Chain Stages · 2 Steps · Linear (no decision gates)

1 ROOT node

AP2 CartMandate Hash-Chain Builder art-595-ap2-cartmandate-hashchain-builder

cart_root, cart_items, and merchant are the CartMandate fields the correlation step checks against a caller-supplied x402_spend_evidence pack.

MCP Call · build_ap2_cartmandate_hashchain

{
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "name": "build_ap2_cartmandate_hashchain",
    "arguments": {
      "agent_id": "did:example:agent-001",
      "subject": "did:example:user-042",
      "merchant": "0x2a1530c4c41db0b0b2bb646cb5eb1a67b7158667",
      "stage": "open",
      "cart_items": [
        { "sku": "SKU-100", "description": "Widget", "quantity": 2, "unit_price": 9.99, "currency": "USD" },
        { "sku": "SKU-200", "description": "Gadget", "quantity": 1, "unit_price": 24.5, "currency": "USD" }
      ]
    }
  },
  "id": 1
}

↓

2 TERMINAL node

🔗 second input: x402_spend_evidence pack (from the x402-spend-evidence chain)

AP2 x402 Cart Correlation art-596-ap2-x402-cart-correlation

independently re-derives cart_chain_intact from cart_items and cart_root, then checks the cart total and merchant against the x402_spend_evidence pack's authorization.value and authorization.to, reporting CORRELATION_STATUS.

MCP Call · correlate_ap2_cartmandate_x402

{
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "name": "correlate_ap2_cartmandate_x402",
    "arguments": {
      "cart_root": "0x2eeb01a35e5facd325ab3b60ba97fe4d26222584419fdf93106d3ca3575729fb",
      "cart_items": [
        { "sku": "SKU-100", "description": "Widget", "quantity": 2, "unit_price": 9.99, "currency": "USD" },
        { "sku": "SKU-200", "description": "Gadget", "quantity": 1, "unit_price": 24.5, "currency": "USD" }
      ],
      "merchant": "0x2a1530c4c41db0b0b2bb646cb5eb1a67b7158667",
      "x402_spend_evidence": {
        "authorization": {
          "from": "0x2a1530c4c41db0b0b2bb646cb5eb1a67b7158667",
          "to": "0x2a1530c4c41db0b0b2bb646cb5eb1a67b7158667",
          "value": "44.480000000000004",
          "validAfter": "0",
          "validBefore": "2000000000",
          "nonce": "0x0000000000000000000000000000000000000000000000000000000000000001"
        },
        "digest": "0xb68e5d60d6169bad9739d30399af8f8c7378d464d25f4d971911ab65ef0b014b",
        "verdict": "AUTHORIZATION_VALID",
        "disclosure": "ev"
      }
    }
  },
  "id": 2
}

Illustrative correlation_status · §8 field shape

A worked composition of the two steps' fields above into the terminal step's output_payload shape. This preview is a static illustration reproduced from the kernel's own golden fixture vector (correlated-chain-intact-total-match-merchant-match); a caller assembles the live object itself from its two actual tool responses; the chain execution model does not pipe one step's output into the next (see the note above).

{
  "correlation_status": "CORRELATED",
  "cart_total_matches_authorization_value": true,
  "merchant_matches_authorization_to": true,
  "cart_chain_intact": true,
  "disclosure": "This tool observes that the cart total and merchant identity are consistent with the x402 authorization's amount and recipient. It does not cryptographically bind the two: no signature, hash, or on-chain reference ties this specific CartMandate to this specific x402 authorization. A party could present a valid CartMandate alongside an unrelated valid x402 authorization and this check would still report CORRELATED.",
  "reasons": []
}