Refactors Bluetooth permission handling and connection logic across several parts of the application

android_app/app/src/main/java/com/health/openscale/core/bluetooth/scales/ModernScaleAdapter.kt

@@ -78,10 +78,6 @@ class ModernScaleAdapter(
 ) : ScaleCommunicator {
     private val TAG = "ModernScaleAdapter"
 
-    private companion object {
-        const val TAG = "ModernScaleAdapter"
-    }
-
     private val adapterScope = CoroutineScope(Dispatchers.Default + SupervisorJob())
     private val mainHandler = Handler(Looper.getMainLooper())
     private lateinit var central: BluetoothCentralManager // Initialisiert in init
@@ -185,35 +181,53 @@ class ModernScaleAdapter(
     }
 
     private fun hasRequiredBluetoothPermissions(): Boolean {
-        val requiredPermissions = if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.S) {
-            listOf(Manifest.permission.BLUETOOTH_SCAN, Manifest.permission.BLUETOOTH_CONNECT)
-        } else {
-            listOf(Manifest.permission.BLUETOOTH, Manifest.permission.BLUETOOTH_ADMIN, Manifest.permission.ACCESS_FINE_LOCATION)
+        val required = listOf(
+            Manifest.permission.BLUETOOTH_SCAN,
+            Manifest.permission.BLUETOOTH_CONNECT
+        )
+        return required.all { ContextCompat.checkSelfPermission(context, it) == PackageManager.PERMISSION_GRANTED }
     }
-        return requiredPermissions.all {
-            ContextCompat.checkSelfPermission(context, it) == PackageManager.PERMISSION_GRANTED
+
+    // Call this after runtime grant or lazily before first connect
+    private fun ensureCentralReady(): Boolean {
+        if (!::central.isInitialized) {
+            val hasScan = ContextCompat.checkSelfPermission(
+                context, Manifest.permission.BLUETOOTH_SCAN
+            ) == PackageManager.PERMISSION_GRANTED
+            val hasConnect = ContextCompat.checkSelfPermission(
+                context, Manifest.permission.BLUETOOTH_CONNECT
+            ) == PackageManager.PERMISSION_GRANTED
+            if (!(hasScan || hasConnect)) return false // at least one check; we hard-fail later if CONNECT is missing
+            central = BluetoothCentralManager(context, bluetoothCentralManagerCallback, mainHandler)
+            LogManager.d(TAG, "BluetoothCentralManager initialized")
         }
+        return true
     }
 
+
     override fun connect(address: String, scaleUser: ScaleUser?) {
         adapterScope.launch {
-            if (!::central.isInitialized) {
-                LogManager.e(TAG, "BluetoothCentralManager nicht initialisiert, wahrscheinlich aufgrund fehlender Berechtigungen.")
-                _eventsFlow.tryEmit(BluetoothEvent.ConnectionFailed(address, "Bluetooth nicht initialisiert (Berechtigungen?)"))
+            // Ensure central exists (may be created after runtime grant)
+            if (!ensureCentralReady()) {
+                _eventsFlow.tryEmit(
+                    BluetoothEvent.ConnectionFailed(address, "Bluetooth permissions missing (SCAN/CONNECT)")
+                )
                 return@launch
             }
 
+            // Ignore duplicate connects
             if (_isConnecting.value || (_isConnected.value && targetAddress == address)) {
-                LogManager.d(TAG, "Verbindungsanfrage für $address ignoriert: Bereits verbunden oder Verbindungsaufbau läuft.")
+                LogManager.d(TAG, "connect($address) ignored: already connecting/connected")
                 if (_isConnected.value && targetAddress == address) {
-                    val deviceName = currentPeripheral?.name ?: "Unbekanntes Gerät"
+                    val deviceName = currentPeripheral?.name ?: "Unknown"
                     _eventsFlow.tryEmit(BluetoothEvent.Connected(deviceName, address))
                 }
                 return@launch
             }
 
+            // Switch target: tear down old connection attempt
             if ((_isConnected.value || _isConnecting.value) && targetAddress != address) {
-                LogManager.d(TAG, "Bestehende Verbindung/Versuch zu $targetAddress wird für neue Verbindung zu $address getrennt.")
+                LogManager.d(TAG, "Switching from $targetAddress to $address")
                 disconnectLogic()
             }
 
