I don't think it is needed that much. Most places go by the date the permit is issued. Most jurisdictions are months or even years behind on adopting a code. If the designer is worried that a Code change will catch them before it is built then they should pull their permits and have the Building Dept. made aware that they are building to the Code in effect on the day they pulled the permit.
I think even the lawyers would accept this one.
If it was easy, anyone could do it.