Événements ponctuels avec des canaux

Some things should happen exactly once, like navigating or showing a toast. Modeling these as state causes them to replay on every rotation.

If you store a snackbar message in StateFlow, a configuration change re-reads it and the message pops up again unexpectedly.

A Channel is a hot pipe where each value is delivered to exactly one receiver and then consumed, never replayed.

You push into a Channel with send, a suspend call. The event waits in the buffer until something is ready to receive it.

Turn the channel into a stream for the UI with receiveAsFlow, which lets exactly one collector consume each event.

Once a collector takes an event from the Channel, it is gone. A later rotation cannot read it again, so no accidental replay.

Define a sealed UiEvent type so every one-off action, like navigation or messages, is explicit and exhaustive.

Collect the event flow inside a LaunchedEffect so it ties to the screen lifecycle and runs each event handler once.

A default Channel suspends the sender if no one receives. You can give it a buffer so sends never block your logic.

A SharedFlow with replay zero can also carry events, but a Channel guarantees single delivery even with no active collector.

The clean pattern: one StateFlow for screen state and one Channel for fire-once events. They never get confused again.

Awesome! A Channel delivers fire-once events like navigation and toasts exactly once, keeping them separate from replayable screen state. 🎯