API Layer That Ages Well — Mock Today, Swap Tomorrow

When cards own fetch calls, every redesign becomes a data refactor. This case study shows a thin repository + service contract used across the portfolio.

Challenge

• UI components coupled to raw data shapes
• No clean path to swap mock for CMS
• Error handling scattered across screens

Approach

• UI → service → repository → data source
• Typed DTOs and normalized errors
• Mock repository first, same interfaces forever
• Never leak raw API shapes into presentational components

Results

Screens stay dumb and replaceable. Backend swaps no longer rewrite the visual system — only the repository implementation changes.