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We study angular spreading in the Fourier-space nonlinearity of the three-dimensional incompressible Navier–Stokes equations on T3\mathbb{T}^3T3. Using the per-mode H˙1/2\dot H^{1/2}H˙1/2 energy transfer, we define sector-based diagnostics that measure how nonlinear interactions redistribute energy across wavevector directions. We prove several exact structural results: the transfer is antisymmetric under Fourier phase conjugation, independent of the Leray projector, homogeneous of degree one in the velocity field, and admits a Sobolev-level scaling identity extending the analysis to H˙s\dot H^sH˙s, s≥0s \ge 0s≥0. For purely imaginary Fourier data, we derive a real transfer formula that reduces the spreading problem to a fully real algebraic expression. We also give an exact finite-mode computation for the Taylor–Green vortex showing perfect second-generation anti-alignment in the nonlinear forcing. We complement these results with pseudo-spectral simulations across multiple resolutions, viscosities, and initial conditions. These experiments indicate persistent negative spreading diagnostics, strong cross-sector dominance, robustness under phase perturbations, and qualitatively different behavior for random-phase and randomized-direction fields. Motivated by these observations, we introduce an affine scale-invariant ratio that isolates directional redistribution from overall transfer magnitude and formulate a heuristic mechanism based on phase structure in the advection operator. The paper is intended as a structural and computational study of angular transfer geometry in Navier–Stokes, together with several exact identities and conjectural implications for depletion and self-regulation.