At the heart of the minimal compact is a metaphor drawn from the "free software" movement. Think of the core provisions of a constitution as a "codebase" maintained by a central registry. Then imagine a multiplicity of communities who are free to embroider on the codebase - free to develop whatever system of law is locally appropriate, with the sole condition that these local "distributions" of the codebase not abrogate the provisions of the original agreement. (Ideally, they would also refer their innovations to the registry for prospective adoption by other signatory communities.)
By permitting arbitrarily many instantiations of the constitution to exist at once ("compact states"), and allowing signatory individuals the right of free passage between them, there is incentive for communities to optimize their jurisprudence.
It's a subtle idea, and one that can seem idealistic to the point of irrelevance in our current milieu, but it at least breaks the deadlock our current metaphors and models of governance have on our imagination. As the compact suggests, "we can hack democracy." -- AdamGreenfield
PDF format http://v-2.org/minimalcompactpublicbeta1.pdf
Ongoing discussion at http://www.marginwalker.org
Okay, how about we up the ante? Since you are proposing a "modular, decentralized, and interoperable body of shared law for human communities of maximal diversity" backward and in high heels, I would suggest adding some other terms:
A real life example of the minimal compact is the relation of the Bill of Rights in the U.S. Constitution to federal and state legislation. The freedoms guaranteed by the Bill of Rights and the principles of checks and balances in the Constitution itself is the codebase while laws passed afterward are the distribution of that code. The Supreme Court checks to see that the distribution does not go against the code, and the code can be modified if any application seems to be beneficial through amendments.