A Conditional Reconstruction Model of the Dark Sector: Symmetry, Topological Defects, and Invariant Capacities

Can dark matter and dark energy arise from different responses of a common physical support? We develop a conditional model within admissible reconstruction, where persistent structures and their supporting platform are selected together, and familiar dynamics describe their continuum read-out. Symmetry organizes responses, topology distinguishes identities, and stability compares admissible capacities. A selected platform–complement configuration space has a shared binary surface-linked obstruction. Its positive quadratic response reaches all five traceless metric-shape directions. An explicit embedded gauge-and-core completion realizes this obstruction with finite energy, balanced supporting stresses, and a calculated weak gravitational metric whose leading mass equals the rest energy. Native selection of that action and its scale remains conditional. A protected nonparticle sector has vacuum-like stress for its leading pure-metric volume action. An explicit rank-five projector, common-unit transport, saturated continuation, and exchange stability give the invariant-capacity partition 14:75:191 under stated hypotheses. With common late-time matter conversion, the nonbaryonic-to-baryonic density ratio is 75/14, consistent with released Planck joint posteriors. Common-parent inheritance gives a primitive mass target near 941.57MeV/c² and a precise scale condition for its gravitational realization. A conditional rank-two neutrino spectrum near 58.8meV in total resolves the small relic contribution and supplies a correlated growth test. Countermodels locate the remaining selection problems. These results provide microscopic and cosmological tests within declared physical correspondences.