Kotlin Coroutine Structured Concurrency Pitfalls in Production

Deep dive into how structured concurrency actually behaves in production Kotlin backends and Android apps — covering the subtle differences between coroutineScope vs supervisorScope exception handling, why catching CancellationException silently breaks your entire coroutine tree, how Job hierarchies interact with Retrofit/Room/Ktor under cancellation, and the specific patterns (atomic cancellation blocks, NonCancellable withContext, idempotent cleanup) that prevent partial writes and silent failures in real systems