I would like to be able to add files without having to hash its contents (like WORM) but being able to modify them and record its changes. Is this possible? In other words, I would like to provide other not-that-expensive mechanism for identifying files of a particular version.
You can edit files that use the WORM backend, as long as the editing changes their size or mtime, or both. If neither changes, git-annex won't be able to keep your edits separate when using WORM.
A perhaps safer compromise can be to use the WORM backend initially, but them
git annex migrate --backend=SHA256Ewhen you have spare CPU cycles.Or, when you commit a change to a file that had been using WORM, use
git annex add $wormy_file --backend=SHA256Eto make the new version use the better backend.