@@ -222,26 +236,54 @@ class ModernScaleAdapter(
             targetAddress = address
             currentScaleUser = scaleUser
 
-            LogManager.i(TAG, "Verbindungsversuch zu $address mit Benutzer: ${scaleUser?.id}")
+            LogManager.i(TAG, "Connecting to $address (user=${scaleUser?.id})")
 
-            // Stoppe vorherige Scans, falls vorhanden
-            central.stopScan()
+            // Stop any previous scans
+            runCatching { central.stopScan() }
+
+            val hasScan = ContextCompat.checkSelfPermission(
+                context, Manifest.permission.BLUETOOTH_SCAN
+            ) == PackageManager.PERMISSION_GRANTED
+
+            val hasConnect = ContextCompat.checkSelfPermission(
+                context, Manifest.permission.BLUETOOTH_CONNECT
+            ) == PackageManager.PERMISSION_GRANTED
+
+            if (!hasConnect) {
+                // Without CONNECT we can't perform GATT ops reliably
+                LogManager.e(TAG, "Missing BLUETOOTH_CONNECT")
+                _eventsFlow.tryEmit(
+                    BluetoothEvent.ConnectionFailed(address, "Missing BLUETOOTH_CONNECT permission")
+                )
+                _isConnecting.value = false
+                targetAddress = null
+                return@launch
+            }
 
             try {
-                // Versuche, direkt ein Peripheral-Objekt zu bekommen, falls die Adresse bekannt ist.
-                //Blessed erlaubt auch das Scannen nach Adresse, was oft robuster ist.
-                //central.getPeripheral(address) ist eine Option, aber scanForPeripheralsWithAddresses ist oft besser.
+                if (hasScan) {
+                    // Preferred path on 12+: short pre-scan by address
                     central.scanForPeripheralsWithAddresses(arrayOf(address))
-                LogManager.d(TAG, "Scan gestartet für Adresse: $address")
+                    LogManager.d(TAG, "Pre-scan started for $address")
+                    // onDiscoveredPeripheral will stop scan and connect
+                } else {
+                    // Fallback: connect without pre-scan (may be less reliable on some OEMs)
+                    LogManager.w(TAG, "BLUETOOTH_SCAN not granted → connecting without pre-scan")
+                    val p = central.getPeripheral(address)
+                    central.connectPeripheral(p, peripheralCallback)
+                }
             } catch (e: Exception) {
-                LogManager.e(TAG, "Fehler beim Starten des Scans für $address", e)
-                _eventsFlow.tryEmit(BluetoothEvent.ConnectionFailed(address, "Scan konnte nicht gestartet werden: ${e.message}"))
+                LogManager.e(TAG, "Failed to start connect/scan for $address", e)
+                _eventsFlow.tryEmit(
+                    BluetoothEvent.ConnectionFailed(address, "Failed to start scan/connect: ${e.message}")
+                )
                 _isConnecting.value = false
                 targetAddress = null
             }
         }
     }
 
+
     private val peripheralCallback: BluetoothPeripheralCallback =
         object : BluetoothPeripheralCallback() {
             override fun onServicesDiscovered(peripheral: BluetoothPeripheral) {

android_app/app/src/main/java/com/health/openscale/core/bluetooth/scalesJava/BluetoothBroadcastScale.java

@@ -17,14 +17,11 @@
 
 package com.health.openscale.core.bluetooth.scalesJava;
 
-import static android.content.Context.LOCATION_SERVICE;
-
 import android.Manifest;
 import android.bluetooth.le.ScanRecord;
 import android.bluetooth.le.ScanResult;
 import android.content.Context;
 import android.content.pm.PackageManager;
-import android.location.LocationManager;
 import android.os.Handler;
 import android.os.Looper;
 import android.util.SparseArray;
@@ -136,19 +133,25 @@ public class BluetoothBroadcastScale extends BluetoothCommunication {
 
     @Override
     public void connect(String macAddress) {
+        // Android 12+ (minSdk=31): scanning requires BLUETOOTH_SCAN, no location needed.
+        boolean canScan = ContextCompat.checkSelfPermission(
+                context, Manifest.permission.BLUETOOTH_SCAN) == PackageManager.PERMISSION_GRANTED;
 
