Oneiris is an interactive, AI-augmented brain-computer interface installation that explores personal and collective dreamscapes through generative artificial intelligence, real-time electroencephalography (EEG) neurofeedback, and Indigenous symbolic systems. Participants wear a wireless EEG headset and contribute dream narratives and hand-drawn sketches on a digital tablet. These inputs are embedded using Contrastive Language–Image Pre-training (CLIP) and matched to ten Lakota dream symbols, displayed as a floating constellation within a 360° projection space. A diffusion-based AI pipeline simultaneously augments participants’ sketches and texts into continuously evolving “dreamscapes”, whose texture and color palette are modulated in real time by neural markers of hypnagogia and brain complexity. A Medicine Wheel–inspired interface—an Indigenous symbol embodying the cyclical nature of life—provides viewers with intuitive feedback about their cognitive state as they watch the visuals unfold. In parallel, an online companion platform archives dream contributions as nodes in a collective semantic map, enabling thematic clustering and public exploration. By striving to ethically integrate Indigenous epistemologies—particularly Lakota dream symbolism—into a neuroscientific and generative AI framework, Oneiris provides an innovative model for culturally sensitive, participatory art-science collaboration. The installation offers concrete methodologies for engaging with personal dreams as culturally embedded cognitive phenomena, creating spaces for introspection, collective storytelling, and cross-cultural dialogue.