A sharing extension is something we definitely want to add, and is planned for the near future. It is very high on our list.
I can imagine it seems like this would be very easy to do, and — if it were — we certainly would have already done it. Unfortunately, such an extension needs to be able to use the Agenda notes data fully, even when Agenda is not actually running. So we need some quite extensive changes under the covers to make this possible.
Nonetheless, it’s an important feature, and we plan to start looking into it in the second half of the year. Sorry for the delay.