-        LocationManager locationManager = (LocationManager)context.getSystemService(LOCATION_SERVICE);
-
-        if ((ContextCompat.checkSelfPermission(context, Manifest.permission.ACCESS_FINE_LOCATION)  == PackageManager.PERMISSION_GRANTED) ||
-                (ContextCompat.checkSelfPermission(context, Manifest.permission.BLUETOOTH_SCAN) == PackageManager.PERMISSION_GRANTED ) &&
-                        (locationManager.isProviderEnabled(LocationManager.GPS_PROVIDER) ||
-                                (locationManager.isProviderEnabled(LocationManager.NETWORK_PROVIDER)))
-        ) {
-            LogManager.d(TAG, "Do LE scan before connecting to device");
-            central.scanForPeripheralsWithAddresses(new String[]{macAddress});
+        if (!canScan) {
+            LogManager.e(TAG, "Missing BLUETOOTH_SCAN → cannot start LE scan for broadcast data.", null);
+            setBluetoothStatus(BT_STATUS.UNEXPECTED_ERROR);
+            // choose a better string if you have one, this is just a visible hint:
+            sendMessage(com.health.openscale.R.string.info_bluetooth_connection_error_scale_offline, 0);
+            return;
         }
-        else {
-            LogManager.e(TAG,"No location permission, can't do anything", null);
+
+        try {
+            LogManager.d(TAG, "Starting LE scan for broadcast scale (no location required)");
+            // We scan by address; when advertising is seen, onDiscoveredPeripheral parses manufacturer data.
+            central.scanForPeripheralsWithAddresses(new String[]{ macAddress });
+        } catch (Exception e) {
+            LogManager.e(TAG, "Failed to start LE scan: " + e.getMessage(), e);
+            setBluetoothStatus(BT_STATUS.UNEXPECTED_ERROR);
         }
     }
 

android_app/app/src/main/java/com/health/openscale/core/bluetooth/scalesJava/BluetoothCommunication.java

@@ -18,14 +18,12 @@
 package com.health.openscale.core.bluetooth.scalesJava;
 
 import static android.bluetooth.BluetoothGatt.GATT_SUCCESS;
-import static android.content.Context.LOCATION_SERVICE;
 
 import android.Manifest;
 import android.bluetooth.BluetoothGattCharacteristic;
 import android.bluetooth.le.ScanResult;
 import android.content.Context;
 import android.content.pm.PackageManager;
-import android.location.LocationManager;
 import android.os.Handler;
 import android.os.Looper;
 import android.os.Message;
@@ -88,7 +86,7 @@ public abstract class BluetoothCommunication {
     public BluetoothCommunication(Context context)
     {
         this.context = context;
-        this.disconnectHandler = new Handler();
+        this.disconnectHandler = new Handler(Looper.getMainLooper());
         this.stepNr = 0;
         this.stopped = false;
         this.central = new BluetoothCentralManager(context, bluetoothCentralCallback, new Handler(Looper.getMainLooper()));
@@ -609,28 +607,50 @@ public abstract class BluetoothCommunication {
      * @param macAddress the Bluetooth address to connect to
      */
     public void connect(String macAddress) {
-        // Running an LE scan during connect improves connectivity on some phones
-        // (e.g. Sony Xperia Z5 compact, Android 7.1.1). For some scales (e.g. Medisana BS444)
-        // it seems to be a requirement that the scale is discovered before connecting to it.
-        // Otherwise the connection almost never succeeds.
-        LocationManager locationManager = (LocationManager)context.getSystemService(LOCATION_SERVICE);
+        // Android 12+ (API 31+): SCAN needed for scanning, CONNECT needed for connect/GATT.
+        final boolean isSPlus = android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.S;
 
