This is a stab at describing a separately implementable part of the smart producer ideas. It might be useful alone or it may not be of much use until the smart producer is here.
The idea may be viewed as an extension of the space bank architecture. The guarded bank is controlled by a key whose dissemination is too gross a way to manage storage reclamation. I think that these ideas can be introduced outside the bank logic.
We may wish to transfer destroy-authority from one person to another. This would allow us to transfer a large object from one user to another without "copying" it.
These things would be done with proper "accountability".
The foremost problem in my mind where these ideas fall short of the smart producer ideas is the lack of evidence that a particular object is built from some some particular stable bank.