fix(utxo-core): update toSignPsbt to properly set witnessUtxo

Update buildToSignPsbt to correctly handle scriptPubKey for witnessUtxo
instead of using witnessScript, which was incorrectly used in this context.
The function now requires scriptPubKey in AddressDetails and properly
sets up both witnessUtxo and witnessScript when present.

Co-authored-by: llm-git <[email protected]>

TICKET: BTC-2372

Author: davidkaplanbitgo

modules/utxo-core/src/bip322/toSign.ts

@@ -3,6 +3,7 @@ import { Psbt, Transaction } from '@bitgo/utxo-lib';
 export type AddressDetails = {
   redeemScript?: Buffer;
   witnessScript?: Buffer;
+  scriptPubKey: Buffer;
 };
 
 /**
@@ -15,10 +16,6 @@ export type AddressDetails = {
  * @returns {string} - The hex representation of the constructed PSBT.
  */
 export function buildToSignPsbt(toSpendTx: Transaction<bigint>, addressDetails: AddressDetails): Psbt {
-  if (!addressDetails.redeemScript && !addressDetails.witnessScript) {
-    throw new Error('redeemScript and/or witnessScript must be provided');
-  }
-
   // Create PSBT object for constructing the transaction
   const psbt = new Psbt();
   // Set default value for nVersion and nLockTime
@@ -31,13 +28,15 @@ export function buildToSignPsbt(toSpendTx: Transaction<bigint>, addressDetails:
     sequence: 0, // vin[0].nSequence = 0
     nonWitnessUtxo: toSpendTx.toBuffer(), // previous transaction for us to rebuild later to verify
   });
+  psbt.updateInput(0, {
+    witnessUtxo: { value: BigInt(0), script: addressDetails.scriptPubKey },
+  });
+
   if (addressDetails.redeemScript) {
     psbt.updateInput(0, { redeemScript: addressDetails.redeemScript });
   }
   if (addressDetails.witnessScript) {
-    psbt.updateInput(0, {
-      witnessUtxo: { value: BigInt(0), script: addressDetails.witnessScript },
-    });
+    psbt.updateInput(0, { witnessScript: addressDetails.witnessScript });
   }
 
   // Set the output

modules/utxo-core/test/bip322/bip322.utils.ts

@@ -14,5 +14,5 @@ export const BIP322_FIXTURE_HELLO_WORLD_TOSPEND_TX = buildToSpendTransaction(
 );
 
 export const BIP322_FIXTURE_HELLOW_WORLD_TOSIGN_PSBT = buildToSignPsbt(BIP322_FIXTURE_HELLO_WORLD_TOSPEND_TX, {
-  witnessScript: BIP322_PAYMENT_P2WPKH_FIXTURE.output as Buffer,
+  scriptPubKey: BIP322_PAYMENT_P2WPKH_FIXTURE.output as Buffer,
 });

modules/utxo-core/test/bip322/toSign.ts

@@ -24,7 +24,7 @@ describe('BIP322 toSign', function () {
       it(`should build a to_sign PSBT for message "${message}"`, function () {
         const toSpendTx = bip322.buildToSpendTransaction(scriptPubKey, Buffer.from(message));
         const addressDetails = {
-          witnessScript: scriptPubKey,
+          scriptPubKey,
         };
         const result = bip322.buildToSignPsbt(toSpendTx, addressDetails);
         const computedTxid = result