Access to all/some contributor's local git repository is a powerful capability but you need to think deeply about 1 or 2 core use cases. "Pull up a chair" is only a surface activity, what's the user's real intent here? Is she trying to understand some part of the codebase or pair programming or debugging together? How can CoDiff help in that core activity?

To get you started here's something I would find useful,

- If I am starting to edit parts of the code that would create conflict with remote or peer's local state, just send us a notification. Much easier to avoid merge conflicts than resolving them.

Also think of developer psychology, e.g. I don't want peers to randomly peek into my WIP code. Things of that sort. Good luck!