How do we handle packages removed from GitHub/GitLab?

[wlandau]

If an R-multiverse package is deregistered or removed from Community, it is not automatically removed from Staging. (The only exception is the dependency freeze phase, when Staging the release candidates.) This makes Staging more stable than otherwise, but it does not completely protect us from package removals. A contributor could take down their source code repository on GitHub or GitLab, which would break parts of Staging if there are reverse dependencies in R-multiverse. This matters because we decided to permanently accept a package into a given Production snapshot as soon as it passes checks once.

I am not sure there is any action we should take in our official policies or infrastructure. It seems very unlikely, and even more unlikely for a removed package to have reverse dependencies in R-multiverse. But I do think it is worth thinking about so we have a plan and know how to respond.

Would we see an error in the "Update universe" workflow? The answer might be just to watch that workflow every so often and handle any errors on a case-by-case basis. It seems like the most convenient and available way to track lost packages, if it does throw an error like that.