FIRAS bounds any post-thermalization energy injection to y below 1.5 × 10⁻⁵ and mu below 9 × 10⁻⁵, a thirty-year-old ledger that retires models on contact and remains the binding constraint on every thermal history. The unmeasured decade below it, where ΛCDM predicts y near 2 × 10⁻⁶ from reionization and mu near 2 × 10⁻⁸ from Silk damping, is the cleanest untapped discriminator between origin stories.
The blackbody's perfection is ΛCDM's silent witness: the model passes FIRAS because its singular origin predates the distortion window, and it treats that passage as exclusive. The assumption is that any alternative origin must have injected detectable energy late, an assumption, not a theorem, that the spectral ledger itself can adjudicate.
SCT's books balance by timing. The collision cascade terminates before one second (P40), and thermalization at redshifts above two million erases every injection into perfect blackbody, Compton scattering outrunning expansion by eighteen orders of magnitude there. The registered accounting in Paper 3, From Chaos To Concordance Spectra, runs all three SCT energy channels through the distortion window, acoustic dissipation, superposition heating, residual collision kinetics, and lands each orders of magnitude inside FIRAS: the cascade's mu-contribution sits near 2 × 10⁻⁶, a factor of 45 below the bound, with y-contributions smaller still (P29, P30 carrying the thermalized state forward). The most dangerous constraint in early-universe physics is passed with margin, not by assumption but by the same termination timing that BBN and the peaks already enforce.
Then SCT signs the ledger: the registered prediction of a dipolar y-distortion at delta-y near 4.5 × 10⁻⁷ (Paper 11, From Chaos to Covariant Completeness), the collision geometry's residual asymmetry written into the photon bath, sitting cleanly in PIXIE territory at forecast significance near 45σ. ΛCDM predicts isotropic distortions; the cascade predicts an oriented one, aligned with the anomaly-axis family, a signature no standard process counterfeits.
Two timing premises balance the books, and the same termination clock anchors BBN, FIRAS, and the acoustic peaks at once: one constraint satisfied three ways.
The ledger cuts both directions: any measured distortion exceeding the cascade accounting, a y or mu above the registered channel sums once PIXIE-class sensitivity arrives, indicts the termination timing directly. And the signature is exposed: a spectral-distortion mission finding the y-sky isotropic at the 10⁻⁷ level, no dipolar component where 4.5 × 10⁻⁷ was registered, falsifies the collision-geometry imprint at high significance.