Where do I have to be to apply for a UK spouse visa?

I am both British and Irish, with a Canadian wife. We live in Canada and want to move to Northern Ireland.

If we move to the Republic of Ireland first, and I get a job in Northern Ireland (while we are still living in the Republic, I just commute across the border each day to go to work), can my wife apply for the UK spouse visa from the Republic of Ireland (where we would be resident), or does she have to return to Canada and apply for it from Canada?

Thanks

apply for it from Canada

Assuming you are applying through the UK Immigration rules as a British Citizen??

Your wife will not be able to switch from 'visitor' status to 'spouse' status while in the UK.