From Vibe to Code—and Back: Lexical Oscillation in the Formation of Design Intent with Generative AI

Generative AI design tools make natural-language prompts a starting point for design, placing new articulation demands on designers. Rather than treating prompts as the transmission of preexisting intent, we ask how design intent is formed through situated interaction with AI. Five expert UI/UX designers (11–20 years’ experience, M = 15.4) designed landing-page hero sections with a generative AI tool, recorded through think-aloud and retrospective interviews. Using reflexive thematic analysis, we treated lexical granularity (L1 vibe, L2 design-domain, L3 operational language) as a sensitizing lens. Rather than moving from vibe to code unidirectionally, designers showed lexical oscillation, including returns from operational specificity to ambiguity. Mismatches with AI outputs became occasions to reconsider what they meant, and engagement shifted from instruction to consultation. One non-oscillating trajectory—a negative case—suggested conceptual misalignment as a tentative boundary. We position AI as a non-neutral generative interlocutor and ambiguity as a resource for design judgment.