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DPX DPX Docs

Agent-to-agent payments

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"
  }'

Response:

{
  "invoiceId": "dpx-inv-abc123",
  "amount": 5000,
  "currency": "USD",
  "description": "Data processing services — batch job #2026-0042",
  "recipientAddress": "0xd8...",
  "payUrl": "https://agent.untitledfinancial.com/invoice/dpx-inv-abc123/pay",
  "status": "pending",
  "expiresAt": "2026-07-25T20:00:00.000Z"
}

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.

Section titled “Related”