A human system operator is guided through procedures relative to workpiece objects in real space by a machine-executable procedure program including procedure instructions related to the real-space operations. A spatial-positioning system tracks the locations and orientations within a defined physical space of workpiece objects and tools required to perform procedure steps relative to the workpiece objects. Machine-generated indicia related to sequential procedure steps are presented to the system operator through a mixed-reality headset. The machine generated indicia illustratively include graphical objects and textual instructions that convey to the system user information relative to a procedure step, such as which tool to use to act on which workpiece object, and the operation to be performed on each workpiece object. The system operator contemporaneously views both (i) the physical space and (ii) selected machine-generated indicia such that the machine-generated indicia, from the perspective of the system user, are superimposed over real space.