Currently, git-annex takes a very lazy approch to displaying progress into. It just lets rsync or whatever display the progress for it, in the terminal.
Something better is needed for the webapp. There needs to be a way for the web app to know what the current progress is of all transfers.
To get this info for downloads, git-annex can watch the file as it arrives and use its size.
TODO: What about uploads? Will i have to parse rsync's progresss output? Feed it via a named pipe? Ugh.
This is one of those potentially hidden but time consuming problems.