Flasing over Window Infill

[MartyMcFly]

Hi I’m planning to put up a Pergola at the back of my house. I am planning to fix one edge of the pergola to the wall but the edge will run over a cavity that has a cement infill panel. I’d like to close the gap with flashing but not sure what would work the best? If attached an image showing in red when the pergola ledger will be and black highlight showing the opening I’d like to close off between the pergola ledger and the existing infill panel.