SPT2349-56 at z = 4.3 carries (11.8 ± 1.2) × 10⁶⁰ erg of hot gas, 6.4σ above TNG-Cluster, five times the universal Compton-Y scaling, and an order of magnitude beyond what collapse of its 9 × 10¹² solar mass halo supplies (Zhou et al. 2025, Nature). The AGN repair needs 120 ± 20 percent thermal coupling efficiency: more heat than the engine makes. The protocluster class keeps arriving earlier, denser, and hotter than assembly schedules permit.
The model heats cluster gas gravitationally, on the assembly clock: thermal energy tracks the halo's collapse history plus bounded feedback. A system holding ten times its gravitational budget at z = 4.3 must borrow from an AGN account that audits at over 100 percent, because nothing else in the model carries heat.
SCT deposits the heat with the structure: protoclusters condense from collision-thermalized material, and intermediate-impact-parameter deposition channels convert collision kinetic energy directly into proto-ICM thermal content (P22, P25), with the registered quantitative chain giving thermal energies of order 4.5 times the virial expectation for SPT2349-56's class, the born-hot ICM. The measured excess is the deposition receipt: gas hot at z = 4.3 because it was thermalized at seeding, not assembled and shocked over subsequent gigayears, so no engine needs to run past unity and no schedule is violated (P29, P30 carry the relic thermal state forward). The registered prediction frames the class: tSZ-selected protoclusters at z above 3 showing thermal energies 3 to 10 times virial, correlated with elevated stellar masses, disk fractions, and overmassive central black holes, the full born-together signature.
The timeline compounding resolves jointly: the same seeding that puts fourteen starbursts in 130 kiloparsecs at z = 4.3 puts the hot gas among them, which is why the system's every component reads as too early by the assembly clock and on time by the deposition one.
This is the same born-hot physics behind the entropy floors and El Gordo's thermal extremity, caught at the epoch of deposition itself. There is no need for feedback engines that out-produce their own energy supply.
The registered kill: ALMA follow-up of ten or more z above 3 protoclusters finding all systems with thermal energies following the TNG-Cluster median, SPT2349-56 reduced to an outlier, would remove the born-hot class; equally, the excess found uncorrelated with the companion signatures (stellar mass, disk fraction, black hole masses) would break the born-together prediction. The class is the test: deposition requires the survey to keep finding hot ones.