Emergent technologies like artificial intelligence have been proposed to address issues of inequity in schools, yet tend to ossify the status quo because they address needs within an already inequitable system. In this paper, we draw from speculative participatory approaches across HCI and the learning sciences, and present a novel approach to co-design that forefronts supporting historically minoritized youth in developing transformative agency to change their schools based on their valued hopes, practices, and concerns. We argue that when co-design spaces forefront relational development, expansive technological objects emerge as a byproduct. We present a case study of expansive dreaming with U.S. historically minoritized students about the use of artificial intelligence to support classroom collaboration. Methodologically, we demonstrate how physically visiting spaces of collective agency serves as a powerful perceptual bridge to imagining joyful, equitable possibilities for schooling. Our approach yields new visions for schooling and new metaphors for artificial intelligence.