Thanks for the info.
We wrote a spec for it here - https://docs.google.com/document/d/1tlfSK1CK8gfHAgraIntOM89IzHjdWSF-qz_uOKDRfYI/edit?usp=sharing
And I've added it to the tracker here - https://tracker.moodle.org/browse/MDL-53729
We've now funded this so please vote for it if you see this as valuable and would also like to see it in core!
Thanks
Alistair