idea how to keep moced backend and c++ interface working for the complete project cycle

If a user starts with Qt Design Studio and implements the UI at some point, he thinks about how this should interact with C++.
When he starts implementing C++ backend -> Qt Design Studio is out of the loop immediately.
Only internals know how to create moc/dummy objects to keep it working.

From web development, I see how GraphQL works - defining the interface for how I want to get the data and, behind it creating the correct database + tables to fulfill that.

Maybe it is a good idea to have a tool/plugin on both tools, Qt Design Studio / Qt Creator -> "Create C++ backend interface", where it defines the functions and properties in the moc and generates the C++ skeleton.

Even parsing that C++ header or/and moc can suggest the change on the other side to the user to help him keep it in sync.