A-Comm Evidence Protocol (AEP)

The open evidence standard for agentic commerce.

AI agents now discover products, carry consumer intent, and complete purchases. When one of those transactions is disputed — "I didn't authorize this," "my agent went rogue," "the goods never arrived" — every party in the payment chain needs a trustworthy answer to a single question:

What actually happened in this transaction?

AEP answers it with a sequential, tamper-evident hash chain of typed evidence artifacts covering the full transaction journey:

discovery → referral → intent → delegation → policy → cart → authorization ─┐
                                                              (seal point)  │
                                          fulfillment · refund ← post-seal ─┘

Each artifact is canonicalized (RFC 8785 JCS), SHA-256-linked to its predecessor, and the chain is sealed with an Ed25519 signature at authorization. The result exports as a DisputeBundle: a verifiable, dispute-grade evidence record that any party can independently re-verify.

AEP is a witness, not a competitor

Agentic commerce already has protocols for identity, mandates, checkout, and settlement. AEP wraps them rather than replacing them. The delegation artifact carries sub-wrappers that preserve — verbatim or by digest — the signatures, mandates, tokens, and receipts of the protocols a transaction actually used, together with the key-discovery path that verified each one:

What no wrapped protocol provides — and AEP does — is the durable outcome trail: identity signatures are ephemeral per-request artifacts, mandates prove authorization-time consent, but none of them produce a sealed, independently verifiable record of what was charged, delivered, refunded, and settled. That record is AEP's job.

Who this is for

Reading the specification

• Draft under review — v1.0.3-rc.2 — a single self-contained HTML page in this repo; open it in a browser.
• Prefer it rendered? The living draft is at aep.a-comm.ai; the immutable rc.2 snapshot, with stable section references, is at aep.a-comm.ai/v1.0.3-rc.2.
• Prior published versions (v1.0.x) will be added as tagged releases.

Suggested reading order for engineers: §2 data model → §4 hash chain & sealing → §3.9 delegation wrappers → §5–6 verification & export → §8.6/§8.7 minimal profiles. Implementer quickstarts live in docs/implementers/.

Design principles

1. Protocol-agnostic witness. Record which protocols carried the transaction and how each envelope verified. Never rank, replace, or adjudicate them.
2. Evidence, not liability. Verification classes and evidence tiers describe cryptographic verifiability and composition — nothing more. No network or scheme rule assigns any outcome to an AEP tier, and the absence of a chain implies nothing about a transaction's legitimacy (spec §3.9.12).
3. Two-plane privacy. The chain carries salted hashes; dispute-usable raw values live encrypted with an Evidence Custodian role, disclosed only on documented dispute triggers, with every disclosure logged as a sealed artifact (§8.2.1).
4. Implementable by anyone. Apache-2.0 with an explicit patent grant (see the specification's License.2 section). Conformance is defined by published test vectors (§6.3), not by any vendor's implementation. No fees, no registration, no permission.

Versioning & stability

Strict SemVer for the wire format (spec §0.2). Chains are never re-versioned after creation; verifiers advertise the spec_version set they support; every published version remains verifiable for at least 24 months after the next MAJOR release. Current draft: v1.0.3-rc.2 (additive/MINOR over v1.0.2), open for ecosystem comment.

Participate

• Comment round — the v1.0.3 review process, the open questions we're explicitly seeking input on, and the public disposition log where every comment gets an answer.
• Issues — section feedback and technical issues (templates provided).
• Discussions — normative proposals and design questions.
• CONTRIBUTING.md — ground rules (Apache 2.0 §5, DCO sign-off, neutrality, primary-source citations).
• SECURITY.md — how to report security issues in the specification privately.

License

Apache License 2.0 — see LICENSE and NOTICE. The specification includes an explicit Apache §3 patent grant covering the AEP wire format, hash-chain construction, signal classification, and evidence-tier ranking. The names "A-Comm Evidence Protocol" and "AEP" are generic identifiers for this specification and are not trademarked.

Repository layout

spec/                     The specification (self-contained HTML, one file per version)
vectors/                  Conformance test vectors (§6.3) — publication gates v1.0.3-final
docs/implementers/        Role-based quickstarts (merchant, agent platform, PSP/acquirer)
COMMENT-ROUND.md          Review process + public disposition log
CONTRIBUTING.md           DCO, neutrality rules, proposal process
GOVERNANCE.md             Maintainer model and standards-body trajectory
SECURITY.md               Private security reporting