So if anyone is looking for the answer to this issue, it seems like the dialog is the one catching the

onBackPressed

event and dismisses the dialog. To have Compose be connected to it, we have to do the following: In your fragment, catches the dialog when created:

private lateinit var dialog: ComponentDialog

override fun onCreateDialog(savedInstanceState: Bundle?): Dialog {
    return BottomSheetDialog(requireContext(), theme).apply {
        fullyExpanded()
        notDraggable()
        withoutBackgroundDim()
    }.also { dialog = it }
}

Prepare the following extensions on `ComponentDialog`:

private val ComponentDialog.asBackPressedDispatcherOwner: OnBackPressedDispatcherOwner
        get() = object : OnBackPressedDispatcherOwner {
            override val lifecycle: Lifecycle
                get() = this@asBackPressedDispatcherOwner.lifecycle
            override val onBackPressedDispatcher: OnBackPressedDispatcher
                get() = this@asBackPressedDispatcherOwner.onBackPressedDispatcher
        }

And then the only missing piece is in your ComposeView to wrap the content with `CompositionLocalProvider`:

CompositionLocalProvider(
    LocalOnBackPressedDispatcherOwner provides dialog.asBackPressedDispatcherOwner
) {
    MainChatScreen(::dismiss)
}

Maybe @Ian Lake will tell me I missed something else, but in the meantime this seems to work 🤔

And AppCompatDialog already extends from ComponentDialog as of AppCompat 1.5.0-alpha01: https://developer.android.com/jetpack/androidx/releases/appcompat#1.5.0-alpha01

And with this change, AppCompatDialog already sets the correct

ViewTreeOnBackPressedDispatcherOwner

on the returned dialog so that

LocalOnBackPressedDispatcherOwner

picks it up

And that change landed on March 16, so I'd expect it to be in the next AppCompat release (e.g., 1.7.0-alpha03)

In the mean time, I'd probably just set the ViewTreeOnBackPressedDispatcherOwner on your Dialog window's decorView

I assume you're already setting the ViewTreeLifecycleOwner and ViewTreeSavedStateRegistryOwner just to get your ComposeView to work in the BottomSheetDialog?