Density regions, integer certificates and packing colorings of distance graphs

We study the interaction between low and high packing colors of integer distance graphs. For D(1,6), the results include exact low-color density regions, component-dependent differences between periodic and ordinary density realization, a logarithmic deficit threshold, and a fixed finite description of eventual low-high regions. The maximum union density of colors 1 through 7 is 211/252, with sharp stability coefficient 137/177 and individual-frequency rigidity. For high indices 36+14t, where t is a nonnegative integer, a complete seven-vertex region has earliest stable residue-class start 36. Applications give 17 <= chi_rho(D(1,6)) <= 20, 18 <= chi_rho(D(1,8)) <= 22 and chi_rho(D(1,9)) <= 17. The mandatory technical supplement and exact computational certificates form part of the proof. Preprint. Not externally peer reviewed. The main paper must be read with the mandatory technical supplement and the accompanying evidence archives.