Recipe: Log an impression once when a screen opens

Problem: fire an analytics impression exactly once when a screen (or item) is shown — not on every recomposition, and not again after a configuration change.

Use CircuitX’s impression effects (circuitx-effects). They run once for the current retained-state registry, so they survive recomposition and rotation.

@Composable
override fun present(): ArticleState {
  // Synchronous, fire-once:
  ImpressionEffect { analytics.logArticleView(screen.articleId) }
  // …
}

For suspending work (a network beacon, a suspend logging call), use LaunchedImpressionEffect. Pass a key when the impression should run again for a different item:

// Fires once per distinct article id.
LaunchedImpressionEffect(screen.articleId) {
  analytics.logArticleViewAsync(screen.articleId)
}

Use a constant key (LaunchedImpressionEffect(Unit) { … }) for “once for the lifetime of this composition, regardless of inputs”.

Re-fire when the user navigates back to the screen

A plain impression effect stays “already fired” when the user pops back to a screen still on the back stack. If you want to log a fresh impression on re-entry, wrap the navigator with rememberImpressionNavigator and use that for navigation:

val navigator = rememberImpressionNavigator(navigator = navigator) {
  analytics.logScreenReentered(screen.articleId)
}

Need	Use
sync, once per composition/key	ImpressionEffect
suspend, once per composition/key	LaunchedImpressionEffect(key)
re-fire when navigated back to	rememberImpressionNavigator

See also: CircuitX effects