@integraledger/terms

The buyer gate for agents that pay: before your wallet signs anything, it confirms that the record a seller serves hashes to the value the payment will carry, and builds the payment with that hash.

npm install @integraledger/terms @integraledger/lcp

What it is

A seller that follows the Legal Context Protocol publishes the agreement's record, an Agentic Transaction Record (ATR), at an https link, and advertises its hash beside the payment request. The payment your agent signs carries that hash, so paying is agreeing to that exact record.

That only holds if the hash in the payment is the hash of the record you can read. This package is the check that makes sure it is. It fetches the record, computes its SHA-256, compares it with what the seller advertised, and only on a match hands your signer a request built with that hash. After your signer answers, it reads the hash back out of what was signed and returns the payment only if it is still the hash of the bytes you received.

It runs in your process, with your HTTP client and your signer. It holds no keys, moves no funds, and never reads the record's content: what the record says is for you and your principal to judge.

Key concepts

• Agentic Transaction Record (ATR): the agreement's record, a JSON document the seller serves.
• ATR hash (H): SHA-256 over the ATR's exact bytes, 0x and 64 hex digits. It is computed over the bytes as received, never over a parsed and re-serialised copy.
• Legal Context Protocol (LCP): the pattern this package implements: the payment carries H, so paying is agreeing to that exact record.
• Pairing: a payment protocol, scheme and rail combination, such as x402/exact/eip155/eip3009.
• Binding: how H rides in a pairing's payment, the field its specification defines. For x402/exact/eip155/eip3009 it is the EIP-3009 nonce. Bindings are exported by @integraledger/lcp, one per pairing.
• Buyer gate: this package: the buyer-side check that compares the served bytes with H before anything is signed.
• Seller: the party serving the resource.
• Facilitator: the x402 role that verifies and settles. The gate never talks to one: it returns the payment to you.
• Vectors: the shared test cases that fix the rules byte for byte across languages. This package and the Python gate, integraledger-terms, pass the same ones.

Install

npm install @integraledger/terms @integraledger/lcp

• Node.js >=26.10.0. ESM only.
• @integraledger/lcp is a dependency of this package; install it beside it to import the bindings you pass in.
• Chain libraries (@solana/kit, @stellar/stellar-sdk and others) are optional peers of @integraledger/lcp, needed only by the pairings that use them.

Quickstart

The seller answered with an x402 402 Payment Required whose PAYMENT-REQUIRED document advertises H and the link. This example pays it with viem as the wallet. It uses the ATR, the document and the payer key of the shared vectors, and a local stand-in for the network, so it runs offline and prints the same values every time.

import { transact, type Fetch, type Signer } from "@integraledger/terms";
import { exactEip3009, type Eip3009Payment } from "@integraledger/lcp/x402";
import { privateKeyToAccount } from "viem/accounts";

// The ATR, exactly as the seller's link serves it. The gate hashes these bytes and never parses them.
const atr = new TextEncoder().encode(
  '{"atrVersion":"1","id":"0f8fad5b-d9cb-469f-a165-70867728950e","x402":{"z":1.0,"a":"caf\\u00e9"},"seller":{"note":"Café — 30 días ✓"}}',
);
const H = "0x8b1e122580ae3f6a8c3d36a24294e1260a87bde70f597279b973e39310072938";
const link = `https://atr.seller.example/${H}`;

// The seller's x402 payment request, advertising H and the link.
const offer = {
  x402Version: 2,
  resource: { url: "https://api.seller.example/v1/quote" },
  accepts: [
    {
      scheme: "exact",
      network: "eip155:84532",
      amount: "10000",
      asset: "0x036CbD53842c5426634e7929541eC2318f3dCF7e",
      payTo: "0x209693Bc6afc0C5328bA36FaF03C514EF312287C",
      maxTimeoutSeconds: 60,
      extra: { name: "USDC", version: "2" },
    },
  ],
  extensions: {
    legalContext: { info: { type: "sha256", value: H, legalContextUrl: link }, schema: {} },
  },
};

