ZIP System Sheathing (sheets of OSB covered in a weather resistant coating) with fluid applied sealant at seams, serves as the assembly's air barrier (and WRB).
In this home, they do that with Huber's Zip R - Wall sheathing, Benjamin Obdyke's rain screen materials, spray foam insulation, LG mini-split heat pumps, a Zehnder energy recovery ventilator, and more.