refactor: Improve hotspot and APK sharing stability

This commit introduces several fixes and refinements to the hotspot sharing and APK handling features, improving stability, user experience, and robustness.

Key changes:

-   **Hotspot Flow:**
    -   Automatically starts the hotspot after the user grants the required Wi-Fi permission, removing the need for a second button press.
    -   Ensures all `HotspotManager` callbacks in `HotspotViewModel` are executed within `viewModelScope` to prevent threading issues and ensure safe UI updates.
    -   Fixes a potential `BroadcastReceiver` leak in `HotspotManager` by tracking its registration state, preventing crashes and resource leaks when stopping the hotspot.
    -   Changes the hotspot `WakeLock` to be non-expiring to prevent the CPU from sleeping while the hotspot is active.

-   **APK Handling & Installation:**
    -   Adds a pre-download disk space check in `UniversalApkManager` to prevent download failures on devices with insufficient storage.
    -   Improves the file move logic after download by falling back to a copy-and-delete strategy if a direct rename fails, making it more robust across different filesystems.
    -   Introduces `InstallResultReceiver` to provide clear Toast notifications to the user about the success or failure of an APK installation, including specific error reasons (e.g., "Not enough storage").

-   **Performance & UI:**
    -   Caches the generated HTML in `ApkWebServer` to improve performance by avoiding regeneration on every request.
    -   Throttles the APK download progress updates to prevent UI jankiness from too-frequent state changes.
    -   Moves hardcoded strings in the "Share App" UI to `strings.xml` for better localization and maintenance.

app/src/main/java/com/bitchat/android/hotspot/ApkWebServer.kt

@@ -30,6 +30,11 @@ class ApkWebServer(
         }
     }
 
+    // Cache the HTML landing page (generated once, reused for all requests)
+    private val cachedHtml: String by lazy {
+        generateLandingPageHtml()
+    }
+
     override fun serve(session: IHTTPSession): Response {
         val uri = session.uri ?: "/"
 
@@ -90,11 +95,10 @@ class ApkWebServer(
      * Serve the HTML landing page.
      */
     private fun serveLandingPage(): Response {
-        val html = generateLandingPageHtml()
         return newFixedLengthResponse(
             Response.Status.OK,
             "text/html",
-            html
+            cachedHtml
         )
     }
 

app/src/main/java/com/bitchat/android/hotspot/HotspotActivity.kt

@@ -169,7 +169,13 @@ fun IntroScreen(onStartHotspot: () -> Unit) {
         else -> null // No runtime permission needed on Android < 10
     }
 
-    val permissionState = requiredPermission?.let { rememberPermissionState(it) }
+    val permissionState = requiredPermission?.let {
+        rememberPermissionState(it) { granted ->
+            if (granted) {
+                onStartHotspot()
+            }
+        }
+    }
 
     Column(
         modifier = Modifier
@@ -280,7 +286,7 @@ fun IntroScreen(onStartHotspot: () -> Unit) {
                     // No permission needed or already granted
                     onStartHotspot()
                 } else {
-                    // Request permission
+                    // Request permission (auto-start handled by onPermissionResult callback)
                     permissionState.launchPermissionRequest()
                 }
             },

app/src/main/java/com/bitchat/android/hotspot/HotspotManager.kt

@@ -56,6 +56,7 @@ class HotspotManager(private val context: Context) {
     private var callback: HotspotCallback? = null
     private var isStarting = false
     private var hasNotifiedStarted = false // Track if we've notified the callback
+    private var isReceiverRegistered = false // Track receiver registration to prevent leaks
 
     // Saved credentials for reconnection
     private var savedSsid: String? = null
@@ -97,12 +98,16 @@ class HotspotManager(private val context: Context) {
 
         Log.d(TAG, "Starting Wi-Fi P2P hotspot")
 
-        // Register broadcast receiver
+        // Register broadcast receiver (only if not already registered)
-        val intentFilter = IntentFilter().apply {
+        if (!isReceiverRegistered) {
-            addAction(WifiP2pManager.WIFI_P2P_STATE_CHANGED_ACTION)
+            val intentFilter = IntentFilter().apply {
-            addAction(WifiP2pManager.WIFI_P2P_CONNECTION_CHANGED_ACTION)
+                addAction(WIFI_P2P_STATE_CHANGED_ACTION)
+                addAction(WIFI_P2P_CONNECTION_CHANGED_ACTION)
+            }
+            context.registerReceiver(broadcastReceiver, intentFilter)
+            isReceiverRegistered = true
+            Log.d(TAG, "Broadcast receiver registered")
         }
-        context.registerReceiver(broadcastReceiver, intentFilter)
 
