BTC Locker SDK: Build Bitcoin Staking Transactions

import { createBTCLocker, TimeUtils } from '@sundial-protocol/btc-locker';

const locker = await createBTCLocker('testnet');

const { privateKey, publicKey, address } = await locker.generateKeyPair();
console.log('Funding address:', address);
// Send testnet BTC to this address before proceeding

// Lock for 30 days from now
const deadline = TimeUtils.addDuration(TimeUtils.DURATIONS.DAY * 30);

const timelockScript = await locker.createTimelockScript(
  deadline,
  publicKey,
);

const escrowScript = await locker.createEscrowScript(
  deadline,
  publicKey,          // "before" branch: user can spend before deadline only with provider co-sig
  providerXonlyPubkey // "after" branch: provider can claim yield after deadline
);

console.log('Timelock address:', timelockScript.address);
console.log('Escrow address:',   escrowScript.address);

import { createBTCLocker, FeePriorities } from '@sundial-protocol/btc-locker';

const locker = await createBTCLocker('testnet');

// Decide the amounts you want to put in each script (in satoshis)
const timelockAmount = 750_000; // amount for the timelock output
const escrowAmount   = 250_000; // amount for the escrow output

// Build the deposit PSBT — the library selects UTxOs from sourceAddress automatically
const unsignedPsbt = await locker.createDepositTransaction({
  sourceAddress:   address,       // your funding address from Step 1
  timelockAddress: timelockScript.address,
  timelockAmount,
  escrowAddress:   escrowScript.address,
  escrowAmount,
  changeAddress:   address,
  priority:        FeePriorities.MEDIUM,
});

// Sign and broadcast
const signedHex = await locker.signTransaction(unsignedPsbt, privateKey);
const txId = await locker.submitTransaction(signedHex);
console.log('Deposit tx:', txId);

const unsignedPsbt = await locker.createWithdrawalTransaction({
  timelockRedeemScript: timelockScript.redeemScript,
  escrowRedeemScript:   escrowScript.redeemScript,
  destination:          yourBitcoinAddress,
  priority:             FeePriorities.MEDIUM,
});

// Pass spendAfterDeadline: true so the escrow finalizer selects the correct branch
const signedHex = await locker.signTransaction(unsignedPsbt, privateKey, {
  spendAfterDeadline: true,
});
const txId = await locker.submitTransaction(signedHex);
console.log('Withdrawal tx:', txId);

const result = await locker.calculateDepositAmounts({
  sourceAddress:        address,    // used to auto-fetch UTxOs if inputs not provided
  desiredTimelockAmount: 750_000,
  desiredEscrowAmount:   250_000,
  includeChange: true,
  feeRate:       10,                // sat/vB; omit to use the default
});

if (!result.feasible) {
  console.warn('Cannot proceed:', result.recommendation);
} else {
  console.log('Estimated fee:', result.estimatedFee, 'sats');
  console.log('Change:',        result.changeAmount,  'sats');
}

const unsignedPsbt = await locker.createDepositTransactionWithScript({
  sourceAddress:   address,
  timelockScript,            // ScriptInfo from createTimelockScript()
  timelockAmount:  750_000,
  escrowAddress:   escrowScript.address,
  escrowAmount:    250_000,
  changeAddress:   address,
});