Stable Continuum-Valued Observables from Finite Refinement Measurements: The RCS Framework and Its Physical Spectrum

This preprint develops a refinement–compatibility–stability (RCS) framework in which finite process occurrences generate rational calibration readouts indexed by a directed refinement system, and studies when such readouts determine a stable continuum value. Main results. Every stable rational thread determines a unique value in the Cauchy completion of the internal rational field. Equality of completed values is equivalent to asymptotic thread equivalence; realization preserves the induced algebraic operations; and the value is invariant under cofinal changes of refinement schedule. For bounded occurrence ratios, asymptotically negligible perturbations to the numerator and denominator preserve the completed value. Nested rational enclosures of vanishing width provide a sufficient, independently checkable stability certificate. The mathematical completion is distinguished from the physically realizable spectrum selected by a declared class of admissible protocols. Occurrence-ratio generation and stability alone do not determine a unique physical spectrum; additional assumptions about admissible channel composition can induce corresponding algebraic structure. A Pell-type recursion yields a stable irrational completion value using finite positive-integer counts, while an oscillatory model shows that qualitative refinement assumptions alone do not guarantee quantitative stability. Computability is treated conditionally: if the refinement system and protocol count functions are computable, and the stability thresholds are effectively obtainable, the completion value is a computable real. The paper does not assume that every physically admissible protocol is effective, and does not claim that physical observables must be computable. Scope. The results depend only on the definitions, axioms, postulates and additional conditions stated in this manuscript. The readout is compared with the partial observables of relational physics, and stability, invariance and physical admissibility are treated as logically distinct requirements. The framework originates in the finite-occurrence and refinement-stability sector of the Observation–Feedback (OF) Closure programme (companion manuscript: Observation Feedback Closure I, v1.5.0, doi:10.5281/zenodo.21859450), which supplies the broader relational motivation. The paper makes no empirical predictions and does not identify the physically realizable spectrum with the full mathematical completion. Status. Preprint; not peer reviewed. The deposit includes the manuscript PDF, LaTeX source and BibTeX bibliography.