This paper proposes a theoretical framework linking Structural–Spectral Computing (SSC) with a speculative form of Quantum Superintelligence (QSI) through the capability of real-time structural coherence control in complex systems. SSC represents evolving networked systems in a reduced spectral coordinate space defined by eigenvalues and modal energies, enabling structural observability of dynamics through three scalar functionals: objective reward, instability, and coherence. These quantities are defined on a structural control manifold endowed with a Riemannian metric, whose curvature measures proximity to instability or regime transitions. The paper derives geodesic dynamics on this manifold, shows that curvature diverges near instability boundaries, and introduces a curvature-adaptive control law that regulates unstable modes through a feedback multiplier proportional to spectral curvature. Under this control law, the system admits an invariant coherence-safe manifold and exponential convergence toward stability, providing a geometric mechanism for maintaining structural stability in complex systems. Within this framework, SSC supplies the structural representation and control geometry, while a hypothetical QSI—defined as an ASI-level intelligence operating with quantum information resources—would provide curvature-aware spectral actuation, enabling adaptive regulation of large-scale complex systems in real time.