Structural Cosmology v1.2: Parameter Constraints and Path Toward Observational Comparison

Structural Cosmology v1.2 develops the parameter-constraint layer of a unified structural-field framework in which a single scalar potential, V(Δ) = ½m²Δ² − ¼λΔ⁴, may provide a unified interpretation of Dark Energy, Observable Matter, and Dark Matter as distinct dynamical regimes of one structural field. Building upon v1.0 (Light and Gravity) and v1.1 (One Potential, Three Phenomena), this paper introduces parameter-space analysis, cohesion-attractor stability, a Difference–Gradient–Reconstruction pipeline, illustrative reconstruction ansatz families, scale-dependent parameters, and a constraint-based falsifiability architecture (C16–C20). The framework establishes a pathway from structural principles through dynamical mechanisms and observable predictions toward quantitative observational comparison. Candidate parameter regions are identified in the (m², λ) space, and a Bayesian-style inference framework is introduced to connect theoretical predictions with cosmological observations. The paper concludes by defining the observational roadmap for v1.3, where the framework will be confronted with cosmological and astrophysical datasets including CMB, BAO, Type Ia supernovae, galaxy surveys, and weak-lensing observations. All computational demonstrations are illustrative and are provided together with a Zenodo-ready Python companion script.