The isotropic gamma-ray background resists clean attribution: blazars bright enough to fill the intensity overpredict its measured anisotropy, star-forming galaxies are smooth enough but underproduce at high energies, and every population's luminosity function is extrapolated beyond its measured range. The residual ledger has been mined for dark matter signals for fifteen years, yielding hints that soften as the astrophysical accounting improves.
The model's source inventory is its assembly history: populations grow hierarchically, so their faint-end counts and high-redshift extensions are predictions of the same machinery under strain elsewhere. An under-attributed background invites the dark sector to claim the difference, keeping a particle interpretation permanently on retainer.
SCT changes both sides of the ledger. The exotic line item is struck permanently: no dark matter annihilation or decay contributes a single photon (P54), so the background must resolve entirely into emitters, an unhedged accounting commitment. And the emitter ledger is deeper than hierarchical bookkeeping allows: collision seeding front-loads the universe with compact objects and active nuclei (P46), the pre-existing matter context populates early epochs with processed, magnetized material (P25, P28), and the JWST-confirmed abundance of early accreting black holes, the Little Red Dot demographic, supplies precisely the numerous, faint, high-redshift gamma-ray sources whose integrated glow fills the mid-range budget without violating the anisotropy bound, because abundant faint sources cluster weakly in the background statistics.
The prediction is compositional: as instruments push the resolution frontier, the unattributed residual should keep dissolving into faint point sources, with the source counts at the faint end running above hierarchical extrapolations, exactly the direction the above-50-GeV sky, already almost fully resolvable, points. The cross-correlation of the residual with structure should track stellar and black hole mass, never a halo annihilation profile.
This is the same deep-inventory reading behind the 511 keV bulge and the cosmic optical background. There is no need to keep a dark matter contribution on retainer for an accounting gap that source physics is steadily closing.
The registered kill: any confirmed dark matter component in the background, a spectral feature or anisotropy signature tracking halo annihilation rather than source populations, falsifies SCT outright. The compositional prediction is also exposed: if deeper Fermi and CTA analyses find the residual irreducible, with faint-end source counts falling below even hierarchical extrapolations while the unattributed intensity persists, the deep-ledger account fails.