Replay a closed period against changed rules without writing anything

When I change a tolerance I have no way to find out what the change would have done until the next month of invoices arrives. So I either ship the change and watch, or I leave it alone.

I want to point a modified rule set at a period that has already closed and see what would have been routed differently. Nothing written back, no approvals raised, no notifications sent. A list of the items whose outcome changed, and the before and after for each one.

Half the questions in this community are people guessing at a threshold. This would let them measure instead.