We demonstrate reconfigurable, field-free superconducting diode behavior in NbN/FePt and NbN/AlN/FePt heterostructures with remanent stripe domains in the FePt layer. NbN films 10 nm thick are capped either directly with FePt or through a thin AlN spacer, which reduces electronic proximity effects while preserving magnetic coupling through stray fields. At zero applied magnetic field, the superconducting diode efficiency reaches approximately 50–60% in NbN/FePt when the stripes are perpendicular to the current and is strongly reduced when they are parallel. The diode effect persists in NbN/AlN/FePt with efficiencies reaching approximately 35–40%, supporting a magnetic origin of the nonreciprocity. We interpret the response as asymmetric vortex transport in the remanent magnetic landscape, with preferential edge vorticity and a Lorentz force that favors inward flux injection or outward motion depending on current polarity. Under applied perpendicular magnetic fields, the interplay between the external field and the magnetic stray fields modifies the flux-flow instability and the apparent instability velocity inferred from transport, with values below those reported for bare NbN films. These results show that stripe-domain ferromagnetic overlayers provide a reconfigurable route to control superconducting nonreciprocity and flux-flow stability in NbN-based heterostructures.