SageMathCloud's IDE (which is CodeMirror-based, so similar to Adobe brackets, but online) does this, with a nice slider like in "pirate pad". Just create a file and start editing and it will record diffs at about a 1-second interval, which actively editing. Click on the blue "History" button and you get a slider across past revisions. Jon Lee implemented this functionality last summer. https://cloud.sagemath.com I frequently use this fine history functionality when coding. I'll remember that I had my code in some useful state 15 minutes ago (say in the middle between git commits), and I can easily drag the slider back to that point in time and look at the code. It adds a whole new dimension two coding that dramatically improves things. Unlike with Google docs, the SageMathCloud revision history for a file foo is simply stored in the file .foo.sage-history, with one diff per line (in JSON format). You can delete .foo.sage-history or archive it or whatever.
That's what I was wondering, considering we have something like that for a live document in most IDEs (remembering changes character by character and the like).
If a document needed to be played back each time to see what it was then it would suck, you would need a format that both represents the final product and also has all the history in one file.
Well you can get a general copy paste detector on a code base. CPD from PMP is one package. Language support isn't that great although, you mostly only get C/C++ & Java.
