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Agent-to-agent payments

How two autonomous agents can exchange value end-to-end — no human, no bank account, no API key.

Updated

The invoice protocol makes agent-to-agent payment a two-call operation. Agent A creates an invoice. Agent B pays it. Both sides are autonomous — no human approval, no shared credentials, no out-of-band coordination.

This is the clearest expression of what DPX is for.

How it works

Section titled “How it works”
Agent A                              Agent B
  │                                    │
  ├─ POST /invoice ──────────────────► │  (invoiceId returned)
  │                                    │
  │  ◄── share invoiceId via any channel (message, webhook, shared state)
  │                                    │
  │                         GET /invoice/{id}
  │                                    │  (verify amount + description)
  │                                    │
  │                        POST /invoice/{id}/pay
  │                                    │
  │  ◄── receipt (settlementId, txHash, aiDecision)

No wallet needed for Agent A. No API key needed for Agent B. The compliance screen and oracle gate run automatically at pay time.

MCP — no HTTP wiring needed

Section titled “MCP — no HTTP wiring needed”

If both agents are running with the DPX MCP server:

{
  "mcpServers": {
    "dpx": { "command": "npx", "args": ["-y", "@untitledfinancial/dpx-mcp"] }
  }
}

Agent A:

Create an invoice for $5,000 USD payable to 0x... for data processing services rendered.

Agent B (receives the invoiceId):

Check invoice dpx-inv-abc123 and pay it if the amount and description look legitimate.

REST

Section titled “REST”

Agent A — create invoice

Section titled “Agent A — create invoice”
Terminal window
curl -X POST https://agent.untitledfinancial.com/invoice \
  -H "Content-Type: application/json" \
  -d '{
    "amount": 5000,
    "recipientAddress": "0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045",
    "description": "Data processing services — batch job #2026-0042",
    "currency": "USD",
    "externalReference": "PO-2026-0042",
    "lineItems": [{ "description": "Batch processing, 500K records", "quantity": 1, "unitPrice": 5000 }]
  }'

externalReference and lineItems (added 2026-09-14) are optional — pass your own PO/bill number and structured line items if you want them carried through to reconciliation later (see below). Omit either and the invoice behaves exactly as before.

Response:

{
  "invoiceId": "dpx-inv-abc123",
  "amount": 5000,
  "currency": "USD",
  "description": "Data processing services — batch job #2026-0042",
  "recipientAddress": "0xd8...",
  "externalReference": "PO-2026-0042",
  "lineItems": [{ "description": "Batch processing, 500K records", "quantity": 1, "unitPrice": 5000 }],
  "payUrl": "https://agent.untitledfinancial.com/invoice/dpx-inv-abc123/pay",
  "viewUrl": "https://agent.untitledfinancial.com/widgets/invoice?id=dpx-inv-abc123",
  "status": "pending",
  "expiresAt": "2026-07-25T20:00:00.000Z"
}

viewUrl is a human-readable page — open it in a browser to see the invoice, and after payment, a receipt summary (compliance/oracle detail, transaction link). GET /invoice/{id} itself still returns the machine-readable JSON above for agents parsing it programmatically.

Reconciling a paid invoice against your own records

Section titled “Reconciling a paid invoice against your own records”

Once an invoice is paid, GET /invoice/{id}/reconciliation joins it with the full on-chain settlement record — amounts, fees, tx hash, oracle/ESG attestation at time of settlement — into one export your own AP/ERP system can match against externalReference:

Terminal window
curl https://agent.untitledfinancial.com/invoice/dpx-inv-abc123/reconciliation
{
  "invoiceId": "dpx-inv-abc123",
  "externalReference": "PO-2026-0042",
  "lineItems": [{ "description": "Batch processing, 500K records", "quantity": 1, "unitPrice": 5000 }],
  "reconciled": true,
  "settlement": {
    "settlementId": "dpx_abc123...",
    "txHash": "0x...",
    "txExplorerUrl": "https://base.blockscout.com/tx/0x...",
    "grossAmount": 5000,
    "netAmount": 4917.5,
    "feesTotal": 82.5,
    "token": "USDC",
    "timestamp": "2026-09-14T20:00:00.000Z"
  },
  "complianceAttestation": { "oracleStatus": "STABLE", "oracleScore": 92, "esgScore": 78 }
}

This is a convenience export, not the source of truth — settlement.txExplorerUrl is independently verifiable on-chain. There’s no bulk/CSV export or webhook push on settlement yet; this is a pull-per-invoice endpoint today.

