# Run the profile facilitator > Start the x402 facilitator for the Tron and Polkadot LCP profiles, configure its networks and store, and call it. Source: https://connectors.integraledger.com/guides/facilitator [`@integraledger/profile-facilitator`](https://github.com/IntegraLedger/integra-agentic-connectors/blob/main/profile-facilitator/README.md) is an x402 facilitator for `x402/exact/tron/lcp-trc20-memo` and `x402/exact/polkadot/lcp-assets-remark`. It verifies and settles payments whose payer-signed transaction carries the ATR hash (H), holds no key and pays no fee. This guide runs it. ## Install ```sh npm install @integraledger/profile-facilitator ``` It needs Node.js `>=26.10.0`, Postgres (the tests run on Postgres 18), and an HTTP endpoint for each network you serve: a Tron FullNode and Solidity node, or a Polkadot Asset Hub RPC node. ## Start it and read what it supports Start the facilitator for Tron mainnet and read what it supports. The node URLs below are java-tron's default HTTP ports on your own node; the facilitator calls them only when a payment arrives. `DATABASE_URL` is your Postgres connection string. ```ts title="supported.ts" import { serveProfileFacilitator } from "@integraledger/profile-facilitator"; const facilitator = await serveProfileFacilitator({ listen: "127.0.0.1:4020", tron: [{ network: "tron:728126428", fullNode: "http://127.0.0.1:8090", solidityNode: "http://127.0.0.1:8091" }], polkadot: [{ network: "polkadot:68d56f15f85d3136970ec16946040bc1", rpc: "http://127.0.0.1:9944" }], store: { url: process.env.DATABASE_URL ?? "postgres://postgres@127.0.0.1:5432/postgres" }, settleWaitMs: 30_000, }); const supported = await (await fetch("http://127.0.0.1:4020/supported")).json(); console.log(JSON.stringify(supported, null, 2)); await facilitator.close(); ``` ```text output { "kinds": [ { "x402Version": 2, "scheme": "exact", "network": "tron:728126428", "extra": { "assetTransferMethod": "lcp-trc20-memo" } }, { "x402Version": 2, "scheme": "exact", "network": "polkadot:68d56f15f85d3136970ec16946040bc1", "extra": { "assetTransferMethod": "lcp-assets-remark" } } ], "extensions": [], "signers": {} } ``` ## Run it as a service The package exports one function that starts the server; it has no command-line entry. A service is a short module that reads its configuration and stops cleanly on a signal: ```ts title="facilitator.ts" server import { serveProfileFacilitator } from "@integraledger/profile-facilitator"; const listen = process.env.LISTEN ?? "127.0.0.1:4021"; const facilitator = await serveProfileFacilitator({ listen, tron: [ { network: "tron:728126428", fullNode: process.env.TRON_FULL_NODE ?? "http://127.0.0.1:8090", solidityNode: process.env.TRON_SOLIDITY_NODE ?? "http://127.0.0.1:8091", }, ], store: { url: process.env.DATABASE_URL ?? "postgres://postgres@127.0.0.1:5432/postgres" }, settleWaitMs: Number(process.env.SETTLE_WAIT_MS ?? 30_000), }); for (const signal of ["SIGINT", "SIGTERM"] as const) { process.once(signal, () => { void facilitator.close().then(() => process.exit(0)); }); } console.log(`facilitator listening on ${listen}`); ``` ```text output facilitator listening on 127.0.0.1:4021 ``` Run it with `node facilitator.ts`: Node.js 26 runs TypeScript directly. `close()` stops accepting requests, closes open connections, disconnects from the Polkadot nodes and closes the Postgres pool. ## Configuration `serveProfileFacilitator(config)` takes a `ProfileFacilitatorConfig`: | Field | Type | Meaning | | -------------- | ------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ | | `listen` | `string` | `"host:port"`; an IPv6 host may be written in brackets. | | `tron` | `{ network, fullNode, solidityNode }[]`, optional | One entry per Tron network. `network` is `tron:`. `fullNode` serves `/wallet/…` and `solidityNode` serves `/walletsolidity/…`; give each its base URL. | | `polkadot` | `{ network, rpc }[]`, optional | One entry per network, `polkadot:68d56f15f85d3136970ec16946040bc1` or `polkadot:67f9723393ef76214df0118c34bbbd3d`. `rpc` is an HTTP JSON-RPC endpoint that serves `state_call` and `author_submitExtrinsic`. | | `store` | `{ url }` | The Postgres connection string. Postgres holds the deduplication table only. | | `settleWaitMs` | `number` | How long `/settle` waits for inclusion before it answers `settlement_pending`. A value that is not a positive finite number means 30 000. | The facilitator serves only the networks it is configured with. A request for any other network is answered `invalid_network`. At start it creates its table if it does not exist; a Polkadot node's runtime metadata is loaded on the first payment for that network, and loaded again whenever the node's runtime version changes. ## Call it Both `POST /verify` and `POST /settle` take the x402 facilitator request: `{x402Version: 2, paymentPayload, paymentRequirements}`, with `paymentPayload.x402Version` 2 and `paymentRequirements.scheme` `"exact"`. ```ts title="verify.ts" import { serveProfileFacilitator } from "@integraledger/profile-facilitator"; const facilitator = await serveProfileFacilitator({ listen: "127.0.0.1:4022", tron: [{ network: "tron:728126428", fullNode: "http://127.0.0.1:8090", solidityNode: "http://127.0.0.1:8091" }], store: { url: process.env.DATABASE_URL ?? "postgres://postgres@127.0.0.1:5432/postgres" }, settleWaitMs: 30_000, }); const request = { x402Version: 2, paymentPayload: { x402Version: 2, payload: { transaction: "0a02" } }, paymentRequirements: { scheme: "exact", network: "tron:3448148188", amount: "10000", asset: "TR7NHqjeKQxGTCi8q8ZY4pL8otSzgjLj6t", payTo: "TCwX1UeSkVfu43HD5xNMmFqDR2Xgjdxihx", maxTimeoutSeconds: 60, extra: { assetTransferMethod: "lcp-trc20-memo" }, }, }; for (const path of ["/verify", "/settle"]) { const res = await fetch(`http://127.0.0.1:4022${path}`, { method: "POST", headers: { "content-type": "application/json" }, body: JSON.stringify(request), }); console.log(path, res.status, JSON.stringify(await res.json())); } await facilitator.close(); ``` ```text output /verify 200 {"isValid":false,"invalidReason":"invalid_network"} /settle 200 {"success":false,"errorReason":"invalid_network","transaction":"","network":"tron:3448148188"} ``` The rail specifics are in the [Tron](https://connectors.integraledger.com/guides/tron) and [Polkadot](https://connectors.integraledger.com/guides/polkadot) guides, and every answer and reason in [the facilitator reference](https://connectors.integraledger.com/reference/profile-facilitator). ## Pending and repeated settles When the wait ends first, `/settle` answers `{success: false, errorReason: "settlement_pending", transaction}` with the transaction id or extrinsic hash; x402 requires that `transaction` not be empty. Call `/settle` again with the same request: it reads the chain from where it stopped, never submits twice, and returns the final answer once there is one. An answer with an empty `transaction` means nothing was submitted. When the store cannot be read, the facilitator cannot know whether the payment was submitted, so it answers `settlement_pending` with the id. ## Security * **No key, no fee.** The facilitator signs nothing. It submits exactly the bytes the payer signed, and the payer pays every fee, as both profiles require. * **Settled once.** Settlements are deduplicated by transaction id or extrinsic hash, atomically, until the validity window ends and for 24 hours after. * **Success only from the chain.** `success: true` is given only when a node shows the transaction in a block with the profile's success conditions. * **What it does not check.** It checks that the payment carries an LCP `sha256` string, not which H the seller issued. The resource server refuses a payment whose H it did not issue for that request (each profile's rule 6), for example through the seller door's `claim`. It checks the amount, asset and payee against the requirements it is given because x402 requires that of a facilitator, and carries no business or legal logic beyond that.