Concurrent editing

**- Do you want to request a *feature* or report a *bug*?**

Feature

**- What is the current behavior?**

Right now I have to verbalize if I am making changes on something that another person may be making changes on... this is very confusing and I could see it leading to problems.

**- What is the expected behavior?**

Not sure what the best fix would be.. a notification of _currently be edited by NAME_ would be helpful to know who to go to. Or when you go to *SAVE* it tells you that's not the most updated version? But then that could cause issues with edits I may have made and then would potentially loose.. I'd be wary against any roadblocks because if someone is editing (but not actively) then that would cause a bottleneck.

The issue names no files, tests, or entry points. Start by clarifying which concurrent-editing behavior is wanted—editing notifications, save-time conflict detection, or another approach—and define the accepted behavior before implementation; the issue does not currently establish what done looks like.

Written by the indexing model from the issue text.