I plan on adding visibility to posts with values (private, friends, public) to allow users to keep posts private, share with friends or share them publicly. Visibility must be used for filtering activities before pagination.
Where does the visibility property go, on the activity or on the model or both? if on both, how are edits to visibility handled?
You could send the visibility in the metadata of the activity as you sent it to Stream. If you also include a foreign ID (an ID value that means something to your application), then you can perform an update on that activity later to change its visibility.