Sigh.
I would, actually, deprecate the hell out of the term “Fundamental Contract” if I could at this late stage, because as I wrote in the above-linked piece, it really, really isn’t one for many of the same reasons and as such this cannot possibly be what they call it in the original Eldraeic. But I don’t have a better term in English for “a restatement of the implications of the fundamental nature of sophoncy in a manner convenient to the understanding of folks used to a format of rights and obligations”, so with it I am stuck. That, and it’s very long-standing canon at this point.
But, hell, the oldest versions of it date back to around -3,000 or so, so perhaps the eldrae can forgive their distant ancestors a certain degree of terminological inexactitude.