A Component-Based Architecture for User Interface Consistency in Retail POS Systems: The Shift UI Approach

In the retail sector, software systems providing services must be user-friendly, efficient and optimized for service delivery. In this study, we present Shift User Interface (UI), a micro-level UI design approach for Point-of-Sale (POS) systems. Shift UI focuses on task-specific UIs such as product listing, cart management, amount entry, partial payment, POS transactions and apply well-known usability principles such as clarity, consistency and error prevention. UI designs are first prototyped in Figma and then implemented using Kotlin, Jetpack Compose and a shared component library (CommonUiObjects) built on design tokens derived from Material Design 3 and Figma. Based on Scrum and Trello, we describe the design goals, core display patterns, underlying component architecture and development process and discuss qualitative observations from internal use demonstrating improvements in User Experience (UX) consistency, maintainability and readiness for future usability studies. This approach has been implemented in the UI layers of Android applications, Sale and SHIFTTECHPOS. This study demonstrates that at the micro level, task-oriented design reduces the number of steps required for common operations. By providing clear feedback at each step, Shift UI helps prevent errors and reduce operator uncertainty.