Professional polish in AI-driven apps comes from applying eight core design principles rather than copying templates or trusting agents alone. Contrast, hierarchy, alignment, proximity, repetition, balance, white space, and unity form a checklist you can use to critique AI output. For example, a Claude-generated layout (V1) mixed clashing colors and competing text elements, while the revised version (V2) placed a single white “Book now” button on a dark backdrop, set a clear top-down reading order, and kept margins consistent. That change alone makes the call to action obvious, guides the eye from hero image to browsing cards, and reinforces a focused brand mood. Alignment and proximity guard against sloppy visuals. In V1, text clusters over photos felt cramped. V2 separates brand messaging from browsing cards, using generous padding to signal shifts in content. Consistency emerges through repetition—one typeface family, uniform pill-shaped buttons, and a single warm accent color tie every screen together. Balance shifts too: V1’s bottom-heavy card stack drags the eye down, but V2 balances a commanding hero shot with a central CTA and a horizontal card scroll at the bottom. White space proves the biggest upgrade. Removing clutter around logos, buttons, and section labels transforms the app’s vibe from overloaded to calm. That negative space isn’t empty; it conveys the brand’s promise of restoration. Unity follows naturally when all elements—nighttime imagery, rounded shapes, consistent margins—align with the same quiet, premium feel. Finally, remember agents treat design as utilitarian code assembly. They’ll give you a bare-bones interface that works but looks generic. Use their output as a starting point. Apply the eight-principle framework to iterate and inject nuance. That’s how you’ll move beyond the homogeneous mass of AI-crafted apps and create something that feels truly professional.