-        if ((ContextCompat.checkSelfPermission(context, Manifest.permission.ACCESS_FINE_LOCATION)  == PackageManager.PERMISSION_GRANTED) ||
-            (ContextCompat.checkSelfPermission(context, Manifest.permission.BLUETOOTH_SCAN) == PackageManager.PERMISSION_GRANTED ) &&
-            (locationManager.isProviderEnabled(LocationManager.GPS_PROVIDER) ||
-            (locationManager.isProviderEnabled(LocationManager.NETWORK_PROVIDER)))
-        ) {
-            LogManager.d("BluetoothCommunication","Do LE scan before connecting to device");
+        if (isSPlus) {
+            boolean canConnect = ContextCompat.checkSelfPermission(
+                    context, Manifest.permission.BLUETOOTH_CONNECT) == PackageManager.PERMISSION_GRANTED;
+            boolean canScan = ContextCompat.checkSelfPermission(
+                    context, Manifest.permission.BLUETOOTH_SCAN) == PackageManager.PERMISSION_GRANTED;
+
+            if (!canConnect) {
+                LogManager.e("BluetoothCommunication",
+                        "API≥31: Missing BLUETOOTH_CONNECT → cannot connect/GATT. Aborting.", null);
+                setBluetoothStatus(BT_STATUS.UNEXPECTED_ERROR);
+                sendMessage(R.string.info_bluetooth_connection_error_scale_offline, 0);
+                return;
+            }
+
+            // Pre-scan improves connect reliability on some devices/scales
+            if (canScan) {
+                LogManager.d("BluetoothCommunication",
+                        "API≥31: Do LE scan before connecting (no location needed)");
                 central.scanForPeripheralsWithAddresses(new String[]{macAddress});
-            stopMachineState();
-        }
-        else {
-            LogManager.d("BluetoothCommunication","No location permission, connecting without LE scan");
+                stopMachineState(); // wait for onDiscoveredPeripheral → connect
+                return;
+            } else {
+                LogManager.w("BluetoothCommunication",
+                        "API≥31: BLUETOOTH_SCAN not granted → connecting without pre-scan (may be less reliable)", null);
                 BluetoothPeripheral peripheral = central.getPeripheral(macAddress);
+                try {
                     connectToDevice(peripheral);
+                } catch (SecurityException se) {
+                    LogManager.e("BluetoothCommunication",
+                            "SecurityException during connect (missing CONNECT?): " + se.getMessage(), se);
+                    setBluetoothStatus(BT_STATUS.UNEXPECTED_ERROR);
+                }
+                return;
             }
         }
 
+        // Defensive fallback (won't run with minSdk=31, but good for clarity)
+        LogManager.w("BluetoothCommunication","connect() called on API<31 path; no legacy handling active.", null);
+    }
+
+
     private void connectToDevice(BluetoothPeripheral peripheral) {
 
         Handler handler = new Handler();

android_app/app/src/main/java/com/health/openscale/ui/screen/bluetooth/BluetoothViewModel.kt

@@ -23,7 +23,6 @@ import android.app.Application
 import android.bluetooth.BluetoothManager
 import android.content.Context
 import android.content.pm.PackageManager
-import android.os.Build
 import android.os.Handler
 import android.os.Looper
 import androidx.compose.material3.SnackbarDuration
@@ -280,36 +279,6 @@ class BluetoothViewModel(
 
     // --- Connection Control ---
 
-    /**
-     * Initiates a connection attempt to the specified Bluetooth device.
-     * If a scan is active, it will be stopped first.
-     * Prerequisites like permissions and Bluetooth status are validated.
-     *
-     * @param deviceInfo The [ScannedDeviceInfo] of the device to connect to.
-     */
-    @SuppressLint("MissingPermission") // Permissions are checked by validateConnectionPrerequisites.
-    fun connectToDevice(deviceInfo: ScannedDeviceInfo) {
-        val deviceDisplayName = deviceInfo.name ?: deviceInfo.address
-        LogManager.i(TAG, "User requested to connect to device: $deviceDisplayName")
-
-        if (isScanning.value) {
-            LogManager.d(TAG, "Scan is active, stopping it before initiating connection to $deviceDisplayName.")
-            requestStopDeviceScan()
-            // Optional: A small delay could be added here if needed to ensure scan stop completes,
-            // but usually the managers handle sequential operations gracefully.
-            // viewModelScope.launch { delay(200) }
-        }
-
-        if (!validateConnectionPrerequisites(deviceDisplayName, isManualConnect = true)) {
-            // validateConnectionPrerequisites logs and shows Snackbar/sets error for ConnectionManager.
-            return
-        }
-
-        LogManager.d(TAG, "Prerequisites for connecting to $deviceDisplayName met. Delegating to BluetoothConnectionManager.")
-        bluetoothConnectionManager.connectToDevice(deviceInfo)
-    }
-
-
     /**
      * Attempts to connect to the saved preferred Bluetooth scale.
      * Retrieves device info from [userSettingsRepository] and then delegates
@@ -511,20 +480,34 @@ class BluetoothViewModel(
 
