configuration versioning: where to store and notify that manual intervention is needed?

[Keivan Motavalli <keivan%motavalli.me@localhost>]

In case the gsoc proposal gets approved, I scheduled writing a tool that 
interactively tries to merge config file changes in phase III, similarly to 
how dispatch-conf, etcupdate or freebsd-update are used.
Such a tool could be called each time a package tries to install CONF_FILES 
and had already been installed in the past, if pkg_install is set to allow for 
user interaction.

(how should I name pkg_install.conf variables that control if a versioning 
system is in use, which one it is, if it's installed in a non standard path, 
if it is remote, remote credentials, if user interaction should be attempted, 
if pkg should also try to provision configuration for this system role and 
hostname from a remote repository and the path for the local repository?) 


But basic functionality should be already implemented at the end of phase I, 
so the INSTALL script would initially only store somewhere on the system the 
information that manual interaction is needed to merge/review configuration 
file changes for the package being installed.

Where would it be appropriate to save that? 
How should the user be notified, and in which phase of the installation/update 
being run?

Thanks