Final Consolidation of a Passive Steady-State Framework for Long-Duration Operation

This paper concludes a three-part conceptual framework on long-duration steady-state operation in fusion systems based on passive thermal impedance and architectural decoupling. It provides the logical and mathematical consolidation of the physical principles introduced in Papers 1 and 2. The analysis is grounded in a governing thermodynamic principle observed in Dewar-type systems, where energy confinement and dissipation emerge from passive architectural organization rather than active control. Non-parametric relations are used to describe flux decoupling, stress localization, thermal balance, and bounded degradation. The work is presented as a self-contained conceptual contribution, intended to be examined or challenged based on its internal physical coherence.