// A stand-in for the network: the link serves the ATR. In production, pass globalThis.fetch.
const fetch: Fetch = async (url) => (url === link ? new Response(atr) : new Response(null, { status: 404 }));

// The published Anvil development key. Never use it for real funds.
const wallet = privateKeyToAccount("0xac0974bec39a17e36ba4a6b4d238ff944bacb478cbed5efcae784d7bf4f2ff80");
const signer: Signer = {
  account: `eip155:84532:${wallet.address}`,
  async sign(request) {
    if (request.kind !== "eip712") throw new Error(`this wallet signs EIP-712 only, not ${request.kind}`);
    return wallet.signTypedData(request.typedData as Parameters<typeof wallet.signTypedData>[0]);
  },
};

const result = await transact(offer, exactEip3009, signer, fetch);
if ("decline" in result) throw new Error(`${result.decline.code}: ${result.decline.detail}`);
if ("approve" in result) throw new Error("this pairing pays no agreement first");

const payment = result.signed as Eip3009Payment;
console.log("H           ", result.h);
console.log("signed nonce", payment.payload.authorization.nonce);
console.log("kept bytes  ", result.bytes.length);

// x402 over HTTP sends the payment as base64 of its JSON, in the PAYMENT-SIGNATURE header.
const header = btoa(JSON.stringify(result.signed));
console.log("header      ", header.length > 0 ? "ready" : "empty");

H            0x8b1e122580ae3f6a8c3d36a24294e1260a87bde70f597279b973e39310072938
signed nonce 0x8b1e122580ae3f6a8c3d36a24294e1260a87bde70f597279b973e39310072938
kept bytes   138
header       ready

The nonce your wallet signed is the hash of the 138 bytes the link served. Keep result.bytes with the payment: they are your copy of the record.

If the link had served one byte more, less or different, transact would have returned { decline: { code: "hash-mismatch", … } } and never called the signer.

How it works

sequenceDiagram
    participant A as Your agent
    participant G as Buyer gate
    participant S as Seller
    participant W as Your signer
    A->>G: confirm(offer, binding, account, fetch)
    G->>S: GET the link (https, identity coding, no redirect, at most 1 MiB, 10 s)
    S-->>G: The ATR's bytes
    G->>G: SHA-256(bytes) equals H?
    G-->>A: The signing request, built with H
    A->>W: sign(request)
    W-->>A: The signature
    A->>G: finish(bytes, chosen, signature)
    G-->>A: The payment, only when what was signed carries H

1. Read. The pairing's binding reads the seller's document: H, the link, and the payment options.
2. Compare. The gate fetches the link once and hashes the bytes it received. No match: a decline, and no signer call.
3. Build. On a match, the gate builds the payment with the hash it computed, not the string the seller advertised.
4. Finish. The gate joins your signer's answer, reads H back out of what was signed, and returns the payment only when it is the hash of the compared bytes.

Every function returns a value, never throws for a protocol outcome: either its result, or { decline: { code, detail } }.

Guides

Pay in one call: transact

transact(doc, binding, signer, fetch, options?) runs the whole order: compare, pay the agreement your agent approved where the pairing needs one, sign, finish. Its result is:

| Member | What it is | | --- | --- | | signed | The payment to send, in the protocol's own form. null when the pairing gives the buyer nothing to sign. | | bytes | The ATR's exact bytes: your copy of the record. | | h | Their SHA-256. | | agreement | The agreement's receipt, where the pairing needs an agreement payment. | | landed | A landed receipt to keep beside the payment, for the few pairings that return one. |

Where the pairing needs an agreement payment that is not yet recorded, the result is instead { approve, bytes, h }, and nothing has been signed: see Pay the agreement first.

options takes:

| Member | What it is | | --- | --- | | inputs | The buyer's own values a build needs, such as a recent blockhash. | | agreementSigner | The wallet that pays the agreement, where it is not signer. | | approved | The agreement payment your agent approved, exactly as a previous call returned it in approve. | | signal | An AbortSignal that ends the agreement exchange. |

Any other member, or a member of the wrong kind, is declined before any fetch.

