I'm having two major pieces of work done on one wall of my house at once: window replacement and mold removal from inside the wall (under the old leaky windows).

The new windows are in, the outside stucco has been patched, but the sheetrock inside has not yet been replaced. I noticed (by way of a California king snake in my living room) that there is a 1/2" gap at the bottom of the exterior of the wall.

This shows the wall frame, the tar paper and at the bottom a metal strip (flashing?) that is nailed to the frame, yet it is not really in contact with the frame, it is gapped up to 1/2" away: https://imgur.com/a/1cwryxU

Another shot: https://imgur.com/a/SJizFWM

The outside (the gap is floating maybe an inch or two over the mulch of this flower bed): https://imgur.com/a/caG1RTH

I don't think the gap is the fault of either the mold removal crew or the window replacement crew. They did not replace the tar paper or that metal strip. At first I thought maybe the demolition of the old stucco could have caused a separation here. But, there is another area where the stucco was not touched, and I can see a similar gap there, so I think this gap predates me living in the house. If that gap had been born recently in an area where the stucco was not replaced, I'd think that I'd see cracks in the old stucco due to the movement of the surface.

The reinstallation of sheetrock will be an improvement, but still not perfect (snakes and their other critter friends could still get into the walls, but not the house).

How should I handle this? I'm thinking the easiest solution is just spray foam that gap (from the inside) while the walls are still open. I know it's not ideal, but short of rebuilding the whole wall I'm not sure what else to do.