This multi-sited critical ethnography investigates how Mexican farmers’ knowledge practices are reclassified as they circulate between smallholder farms in Mexico and greenhouses in Canada. These farmers are recognized as skilled at home and reclassified as ‘unskilled’ in Canada, a shift reinforced by surveillance technologies and managerial control. From this empirical work, we introduce the prism of labour. The prism traces how knowledge practices, skill classifications, and sociotechnical systems interrelate to form labour infrastructures, and provides a lens for analysis and intervention to consider how these infrastructures are formed, stabilized, and contested. Our contributions are threefold: we provide novel empirical research on migrant farm workers in HCI, introduce the prism as an analytic and intervention tool, and show how migration reorganizes expertise through classification, producing hybrid knowledge practices that reshape how technologies are adopted.