<i>β</i> -motifs and molecular flux promote amyloid nucleation at condensate interfaces

-prone segments. Second, varying segment rigidity and molecular supply rate organizes a non-equilibrium phase diagram with four interfacial growth morphologies, ranging from uniform wetting to fibrillar protrusions and inter-condensate bridging networks. Third, directional fibril elongation displays an inverse relationship with drift velocity, consistent with a mechanism in which higher transport rates to the interface favor planar saturation over directed tip incorporation. Together, these results support a picture in which condensate interfaces can act as kinetically favorable nucleation environments, sequence-encoded rigidity helps determine whether interfaces remain liquid-like or become fibrillar, and molecular flux emerges as an additional control axis in the model for condensate aging trajectories.