An exemplary stair nosing assembly comprises an elongated base, a plate adhered to the base, and a cover temporarily covering the base and the plate. The base has at least one anchor portion extending downwardly from the upper portion for attaching to a lip of a tread pan and/or embedding in a concrete tread. The plate can have various features to enhance traction and visibility. The cover has front and rear lips that engage with front and rear edges of the base, and a weakened region adjacent the rear lip. When the assembly is embedded in a concrete tread, the cover is configured to fracture at the weakened region when the front lip of the cover is lifted upward from the base, leaving the rear lip remaining embedded in the concrete and allowing the rest of the cover to be removed to expose upper surfaces of the base and plate.