Definitely long coat (imo). LC is the recessive, so mom must carry a gene for it too. My boy's sire carries the long coat gene as well, but his mother does not so he is a stock coat who could potentially carry the LC gene (I may test at a later date).
I wouldn't call liver rare, so much as "undesireable" in the breed. It is interesting looking. I love the look of blue shepherds (saw a pic or two of one on Pedigree Database that was absolutely stunning), but it is a fault that should not be bred for (and, if I recall correctly, that blue GSD popped up in a reputable breeder's litter)
Your boy is cute - there are a few Liver and tan GSDs on Instagram you could follow, but I'm unsure about here.
+ Kalbi CGC 6/21/2015
+ Blackthorn's Out of the Frying Pan NW1 ORT SEN SCN BCAT SIN RATN TKN (Katsu) 9/12/2017
+ Blackthorn's Skofnung CGC TKN RATI RATO (Steel) 07/23/2018