This paper introduces the Zero-zone within the Sandhi framework, redefining zero in causal decision systems as a bounded region rather than a point. The zero-zone is the set of states from which reversal to inaction incurs zero cost and no irreversible commitment has been initiated. Its width and geometry are determined entirely by system-specific Sandhi thresholds, generalizing from a one-dimensional interval to an ellipsoidal region in multi-dimensional causal state-space. The central claim is that the zero-zone is structurally distinct from classical metastability. It does not resolve spontaneously and cannot be observed without triggering commitment. The framework predicts a topological discontinuity in commitment probability: for probe energy below a system-defined threshold (ES), commitment probability is exactly zero; at threshold, it transitions discontinuously to one. This distinguishes it from continuous, noise-driven resolution in metastable systems. All results follow from existing Sandhi definitions without introducing new axioms, under explicitly stated assumptions of deterministic dynamics within the zero-zone and monotonic state transitions with respect to input energy. A falsifiable experimental protocol using bistable threshold devices is proposed, with distinguishing predictions specified against classical metastability. The framework makes concrete, testable predictions: absence of spontaneous resolution below ES and a topologically discontinuous step-function transition at threshold.
Uthraa Murali (Sun,) studied this question.