     /**
      * Checks if the necessary Bluetooth permissions are currently granted.
-     * Handles different permission sets for Android S (API 31) and above vs. older versions.
+     * Handles different permission sets for Android S (API 31) and above.
      * @return `true` if permissions are granted, `false` otherwise.
      */
     private fun checkInitialPermissions(): Boolean {
-        return if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.S) {
-            // Android 12 (API 31) and above require BLUETOOTH_SCAN and BLUETOOTH_CONNECT
-            ContextCompat.checkSelfPermission(application, Manifest.permission.BLUETOOTH_SCAN) == PackageManager.PERMISSION_GRANTED &&
-                    ContextCompat.checkSelfPermission(application, Manifest.permission.BLUETOOTH_CONNECT) == PackageManager.PERMISSION_GRANTED
-        } else {
-            // For older Android versions (below S / API 31)
-            ContextCompat.checkSelfPermission(application, Manifest.permission.BLUETOOTH) == PackageManager.PERMISSION_GRANTED &&
-                    ContextCompat.checkSelfPermission(application, Manifest.permission.BLUETOOTH_ADMIN) == PackageManager.PERMISSION_GRANTED &&
-                    ContextCompat.checkSelfPermission(application, Manifest.permission.ACCESS_FINE_LOCATION) == PackageManager.PERMISSION_GRANTED
+        val hasConnect = ContextCompat.checkSelfPermission(
+            application, Manifest.permission.BLUETOOTH_CONNECT
+        ) == PackageManager.PERMISSION_GRANTED
+
+        val hasScan = ContextCompat.checkSelfPermission(
+            application, Manifest.permission.BLUETOOTH_SCAN
+        ) == PackageManager.PERMISSION_GRANTED
+
+        when {
+            !hasConnect && !hasScan -> {
+                LogManager.w(TAG, "Missing permissions: BLUETOOTH_CONNECT & BLUETOOTH_SCAN → BLE disabled (no connect, no scan).")
             }
+            !hasConnect -> {
+                LogManager.w(TAG, "Missing permission: BLUETOOTH_CONNECT → cannot perform GATT ops (connect/read/write).")
+            }
+            !hasScan -> {
+                LogManager.w(TAG, "Missing permission: BLUETOOTH_SCAN → cannot scan/pre-scan (no discovery, less reliable connect).")
+            }
+            else -> {
+                LogManager.d(TAG, "All required Bluetooth permissions granted (SCAN & CONNECT).")
+            }
+        }
+
+        return hasConnect && hasScan
     }
 
     /**

android_app/app/src/main/java/com/health/openscale/ui/screen/overview/OverviewScreen.kt

@@ -17,8 +17,16 @@
  */
 package com.health.openscale.ui.screen.overview
 
+import android.Manifest
+import android.app.Activity
+import android.bluetooth.BluetoothAdapter
 import android.content.Context
+import android.content.Intent
 import android.widget.Toast
+import androidx.activity.compose.ManagedActivityResultLauncher
+import androidx.activity.compose.rememberLauncherForActivityResult
+import androidx.activity.result.ActivityResult
+import androidx.activity.result.contract.ActivityResultContracts
 import androidx.compose.animation.AnimatedVisibility
 import androidx.compose.foundation.BorderStroke
 import androidx.compose.foundation.background
@@ -137,31 +145,47 @@ fun determineBluetoothTopBarAction(
     currentNavController: NavController,
     bluetoothViewModel: BluetoothViewModel,
     sharedViewModel: SharedViewModel,
-    currentDeviceName: String?
+    currentDeviceName: String?,
+    permissionsLauncher: ManagedActivityResultLauncher<Array<String>, Map<String, @JvmSuppressWildcards Boolean>>,
+    enableBluetoothLauncher: ManagedActivityResultLauncher<Intent, ActivityResult>
 ): SharedViewModel.TopBarAction? {
-    // Logic to determine if a connection or disconnection process is currently active
-    val btConnectingOrDisconnecting = savedAddr != null &&
-            (connStatusEnum == ConnectionStatus.CONNECTING || connStatusEnum == ConnectionStatus.DISCONNECTING) &&
-            // When connecting, connectedDevice might be null or the address being connected to.
-            // When disconnecting, connectedDevice should be the address of the device being disconnected.
-            (connectedDevice == savedAddr || connStatusEnum == ConnectionStatus.CONNECTING || (connStatusEnum == ConnectionStatus.DISCONNECTING && connectedDevice == savedAddr))
 
