How to make sure macports only upgrades to ports that are at least a month old? The goal is to insulate a code base from potential problems with new port upgrades.

So maybe if a port upgrade outdated command can be amended not to use the freshest of the fresh ports, you can avoid tracking down errors in ports affecting your code.

As far as I see,  port info port_name doesn't have any extra release date options:

$ port help info
Usage: info --category --categories --depends_fetch --depends_extract --depends_build --depends_lib
            --depends_run --depends --description --epoch --fullname --heading --homepage     --index --license --line
            --long_description --maintainer --maintainers --name --platform --platforms --portdir --pretty
            --replaced_by --revision --subports --variant --variants --version


I suppose the best alternative to this is to perform daily incremental upgrades. Then when something breaks, it's easier to rollback since likely only a few ports will change per day.
You could potentially monitor the SVN repo that all the Portfiles are distributed in to determine when last each port was changed.

Take a look here: http://guide.macports.org/#development.local-repositories, and set up a local copy of the macports trunk. Once in a while go see what revision number (#####) was committed about a month ago, and svn upgrade -r #####

Make sure you remove the default macports source, though:

#rsync://rsync.macports.org/release/ports [default]


Clearly a different approach to where you were heading with the port command, but it would work.