Could you please refrain from making assumptions? I do recall hearing that Amiga Inc has no source code. And thats from unofficial contacts. I could be wrong as this was 4 years ago.
OS4/4.1 is based indeed on source code from os3.1/3.9. But it came from another source, not A Inc.
I head much the same thing, so what did happen to the 3.1 source code...it's it still on a couple of floppy disks in a dusty filing cabinets at Gateway? Or did it (at least officially) get 'lost in the post' along the way after Commodore exploded? Who actually owns it these days?
Our of interest. How much of the 3.1 code was available to the 3.5 developers, I wonder if anything was missing that had to be re-done from scratch.