Unitary Gauge Symmetry from Selector Geometry in the Trinity Geometric Model

This paper derives the unitary structure of gauge symmetry from the selector geometry of the Trinity Geometric Model (TGM), a framework in which time, space, and energy arise as observer-dependent decompositions of a single invariant spacetime interval consistent with local Lorentz symmetry. Localized spacetime regions ("trinities") possess internal selector degrees of freedom whose scalar-clock dynamics define a natural fiber-bundle structure over spacetime. Selector amplitudes define overlap-based invariants that require a positive-definite Hermitian inner product on each selector fiber. Local transformations preserving these invariants form the unitary group U(N), establishing the natural structure group of the selector bundle. Gauge connections arise from overlap-maximizing transport between neighboring trinities and are shown to be metric-compatible, implying anti-Hermitian connections valued in the Lie algebra u(N). Additional geometric constraints, such as preservation of oriented expansion volume, reduce the symmetry to SU(N) in confinement sectors. This work provides a geometric explanation for why gauge symmetry is unitary and complements earlier work deriving SU(3) confinement symmetry as the stationary sector of the Trinity action.