Cluster X-ray cavities cost more than their designated engine earns: excavation energies exceed the central AGN's luminosity and duty cycle by factors of several, cavities run too large, numerous, and old for the current outburst, and some clusters hold cavity generations with no AGN record at the required epochs (McNamara and Nulsen 2007; Fabian 2012).
The model assigns all cavity carving to one engine, the central supermassive black hole, because its nuclear-seeding picture puts exactly one such engine per cluster core. Every cavity must then be a receipt from that single account, and the account keeps coming up short.
SCT audits the energy ledger with a larger engine inventory. The cascade seeded compact objects across a mass spectrum and a spatial distribution set by deposition geometry rather than nuclear assembly (P46, P25), so cluster cores host accreting engines beside and beneath the catalogued central AGN, the same undercounted demography carrying the radio background (recid 159), the FRB second pedigree (recid 153), and the transient engines (recid 149). Cavity systems then draw on multiple accounts: the central AGN supplies its observed share, and seeded engines, flaring on their own schedules, supply the excess, the oversized energetics, the multiple generations without central-AGN records, and the cavities at radii and position angles a single nuclear jet history strains to reach.
The framework also asks less of the regulation: the cooling-flow problem the AGN ledger must solve is gentler in SCT because the relic entropy floor sets a conserved thermodynamic baseline under the core (recid 215, recid 126), so feedback tops up rather than single-handedly balances. The registered discriminant is positional: cavity systems should show statistics, multiplicity, off-axis placements, and generation timing, consistent with a distributed engine population rather than one precessing central jet, and deep X-ray plus radio mapping should find the seeded engines' counterparts as off-nuclear point sources in the deepest exposures. The seeding inventory is in Paper 4, From Chaos To Collisothermal Cosmogenesis.
Keystone economy: P46 adds the engines, P25 fuels them. The ledger balances once the books list every account.
The kill is the census: if deep Chandra and Athena cavity surveys, with complete radio histories, reconcile every cavity system's energetics and timing with reconstructed central-AGN duty cycles alone, the additional engines are unnecessary. SCT separately requires the distributed population to exist observably: cavity-rich cores showing no off-nuclear accreting sources in the deepest X-ray and radio maps, at the abundance the energy deficit implies, would refute the multi-engine ledger directly.