Navigation Controllers Hierarchy

The app uses a nested navigation strategy to handle Bottom Tabs and full-screen flows properly.

1. LocalRootNavController

• Scope: Global (The entire Activity).
• Provider: AppNavHost.
• Usage:
• Auth flows (Login -> Onboarding).
• Full-screen features that should cover the BottomBar (e.g., Settings, creating a new Group, adding an Expense).
• Back navigation from "leaf" screens.

2. LocalTabNavController

• Scope: Local (Inside MainScreen tabs).
• Provider: MainScreen.
• Usage:
• Navigation within a specific tab (e.g., Groups List -> Group Detail).
• Preserves the back stack of each tab independently.

How to use

We use CompositionLocal to access them easily in our composables without passing them down as parameters everywhere.

// 1. To navigate to a full-screen feature (hiding bottom bar)
// Used by FABs or Settings items
val rootNav = LocalRootNavController.current
rootNav.navigate(Routes.SETTINGS)

// 2. To navigate inside the current tab (keeping bottom bar visible)
// Used by list items to drill down to details
val tabNav = LocalTabNavController.current
tabNav.navigate(Routes.GROUP_DETAIL) 

Pro Tip: In MainScreen, we explicitly capture the LocalTabNavController for the active tab and expose it via CompositionLocalProvider. This ensures that any child component (like a list item inside the Expenses tab) automatically gets the correct controller for that tab when it calls LocalTabNavController.current.