Interaction studies and prototypes, built to answer the questions a static frame can't. Some shipped, some didn't.
The actual problem: two fingers on the chart should select a range, not a point, and SwiftUI gestures only ever expose one touch. A bare UIView underneath reports raw multi-touch instead, so the chart owns the gesture, recolors the band by direction, and swaps the hero to a two-date delta while the rest of the screen is locked from scrolling out from under it.
Hero carousel that zooms into the campaign it was showing, so the card you tapped is the page you land on rather than a new screen that replaces it. Artwork drives the backdrop, and the entrance choreography runs once per launch instead of on every return.
Rebuilt the color foundation of a live banking app as a two-tier token system, primitives carrying values, semantics carrying intent, so modes resolve at the semantic layer instead of a 1:1 hex inversion. Brand purple stays a fixed anchor across both modes, status colors range-switch instead of inverting, same screen, one design file.