Merge 11097a629a19637e8df3aa5aec40e7e1ad6777f4 into c127eb83ab94c069c32d37530d2faecd381cd2a8

app/src/main/java/com/bitchat/android/MainActivity.kt

@@ -4,7 +4,7 @@ import android.content.Intent
 import android.os.Build
 import android.os.Bundle
 import android.util.Log
-import androidx.activity.OnBackPressedCallback
+import androidx.activity.compose.BackHandler
 import androidx.activity.compose.setContent
 import androidx.activity.enableEdgeToEdge
 import androidx.activity.viewModels
@@ -313,23 +313,13 @@ class MainActivity : OrientationAwareActivity() {
             }
 
             OnboardingState.CHECKING, OnboardingState.INITIALIZING, OnboardingState.COMPLETE -> {
-                // Set up back navigation handling for the chat screen
-                val backCallback = object : OnBackPressedCallback(true) {
-                    override fun handleOnBackPressed() {
-                        // Let ChatViewModel handle navigation state
-                        val handled = chatViewModel.handleBackPressed()
-                        if (!handled) {
-                            // If ChatViewModel doesn't handle it, disable this callback
-                            // and let the system handle it (which will exit the app)
-                            this.isEnabled = false
-                            onBackPressedDispatcher.onBackPressed()
-                            this.isEnabled = true
-                        }
-                    }
+                val canHandleBack by chatViewModel.canHandleBack.collectAsState()
+                // Disabled rather than always-on so predictive back can preview
+                // the exit instead of the app claiming every gesture.
+                BackHandler(enabled = canHandleBack) {
+                    // enabled trails the state by a dispatch and a recomposition.
+                    if (!chatViewModel.handleBackPressed()) finish()
                 }
-
-                // Add the callback - this will be automatically removed when the activity is destroyed
-                onBackPressedDispatcher.addCallback(this, backCallback)
                 ChatScreen(viewModel = chatViewModel)
             }
             

app/src/main/java/com/bitchat/android/ui/ChatState.kt

@@ -170,6 +170,26 @@ class ChatState(
             initialValue = false
         )
     
+    // Mirrors the branches of ChatViewModel.handleBackPressed. The back handler
+    // is enabled from this and the press consumed by that, so they must agree.
+    val canHandleBack: StateFlow<Boolean> = combine(
+        _showAppInfo,
+        _showPasswordPrompt,
+        _selectedPrivateChatPeer,
+        _privateChatSheetPeer,
+        _currentChannel
+    ) { showAppInfo, showPasswordPrompt, privateChatPeer, privateChatSheetPeer, channel ->
+        showAppInfo ||
+            showPasswordPrompt ||
+            privateChatPeer != null ||
+            privateChatSheetPeer != null ||
+            channel != null
+    }.stateIn(
+        scope = scope,
+        started = WhileSubscribed(5_000),
+        initialValue = false
+    )
+
     // Getters for internal state access
     fun getMessagesValue() = _messages.value
     fun getConnectedPeersValue() = _connectedPeers.value

app/src/main/java/com/bitchat/android/ui/ChatViewModel.kt

@@ -387,6 +387,7 @@ class ChatViewModel(
     val passwordPromptChannel: StateFlow<String?> = state.passwordPromptChannel
     val hasUnreadChannels = state.hasUnreadChannels
     val hasUnreadPrivateMessages = state.hasUnreadPrivateMessages
+    val canHandleBack = state.canHandleBack
     val showCommandSuggestions: StateFlow<Boolean> = state.showCommandSuggestions
     val commandSuggestions: StateFlow<List<CommandSuggestion>> = state.commandSuggestions
     val showMentionSuggestions: StateFlow<Boolean> = state.showMentionSuggestions

app/src/test/kotlin/com/bitchat/android/ui/ChatStateBackNavigationTest.kt

@@ -0,0 +1,90 @@
+package com.bitchat.android.ui
+
+import kotlinx.coroutines.ExperimentalCoroutinesApi
+import kotlinx.coroutines.Job
+import kotlinx.coroutines.launch
+import kotlinx.coroutines.test.TestScope
+import kotlinx.coroutines.test.UnconfinedTestDispatcher
+import org.junit.After
+import org.junit.Assert.assertFalse
+import org.junit.Assert.assertTrue
+import org.junit.Before
+import org.junit.Test
+
+/**
+ * `canHandleBack` must agree with the branches of
+ * [ChatViewModel.handleBackPressed]: the back handler is enabled from one and
+ * the press consumed by the other.
+ */
+@OptIn(ExperimentalCoroutinesApi::class)
+class ChatStateBackNavigationTest {
+
+    private lateinit var scope: TestScope
+    private lateinit var state: ChatState
+    private lateinit var subscription: Job
+
+    @Before
+    fun setUp() {
+        scope = TestScope(UnconfinedTestDispatcher())
+        state = ChatState(scope)
+        // Shared WhileSubscribed, so it only tracks its sources while collected.
+        subscription = scope.launch { state.canHandleBack.collect { } }
+    }
+
+    @After
+    fun tearDown() {
+        subscription.cancel()
+    }
+
+    @Test
+    fun `is false on the bare chat screen`() {
+        assertFalse(state.canHandleBack.value)
+    }
+
+    @Test
+    fun `is true while the app info dialog is open`() {
+        state.setShowAppInfo(true)
+
+        assertTrue(state.canHandleBack.value)
+    }
+
+    @Test
+    fun `is true while the password prompt is open`() {
+        state.setShowPasswordPrompt(true)
+
+        assertTrue(state.canHandleBack.value)
+    }
+
+    @Test
+    fun `is true while a private chat is selected`() {
+        state.setSelectedPrivateChatPeer("peer-a")
+
+        assertTrue(state.canHandleBack.value)
+    }
+
+    @Test
+    fun `is true while the private chat sheet is open`() {
+        state.setPrivateChatSheetPeer("peer-a")
+
+        assertTrue(state.canHandleBack.value)
+    }
+
+    @Test
+    fun `is true while a channel is open`() {
+        state.setCurrentChannel("#bitchat")
+
+        assertTrue(state.canHandleBack.value)
+    }
+
+    @Test
+    fun `returns to false once the last overlay closes`() {
+        state.setCurrentChannel("#bitchat")
+        state.setShowAppInfo(true)
+
+        state.setShowAppInfo(false)
+        assertTrue("the channel is still open", state.canHandleBack.value)
+
+        state.setCurrentChannel(null)
+        assertFalse("nothing is left to unwind", state.canHandleBack.value)
+    }
+}