Agent Payment Event (APE) v0.1

An open, rail-neutral record of one AI agent payment: which agent paid, for whom, on whose instruction, on which rail, and the network proofs that came with it.

• Schema: ape/v0.1.json, JSON Schema 2020-12. Canonical URL: https://schema.halvorai.com/ape/v0.1.json.
• Fields: docs/FIELDS.md, generated from the schema.
• Mappings to AP2, Mastercard Verifiable Intent, Visa Trusted Agent Protocol, x402 v2, MPP and Stripe: docs/MAPPINGS.md.
• Examples: examples/: x402 settled, Stripe Issuing authorization with AP2 and TAP evidence, Stripe failed payment.

Design goals

1. Rail-neutral: one event shape for card, Stripe, x402, MPP, stablecoin and bank transfer payments.
2. Attributed: every event names the agent, the owner it acts for, and the instruction it acted on.
3. Evidence travels with the payment: network proofs are attached verbatim so any party can verify them later.
4. No spend limits of its own: mandate constraints come from the network credential.
5. Tamper-evident: producers sign each event; receivers chain them.
6. Privacy by default: instructions are a hash plus an optional redacted summary; card numbers never appear.

Validate an event

import Ajv2020 from 'ajv/dist/2020.js';
import addFormats from 'ajv-formats';
import schema from './ape/v0.1.json' with { type: 'json' };

const ajv = new Ajv2020({ strict: false });
addFormats(ajv);
const validate = ajv.compile(schema);

if (!validate(event)) console.error(validate.errors);

JSON Schema cannot express every rule. Receivers must also reject an event whose free-text fields contain a possible card number (a Luhn-valid run of 13 to 19 digits). docs/FIELDS.md lists exactly which fields are free text.

conformance/ holds events every implementation must accept or reject, plus signing and canonical-JSON test vectors. SDKs and receivers should run them in their own tests.

Signing

An envelope is { "event": { ... }, "sig": "<detached JWS>" }. The JWS header is {"alg":"EdDSA","kid":"<source id>","typ":"ape+jws","ape":"0.1"} and the payload is the RFC 8785 (JCS) canonical form of event, detached per RFC 7515 Appendix F.

Versioning

ape_version is MAJOR.MINOR. Minor versions only add optional fields, and receivers pick the schema by ape_version. Within a version, unknown top-level fields and unknown rail_ref keys are rejected; keys inside labels and evidence[].value are open, and receivers ignore the ones they do not use. v0.x may change between minors until v1.0.

The sha256 values in the examples are placeholders; real events carry the digest of their evidence value.

Feedback

Open an issue, or write to hello@halvorai.com. Open questions for reviewers are in the issue tracker.

License

Apache-2.0. See LICENSE.