The bar end shifter is a parking brake, could be a drag brake, that operates the rear V brake. This is standard JD, Orbit, practice.
So V front, disc rear for main braking and 3rd, parking brake, on bar end.
One day when the world starts up again we'll come and see you with it, you are near Limoges, no? We have a house about 1h NE of Limoges.
We were going to the international in Salviac but maybe that'll be next year now.