The framework fundamentally relies on the continuation API added in Java 21 (which is currently internal to the JDK). Continuations allow for call stacks to be saved to the heap and resumed later.
The async framework allows command bodies to be written in an imperative style. However, an async command will need to be actively cooperative and periodically call coroutine.yield() in loops to yield control back to the command scheduler to let it process other commands.
There are also some other additions like priority levels (as opposed to a blanket yes/no for ignoring incoming commands), factories requiring names be provided for commands, and the scheduler tracking all running commands and not just the highest-level groups. However, those changes aren't unique to an async framework, and could just as easily be used in a traditional command framework.
libprotobuf is a very annoying dependency to deal with, and with the switch to nanopb for generated C++ code, libprotobuf is only used for dynamic decode in the GUI apps. libprotobuf has been swapped out with upb, a much smaller C-based library that supports reflection and can therefore do dynamic decode. This means we can remove the libprotobuf dependency and stop dealing with build issues because of it.
