There are several different bag types in the world

1- normal bag can use it in a character inventory slot(one of the 6 slots), bank,shared bank,use in broker slot, house vault and they will hold every thing
2- harvest box, only hold harvest items and can only be used in a bank slot
3- harvest bag, that only on holds harvest items but will work in bank slots and character inventory slots

i would like a db change to do this and then i could write the code to support it but i dont know the best place to put it, i would assume in item_details_bag somewhere

Yea the best place for that would be an added field in item_details_bag. I can't currently push db changes out to the patcher but you can make the changes locally and send me the alter sql and I can push them out as soon as I am able.