This paper defines a thermally driven architectural solution for high-dexterity robotic hands based on palm-centralized actuation and axial heat export through a conductive wrist into a forearm thermal mass. Fluid-channel tendons provide simultaneous force transmission and distributed heat transport, while embedded phase-change material buffers transient thermal spikes. The design eliminates distal heat concentration, removes dependence on airflow cooling, and maintains human-safe external surface temperature in vacuum, atmospheric, or dust environments. A bench-top validation configuration with measurable thermal performance metrics is presented. The architecture directly addresses the dominant reliability, grip strength, and actuator density limitations currently preventing production-scale humanoid manipulation.