Adaptive smart windows require stable optical states to regulate solar heat gain while maintaining visual functionality. However, achieving addressable multicolor operation remains challenging. Reversible metal electrodeposition (RME) offers broad optical modulation, but partially deposited intermediate states are typically transient and difficult to stabilize as distinct optical modes. Here, we transform these transient intermediates into stable plasmonic color states using a three-dimensional indium tin oxide nanotree (INT) scaffold. In combination with nucleation–growth-decoupled voltage programming (NGD-VP), the transparent INT architecture spatially directs Ag nucleation and suppresses planar coalescence, providing combined electrochemical and structural control over particle evolution. The resulting device exhibits four distinct and stable optical modes: transparent, plasmonic-colored, black, and mirror states. Finite-difference time-domain (FDTD) simulations elucidate the optical origins of these states through wavelength-specific electric-field localization. Complementary machine-learning analysis further identifies the growth voltage as the primary determinant of color intensity and the scaffold geometry as a key factor governing the Ag growth pathway. The optimized INT scaffold, with a height of 1000 nm, stabilizes intermediate states mediated by localized surface plasmon resonance (LSPR) for up to 5400 s. Furthermore, the device enables stepwise control of solar transmittance, achieving a solar modulation of approximately 89% and a difference of 8 °C in absorber-temperature under 1-sun illumination. Together with climate-dependent EnergyPlus simulations and wireless device operation, these results demonstrate that stabilized Ag-deposition intermediates can serve as programmable optical states for adaptive façades with multicolor and multistate functionality.

Reversible metal electrodeposition (RME),Smart windows,Localized surface plasmon resonance (LSPR),3D ITO nanotrees