Future-Splitting State Recruitment in History-Dependent HCP Magnesium Mechanics: A Minimum-Decisive Prospective Protocol for State Sufficiency, Probe Selection, and Mechanism Localisation

This preprint specifies a minimum-decisive prospective experimental protocol for testing the Future-Sufficient Address Invariant / Future-Splitting State Recruitment (FSAI/FSSR) family in history-dependent HCP magnesium mechanics, using AZ31/AZ31B as the default reference system. It does not claim discovery of twinning, detwinning, hysteresis, constitutive memory, or a new physical law. Instead, it begins from the strongest practical predeclared domain-native constitutive state and asks whether a lawful reversal selected specifically to expose false state equivalence can produce a held-out future split beyond a frozen tolerance. If a split survives state-matching, challenge, boundary, measurement, stochastic, and probe-induction nulls, the protocol requires the smallest predeclared measurable physical augmentation that restores held-out predictive closure, followed by remove/restore testing. The FSSR-selected challenge is also compared under matched budget with a standard parameter-information experimental-design challenge. State sufficiency, challenge-design value, mechanism localisation, and prospective lead are reported as four independent verdicts. Preservation and NULL outcomes are explicitly valid results. This paper reports a prospective protocol only; no empirical experiment or positive MKUFT result is reported.