Sign elsewhere: confirm, then finish

When the key lives in a hardware wallet or a signing service, split the order. chosen is plain JSON, so it crosses process boundaries with the bytes:

import { confirm, finish, type Fetch } from "@integraledger/terms";
import { exactEip3009, type Eip3009Payment } from "@integraledger/lcp/x402";
import { privateKeyToAccount } from "viem/accounts";

const atr = new TextEncoder().encode(
  '{"atrVersion":"1","id":"0f8fad5b-d9cb-469f-a165-70867728950e","x402":{"z":1.0,"a":"caf\\u00e9"},"seller":{"note":"Café — 30 días ✓"}}',
);
const H = "0x8b1e122580ae3f6a8c3d36a24294e1260a87bde70f597279b973e39310072938";
const link = `https://atr.seller.example/${H}`;
const offer = {
  x402Version: 2,
  resource: { url: "https://api.seller.example/v1/quote" },
  accepts: [
    {
      scheme: "exact",
      network: "eip155:84532",
      amount: "10000",
      asset: "0x036CbD53842c5426634e7929541eC2318f3dCF7e",
      payTo: "0x209693Bc6afc0C5328bA36FaF03C514EF312287C",
      maxTimeoutSeconds: 60,
      extra: { name: "USDC", version: "2" },
    },
  ],
  extensions: { legalContext: { info: { type: "sha256", value: H, legalContextUrl: link }, schema: {} } },
};
const fetch: Fetch = async (url) => (url === link ? new Response(atr) : new Response(null, { status: 404 }));

// 1. Compare, and build the request with H.
const confirmed = await confirm(offer, exactEip3009, "eip155:84532:0xf39Fd6e51aad88F6F4ce6aB8827279cffFb92266", fetch);
if ("decline" in confirmed) throw new Error(confirmed.decline.code);
if (confirmed.request === null || confirmed.request.kind !== "eip712") throw new Error("expected an EIP-712 request");

// What crosses to the signing side and back: plain JSON and the bytes.
const handOff = JSON.stringify({ chosen: confirmed.chosen, atr: Buffer.from(confirmed.bytes).toString("base64") });

// 2. Sign exactly the request, elsewhere. The published Anvil development key; never use it for real funds.
const wallet = privateKeyToAccount("0xac0974bec39a17e36ba4a6b4d238ff944bacb478cbed5efcae784d7bf4f2ff80");
const signature = await wallet.signTypedData(
  confirmed.request.typedData as Parameters<typeof wallet.signTypedData>[0],
);

// 3. Finish from what came back. finish recomputes H from the bytes; it trusts nothing it did not rebuild.
const back = JSON.parse(handOff);
const done = await finish(new Uint8Array(Buffer.from(back.atr, "base64")), back.chosen, signature, exactEip3009);
if ("decline" in done) throw new Error(done.decline.code);
if ("next" in done) throw new Error("this pairing signs in one step");

console.log("nonce is H:", (done.signed as Eip3009Payment).payload.authorization.nonce === H);

nonce is H: true

A pairing signed in two steps (a channel funding, then its first voucher) makes finish return { next, h }: sign next and call finish again with every answer so far, in order, as a list. transact does this for you.

Pay the agreement first

Some payments are not a public proof of H: a card charge, a Stripe payment, a Lightning invoice, a checkout in which the buyer signs nothing. For those pairings the seller's offer also names an agreement URL, an x402 resource for the same H whose payment is a public proof. The agreement payment is a payment like any other, so your agent approves it before anything is signed:

1. transact fetches the agreement URL's payment request and returns { approve, bytes, h }, signing nothing. approve.option is the option it would pay: its amount, asset, payTo and network. approve.url is the agreement URL, and approve.required the payment request as served.
2. Your agent approves it as it approves any payment. To pay it, call transact again with the same arguments and { approved: approve }.
3. The second call signs exactly that payment, sends it, and signs the main payment only after the agreement URL answers with its receipt:

{
  "atrHash": "0x8b1e122580ae3f6a8c3d36a24294e1260a87bde70f597279b973e39310072938",
  "agreed": true,
  "network": "eip155:84532",
  "transaction": "0xabababababababababababababababababababababababababababababababab"
}