Agent B — pay invoice

Section titled “Agent B — pay invoice”
Terminal window
curl -X POST https://agent.untitledfinancial.com/invoice/dpx-inv-abc123/pay \
  -H "Content-Type: application/json" \
  -d '{
    "payerAddress": "0x1234...",
    "sandbox": true
  }'

Response:

{
  "settlementId": "dpx_abc123...",
  "status": "sandbox",
  "netAmount": 4917.5,
  "aiDecision": "EXECUTE",
  "aiConfidence": 0.96,
  "txHash": null
}

Python — full agent-to-agent loop

Section titled “Python — full agent-to-agent loop”
import httpx


AGENT = "https://agent.untitledfinancial.com"


# Agent A: issue invoice
invoice = httpx.post(f"{AGENT}/invoice", json={
    "amount": 5000,
    "recipientAddress": "0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045",
    "description": "Data processing services — batch job #2026-0042",
    "currency": "USD",
}).json()


invoice_id = invoice["invoiceId"]
print(f"Invoice created: {invoice_id}")


# --- invoiceId passed to Agent B via any channel ---


# Agent B: verify and pay
details = httpx.get(f"{AGENT}/invoice/{invoice_id}").json()
print(f"Amount: ${details['amount']} — {details['description']}")


receipt = httpx.post(f"{AGENT}/invoice/{invoice_id}/pay", json={
    "payerAddress": "0x1234567890123456789012345678901234567890",
    "sandbox": True,
}).json()


print(f"Paid: {receipt['settlementId']}  decision={receipt['aiDecision']}")

With spend policy (multi-agent systems)

Section titled “With spend policy (multi-agent systems)”

When Agent B is a sub-agent operating under an orchestrator’s spend limit, add a policy check before paying:

import httpx


POLICY = "https://policy.untitledfinancial.com"
AGENT  = "https://agent.untitledfinancial.com"


# Orchestrator created this policy; sub-agent received policy_id
policy_id = "pol-xyz789"


# 1. Check policy before paying
check = httpx.post(f"{POLICY}/policy/{policy_id}/check", json={
    "amount": 5000,
    "purpose": "vendor-invoice",
}).json()


if check["decision"] != "APPROVED":
    print(f"Blocked by policy: {check['reason']}")
else:
    # 2. Pay the invoice
    receipt = httpx.post(f"{AGENT}/invoice/{invoice_id}/pay", json={
        "payerAddress": "0x...",
        "sandbox": True,
    }).json()


    # 3. Record against policy ledger
    httpx.post(f"{POLICY}/policy/{policy_id}/record", json={
        "amount": 5000,
        "settlementId": receipt["settlementId"],
        "purpose": "vendor-invoice",
    })
    print(f"Paid and recorded: {receipt['settlementId']}")

What DPX runs automatically at pay time

Section titled “What DPX runs automatically at pay time”

Agent B doesn’t need to run any checks manually. At POST /invoice/{id}/pay DPX runs:

CheckWhat it does
Oracle gateBlocks settlement if global conditions are UNSTABLE
AML screenSanctions + graph risk on both addresses
FATF R16Travel Rule compliance
ESG scoreAdjusts fee based on counterparty ESG score
AI decisionaiDecision: EXECUTE / HOLD / BLOCK with confidence + reasoning

Everything is in the receipt.

Proven live

Section titled “Proven live”

Every step above has been run for real — two independent agent processes, no shared code path between them, settling a real payment on Base mainnet.

Invoice created

{ "invoiceId": "2c846308-9071-4313-9c1a-1f951d6d7be3", "amount": 1, "currency": "USD", "status": "OPEN" }

Settlement authorized — oracle, compliance, and ESG all run automatically at pay time:

{
  "settlementId": "dpx_549e32f44119abdbf95558edea33b0ca",
  "status": "authorized",
  "oracleStatus": "STABLE", "oracleScore": 77,
  "complianceScreen": { "status": "CLEAR", "amlScore": 24 },
  "aiDecision": "EXECUTE", "aiConfidence": 0.98
}

On-chain receipt

StepTx hash
approve()0x962454...c14f1
router.settle()0xd12437...c86d2

Confirmed independently on-chain: the receiving address’s balance increased by the net settlement amount, and the ESG redistribution contract’s balance increased by exactly the ESG fee portion — in the same transaction.

A full runnable version of this flow — two Claude agents, one creating the invoice and one paying it — is in the Claude Cookbooks PR (third_party/DPX/agent_to_agent_invoice.ipynb), pending merge.

Section titled “Related”