Building a #flatpak is insane. You people are kidding, right?
Just specifying the sdk in the #flatpak manifest causes the build to fail. It never even gets to my janky source code.
"""
Dependency Sdk: org.gnome.Sdk master
Installing org.gnome.Sdk/x86_64/master from flathub
error: Nothing matches org.gnome.Sdk in remote flathub
"""

That rocks.

@jeff The master branch for the gnome sdk is on the gnome nightly flatpak repo (https://nightly.gnome.org/).

Ideally if you don't specifically need the latest git of any gnome libraries you should probably just stick to the last stable release aka 50, that one is on flathub at least.

Nightly GNOME Apps

Learn how to install and run GNOME Nightly apps.

@stupidduos the problem is that even the #flatpak examples don't specify a "runtime-version" option. The tutorial for building your first flatpak omits it. Yes. i chose a version, and I eventually built a flatpak. It required me to guess that "runtime-version" is effectively mandatory under a default configuration.

Somehow #flatpak makes building a #snap seem sensible (it's not).