One of the common problems with traditional spec is that it's usually out of date. However, if we use a list of user stories as the spec, the thing is that the requirement may be scattered and cannot follow once it becomes complex.
For example, we delivered a user story and some time later, we decide to change some behaviors which make some acceptance criteria of that user story obsolete.
If we don't update that user story and just create new one, long time later the new member cannot follow the changes. While doing regression test, our QC may miss those old changes. How can we prevent this?
If we update the user story, then how to version those changes throughout the time?