         // Acquire locks
         acquireLocks()
@@ -147,11 +152,16 @@ class HotspotManager(private val context: Context) {
         // Release locks
         releaseLocks()
 
-        // Unregister receiver
+        // Unregister receiver (only if registered)
-        try {
+        if (isReceiverRegistered) {
-            context.unregisterReceiver(broadcastReceiver)
+            try {
-        } catch (e: Exception) {
+                context.unregisterReceiver(broadcastReceiver)
-            Log.w(TAG, "Error unregistering receiver", e)
+                isReceiverRegistered = false
+                Log.d(TAG, "Broadcast receiver unregistered")
+            } catch (e: IllegalArgumentException) {
+                Log.w(TAG, "Receiver was not registered", e)
+                isReceiverRegistered = false
+            }
         }
 
         currentGroup = null
@@ -325,7 +335,7 @@ class HotspotManager(private val context: Context) {
                 PowerManager.FULL_WAKE_LOCK,
                 "BitChat:HotspotWakeLock"
             )
-            wakeLock?.acquire(10 * 60 * 1000L) // 10 minutes max
+            wakeLock?.acquire()
 
             val wifiManager = context.getSystemService(Context.WIFI_SERVICE) as android.net.wifi.WifiManager
             val lockType = if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) {

app/src/main/java/com/bitchat/android/hotspot/HotspotViewModel.kt

@@ -46,49 +46,55 @@ class HotspotViewModel(application: Application) : AndroidViewModel(application)
 
                 manager.startHotspot(object : HotspotManager.HotspotCallback {
                     override fun onHotspotStarted() {
-                        Log.d(TAG, "Hotspot started successfully")
+                        viewModelScope.launch {
+                            Log.d(TAG, "Hotspot started successfully")
 
-                        // Get connection info
+                            // Get connection info
-                        val info = manager.getConnectionInfo()
+                            val info = manager.getConnectionInfo()
-                        if (info == null) {
+                            if (info == null) {
-                            _state.value = HotspotState.Error("Failed to get hotspot connection info")
+                                _state.value = HotspotState.Error("Failed to get hotspot connection info")
-                            return
+                                return@launch
-                        }
+                            }
 
-                        // Start web server
+                            // Start web server
-                        try {
+                            try {
-                            val server = ApkWebServer(context, apkFile)
+                                val server = ApkWebServer(context, apkFile)
-                            server.startServer()
+                                server.startServer()
-                            webServer = server
+                                webServer = server
 
-                            Log.d(TAG, "Web server started on port ${ApkWebServer.DEFAULT_PORT}")
+                                Log.d(TAG, "Web server started on port ${ApkWebServer.DEFAULT_PORT}")
 
-                            // Update state with connection info
+                                // Update state with connection info
-                            _state.value = HotspotState.Active(
+                                _state.value = HotspotState.Active(
-                                ssid = info.ssid,
+                                    ssid = info.ssid,
-                                password = info.password,
+                                    password = info.password,
-                                ipAddress = info.ipAddress,
+                                    ipAddress = info.ipAddress,
-                                port = ApkWebServer.DEFAULT_PORT,
+                                    port = ApkWebServer.DEFAULT_PORT,
-                                connectedPeers = info.connectedPeers
+                                    connectedPeers = info.connectedPeers
-                            )
+                                )
-                        } catch (e: Exception) {
+                            } catch (e: Exception) {
-                            Log.e(TAG, "Failed to start web server", e)
+                                Log.e(TAG, "Failed to start web server", e)
-                            manager.stopHotspot()
+                                manager.stopHotspot()
-                            _state.value = HotspotState.Error("Failed to start web server: ${e.message}")
+                                _state.value = HotspotState.Error("Failed to start web server: ${e.message}")
+                            }
                         }
                     }
 