     val deviceNameForMessage = currentDeviceName ?: context.getString(R.string.fallback_device_name_saved_scale)
 
+    // Busy while connecting/disconnecting to the currently saved device
+    val isBusy = savedAddr != null &&
+            (connStatusEnum == ConnectionStatus.CONNECTING || connStatusEnum == ConnectionStatus.DISCONNECTING) &&
+            (connectedDevice == savedAddr || connStatusEnum == ConnectionStatus.CONNECTING ||
+                    (connStatusEnum == ConnectionStatus.DISCONNECTING && connectedDevice == savedAddr))
+
+    // Helper to request enabling Bluetooth (actual connect is done in onActivityResult when OK)
+    val requestEnableBluetooth = {
+        val intent = Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE)
+        enableBluetoothLauncher.launch(intent)
+    }
+
+    // Helper to request runtime permissions (actual connect is done in onResult when granted)
+    val requestBtPermissions = {
+        permissionsLauncher.launch(
+            arrayOf(
+                Manifest.permission.BLUETOOTH_SCAN,
+                Manifest.permission.BLUETOOTH_CONNECT
+            )
+        )
+    }
+
     return when {
-        // Case 1: Connection or disconnection process is actively running
-        btConnectingOrDisconnecting -> SharedViewModel.TopBarAction(
-            icon = Icons.AutoMirrored.Filled.BluetoothSearching, // Icon for "searching" or "working"
+        // 1) Show non-interactive feedback while a user-initiated operation is ongoing
+        isBusy -> SharedViewModel.TopBarAction(
+            icon = Icons.AutoMirrored.Filled.BluetoothSearching,
             contentDescription = context.getString(R.string.bluetooth_action_connecting_disconnecting_desc),
             onClick = {
-                // Typically, the button is not interactive during this time,
-                // but a Snackbar can confirm the ongoing process.
                 sharedViewModel.showSnackbar(
                     message = context.getString(
                         when (connStatusEnum) {
                             ConnectionStatus.CONNECTING    -> R.string.snackbar_bluetooth_connecting_to
                             ConnectionStatus.DISCONNECTING -> R.string.snackbar_bluetooth_disconnecting_from
-                            else -> R.string.snackbar_bluetooth_processing_with // Fallback
+                            else                           -> R.string.snackbar_bluetooth_processing_with
                         },
                         deviceNameForMessage
                     ),
@@ -170,9 +194,9 @@ fun determineBluetoothTopBarAction(
             }
         )
 
-        // Case 2: No Bluetooth scale is saved
+        // 2) No saved device → navigate to Bluetooth settings
         savedAddr == null -> SharedViewModel.TopBarAction(
-            icon = Icons.Default.Bluetooth, // Default Bluetooth icon
+            icon = Icons.Default.Bluetooth,
             contentDescription = context.getString(R.string.bluetooth_action_no_scale_saved_desc),
             onClick = {
                 sharedViewModel.showSnackbar(
@@ -183,71 +207,40 @@ fun determineBluetoothTopBarAction(
             }
         )
 
-        // Case 3: Successfully connected to the saved scale
+        // 3) Connected → offer disconnect
         savedAddr == connectedDevice && connStatusEnum == ConnectionStatus.CONNECTED -> SharedViewModel.TopBarAction(
-            icon = Icons.Filled.BluetoothConnected, // Icon for "connected"
+            icon = Icons.Filled.BluetoothConnected,
             contentDescription = context.getString(R.string.bluetooth_action_disconnect_desc, deviceNameForMessage),
             onClick = {
-                // Trigger the action first, then show the Snackbar
-                bluetoothViewModel.disconnectDevice() // IMPORTANT: Trigger disconnection here!
+                bluetoothViewModel.disconnectDevice()
                 sharedViewModel.showSnackbar(
-                    message = context.getString(R.string.snackbar_bluetooth_disconnecting_from, deviceNameForMessage), // Adjusted message
+                    message = context.getString(R.string.snackbar_bluetooth_disconnecting_from, deviceNameForMessage),
                     duration = SnackbarDuration.Short
                 )
             }
         )
 
