Agentic Payment Verification

Section 01

Why agentic payment verification

Autonomous payment agents introduce a hard problem: an agent spends money without a human in the loop to eyeball each transaction. Whoever receives the funds needs proof that the payment was intended, well-formed, and actually completed, without asking you to copy personal data onto someone else's stack.

AffixIO solves this with cryptographic proofs that are zero-PII, replay-safe, and machine-verifiable. The agent's host holds the record, runs the proof locally, and signs the outcome with ML-DSA-65 (FIPS 204). The recipient can verify the verdict, or attach it to a payment intent that the provider can audit: no PAN, name, address, or DOB ever crosses the wire.

• Zero-PII: only hashes and binary verdicts travel; the underlying record stays on your host.
• Replay-safe: spend journal, Merkle leaf, and intent binding make a proof impossible to reuse on another transaction.
• Machine-verifiable: a yes / no with signed evidence that another agent or platform can check autonomously.
• Post-quantum: ML-DSA-65 (FIPS 204) signatures, so the proof survives a future quantum attacker.

Section 02

Where to wire AffixIO in

There are three natural integration points in an agentic payment flow. Each yields a different data footprint and calls a different AffixIO method:

Initialise the SDK

import { AffixSDK, createAgentTrust } from "affixio";

const sdk = new AffixSDK({ apiKey: process.env.AFFIX_API_KEY });

// optional: enrolthe agent so its capability spec binds to its identity
const trust = createAgentTrust({ apiKey: process.env.AFFIX_API_KEY });
await trust.enrol({
  agentId: "agent://procurement/prod",
  capabilities: [{ action: "pay.intent.create", resource: "afp://acme.com/v1/*" }],
});

What this proves: the SDK initialised with a Hub licence key, and any agent is enrolled with a signed capability spec, the baseline for trust, before any money moves.

Section 03

How to implement: step by step

Wire the SDK into your agent's payment path in five steps. Each block gives the code, then a "what this proves" note the jan auditor can read.

npm install affixio
npx affixio set-key --api-key aio_your_key

const sdk = new AffixSDK({
  apiKey: process.env.AFFIX_API_KEY,
  apiBase: "https://api.affix-io.com",
  mode: "auto", // offline | auto | online
});

const intentProof = await sdk.prove({
  mode: "offline",
  circuitId: "simple_yesno",
  fields: {
    claim: "intent",
    intentId: "afp_7721",
    amount, "420.00",
    payee: "supplier://acme.com",
    required: "intent",
  },
});

// attach the signed proof to the provider transaction
await provider.charge({
  idempotencyKey: intentProof.proof_id,
  proof: intentProof.envelope,
});

// attach the proof envelope to the provider call
const resp = await provider.createIntent({
  amount: 420.00,
  currency: "GBP",
  idempotencyKey: intentProof.proof_id,
  proof: intentProof.envelope, // zero-PII carrier
  agentCredential: trustCredential,
});

// forward a signed receipt to the merchant side for audit
await merchant.webhook.post("/verify", {
  proof: resp.envelope,
  ref: resp.txn_ref,
});

const check = await sdk.verifyLocal(
  "simple_yesno",
  resp.proof.proof,
  { envelope: resp.proof.envelope }
);

if (!check.valid) throw new Error("Rejected by replay-safe proof");

// optional: anchor the leafonthe Merkle audit trail
const leaf = buildMerkleTree([resp.proof.proof_digest]);

import requests

r = requests.post(
    "https://api.affix-io.com/v1/verify",
    json={"proof": proof_envelope, "circuit": "simple_yesno"},
    headers={"Authorization": "Bearer " + api_key},
)
if r.json()["valid"] is not True:
    raise SystemExit("proof rejected")
print("verified:", r.json()["decision"])

Section 04

3D interactive example

A lightweight Three.js scene that moves a payment token between an autonomous agent node and a payment provider node. Click the boxes to simulate a payment; toggle between running without Affix (red, unverified, PII-style risk) and with Affix (green, verified). A static fallback image loads when WebGL or reduced motion is unavailable.

Accessibility: the scene degrades gracefully. If WebGL is absent, the static SVG diagram remains; keyboard users can press Enter / Space on the mode toggles, and screen readers get a textual status line. Reduced motion shows the static frame instead of the animation.

Section 05

Examples and use cases

Three concrete patterns: procurement, refunds, and marketplace split payments. Each follows the same five-step wiring: intent, generation, attach, verify.

Section 06

FAQ / troubleshooting

Common questions when wiring AffixIO into agentic payments. Each answer is linkable via its anchor id.