The friendly chat application.
If you don't know what you're doing:
Get protobuf/protoc from your distro, as well as Qt packages.
git clone --recurse-submodules https://github.com/harmony-development/Challah
cd Challah
qbs -j4 project.vendoredQQC2BreezeStyle:true project.vendoredKirigami:true
If you do know what you're doing and want to develop against system dependencies. Probably requires git master KDE software.
qbs -j4