Observer-history-dependent cosmology: reconstructive memory, the coherence law, and the emergence of geometry

Observer-History-Dependent Cosmology (CDHO): coherence law, geometric route, and an empirical arc We develop a framework in which spacetime is not presupposed but reconstructed: histories read one another, and geometry emerges from the structure of those readings. The central exact result is the coherence law C (c) = (1+c) e^ (−c), a theorem describing how the orientation of a frame under stochastic boosts is forgotten; it is verified by two blind, independent Monte Carlo simulations, and the kinematic sector is shown to contain special relativity (Wigner rotation matched to 10⁻¹⁵; Thomas precession, with its measured factor ½, to 10⁻⁸). On the cosmological front we document a complete arc. The photometric bridge (flux modulated by coherence) was confronted with the binned Pantheon supernovae and is disfavored (χ² ≈ 160 versus ≈ 50 for ΛCDM; given full freedom, the data switch the effect off), with a structural diagnosis: a no-go theorem shows that any depth accumulated along the line of sight yields monotonic dimming, unable to match the observed turnover. The reformulation demanded by the framework's own ontology — coherence does not attenuate the flux but weights the clock, dt = tP·C (c) ·dτ, with depth anchored to the epoch of each tick — was executed under pre-registration and is favored by the same frozen bench at an equal number of shape parameters (χ² = 45. 8 versus 49. 7), with the fitted shape parameter landing inside the window frozen in advance and the parameter-free chains Ωₘ, eff = 0. 325 and H₀t₀ = 0. 958 compatible with their measured values. The verdict is conditioned on the pending confrontation with the full Pantheon+ sample and total covariance. The same weighted clock implies a finite total consensual time, whose relations to H₀ and Λ are set out — together with a declared bifurcation: the mechanism that would generate the cosmological hierarchy produces no observable signal, and the value of the decoherence rate remains underived. A registered risky prediction: the framework's effective dark energy is not a cosmological constant (wₑff ≈ −1. 29 today), and the curves separate from ΛCDM beyond the reach of current catalogues. We carefully distinguish theorems, frameworks, imports, and conjectures. We do not claim a completed unification: we offer a set of exact results, a published negative, a favored but conditioned prediction, and a route with its scope measured. This record contains the English and Spanish versions of the article and the LaTeX sources.