--all would make git-annex operate on either every key with content present (or in some cases like get and copy --from on every keys with content not present).

This would be useful when a repository has a history with deleted files whose content you want to keep (so you're not using dropunused). Or when you have a lot of branches and just want to be able to fsck every file referenced in any branch. It could also be useful (or even a good default) in a bare repository.

A problem with the idea is that .gitattributes values for keys not currently in the tree would not be available (without horrific anounts of grubbing thru history to find where/when the key used to exist). So numcopies set via .gitattributes would not work. This would be a particular problem for drop and for --auto.

--Joey