how to sign PSBT using HD wallet

[Taha-daboussi]

Hi , am trying to Sign a PSBT that was give from a specific site to complete the purchase process ,
only thing that I was able to do Is to debug the website code to find how they generate the unsigned base64 and convert it to the Hex version .

while still lacking the knowledge to Sign the PSBT to be able to complete the purchase process and example PSBT :

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

[kajoseph]

That hex string does not appear to be a valid transaction. Perhaps you converted the base64 string incorrectly?

For reference, here is how I would do it:

const buf = Buffer.from('base64 string', 'base64');
const tx = new lib.Transaction(buf);

When trying to decode that hex string, it decodes that it has 2205801054209 tx inputs which is obviously incorrect, hence why I think you may have converted the base64 to hex incorrectly.