Schematic overview of the kcwiulb pipeline. The framework operates on standard KCWI DRP outputs and applies four processing stages: preprocessing and astrometric refinement, mode- and channel-dependent sky subtraction, covariance-aware coaddition, and post-co-added signal extraction. The sky-subtraction stage is the dominant component of the pipeline and is implemented differently for KCWI-blue, KCWI-red, and NAS observations, addressing the distinct systematics in each configuration.