We're not super consistent about whether weeks start on Sunday or Monday. This is a bit of a holdover from older times, when we wanted the planner view to match the printed planbook. Then, we wanted imported schedules to match the familiar schedule grid, and so it made sense to start the week view on Monday and match the planner. However, when the month view and datepicker were added, it made sense to have those start on Sunday so that they matched every other calendar in existence... We probably should make this consistent and have it as an option somewhere, though I'm not sure how we want to handle the planner? I don't know if it might get confusing having weekends split in half? It's probably more confusing being split on the start day though....
There may also be some APIs that are dependent on weeks starting on Monday that might have to get changed for this to happen. I think this shouldn't be the case with the calendar and its generic getView API, but the planner stuff is very old and some of those API calls were not very well thought out...
We're not super consistent about whether weeks start on Sunday or Monday. This is a bit of a holdover from older times, when we wanted the planner view to match the printed planbook. Then, we wanted imported schedules to match the familiar schedule grid, and so it made sense to start the week view on Monday and match the planner. However, when the month view and datepicker were added, it made sense to have those start on Sunday so that they matched every other calendar in existence... We probably should make this consistent and have it as an option somewhere, though I'm not sure how we want to handle the planner? I don't know if it might get confusing having weekends split in half? It's probably more confusing being split on the start day though....
There may also be some APIs that are dependent on weeks starting on Monday that might have to get changed for this to happen. I think this shouldn't be the case with the calendar and its generic getView API, but the planner stuff is very old and some of those API calls were not very well thought out...