We had client-side notification stacking in the tray since launch, but now we want to stack notifications in the notifications page, in API responses and in email bundles.
Is confusing since "source" already captures the origin of the notifications. It's
needed to interpret things at rendering time, so we can query things as needed there.
Instead of delegating. With a polymorphic relationship, relying on a certain
attribute implies doing things like aliasing "mentioner" to "creator" or similar.
Previously when an item was `created`, we'd track the event, update the
summary text, and broadcast the notifications. But now that we have a
draft state, we shold do all of this when it's published instead.
Alp Keser