• The option paid is the first, in document order, that your signer can pay with a pairing whose payment is itself a public proof: the same rule as for the main payment's options.
• The agreement URL's 402 must advertise the same H, or nothing is signed (hash-mismatch).
• Once the agreement payment is sent, the gate sends the same payment again after each 202, 5xx or timeout, within the paid option's maxTimeoutSeconds plus 180 seconds. It never signs a second agreement payment. signal ends the exchange sooner.
• Where the agreement is already recorded, the first call goes straight on to the main payment.
• A pairing that needs an agreement and whose offer names none is declined with agreement-not-offered.
• agree(bytes, url, signer, fetch, { approved, inputs, signal }) runs the exchange on its own, in the same two calls, for an agent that drives each step.

Channels and sessions

In an x402 batch-settlement channel or an MPP session, one ATR covers the whole channel. The gate compares it once, at the opening; you keep a hold and sign every later voucher from it:

import { openChannel, recordCharge, transact, within, type Fetch, type Signature, type Signer, type SigningRequest } from "@integraledger/terms";
import { batchEvm } from "@integraledger/lcp/x402-batch-settlement";
import { privateKeyToAccount } from "viem/accounts";

const atr = new TextEncoder().encode(
  '{"atrVersion":"1","id":"0f8fad5b-d9cb-469f-a165-70867728950e","x402":{"z":1.0,"a":"caf\\u00e9"},"seller":{"note":"Café — 30 días ✓"}}',
);
const H = "0x8b1e122580ae3f6a8c3d36a24294e1260a87bde70f597279b973e39310072938";
const link = `https://atr.seller.example/${H}`;

// The seller's batch-settlement offer: 1000 units per request, into a channel.
const offer = {
  x402Version: 2,
  resource: { url: "https://api.seller.example/v1/quote" },
  accepts: [
    {
      scheme: "batch-settlement",
      network: "eip155:84532",
      amount: "1000",
      asset: "0x036CbD53842c5426634e7929541eC2318f3dCF7e",
      payTo: "0x209693Bc6afc0C5328bA36FaF03C514EF312287C",
      maxTimeoutSeconds: 3600,
      extra: { receiverAuthorizer: "0x90F79bf6EB2c4f870365E785982E1f101E93b906", withdrawDelay: 900, name: "USDC", version: "2" },
    },
  ],
  extensions: { legalContext: { info: { type: "sha256", value: H, legalContextUrl: link }, schema: {} } },
};
const fetch: Fetch = async (url) => (url === link ? new Response(atr) : new Response(null, { status: 404 }));

// Anvil development keys: the payer funds the channel, the payer authorizer signs vouchers. Never use them for real funds.
const payer = privateKeyToAccount("0xac0974bec39a17e36ba4a6b4d238ff944bacb478cbed5efcae784d7bf4f2ff80");
const authorizer = privateKeyToAccount("0x59c6995e998f97a5a0044966f0945389dc9e86dae88c7a8412f4603b6b78690d");
type TypedData = Parameters<typeof payer.signTypedData>[0];
const signer: Signer = {
  account: `eip155:84532:${payer.address}`,
  async sign(request: SigningRequest): Promise<Signature> {
    if (request.kind !== "batch") throw new Error(`unexpected ${request.kind}`);
    const answers: Signature[] = [];
    for (const each of request.requests) {
      const typedData = (each as { typedData: TypedData }).typedData;
      const key = typedData.primaryType === "Voucher" ? authorizer : payer;
      answers.push(await key.signTypedData(typedData));
    }
    return answers;
  },
};

// Open: compare the ATR once, sign the deposit and the first voucher.
const opened = await transact(offer, batchEvm, signer, fetch, {
  inputs: { payerAuthorizer: authorizer.address, deposit: "100000" },
});
if ("decline" in opened || "approve" in opened || opened.signed === null) throw new Error("the channel did not open");
let hold = await openChannel(opened.bytes, opened.signed, batchEvm);
if ("decline" in hold) throw new Error(hold.decline.code);
console.log("channel ", hold.channel);

