Sign Transactions on NEAR

const response = await circleDeveloperSdk.createWallets({
  accountType: "EOA",
  blockchains: ["NEAR-TESTNET"],
  count: 2,
  walletSetId: "<wallet-set-id>",
});

import { initiateDeveloperControlledWalletsClient } from "@circle-fin/developer-controlled-wallets";
import { connect, utils } from "near-api-js";
import { baseDecode, baseEncode } from "@near-js/utils";
import { PublicKey } from "@near-js/crypto";
import {
  createTransaction,
  actionCreators,
  encodeTransaction,
} from "@near-js/transactions";
import axios from "axios";
import fs from "fs";

const NEAR_CONFIG = {
  networkId: "testnet",
  nodeUrl: "https://rpc.testnet.near.org",
};

// fill in these variables
const CIRCLE_API_KEY = "";
const CIRCLE_ENTITY_SECRET = "";
const CIRCLE_WALLET_PUBLIC_KEY = ""; // with `ed25519:` scheme
const CIRCLE_WALLET_ID = "";
const CIRCLE_TX_MEMO = "";
const MASTER_ACCOUNT = "";
const RECEIVER = "";
const AMOUNT = "0.001";

async function main() {
  const client = initiateDeveloperControlledWalletsClient({
    apiKey: CIRCLE_API_KEY,
    entitySecret: CIRCLE_ENTITY_SECRET,
  });

  try {
    // setup client and account
    const near = await connect({ ...NEAR_CONFIG });
    const sender = await near.account(MASTER_ACCOUNT);

    // get latest finalized block
    const block = await near.connection.provider.block({ finality: "final" });
    const blockHash = block.header.hash;

    // get sender nonce
    const senderAccessKey = await sender.getAccessKeys();
    let nonce = BigInt(0);
    for (let i = 0; i < senderAccessKey.length; i++) {
      if (senderAccessKey[i].public_key === CIRCLE_WALLET_PUBLIC_KEY) {
        nonce = senderAccessKey[i].access_key.nonce + BigInt(1);
      }
    }
    if (nonce === BigInt(0)) {
      console.error(
        `couldn't find corresponding access key: ${CIRCLE_WALLET_PUBLIC_KEY}`,
      );
      return;
    }

    // build raw transaction
    const actions = [
      actionCreators.transfer(
        BigInt(utils.format.parseNearAmount(AMOUNT) || 0),
      ),
    ];
    const signerPublicKey = PublicKey.fromString(CIRCLE_WALLET_PUBLIC_KEY);
    const transaction = createTransaction(
      MASTER_ACCOUNT,
      signerPublicKey,
      RECEIVER,
      nonce,
      actions,
      baseDecode(blockHash),
    );

    // serialize borsh
    const message = encodeTransaction(transaction);

    // base64 encode
    const base64EncodedTx = Buffer.from(message).toString("base64");

    // call Circle's API to sign tx
    const signedTx = await client.signTransaction({
      walletId: CIRCLE_WALLET_ID,
      rawTransaction: base64EncodedTx,
      memo: CIRCLE_TX_MEMO,
    });
  } catch (err) {
    if (axios.isAxiosError(err)) {
      console.error(`status: ${err.response?.status}`);
      console.error(`data: `, err.response?.data);
    } else {
      console.error(`unknown err: `, err);
    }
  }
}

(async () => {
  await main();
})();