<p>This postdigital policy study examines the emergence, translation, and eventual destabilization of South Korea’s AI Digital Textbook (AIDT) initiative. Drawing on Actor Network Theory), we trace how the policy was assembled through shifting configurations of human and non-human actors—including government ministries, evaluation bodies, textbook publishers, EdTech companies, teachers, legal regulations, funding streams, data infrastructures, and sociotechnical imaginaries. Using policy documents, media texts, and 26 stakeholder interviews, we identify five key moments in the lifespan of the reform: the ideation of AIDT as a national solution to ‘personalized learning’, the rapid expansion of actors through state-led partnerships, the institutional inscription of authorization guidelines, the fracturing of the assemblage through data breaches and political contestation, and the reclassification of AIDT from official textbook to optional supplementary material. Rather than a linear failure of implementation, the study reveals AIDT as a contingent and contested postdigital assemblage whose trajectory was shaped by persistent tensions between discursive optimism and material constraints. By foregrounding the multiplicity of assemblages and the mediating roles of non-human actors, the analysis highlights the need for postdigital policy approaches that attend to the unpredictable, unfinished, and continually shifting nature of EdTech reform.</p>