Currently there are 2 categories of applications in GNOME. Core Apps and Circle Apps (see apps.gnome.org). There are many apps inbetween these 2 categories which are nomansland like Fractal, Sound Recorder, Highscore, Easytag, Balsa and so on. I wonder if there is a third category missing. Or is it only just too early and these are subject to be applied to the Circle category?
I just realized that visibility is really lacking for these apps and i think this is not a good situation.
That’s mostly a question that should be answered by the respective projects. However, not all projects you listed seem to be oriented on the current GNOME Human Interface Guidelines, which is a requirement for Circle.
But the place in which the Extra Apps are truly defined with some officialdom is really only in gnome-build-meta, which incorporates them as part of what it calls “world”:
There is not 100% consistency between “world” and “Extra,” but they are pretty close to being Close Enough ™ to being one and the same conceptually.
In my view, what constitutes an Extra App should be better defined and more consistent across the ecosystem, and this categorization should be more clearly presented in end-user-facing material (be it the wiki or apps dot gnome dot org).
People frequently make up random categories. Those listed ‘extra’ apps for example have a clear category (wasn’t the same at issue creation):
Builder (Core Devel)
Devhelp (Core Devel)
Extensions (Core)
Kings Cross (Core)
Podcasts (Circle)
Polari (Circle)
But I totally agree that things can be quite messed up. You probably have noticed that there is already a corresponding initiative when browsing the initiatives issue tracker.