                     override fun onConnectionInfoUpdated(info: HotspotManager.ConnectionInfo?) {
-                        // Update peer count if we're active
+                        viewModelScope.launch {
-                        val currentState = _state.value
+                            // Update peer count if we're active
-                        if (currentState is HotspotState.Active && info != null) {
+                            val currentState = _state.value
-                            _state.value = currentState.copy(connectedPeers = info.connectedPeers)
+                            if (currentState is HotspotState.Active && info != null) {
+                                _state.value = currentState.copy(connectedPeers = info.connectedPeers)
+                            }
                         }
                     }
 
                     override fun onError(message: String) {
-                        Log.e(TAG, "Hotspot error: $message")
+                        viewModelScope.launch {
-                        _state.value = HotspotState.Error(message)
+                            Log.e(TAG, "Hotspot error: $message")
+                            _state.value = HotspotState.Error(message)
+                        }
                     }
                 })
 

app/src/main/java/com/bitchat/android/receiver/InstallResultReceiver.kt

@@ -0,0 +1,79 @@
+package com.bitchat.android.receiver
+
+import android.content.BroadcastReceiver
+import android.content.Context
+import android.content.Intent
+import android.content.pm.PackageInstaller
+import android.util.Log
+import android.widget.Toast
+import com.bitchat.android.R
+import com.bitchat.android.util.ApkInstaller
+
+/**
+ * Receives installation results from PackageInstaller.
+ * Shows toast messages to inform user of success/failure.
+ */
+class InstallResultReceiver : BroadcastReceiver() {
+    companion object {
+        private const val TAG = "InstallResultReceiver"
+    }
+
+    override fun onReceive(context: Context, intent: Intent) {
+        if (intent.action != ApkInstaller.ACTION_INSTALL_COMPLETE) {
+            return
+        }
+
+        val status = intent.getIntExtra(PackageInstaller.EXTRA_STATUS, PackageInstaller.STATUS_FAILURE)
+        val message = intent.getStringExtra(PackageInstaller.EXTRA_STATUS_MESSAGE)
+
+        when (status) {
+            PackageInstaller.STATUS_PENDING_USER_ACTION -> {
+                // System is asking for user confirmation
+                Log.d(TAG, "Installation pending user action")
+                val confirmIntent = intent.getParcelableExtra<Intent>(Intent.EXTRA_INTENT)
+                if (confirmIntent != null) {
+                    confirmIntent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK)
+                    try {
+                        context.startActivity(confirmIntent)
+                    } catch (e: Exception) {
+                        Log.e(TAG, "Failed to start confirmation intent", e)
+                        Toast.makeText(
+                            context,
+                            "Installation failed: Could not show confirmation dialog",
+                            Toast.LENGTH_SHORT
+                        ).show()
+                    }
+                }
+            }
+
+            PackageInstaller.STATUS_SUCCESS -> {
+                Log.d(TAG, "Installation succeeded")
+                Toast.makeText(
+                    context,
+                    "BitChat installed successfully!",
+                    Toast.LENGTH_LONG
+                ).show()
+            }
+
+            PackageInstaller.STATUS_FAILURE,
+            PackageInstaller.STATUS_FAILURE_ABORTED,
+            PackageInstaller.STATUS_FAILURE_BLOCKED,
+            PackageInstaller.STATUS_FAILURE_CONFLICT,
+            PackageInstaller.STATUS_FAILURE_INCOMPATIBLE,
+            PackageInstaller.STATUS_FAILURE_INVALID,
+            PackageInstaller.STATUS_FAILURE_STORAGE -> {
+                Log.e(TAG, "Installation failed with status $status: $message")
+                val errorMsg = when (status) {
+                    PackageInstaller.STATUS_FAILURE_ABORTED -> "Installation was cancelled"
+                    PackageInstaller.STATUS_FAILURE_BLOCKED -> "Installation blocked by system policy"
+                    PackageInstaller.STATUS_FAILURE_CONFLICT -> "Package conflicts with existing installation. Try uninstalling first."
+                    PackageInstaller.STATUS_FAILURE_INCOMPATIBLE -> "Package is incompatible with this device"
+                    PackageInstaller.STATUS_FAILURE_INVALID -> "Package is invalid or corrupted"
+                    PackageInstaller.STATUS_FAILURE_STORAGE -> "Not enough storage space"
+                    else -> "Installation failed: ${message ?: "Unknown error"}"
+                }
+                Toast.makeText(context, errorMsg, Toast.LENGTH_LONG).show()
+            }
+        }
+    }
+}

