See exactly what
a transaction is doing.

$ btx extract 0200000001...
txid     = 9f2c…8e44
inputs   = 2
sigs     = 2
verified = true
  [0] P2WPKH  r=c8b3…4a2f  s=1d6e…92bc
  [1] P2TR    taproot key-path  z=7a91…05d3

# parse, extract, verify — three lines.
from btx import parse_tx, extract_signatures, verify_signature

tx, _ = parse_tx(bytes.fromhex(raw_hex))
records = extract_signatures(tx)

for rec in records:
    ok = verify_signature(rec.z, rec.signature, rec.public_key)
    print(rec.txid, rec.input_index, ok)

# detect & recover from ECDSA nonce reuse
from btx.signature.attack import (
    detect_nonce_reuse, recover_from_nonce_reuse,
)

groups = detect_nonce_reuse(collection)

for g in groups:
    result = recover_from_nonce_reuse(
        collection.records[g.indices[0]],
        collection.records[g.indices[1]],
    )
    print("private_key =", result.private_key)

# BIP-174 round-trip — parse, edit, serialize
from btx import parse_psbt, serialize_psbt, PsbtEditor

psbt = parse_psbt(raw_bytes)

with PsbtEditor(psbt) as ed:
    ed.set_input(0, sighash=0x01)
    ed.add_signature(0, der_sig, pubkey)

out = serialize_psbt(ed.finalize())