The Quantized Dimensional Ledger (QDL) program treats physical theory construction as a problem of structural admissibility, closure completion, transformation stability, and residual survival. Earlier QDL work developed conditional spectrum selection, electroweak numerical closure, flavor-rank closure, SMEFT operator governance, and classical gravitational closure. The cosmological constant is the most difficult remaining numerical target because it is not merely a local particle-physics parameter. It is a global curvature-scale residual. This paper develops the QDL cosmological-closure layer in a deliberately bounded form. It does not claim to derive the cosmological constant as a completed hard-physics result. It does not solve the full vacuum-energy problem, compute the cancellation of all quantum-field zero-point contributions, derive the bare cosmological constant, prove w = -1, resolve the Hubble tension, replace Lambda-CDM parameter fitting, solve dark matter, or derive inflation. Its contribution is more limited: it identifies the correct QDL target for Lambda, separates the distinct ledgers usually conflated under dark energy, formulates a horizon-screening interpretation, and presents a first numerical ansatz that reconstructs the observed Planck-normalized curvature scale. The cosmological constant has dimension L^-2. Therefore QDL cannot derive Lambda as an isolated raw number such as 10^-52 m^-2 without specifying the length scale relative to which it is measured. The admissible dimensionless target is lambdaLambda = Lambda lP², or equivalently the logarithmic curvature ledger HLambda = -log10 (Lambda lP²). Using the observed Lambda-CDM-scale curvature, Lambda of order 10^-52 m^-2, and the Planck length, one obtains Lambda lP² of order 10^-122 and therefore HLambda of order 121. 5 to 122. The central interpretation is that the observed cosmological constant is not a raw sum of local quantum-field vacuum energies. It is treated as a horizon-screened curvature residual. A positive cosmological constant defines a horizon scale RLambda of order Lambda^-1/2 and a horizon-area ledger NLambda of order ALambda / lP². Since ALambda is of order RLambda² and therefore of order Lambda^-1, one obtains NLambda of order 1 / (Lambda lP²), or Lambda lP² of order NLambda^-1. Thus cosmic curvature is interpreted as the inverse of a horizon-area ledger. The paper then presents a first horizon-screening ansatz. Let Hᵥ = -log10 (G v² / hbar c) be the Planck-electroweak hierarchy ledger. Let Tₐlpha = 9 + 1/27, CW = 53/18, and Cₗambda = 49/72. The proposed QDL horizon-screening ansatz is HLambdaQDL = 4 Hᵥ - sqrt (alpha^-1) + (Tₐlpha + CW - Cₗambda + 1/18) / sqrt (alpha^-1) - log10 (4 pi). Using representative QDL values Hᵥ approximately 33. 38 and alpha^-1 approximately 137. 035999177, this gives HLambdaQDL approximately 121. 7, and therefore LambdaQDL lP² approximately 10^-121. 7, of order 10^-122. This reconstructs the observed Planck-normalized cosmological-constant scale at ansatz level. It is not yet a hard derivation. The formula must eventually be derived from a deeper QDL horizon action, entropy principle, global curvature-source closure theorem, or vacuum-screening mechanism. Until then, its correct status is: first-pass horizon-screened curvature ansatz, not a completed solution to the cosmological constant problem. The paper also separates the cosmological constant from dark matter, dynamical dark energy, inflation, H0, OmegaLambda, and vacuum-energy bookkeeping. It identifies residual tests and limitations, including the dimensionless-target test, horizon-formula derivation test, vacuum-energy cancellation test, equation-of-state test, cosmological-dataset test, Hubble-tension test, dark-matter separation test, Planck-electroweak hierarchy dependency test, and ansatz robustness test. The final bounded result is that QDL reduces Lambda to a dimensionless horizon-screened curvature residual and reconstructs its observed scale at first-pass ansatz level. The next hard-physics step is to derive the horizon-screening formula from a QDL action, entropy principle, or global curvature-source closure theorem, or else downgrade it to numerical compression.
James D. Bourassa (Fri,) studied this question.