Void boundaries are too crisp: galaxy counts and matter density climb steeply over a small radial range where simulations grown from Gaussian patches predict smoother, softer transitions (Colberg 2005; Hamaus 2014; Ceccarelli 2013). Matching the observed cliff-like edges requires bias and feedback prescriptions tuned case by case.
The model's voids are slow exhalations, underdense patches drifting empty over billions of years, and gradual processes draw gradual profiles. A steep edge has to be manufactured afterward by tuned galaxy bias or feedback, because nothing in the formation mechanism itself ever drew a sharp line.
SCT's voids have sharp edges because their boundaries are not transition zones at all; they are the flanks of deposited filaments. The cascade laid down each stream with a defined width set by the smaller pocket's self-gravity at the moment of the head-on event (P33), so the line between dense filament and empty gap was drawn at deposition with the crispness of the collision geometry, not smeared by billions of years of drift (P34). A quasi-compensated profile with a ridge at the boundary is exactly the cross-section of a compressed stream sitting beside a deposited gap.
Time then sharpens rather than softens the contrast: enhanced Λ_eff inside the underdense interior accelerates the local apparent expansion (P17, P19), evacuating the void center faster than constant-Λ dynamics permit while the filament flank stays bound, steepening the gradient between them. The two halves of the mechanism are the same pair carrying the whole void sector, deposition architecture (recid 95) plus Λ_eff dynamics (recid 86, recid 89); edge sharpness is the profile-shaped reading of one story. The deposition geometry is in Paper 1, From Chaos to Convergent Foundations, with the expansion machinery in Paper 7, From Chaos To Cosmic Expansion.
Keystone economy: P33 draws the line, P19 deepens the contrast. No bias tuning, no feedback choreography, no case-by-case calibration; the edge was always there.
Stacked DESI and Euclid void profiles carry the kill: if edge gradients across thousands of selection-controlled voids converge on the smooth ΛCDM N-body prediction, with the cliff-like cases dissolving into bias artifacts, the deposited-edge origin is refuted. SCT additionally requires edge sharpness to correlate with the bounding filament's properties rather than with the void's own size, a population-level signature the exhalation picture cannot produce.