Why isn’t the Taproot Transaction Builder (BuildTaproottx using @cmdcode/tapscript) working as expected?

I wrote the following function to build and sign a Taproot (P2TR) transaction using @cmdcode/tapscript: My intention is to support spending on both key and script paths.

The problem is that it doesn’t work as expected.

Script-Path spending often fails validation (e.g. block error, invalid witness, or failed script execution).

Can someone review my code and point out what’s wrong with my logic or implementation? I especially appreciate the advice on how to fix performance improvements in script path failures and key path cases.

import { Address, Signer, Tap, Tx } from '@cmdcode/tapscript';

protected buildTaprootTx(
  senderKey: { publicKey: Uint8Array; privateKey: Uint8Array },
  utxos: Array<{ txid: string; vout: number; value: number }>,
  recipient: string,
  amountSat: number,
  feeSat: number,
  mode: 'key' | 'script' | 'both',
  scriptLeaves: Array = (),
  opReturnData?: Uint8Array | string,
  changeAddr?: string
): string {
  // ... (full code as in my gist, see link below)
}

Complete code

question:

• What am I doing wrong, especially when it comes to script path spending?

• Is there a better way to configure or optimize features for performance and accuracy?

• If you find any obvious bugs or misconceptions in how you use TapRoot key/Script Path Logic, please point them out.

Code reviews, suggestions, or references to practical examples are highly appreciated. thank you!