A Closure-First MAT Baryon Readout and Boundary-Trace Source-Operator Test of the Primordial Lithium-7 Discrepancy

The primordial lithium problem is the persistent excess of standard Big Bang nucleosynthesis mass-seven predictions over the lithium abundance inferred from old metal-poor stars, despite the success of the same framework for deuterium and helium. This paper gives a reduced, falsifiable closure-first MAT (Mittermeier Attractor Theory) source-operator chain for the discrepancy. First, the MAT baryon asymmetry fixes the physical baryon density before lithium information is used. When this density is propagated through the ordinary standard-BBN bulk transfer, it lands on the high Planck-era mass-seven production scale rather than on the observed low stellar scale. The failure is therefore not hidden by retuning the baryon density. Second, the terminal primordial 3He(alpha,gamma)7Be parent source is reclassified as a finite-support boundary source, while the thermonuclear energy-space rate and the protected deuterium and helium bulk sectors remain standard. The reduced result factorizes into an ordinary kinetic response and an independently fixed geometric source trace: Y7^MAT = Y7^SBBN * (eta10^MAT/eta10^BBN)^(2 - 4 gamma_D) / S_th^MAT. The support entropy is fixed upstream by the MAT support radius and the compactness-crossing Bekenstein-Hawking entropy; it is not adjusted to lithium. The reduced numerical prediction is Y7^MAT = 1.4487709440898085e-10, at the stellar lithium anchor within the quoted uncertainty. The mechanism uses no decaying dark matter, no unobserved resonance, no universal laboratory S34 shift, and no final abundance post-scaling. In the reduced source-operator formulation, the mass-seven anomaly is a finite-support carrier-measure effect of the terminal Z1Z2 = 4 parent source rather than evidence for an additional beyond-Standard-Model lithium sink. The remaining microscopic validation target is a channel-resolved full-network implementation of the same homogeneous source-operator projection. Such a test must apply the finite-support source operator only to the primordial terminal 7Be parent source and verify that D/H, Yp, 3He, 6Li, and laboratory/solar S34 remain protected.