From Possibility to Measurement Foundations of a Structural-Realist Ontology of Physical Reality

**New in v29:** The framework now has an explicit four-level architecture. Level 1 (Structure): κ, φ, π₁^κ. Level 2 (Geometry): d = −log κ, necessarily emergent via Corollary 2.3.1 (v28). Level 3 (Dynamics): a compatibility threshold κ_crit > 0 governing which actualization sequences are physically realizable. Level 4 (Physics): causal structure, finite propagation speed, and the emergence of c. The central new result of v29: κ_crit > 0 is not a free parameter but a structural necessity — without a threshold, no stable actualization sequences exist, and therefore no physics. This is formally equivalent to the well-known statement that a universe with causality requires a finite information propagation speed — but whereas in standard physics this is an assumption, in QRF it is derived from the stability condition on actualization sequences. The numerical value of κ_crit (and therefore c) is not yet determined; this is Task 4. The framework proposes the testable prediction γ_obs/κ = E/ℏ.