I think it would be useful to supplement the reinject command with an automatic mode which calculates the checksum of the source file and injects the file if it is known to the repository (without the need to provide a destination filename). In addition, this could be done recursively if the user provides a directory to inject. All this can probably be done already with some plumbing, but a simple reinject --auto (or scour, or scavenge, if you like) would be a nice addition. Of course this would only work for the checksum backends.

Example use cases would be:

• Recovering data from lost+found easily
• Making use of old (pre-git-annex) archival volumes with useful files scattered among non-useful files
• Sneaker-netting files between disconnected git-annex repositories