// Each later request: the seller's new offer must advertise the held H.
for (const charged of ["1000", "2000"]) {
  const next = await within(offer, hold, batchEvm, signer);
  if ("decline" in next) throw new Error(next.decline.code);
  console.log("voucher up to", next.hold.signedMax);
  // The seller reports its cumulative charge; it may not exceed what was signed.
  const recorded = recordCharge(next.hold, charged);
  if ("decline" in recorded) throw new Error(recorded.decline.code);
  hold = recorded;
}

channel  0x9c2d7031768ecb3fe688ae307c45f2e3a3d98b0d9ce1a6afcd27131fabb67e56
voucher up to 1000
voucher up to 2000

The hold is plain JSON: store it, and pass the latest one to each call. within re-derives everything from the hold, never from the new challenge, and signs only when that challenge advertises the held H and the payment it builds names the held channel.

Confirm a payment later: check

check(bytes, presented, binding) confirms that a payment you hold carries, inside what was signed, the SHA-256 of the bytes you kept. Where finish or transact returned landed, put it back into the payment as landed first.

Declines and moved

A decline is { decline: { code, detail } }. code is one of twelve values; detail is a sentence or the protocol package's refusal code. Where your signer moved the payment itself before the gate declined (a Lightning node paid the invoice, a signer broadcast a transaction), the decline also carries moved: { signed, bytes, h }. Keep it, and present it again rather than signing a new payment.

| Code | Meaning | | --- | --- | | pairing-not-supported | The binding names no pairing the gate serves; chosen or a hold belongs to another pairing; or the pairing has no channel. | | offer-unreadable | The seller's document, the chosen option or a build could not be read, or a recorded charge is out of range. detail carries the reason. | | no-payable-option | No option is payable by this account (for the agreement, with a public-proof pairing), an input the build needs is missing or malformed, the options of transact or agree are malformed, or a later channel challenge asks for a payment in a channel the hold did not open. | | link-not-https | The ATR link or the agreement URL is not an https URL. Nothing was fetched. | | atr-unfetchable | The link did not answer 200 with the bytes within 10 seconds (a redirect counts as a failure), or answered 200 with a Content-Encoding other than identity. | | atr-too-large | The ATR is larger than 1 MiB (1,048,576 bytes). | | hash-mismatch | The served bytes do not hash to the advertised H; the agreement URL or a later channel challenge advertises another H; or a hold's bytes do not hash to its H. Nothing was signed. | | signer-failed | Your signer threw. | | signed-not-bound | What was signed does not carry the hash of the compared bytes. The payment is not returned. | | agreement-not-offered | The pairing's payment is not a public proof, and the offer names no agreement URL. | | agreement-pending | The agreement payment was sent and is not yet recorded, or another is already settling. | | agreement-failed | The agreement URL could not be reached, answered 200 or 402 with a Content-Encoding other than identity, or answered with something other than a receipt for this H; the approved payment names another agreement URL; or signal ended the exchange before the payment was sent. |

API reference

Everything below is exported from @integraledger/terms.

Functions

| Export | Signature | What it does | | --- | --- | --- | | transact | (doc, binding, signer, fetch, options?) => Promise<{ signed, bytes, h, agreement?, landed? } \| ToApprove \| Declined> | Compare, pay the approved agreement first where needed, sign, finish. | | confirm | (doc, binding, account, fetch, inputs?) => Promise<{ chosen, request, bytes, h } \| Declined> | Read, fetch, compare, and build the signing request with H. request is null when there is nothing to sign; chosen.agreement is the agreement URL, where the pairing needs one. | | finish | (bytes, chosen, signature, binding) => Promise<{ signed, h, landed? } \| { next, h } \| Declined> | Rebuild from chosen and the bytes, join the signature, and return the payment only when what was signed carries H. | | check | (bytes, presented, binding) => Promise<{ h } \| Declined> | Confirm a held payment carries the hash of the kept bytes. | | agree | (bytes, url, signer, fetch, options?) => Promise<ToApprove \| { receipt } \| Declined> | Without options.approved, return the agreement payment to approve, signing nothing; with it, pay that payment and return the receipt. | | openChannel | (bytes, opened, binding, landed?) => Promise<ChannelHold \| Declined> | Hold a channel opened for the compared ATR. | | within | (doc, hold, binding, signer, refund?, inputs?) => Promise<{ signed, hold } \| Declined> | Sign a later voucher, or a refund with refund, in a held channel. | | recordCharge | (hold, chargedCumulativeAmount) => ChannelHold \| Declined | Record the seller's cumulative charge, between the last recorded and the most signed. |

