For pretty much a year, i.e. the point at which Mentat became an app that you could run and create Things, the model of containment was very simple: you had Workspaces and workspaces contained Things. The end.
This had the benefit of being simple but it chafed. I had been pondering adding layers as a way of hiding Things that you didn’t want to work with. In trying to implement this I realised that I was skirting around the fact that I needed nested containment. And I was skirting around it because I thought it would be hard to retro-fit.
As it happens it was not as hard as I imagined and it lead to a great simplification of the model. Things can now contain Things and Workspaces are now Things, that contain Things (but not other Workspaces). At some point Workspace is going to be renamed Application which more suits the concept I originally had in mind.
Now I have nested containers implemented and a more consistent data model, which is good. The UI needs to catch up but that will come soon.
Containment was the last of the big ticket items from the original 1.0 roadmap. And so I get closer to a (private) release.