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

@@ -740,7 +740,7 @@ fun AboutSheet(
                                                 color = colorScheme.onSurface
                                             )
                                             Text(
-                                                text = "Create Wi-Fi hotspot to share offline",
+                                                text = stringResource(R.string.hotspot_share_via_subtitle),
                                                 style = MaterialTheme.typography.bodySmall,
                                                 color = colorScheme.onSurface.copy(alpha = 0.6f),
                                                 lineHeight = 16.sp
@@ -805,7 +805,7 @@ fun AboutSheet(
                                                 color = colorScheme.onSurface
                                             )
                                             Text(
-                                                text = "Use standard Android sharing",
+                                                text = stringResource(R.string.hotspot_share_other_subtitle),
                                                 style = MaterialTheme.typography.bodySmall,
                                                 color = colorScheme.onSurface.copy(alpha = 0.6f),
                                                 lineHeight = 16.sp
@@ -1199,8 +1199,14 @@ private suspend fun downloadUniversalApk(
     onResult: (ApkPreparationStatus) -> Unit
 ) {
     withContext(Dispatchers.IO) {
+        var lastUpdateTime = 0L
         val result = apkManager.downloadUniversalApk { progress ->
-            onProgress(progress)
+            // Throttle updates to max 10 per second (100ms interval) to avoid janky UI
+            val now = System.currentTimeMillis()
+            if (now - lastUpdateTime >= 100 || progress == 100) {
+                lastUpdateTime = now
+                onProgress(progress)
+            }
         }
 
         val status = if (result.isSuccess) {

app/src/main/java/com/bitchat/android/util/UniversalApkManager.kt

@@ -123,6 +123,24 @@ class UniversalApkManager(private val context: Context) {
         }
     }
 
+    /**
+     * Check if there's enough disk space to download the APK.
+     * Requires 1.5x the file size for safety margin (temp + final file).
+     * @throws IOException if insufficient space
+     */
+    private fun checkDiskSpace(requiredSize: Long) {
+        val availableSpace = cacheDir.usableSpace
+        val requiredWithMargin = (requiredSize * 1.5).toLong()
+
+        if (availableSpace < requiredWithMargin) {
+            val requiredMB = requiredWithMargin / 1024 / 1024
+            val availableMB = availableSpace / 1024 / 1024
+            val error = "Insufficient storage: need ${requiredMB}MB, have ${availableMB}MB"
+            Log.e(TAG, error)
+            throw IOException(error)
+        }
+    }
+
     /**
      * Download the universal APK from GitHub.
      * @param progressCallback Called with progress percentage (0-100)
@@ -144,6 +162,9 @@ class UniversalApkManager(private val context: Context) {
             Log.d(TAG, "Downloading from: $url")
             Log.d(TAG, "Expected size: ${expectedSize / 1024 / 1024}MB")
 
+            // Check available disk space before downloading
+            checkDiskSpace(expectedSize)
+
             // Download to temporary file first
             val tempFile = File(cacheDir, "download_temp.apk")
             if (tempFile.exists()) {
@@ -218,7 +239,14 @@ class UniversalApkManager(private val context: Context) {
             if (finalFile.exists()) {
                 finalFile.delete()
             }
-            tempFile.renameTo(finalFile)
+
+            // Try rename first (fast), fallback to copy if it fails (different partitions/filesystems)
+            val moved = tempFile.renameTo(finalFile)
+            if (!moved) {
+                Log.w(TAG, "Rename failed, falling back to copy")
+                tempFile.copyTo(finalFile, overwrite = true)
+                tempFile.delete()
+            }
 
             // Save metadata
             saveMetadata(

app/src/main/res/values/strings.xml

@@ -182,7 +182,9 @@
 
   <!-- Hotspot Sharing -->
   <string name="hotspot_share_via">Share via Hotspot</string>
+  <string name="hotspot_share_via_subtitle">Create Wi-Fi hotspot to share offline</string>
   <string name="hotspot_share_other">Share via Bluetooth/Email</string>
+  <string name="hotspot_share_other_subtitle">Use standard Android sharing</string>
 
   <!-- APK Installation -->
   <string name="install_bitchat_title">Install Received APK</string>