What's the magic key version bytes for BIP49 I'm implementing BIP49-compatible key derivation for bitcoin-s, but I'm having a hard time finding the magic version bytes to use for the extended keys. 

I've been looking at BIP49, but can't find anything there. 

Also, is there multiple schemes for deriving P2WPKH-nested-in-P2SH? I've been looking at the Samourai fork of BitcoinJ, Trezor's implementation and the test vectors in BIP49, and I can't get the vectors to pass by using the magic version bytes from Trezor/Samourai. 

Maybe I'm confused by which magic bytes from Samourai corresponds to mainnet/testnet P2WPKH-nested-in-P2SH, so any clarification is appreciated here. From my understanding, the mainnet version bytes are 0x049D7CB2 (pub) and 0x049D7878 (priv) and testnet are 0x044a5262 (pub) and 0x044a4e28 (priv).

As a final thing, any pointers to test vectors for BIP49 and BIP84 is appreciated. Currently I've come across the BIPs themselves, as well as SLIP132.
I'm implementing BIP49-compatible key derivation for bitcoin-s, but I'm having a hard time finding the magic version bytes to use for the extended keys.


It's prefixes are: YPUB = 0x049D7CB2 and YPRV = 0x049D7878


  Is there multiple schemes for deriving P2WPKH-nested-in-P2SH?


You are confusing the two. 77429938 that you have linked in Trezor is used to derive ypub. If you scroll down on Samourai code you will see 0x049D7CB2 for ypub which is same as 77429938 in decimal. xpub stands for extended public key and allows you to generate addresses and scan all the funds associated with them, but not spend them. ypub is exactly like an xpub, except the 'Y' denotes with certainty that this particular extended public key belongs to a wallet that is also following the BIP49 bitcoin standard. This instructs the wallet to definitely scan for P2SH(P2WPKH) addresses. There is also zpub, and that instructs the wallet to only scan for bech32 addresses that starts with bc.