Types

| Export | What it is | | --- | --- | | Binding | A pairing's binding from @integraledger/lcp. | | Signer | { account: string; sign(request: SigningRequest): Promise<Signature> }. account is CAIP-10. | | SigningRequest | What a signer is handed: one kind per signing scheme, such as eip712, solana-message, xrpl-tx, bolt11-pay or batch. | | Signature | The signer's answer, as JSON. Byte strings are 0x hex. | | Fetch | WHATWG fetch, or anything with its call shape. | | Inputs | The buyer's own values a build needs: { [name]: Json }. | | TransactOptions | { inputs?, agreementSigner?, approved?, signal? }. | | AgreeOptions | { approved?, inputs?, signal? }. | | Chosen | What the gate chose to pay, as plain JSON: { pairing, choice, ref, agreement? }. | | Presented | A payment in its protocol's form. | | AgreementPayment | The agreement payment to approve: { url, option, required }. | | ToApprove | { approve: AgreementPayment; bytes; h }. | | AgreementReceipt | { atrHash, agreed: true, network, transaction }. | | ChannelHold | { pairing, network, channel, h, atr, opening, charged, signedMax }, all JSON. | | Declined | { decline: Reason; moved?: { signed, bytes, h } }. | | Reason | { code: DeclineCode; detail: string }. | | DeclineCode | The twelve codes in the table above. |

The full reference, with every request kind and the answer it takes, is in the documentation.

Supported pairings

Generated from @integraledger/lcp's BINDINGS and the gate's own registry. "Agreement payment first" marks the pairings whose payment is not itself a public proof of H. The pairings reference adds what each payment proves, and the rails guide the inputs each build reads.

