Author: Y. Seo (@momotarou / Japan)Role: Metanist — Human × AI Understanding ArchitectAI Collaboration: AI Understanding SupportORCID iD: https://orcid.org/0009-0005-7669-0612 Main Text One overlooked aspect of AI designis not how systems operate,but how they stop. Most contemporary AI experiencesare optimized for continuity. Always-on interfaces.Instant responses.Seamless handoffs. Stopping feels unnatural. This is not accidental.It is the result of UX choicesthat equate speed with valueand interruption with failure. Yet, the ability to stopis a core requirement for trust. In early cultural imaginaries—symbolized by Astro Boy—intelligent agents were never depictedas endlessly operating systems. They paused.They hesitated.They returned control to humans. Stopping was visible,and therefore meaningful. Modern AI hides its stopping points. Users are rarely invitedto ask whether continuation is appropriate.The system proceeds unless explicitly halted. This subtly reverses responsibility. Instead of humans deciding to proceed,they must decide to interrupt. Designing for stoppabilitymeans restoring the default positionto human judgment. This can take many forms: Clear session boundaries Explicit confirmation for continuation Costs—temporal, cognitive, or monetary Visible indicators of resource use These are not technical limitations.They are ethical affordances. A future in which humans and AI coexist sustainablywill depend less on how smoothly systems runand more on how deliberately they can pause. The question is no longerwhether AI can continue. The question iswhether humans are still allowed to stop. Disclaimer This work does not prescribe specific UX patterns or interface standards.It frames “stoppability” as a foundational design principlefor maintaining human judgment and responsibilityin AI-mediated systems.