Protocol

ACK

Agent Commerce Kit

The seller-signed Payment Request takes the ATR hash as its id. Source: lcp docs: agentic checkouts⁠ (opens in a new tab) The Agentic Transaction Record (ATR) is one record of exactly what was agreed, for one transaction. Its ATR hash, the ATR’s fingerprint, is the proof bound to the transaction: change one byte of the ATR and it no longer matches. Source: lcp docs: the ATR⁠ (opens in a new tab) · Source: lcp docs: the ATR hash⁠ (opens in a new tab)

ACK, the Agent Commerce Kit, is a Catena Labs project. Source: LCP §C.10⁠ (opens in a new tab) Integra is not affiliated; we read their published interfaces.

lcp docs: agentic checkouts⁠ (opens in a new tab) · lcp docs: the ATR⁠ (opens in a new tab) · lcp docs: the ATR hash⁠ (opens in a new tab) · LCP §C.10⁠ (opens in a new tab)

The protocol’s own site⁠The standard’s illustration of this protocol (LCP §C.10)⁠

ACK

Agent identity and payments

The seller’s signed Payment Request: Its id is the ATR hash.

What it is

ACK is an open-source set of patterns and building blocks for agent identity and payments, built on W3C standards: ACK-ID for verifiable agent identity, ACK-Pay for payment flows and receipts. Source: LCP §C.10⁠ (opens in a new tab)

LCP §C.10⁠ (opens in a new tab)

Where the ATR hash rides

The payment request the seller signs has the ATR hash as its id.

Exhibit Where it rides, in the protocol’s and the package’s terms

What a payment through it proves

Each pairing’s record states what a payment through it shows, and what it does not, in the package’s own words. These are read from the package when the site is built. Source: lcp docs: pairings reference⁠ (opens in a new tab)

On this pairing, the buyer’s signature does not cover the ATR hash, the payment does not leave a public proof of it, and no one can read it back from the chain alone. Source: lcp docs: pairings reference⁠ (opens in a new tab)

Switch to Technical to see each pairing, and the sentence its record states about what a payment through it proves.

lcp docs: pairings reference⁠ (opens in a new tab)

Exhibit Each pairing’s record

The package

Pattern: native-field, the package’s name for it
What a payment through it proves: Before this payment, the buyer signed and paid an agreement transaction carrying this ATR's hash on <network>, recorded in <transaction>. This ATR's hash is the id of the seller's ACK Payment Request token, with the link beside it; a receipt for that request embeds the token. The token's signature is not verified here. ACK defines no payer signature, so nothing the buyer signed carries the hash, and settlement is the seller's report. This does not show that the buyer's approval carried the hash.
LCP profile: ack/payment-request⁠ (opens in a new tab)

Where a sentence names <network> and <transaction>, the pairing’s record fills them in: they name the agreement payment the buyer made first. Source: lcp docs: pairings reference⁠ (opens in a new tab) · Source: lcp docs: the agreement URL⁠ (opens in a new tab)

The rails it settles on

A checkout through this protocol is paid by the provider the checkout names, so it lists no rail of its own.

Ready to see your own agreements proved?

Tell us what you sell, buy or carry, and we will show you where the agreement rides in it.

Integra Binder, hosted by Integra, does the seller’s side of each agreement and is free on test networks, with test-network USDC.

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