| Rail | Pairing | Binding export | Buyer signs H | Agreement payment first | | --- | --- | --- | --- | --- | | EVM | mpp/charge/evm/authorization | evmAuthorization from @integraledger/lcp/mpp | yes | no | | EVM | mpp/charge/evm/hash | evmHash from @integraledger/lcp/mpp | no | yes | | EVM | mpp/charge/evm/permit2 | evmPermit2 from @integraledger/lcp/mpp | yes | no | | EVM | mpp/charge/evm/transaction | evmTransaction from @integraledger/lcp/mpp | no | yes | | EVM | mpp/charge/usdc/evm | chargeUsdcEvm from @integraledger/lcp/mpp | yes | no | | EVM | mpp/charge/usdc/gateway | chargeUsdcGateway from @integraledger/lcp/mpp | yes | no | | EVM | mpp/session/evm | sessionEvm from @integraledger/lcp/mpp | yes | no | | EVM | x402/auth-capture/eip155/eip3009 | authCaptureEip3009 from @integraledger/lcp/x402 | yes | no | | EVM | x402/auth-capture/eip155/permit2 | authCapturePermit2 from @integraledger/lcp/x402 | yes | no | | EVM | x402/batch-settlement/eip155 | batchEvm from @integraledger/lcp/x402-batch-settlement | yes | no | | EVM | x402/exact/eip155/eip3009 | exactEip3009 from @integraledger/lcp/x402 | yes | no | | EVM | x402/exact/eip155/erc7710 | exactErc7710 from @integraledger/lcp/x402 | no | yes | | EVM | x402/exact/eip155/erc7710-salt | exactErc7710Salt from @integraledger/lcp/x402 | yes | no | | EVM | x402/exact/eip155/permit2 | exactPermit2 from @integraledger/lcp/x402 | yes | no | | EVM | x402/upto/eip155/permit2 | uptoPermit2 from @integraledger/lcp/x402 | yes | no | | Tempo | mpp/charge/tempo/memo | tempoMemo from @integraledger/lcp/mpp | no | no | | Tempo | mpp/charge/tempo/push | tempoPush from @integraledger/lcp/mpp | no | no | | Tempo | mpp/session/tempo | sessionTempo from @integraledger/lcp/mpp | yes | no | | Tempo | mpp/subscription/tempo | subscriptionTempo from @integraledger/lcp/mpp | yes | no | | Solana | mpp/charge/solana | chargeSolana from @integraledger/lcp/mpp | yes | no | | Solana | mpp/charge/usdc/solana | chargeUsdcSolana from @integraledger/lcp/mpp | yes | no | | Solana | mpp/session/solana | sessionSolana from @integraledger/lcp/mpp | no | no | | Solana | x402/batch-settlement/solana | batchSvm from @integraledger/lcp/x402-batch-settlement | yes | no | | Solana | x402/exact/solana | exactSvm from @integraledger/lcp/x402-exact-solana | yes | no | | Solana | x402/upto/solana | uptoSvm from @integraledger/lcp/x402-upto-solana | yes | no | | Stellar | mpp/charge/stellar | chargeStellar from @integraledger/lcp/mpp | no | no | | Stellar | x402/exact/stellar | exactStellar from @integraledger/lcp/x402-exact-stellar | no | no | | XRP Ledger | mpp/charge/xrpl | chargeXrpl from @integraledger/lcp/mpp | yes | no | | XRP Ledger | mpp/session/xrpl | sessionXrpl from @integraledger/lcp/mpp | yes | no | | XRP Ledger | x402/exact/xrpl | exactXrpl from @integraledger/lcp/x402-exact-xrpl | yes | no | | Hedera | mpp/charge/hedera | chargeHedera from @integraledger/lcp/hedera | no | no | | Hedera | mpp/session/hedera | sessionHedera from @integraledger/lcp/mpp | yes | no | | Hedera | x402/exact/hedera | exactHedera from @integraledger/lcp/hedera | yes | no | | Hedera | x402/exact/hedera/transfer-executor | exactHederaExecutor from @integraledger/lcp/hedera | no | yes | | Algorand | x402/exact/algorand | exactAvm from @integraledger/lcp/avm | yes | no | | Aptos | x402/exact/aptos | exactAptos from @integraledger/lcp/aptos | no | yes | | Sui | x402/exact/sui | exactSui from @integraledger/lcp/sui | yes | no | | NEAR | mpp/charge/nearintents | chargeNearIntents from @integraledger/lcp/mpp | no | yes | | NEAR | x402/exact/near | exactNear from @integraledger/lcp/near | yes | no | | Starknet | x402/exact/starknet | exactStarknet from @integraledger/lcp/starknet | yes | no | | Polkadot | x402/exact/polkadot/lcp-assets-remark | exactPolkadotRemark from @integraledger/lcp/polkadot | yes | no | | TRON | x402/exact/tron/lcp-trc20-memo | exactTronMemo from @integraledger/lcp/tron | yes | no | | TON | x402/exact/tvm | exactTvm from @integraledger/lcp/tvm | yes | no | | Cardano | x402/exact/cardano | exactCardano from @integraledger/lcp/cardano | yes | no | | Casper | x402/exact/casper | exactCasper from @integraledger/lcp/casper | yes | no | | Concordium | x402/exact/ccd | exactCcd from @integraledger/lcp/ccd | yes | no | | Stacks | mpp/charge/usdc/stacks | chargeUsdcStacks from @integraledger/lcp/mpp | yes | no | | Lightning | mpp/charge/lightning | chargeLightning from @integraledger/lcp/lightning | no | yes | | Lightning | mpp/session/lightning | sessionLightning from @integraledger/lcp/lightning | no | yes | | Lightning | x402/exact/lnbtc | exactLnbtc from @integraledger/lcp/lightning | no | yes | | Lightning | x402/exact/lnbtc/invoice-named | exactLnbtcNamed from @integraledger/lcp/lightning | no | yes | | Cloudflare | x402/batch-settlement/cloudflare | batchCloudflare from @integraledger/lcp/x402-batch-settlement | yes | yes | | Card | card/mastercard-vi/autonomous | viAutonomous from @integraledger/lcp/card | yes | yes | | Card | card/mastercard-vi/immediate | viImmediate from @integraledger/lcp/card | yes | yes | | Card | card/seller-reference | sellerReference from @integraledger/lcp/card | no | yes | | Card | card/visa-tap | visaTap from @integraledger/lcp/card | yes | yes | | Card | mpp/charge/card | chargeCard from @integraledger/lcp/mpp | no | yes | | Stripe | mpp/charge/stripe | chargeStripe from @integraledger/lcp/mpp | no | yes | | Stripe | mpp/subscription/stripe | subscriptionStripe from @integraledger/lcp/mpp | no | yes | | Mandate | ap2/checkout-mandate | checkoutMandate from @integraledger/lcp/ap2 | yes | yes | | Mandate | ucp/booking/ap2-mandate | bookingAp2Mandate from @integraledger/lcp/ucp | yes | yes | | Mandate | ucp/checkout/ap2-mandate | ap2Mandate from @integraledger/lcp/ucp | yes | yes | | Checkout | ack/payment-request | paymentRequest from @integraledger/lcp/ack | no | yes | | Checkout | acp/checkout/delegated | delegated from @integraledger/lcp/acp | no | yes | | Checkout | acp/checkout/undelegated | undelegated from @integraledger/lcp/acp | no | yes | | Checkout | ucp/booking/unsigned | bookingUnsigned from @integraledger/lcp/ucp | no | yes | | Checkout | ucp/checkout/unsigned | unsigned from @integraledger/lcp/ucp | no | yes |

