "groth16-bn254",
    "imageId": "sha256:a1a0bc89b5b1febaeda3519f6dbade0fa5ac16beeb143c4e1b01689573567bc6",
    "seal": "AL7oz56T9R3dWfHvO0z6DgdMo8xd0C9QloG+Kb/aAGYUKucatFLhLkt4gf+Ao5FC3hfA6IiDaCnYTc4ezht8UAoBQnUE6TSslpAZx7AFUnTBWXH5Cv5YGtSjV0UksdyiFfeHtYegI/Mc79dXTg6PwYrA8Fm1s2ddBnMWoKLmJ54F6nZTSX4IOJ0NRhuLdLWwZ3doP9JINjkplpiEJ4OryibNDTTaU1m4LcIvIVYpTIpgNvVI52H0EPfaqH1Rty0FCPezWfAkNXs1Jz308bhleAD/12IjijDe9EZwgXcJqSEGWgezCcaNOgRcnN+tmHFg5fzJgMZgH/qxZlwnp8AKWg==",
    "journal": {
      "chaingraph_version": "0.4.0",
      "kernel_digest": "sha256:828c4890e7f551a049a00ccacf21c33350300f9b10d047e2d05904d0f97e5c62",
      "output": {
        "error_count": 0,
        "finding_count": 0,
        "findings": [],
        "note": "Deterministic, verify-only structural lint of a caller-supplied UCP checkout resource against the schema pinned at tag v2026-04-08 of github.com/Universal-Commerce-Protocol/ucp. Never fetches a live spec version and never contacts a UCP/ACP endpoint. UCP composes with AP2 (Google developer blog) and is not presented here as a competitor to ACP or AP2.",
        "rationale": [
          "Pinned schema: UCP v2026-04-08 source/schemas/shopping/checkout.json (https://github.com/Universal-Commerce-Protocol/ucp/tree/v2026-04-08/source/schemas/shopping/checkout.json).",
          "payload declares UCP version 2026-04-08, within the pinned allowlist.",
          "0 error-severity finding(s), 0 warning-severity finding(s) against the pinned checkout resource shape.",
          "This lints a full checkout RESOURCE against the schema's resource-level required[] set, not a partial create/update/complete request body (the schema's narrower ucp_request per-verb profile is out of scope).",
          "Verify-only: never contacts a UCP or ACP endpoint; the caller supplies the payload."
        ],
        "ucp_spec_pinned_tag": "v2026-04-08",
        "ucp_spec_source": "https://github.com/Universal-Commerce-Protocol/ucp/tree/v2026-04-08/source/schemas/shopping/checkout.json",
        "ucp_version_declared": "2026-04-08",
        "verdict": "CONFORMANT",
        "warning_count": 0
      }
    }
  }
}