packrat::init() assumes that you have internet connection

Of course this should be fine most of the time - yet only most of the time ;-)

Couldn't you keep packrat's source as retrieved on the first install somewhere and use that instead? At least optionally.

Also this question just popped up: based on the status messages I'm guessing that the version of packrat that is fetched when running packrat::init() corresponds to the respective latest stable version. But the user might have installed his system-wide version of packrat quite a while ago when initializing his particular new packrat-controlled project. Isn't there some potential risk of the newer project-bound versions behaving differently than the system-wide version? As a user, I would probably expect the project-bound packrat installation to be the same as the system-wide?

Start at the packrat::init() entry point and trace how the project-bound packrat source is retrieved and versioned. Clarify the expected offline reuse behavior and how the project-bound version should relate to the system-wide installation; done should include agreed behavior for both concerns and corresponding coverage, though no file or test is named.