This is part I https://zenodo.org/records/16978450  
This is part II https://zenodo.org/records/16978117  
This is part IV https://zenodo.org/records/16978234  

This work develops a black hole cosmological framework in which the observable universe is the interior of a black hole with Schwarzschild radius equal to the Hubble radius. The model decomposes the observed cosmological constant into two physically derivable components: a geometric term arising from black hole curvature and an informational term from holographic saturation, together reproducing the observed value without fine-tuning. It predicts an age gradient across cosmic history, naturally explaining JWST’s discovery of chemically evolved galaxies at redshifts z > 10 and resolving the Hubble tension. Falsifiable predictions include negative redshift drift (opposite in sign to ΛCDM), measurable by ELT-HIRES in the 2030s. Convergent evidence is presented from DESI DR2 (neutrino mass bounds, evolving dark energy), stellar population data, and structure formation. This preprint extends earlier parts of the Information Saturation series and positions black hole cosmology as a testable alternative to ΛCDM.