Generative Entrenchment

Borrowed from Schank & Wimsatt (evolutionary developmental biology): the degree to which a feature is locked into a developmental process so that everything later depends on it. Likavčan uses it as the mechanism of substrate-agnostic ecology's vertical structure: planetary layers carry a temporal-depth index (geosphere 0, biosphere 1, technosphere 2, the solar system −1), and constraints propagate upward only — younger layers can modify older ones but never replace them as platform (fn. 11). This lets habitability be diagrammed in abstraction from any particular substrate. Compare Walker's assembly "depth in time" and Bratton's layered Stack; all three are sedimentation images of constraint.