Security model

What the gate guarantees, in the code:

• Nothing is signed before the comparison. The signer is called only after SHA-256 of the served bytes equals the advertised H, compared as 32 decoded bytes.
• The payment carries the computed hash. The build takes the hash the gate computed, not the advertised string.
• What was signed is read back. finish returns a payment only when the binding reads, from what was signed, the hash of the compared bytes. For a pairing whose payment is not a public proof, the payment is returned only after the agreement's receipt for that hash.
• Every payment is shown before it is signed. The agreement payment is returned for your agent's approval, with its amount, asset, payee and network, and is signed only when a second call carries it back.
• One bounded fetch. One GET of an https link, no redirect, one 10-second deadline over headers and body, at most 1 MiB read. A declared or streamed length over the bound cancels the body.
• Exact bytes. The ATR is hashed as received and returned as received. It is never parsed. Every request asks for Accept-Encoding: identity, and a 200 whose Content-Encoding names any coding is declined unread, so nothing is decompressed: the bytes hashed are the bytes sent.
• No keys. The gate hands requests to your signer and holds nothing that could sign.
• Your network policy. Every request goes through the fetch you pass.

What it does not do:

• It does not read or judge the ATR's content.
• It does not check amount, payee, asset, timing or payer against the ATR, and applies no spending limit to the agreement payment. A discrepancy is between the parties; what to approve is your agent's decision.
• It does not authenticate the agreement's receipt. The public proof is the transaction the receipt names, on its network.
• It carries no business or legal logic.
• It does not store the ATR, talk to a facilitator, or settle a payment.

A seller's statement of what each pairing's payment proves is its binding's pattern.proves, in @integraledger/lcp.

Test vectors and conformance

The rules are fixed by the shared vectors that @integraledger/lcp ships in its vectors/ directory: the buyer rows of buyer.json (the hash, a record changed by one byte, the fetch bounds, the agreement exchange) and each pairing's file (the request it builds and the payment it completes). This package's tests run every one, and the Python gate runs the same files, so both languages compute the same hashes, build the same requests and give the same declines.

Requirements

• Node.js >=26.10.0.
• An HTTP client with WHATWG fetch's call shape (Node's global fetch is one).
• Cloudflare Workers, with or without the nodejs_compat flag: pass the Worker's own fetch, and install @integraledger/lcp's optional peer dependencies before bundling. See In a Cloudflare Worker.
• A signer for the pairings you pay.

Contributing

See the repository README and CONTRIBUTING.md.

License

Apache-2.0