Boundary Transport Multiplicity and the Triad-Boundary Decomposition of G

T106 derives the boundary multiplicity factor appearing in the mirror-to-baryonic geometric ratio. The baryonic interface admits three irreducible transport outcomes: \[T_B=\{Tadmit,Tᵣₑₜᵤᵣₙ,Tresidual\}.\] These correspond respectively to admissible phase crossing, complement-sector circulation and return, and residual source formation arising from failed admissible reinjection. Because these transport channels are architecturally distinct, \[Gboundary=#T_B=3.\] This boundary multiplicity combines with the triadic leakage-sector multiplicity \[Gtriad=3\] associated with the leakage modes \[e_3,\;e_4,\;e_5,\] yielding \[G=Gtriadboundary=3×3=9.\]