developer priority with special rules

A developer may have many issues assigned to them. It would be nice if they could assign a priority code to them that indicated, within the list of open issues they had, the order in which they intended to take them. This could be accompiled with a custom field however there are some special rules which would have to be implemented.

They could assign only sequencial numbers starting with 1. So, for example, They assign an issue a code of 1, then another the code of 2, etc.

If they close or reassign an issue, all higher number codes are reset to the next lower number. So, if they close #2, then #3 becomes #2 etc. This assures that all open issues that have a number are sequencial from 1..N

If there are N issues asssigned priorities 1..N and they assign an issue, not in that set, to priority 1<m<N, then all issue with priority greater than m are incremented. There are thus N+1 issues with sequential priority.

If an issue is reassigned or closed, its priority code is nulled out.

All this this would allow, at a quick glance, a person to see in what order a developer had intended to work on a set of issues. Had the user entered some kind of estimatedDays, a person could get an quick estimate of when the issue that they cared about would be done.

Could we get this done on a consulting basis for a fee if it is not in the roadmap?