If your training dashboard starts as one HTTP request and grows into athletes, activities, wellness, workouts, gear, and performance data, a hand-written fetch wrapper becomes expensive to maintain. Every new endpoint adds another URL, another response shape, and another place to get authentication or retry behavior wrong. This tutorial shows a small, reproducible path with intervals-icu , an open-source TypeScript client for the Intervals.icu API . The goal is not to build a complete train...