I wonder if it could be possible to write apps which can take data from all group apps to give the user an overview of all group app data.
Especially for a calendar this would be great. There could be normal Webxdcs in groups and one above-group-level Calendar rendering all my personal events. From there it would be easy to accept or cancel events because of the total overview.
Another app could aggregate all highscores of games so that I can see where someone beats me.
Or take 3 groups with one ToDo list each . One above group-level app could display all pending tasks at once .
Sure, a possible solution could be to create a huge group with all possible event attendees, but each attendee have to add their possible attendees so that, in the end, each delta chat user ends up in this group. (Because, you know, each human on earth is connected over 3-5? persons with each other)
Maybe, allowing updates for those apps would make things complicated, but a read-only permission would be enough to decide, if I can attend an event or to display other important personal aggregations.
Specific for delta chat:
I personally think a calendar should be built into delta chat itself, it is common to send events asics file over email, so it could be similar to another attachment type and there is already the concept of a global gallery, that could just get a calendar tab that is not a list, but a calendar view.
See also: shopping list app. You may have a shopping list for your home (edited by whoever lives in the household), one for a friendly elderly neighbor, one for your workplace (edited by coworkers or your boss), one for a community the kids participate in (edited by the leaders or parents). Each could be added to by their respective circle of members, while reading and procurement would be your responsibility.
Your task then would be to go to the grocery store purchase everything on any of the lists. As you pick each grocery off the shelf, you remove it from the list, so it can be see what you couldn’t purchase in a given shopping trip.
I don’t think DC should integrate a global shopping list app or the next idea that comes up, built upon the same scheme.