Tutor, Not Solver: Designing a Guardrailed AI Assistant for Learning in Higher Education: A Design Case of PeteChat

arXiv:2606.09845v1 Announce Type: new Abstract: Generative AI tutors hold significant promise for higher education, yet designing systems that scaffold learning without undermining academic integrity remains an open design challenge. This paper presents PeteChat, a course-aligned AI tutor developed and deployed at Purdue University, documented through the lens of design-based research (DBR). Drawing on literature-informed design inputs, a pre-deployment baseline analysis of authentic student-system interactions, and formative expert evaluation with teaching assistants and UX/developer stakeholders, we report eight transferable design principles for assessment-aware AI tutors: from homework guardrails and debugging scaffolds to self-regulated learning support and instructor-facing customization tools. The system is built on a locally hosted Llama-3 model enhanced with retrieval-augmented generation (RAG) grounded in course-specific materials. Rather than reporting controlled experimental outcomes, this design case foregrounds the situated design reasoning, iterative refinement, and principled decision-making that shaped PeteChat across multiple development phases. The resulting principles and methodological approach offer actionable guidance for institutions seeking to deploy responsible, integrity-preserving AI tutors at scale.