hi-manshu Compose state and effects
Core principle
Give every piece of UI state one lowest responsible owner, then run imperative work through the effect whose lifecycle follows that owner. Composition renders; state and effects make rendering change safely.
Procedure
- Inventory mutable UI state, app state, event streams, app dependencies, and imperative work in the affected screen or component.
- Place each state value at its lowest necessary owner: local UI state, hoisted state, a plain UI state holder, or a screen state holder.
- Keep app wiring and business state at the screen boundary; expose plain UI state and explicit callbacks to previewable rendering.
- Choose an effect API whose lifecycle matches the work, and key it by the semantic input that should restart or dispose it.
- Load the focused reference for every material concern below. Do not use a reference merely because its topic is adjacent.
- Route frame-rate reads, cross-phase back-writing, and
@ReadOnlyComposablecontracts to Compose performance. - Finish when every state value has one owner, every effect has a justified lifecycle and key, and the UI can be previewed and tested without app dependencies.
Topic router
| Signal | Read |
|---|---|
Bare local var, remember { mutableStateOf(...) }, state lists/maps, or reset state |
Local state |
| State shared by siblings, UI state holders, ViewModel/component wiring, or previewable screen boundaries | State hoisting |
LaunchedEffect, DisposableEffect, SideEffect, snapshotFlow, rememberCoroutineScope, rememberUpdatedState, produceState, imperative requestFocus, callbacks, event Flow collection, snackbar, navigation, or analytics |
Side effects |
| Focus ownership and keyboard/TV/D-pad behavior | Compose focus navigation |
| Tests or previews for the resulting UI contract | Compose UI testing patterns |
RED/GREEN agent scenarios
- RED keeps a component, collected
StateFlow, navigation event, and screen layout in one composable. GREEN leaves wiring and effects at the screen boundary and gives plain rendering immutable state plus callbacks. - Novel case: a query drives repository suggestions while a list state and focus requester coordinate UI behavior. GREEN puts query and suggestions in the screen state holder, but keeps Compose runtime objects in plain UI state.
- Counterexample: a one-off expandable badge has one private Boolean. GREEN keeps it local and does not introduce a state holder or an effect.