Oh, I know. The idea is to come up with a sufficiently useful set of assumptions about the stored objects that will offer a useful set of behaviours. And those assumptions will be documented so users will be aware of the issues. The next step after that is to provide hooks so objects can, if necessary be complicit with Pixie.

Encapsulation is overrated anyway. Hell, even Smalltalk, the granddaddy of OO systems, provides tools (inspectors, browsers...) to get round encapsulation.