Script to reserve a Farcaster usernaem. https://dololand.com/reserve-farcaster-username

reserve-fname.ts

/**
 * Reserve a Farcaster username (fname) for a given FID.
 *
 * This script:
 * - Loads an account from a mnemonic
 * - Checks if a desired username is available
 * - Signs an EIP-712 claim proving ownership of the FID
 * - Submits the claim to the Fname Registry API
 *
 * Requirements:
 * - A registered Farcaster ID (FID)
 * - A signer capable of signing typed data
 *
 * .env:
 * WALLET_MNEMONIC="your twelve word seed phrase"
 * WALLET_FID=1234
 */

import { mnemonicToAccount } from 'viem/accounts';

const FNAME_API_ENDPOINT = 'https://fnames.farcaster.xyz';

// Load the wallet and FID from environment variables
const account = mnemonicToAccount(process.env.WALLET_MNEMONIC!);
const fid = Number(process.env.WALLET_FID);

// Define the username you'd like to reserve
const name = 'dololand';
console.log(`Attempting to reserve "${name}" for fid ${fid}...`);

// Check if the username is available via Fname Registry API
const transferResponse = await fetch(`${FNAME_API_ENDPOINT}/transfers/current?name=${name}`);
const transferData = (await transferResponse.json()) as any;

// If the name is not registered or not assigned, it's available
const isAvailable = transferResponse.status === 404 || transferData.transfer.to === 0;

if (!isAvailable) {
	console.log('Username is not available.');
	process.exit(0);
}

// Create a timestamped EIP-712 structured message for name ownership proof
const timestamp = Math.floor(Date.now() / 1000);

const proofMessage = {
	name,
	owner: account.address,
	timestamp: BigInt(timestamp),
};

const proofTypedData = {
	domain: {
		name: 'Farcaster name verification',
		version: '1',
		chainId: 1,
		verifyingContract: '0xe3be01d99baa8db9905b33a3ca391238234b79d1',
	},
	types: {
		UserNameProof: [
			{ name: 'name', type: 'string' },
			{ name: 'timestamp', type: 'uint256' },
			{ name: 'owner', type: 'address' },
		],
	},
	primaryType: 'UserNameProof',
	message: proofMessage,
} as const;

// Sign the proof using the account's private key
const signature = await account.signTypedData(proofTypedData);
console.log('Proof Signature:', signature);

// Submit the signed claim to the Fname Registry API
const claimResponse = await fetch(`${FNAME_API_ENDPOINT}/transfers`, {
	method: 'post',
	headers: { 'Content-Type': 'application/json' },
	body: JSON.stringify({
		name,
		from: 0,
		to: fid,
		fid,
		owner: account.address,
		signature,
		timestamp,
	}),
});

// Log the API response
const claimData = await claimResponse.json();
console.log('Response:', claimData);