Kitchen remodel to studs, infilling a window, no insulation, no building wrap!

looking for some urgent feedback.

My Husband and I are remodeling our kitchen. We're down to the studs, and two of the walls are exterior. The house is a 1920's bungalow. We're actually making our kitchen a bit smaller, and in order to put the new interior wall where we needed to, we have to remove one of the 4 windows in our kitchen.

We're doing the work ourselves (I'm an architect, but work in the commercial market), and are meeting codes and have been permitted.

So here's my issue, which we discovered this morning when we took out the window. The walls were lathe and plaster, that has all been removed. My house has no insulation, which we knew. However, when we removed our exterior window, we also found out that the house has no building wrap. It has 1 layer of wood shiplap sheathing, one layer of old ship lap siding, and the final layer of cedar shingles, which are painted.

The area we are infilling is about 36×48. Initially, my intent was to put up plywood sheathing to match the depth out to the old shingles, put the building paper over it, and then put the new shingles on, and paint. However there doesn't seem to be a point to do building wrap in this one area, since it isn't anywhere else in the house.

It also does seem to make sense to insulate the walls. In fact, that seems like it would be a really bad idea given that there is no building wrap. Any moisture that gets through my several layers of siding would sit in the insulation and could cause issues.

So I'm tempted to just infill the the window with studs and plywood, put shingles on, and not insulate before I put up the drywall. I'm not sure if the code official will give us any issue on that (I'm in portland, and we're a little looney with the energy code.

It's a toss up for me on the building paper – on one hand, it's kind of silly, on the other hand I could use it to bridge the gap between where we put the plywood in to where it matches the shingles.

Any thoughts or tips? I'm just at a bit of a loss. I've requested an urgent response as I'm sitting in my living room with a big hole in my house!

Thanks,
Kim