P2SH-P2WPKH stack

Question

I'm studying P2SH-P2WPKH and when I create the signed transaction I can see this stack (using btcdeb)

script                                   |                                                             stack 
-----------------------------------------+-------------------------------------------------------------------
OP_DUP                                   | Public Key
OP_HASH160                               | Signature
3ecfc6b4....a49                          | 
OP_EQUALVERIFY                           | 
OP_CHECKSIG                              | 

The question is Where and When I push OP_DUP e OP_CHECKSIG? I don't find anything inside Bitcoin code in GitHub, maybe during signrawtransactionwithkey?

I understand that the stack contains the

OP_DUP OP_HASH160 <PubKHash> OP_EQUALVERIFY OP_CHECKSIG

like P2PKH, but I don't understand why are inside the stack.

It's my UTXO and I don't find 1a83d46422201593cb8f42f44a22a29e86ad652f inside my stack.

{
  "asm": "OP_HASH160 1a83d46422201593cb8f42f44a22a29e86ad652f OP_EQUAL",
  "hex": "a9141a83d46422201593cb8f42f44a22a29e86ad652f87",
  "reqSigs": 1,
  "type": "scripthash",
  "addresses": [
    "2MufRUxRcGnwbdL4PWKzKb7uSFzBT1wQL7u"
  ]
}

UPDATE I don't find the code inside Github, but maybe thanks to the witness program (<0 <20-byte-key-hash>>) the software is triggered and create the stack with P2PKH. For the older node is ANYONE_CAN_SPEND, for newer node check if hash160 (pubkey) == pubkeyhash and then check the signature.

In that case When the UTXO is involve only for TXID and Amount, not for validation (scriptPubKey) like P2SH and P2PKH.

Answer 1

The question is Where and When I push OP_DUP e OP_CHECKSIG?

You don't. Neither the transaction creating the output or the transaction spending it explicitly contain these instructions.

When verifying a P2WPKH spend (which means either the scriptPubKey or the P2SH redeemScript is exactly OP_0 <20-byte hash>), special logic is triggered which verifies the witness stack against the script OP_DUP OP_HASH160 <20-byte-hash> OP_EQUALVERIFY OP_CHECKSIG.

See the examples in BIP 141 for more information.