Kotlin coroutines, Compose, and background processing.
5 questions in Mobile Engineering.
Jank in a Compose list is usually excessive or unstable recomposition, caused by unstable parameter types, reading state too high in the tree, or lambdas that break skipping, found with the Layout Inspector's recomposition counts and fixed by narrowing what each composable reads.
Structured concurrency ties a coroutine's lifetime to a CoroutineScope so cancellation propagates automatically, but a leak still happens when a coroutine is launched in a scope that outlives the component that should own it, such as GlobalScope or a manually retained scope nobody cancels. Use this KOTLIN answer to show the decision, trade-off, and evidence rather than a memorised definition.
A ViewModel outlives a configuration change like rotation because the Activity is recreated while the ViewModelStore is retained, but it does not survive process death from memory pressure, which is what SavedStateHandle exists to restore state across.
WorkManager is the default for deferrable work that must eventually run, a foreground service is for work the user is actively aware of right now, and AlarmManager is only for work that must fire at a specific wall-clock time regardless of system state.
The queue records that work was sent but cannot know whether the server received it, so any crash between sending and recording the acknowledgement replays the action. At-least-once delivery is the only thing a mobile client can guarantee, so the fix is to make the operation idempotent with a client-generated key persisted alongside the queued action, not to try harder to deliver exactly once.