Snackbar Handling Guide

This guide explains the shared snackbar flow that powers every platform.

Core Components

core/presentation/src/commonMain/kotlin/com/softartdev/notedelight/interactor/SnackbarInteractor.kt – multiplatform contract with setDependencies, releaseDependencies, and showMessage returning a Job?.
ui/shared/src/commonMain/kotlin/com/softartdev/notedelight/interactor/SnackbarInteractorImpl.kt – Compose-aware implementation that wires a SnackbarHostState, clipboard access, and coroutine scope.
ui/shared/src/commonMain/kotlin/com/softartdev/notedelight/ui/GlobalSnackbarHost.kt – composable that installs a global SnackbarHost and feeds the implementation via DisposableEffect.
ui/shared/src/commonMain/kotlin/com/softartdev/notedelight/App.kt – registers the host at the root and injects SnackbarInteractor through Koin.

Keep the interface free from Compose types so it can be used in tests and on non-Compose platforms.

SnackbarMessage is a sealed interface designed for AI-facing ergonomics:

Simple(text: String) – fire-and-forget message.
Copyable(text: String) – shows a Copy action and writes to the clipboard when the action is triggered.
Resource(res: SnackbarTextResource, suffix: String = "") – resolves a string resource (SAVED, EMPTY, DELETED) and optionally appends context text.

If you need a new reusable message, extend SnackbarTextResource instead of duplicating strings.

GlobalSnackbarHost creates a host state, clipboard, and coroutine scope, then calls setDependencies on the interactor.
SnackbarInteractorImpl.showMessage launches work on that scope, routing messages to the host and clipboard.
When the host leaves composition releaseDependencies clears references, preventing leaks on iOS/desktop.

Do not re-create or inject SnackbarHostState elsewhere—always rely on the global host.

Inject SnackbarInteractor in the ViewModel constructor (see Koin registrations in ui/shared/di/uiModules.kt).
Call snackbarInteractor.showMessage(...) directly; the coroutine is launched inside the interactor so viewModelScope.launch is unnecessary unless you need structured cancellation.
Optionally keep the returned Job if you need to cancel an in-flight snackbar before triggering another one.

Example usage inside NoteViewModel:

snackbarInteractor.showMessage(
    message = SnackbarMessage.Resource(
        res = SnackbarTextResource.SAVED,
        suffix = noteTitle,
    )
)

✅ Add new snackbar entry points through the interactor, never by manipulating SnackbarHostState yourself.
✅ Use SnackbarMessage.Resource for translated strings—resources live in ui/shared/src/commonMain/composeResources/values.
✅ Keep UI wiring in GlobalSnackbarHost; screens should only consume the interactor.
⚠️ Remember to update tests: use a fake implementation of SnackbarInteractor rather than asserting on Compose state.
⚠️ Clean up any manual clipboard usage; Copyable already performs the write.