It doesn't seem to work. Is there anything else I need to do?
This is likely because you've added "desc" in lowercase and it should be uppercase (it's case-sensitive). Choices are:
Terrasoft.OrderDirection.ASC (or a 1)
Terrasoft.OrderDirection.DESC (or a 2)
Terrasoft.OrderDirection.NONE (or a 0)
Changing the edit page schema to specify sort direction did not appear to work for me, however another method which did work for me and will persist wherever the detail is used (useful if you want that) is by overriding the addGridDataColumns function in the detail schema and adding a sorted column to the Entity Schema Query like so: