Immediately before an edit form is shown, we'd need to do a git pull, to reduce chance of conflict.

We should have an overwrite-on-conflict rule (merge being disabled), as conversions would make merging very difficult.

Composr should force sync on all adds/edits/deletes.

This is over-complex. No changes are needed to allow git to be run for a particular Repository-fs directory. You could just make a directory, put a symlink into it to a webdav mounted path, and then initialise git for that directory. Then you manually commit each time you finish making major changes within Composr.

That is reflective of a pretty typical git workflow for a developer. You're not supposed to have commits for each individual change, it's supposed to be change-sets.