Design justification documentation
A new developer joining our team may have trouble understanding some of the design choices made in iota2. A documentation effort has been done for builders and scheduling, but there are still some major modules that need documentation (sensor modeling, is one that comes to mind).
I suggest that newcomers (@HugoTrentesaux and to a lesser extent @tardyb) start making a list of parts of the code that need explanations (about the high level choices). After that, we will be able to make priorities and start writing.