The Timeless Energy Principle – Unified Coherence Framework (TEP–UCF) introduces a deterministic phenomenological model in which geometric expansion, coherence decay and effective energy are coupled through the conserved scaling invariant Ξ = E/(g φ). This invariant emerges as a consequence of the phenomenological coupling γ = α − β and the unity condition gφ ≈ 1. We demonstrate internal consistency through (i) Exact exponential solutions, (ii) Numerical integration with sub-0.1% drift, (iii) Lyapunov stability analysis, and (iv) Planck-unit normalization. A coherence-feedback modification to the Friedmann equation is proposed phenomenologically as H² = (8πG/3) ρ [1 + φ̇/(4Hφ)]. Synthetic Pantheon+-like distance-modulus data generated within the TEP– UCF framework yield a reduced χ²/d.o.f. ≈ 1.02 under the adopted mock-data assumptions. The framework offers a fine-tuning-free alternative mechanism for late-time acceleration driven by informational coherence dynamics. The framework provides a phenomenological, fine-tuning-free alternative for modeling late-time cosmic acceleration through informational coherence dynamics. Its observational viability will ultimately depend on successful confrontation with official Pantheon+, DESI BAO, and Planck datasets. Ξ = E / (g φ) = constant