Script to set the username for your Farcaster account. https://dololand.com/set-farcaster-username

set-username.ts

/**
 * Set a Farcaster username by submitting a signed message to a hub.
 *
 * This script:
 * - Loads an authorized signer key
 * - Creates a UserDataAdd message to set the username
 * - Signs and submits the message to a Farcaster hub
 *
 * Requirements:
 * - A reserved fname via the Fname Registry
 * - An authorized signer key added to the FID
 *
 * .env:
 * WALLET_FID=1234
 * WALLET_SIGNER_PRIVATE_KEY="0x..." (hex-encoded Ed25519 private key)
 */

import { hexToBytes, type Hex } from 'viem';
import {
	FarcasterNetwork,
	makeUserDataAdd,
	Message,
	NobleEd25519Signer,
	UserDataType,
} from '@farcaster/core';

const HUB_ENDPOINT = 'https://hub.pinata.cloud'; // Farcaster hub endpoint
const fid = Number(process.env.WALLET_FID);

// Load the authorized signer (must be registered to this FID)
const privateKeyBytes = hexToBytes(process.env.WALLET_SIGNER_PRIVATE_KEY! as Hex);
const signer = new NobleEd25519Signer(privateKeyBytes);

// Define the username to link (must already be reserved via the Fname Registry)
const username = 'dooloo';

// Create a signed UserDataAdd message to link the username to the FID
const message = await makeUserDataAdd(
	{ type: UserDataType.USERNAME, value: username },
	{ fid, network: FarcasterNetwork.MAINNET },
	signer
);

console.log('Signed message:', message);

// Encode the message to binary format for submission
const data = Message.encode(message.value).finish();

// Submit the message to the hub
const response = await fetch(`${HUB_ENDPOINT}/v1/submitMessage`, {
	method: 'post',
	headers: { 'Content-Type': 'application/octet-stream' },
	body: data,
});

// Print the hub's response
console.log('Hub response:', await response.json());