-        // Case 4: Connection error, and an address is saved
-        connStatusEnum == ConnectionStatus.FAILED && savedAddr != null -> SharedViewModel.TopBarAction(
-            icon = Icons.Filled.Error, // Error icon
-            contentDescription = context.getString(R.string.bluetooth_action_retry_connection_desc, deviceNameForMessage),
-            onClick = {
-                sharedViewModel.showSnackbar(
-                    message = context.getString(R.string.snackbar_bluetooth_retry_connection, deviceNameForMessage),
-                    duration = SnackbarDuration.Short
-                )
-                bluetoothViewModel.connectToSavedDevice()
-            }
-        )
-
-        // Case 5: Connection error, and NO address is saved
-        connStatusEnum == ConnectionStatus.FAILED && savedAddr == null -> SharedViewModel.TopBarAction(
-            icon = Icons.Filled.Error, // Error icon
-            contentDescription = context.getString(R.string.bluetooth_action_error_check_settings_desc),
-            onClick = {
-                sharedViewModel.showSnackbar(
-                    message = context.getString(R.string.snackbar_bluetooth_error_check_settings),
-                    duration = SnackbarDuration.Short
-                )
-                currentNavController.navigate(Routes.BLUETOOTH_SETTINGS)
-            }
-        )
-
-        // Case 6: Saved device exists but is not connected (disconnected, idle, etc.)
-        // This case also covers if connStatusEnum = DISCONNECTED, IDLE, or NONE.
-        savedAddr != null && (connStatusEnum == ConnectionStatus.DISCONNECTED || connStatusEnum == ConnectionStatus.IDLE || connStatusEnum == ConnectionStatus.NONE) -> SharedViewModel.TopBarAction(
-            icon = Icons.Filled.BluetoothDisabled, // Icon for "disconnected" or "ready to connect"
-            contentDescription = context.getString(R.string.bluetooth_action_connect_to_desc, deviceNameForMessage),
-            onClick = {
-                sharedViewModel.showSnackbar(
-                    message = context.getString(R.string.snackbar_bluetooth_attempting_connection, deviceNameForMessage),
-                    duration = SnackbarDuration.Short
-                )
-                bluetoothViewModel.connectToSavedDevice()
-            }
-        )
-
-        // Fallback: If an address is saved, but the state was not specifically covered above,
-        // offer to connect. Ideally, this shouldn't be hit often if the logic above is complete.
-        // If no device is saved and there's no error/connection attempt,
-        // this was already covered by 'savedAddr == null' (leads to settings).
-        else -> {
-            if (savedAddr != null) {
-                // This serves as a generic "Connect" button if a rare state occurs
-                SharedViewModel.TopBarAction(
+        // 4) Disconnected / Idle / None / Failed → guarded connect (request first, connect later via callbacks)
+        savedAddr != null && (
+                connStatusEnum == ConnectionStatus.DISCONNECTED ||
+                        connStatusEnum == ConnectionStatus.IDLE ||
+                        connStatusEnum == ConnectionStatus.NONE ||
+                        connStatusEnum == ConnectionStatus.FAILED
+                ) -> SharedViewModel.TopBarAction(
             icon = Icons.Filled.BluetoothDisabled,
             contentDescription = context.getString(R.string.bluetooth_action_connect_to_desc, deviceNameForMessage),
-                    onClick = {
+            onClick = onClick@{
+                // a) Ask for permissions if missing (do NOT connect here; wait for onResult)
+                if (!bluetoothViewModel.permissionsGranted.value) {
+                    requestBtPermissions()
+                    return@onClick
+                }
+                // b) Ask to enable BT if off (do NOT connect here; wait for onActivityResult)
+                if (!bluetoothViewModel.isBluetoothEnabled()) {
+                    requestEnableBluetooth()
+                    return@onClick
+                }
+                // c) All good → connect now (explicit user tap; no autoconn)
                 sharedViewModel.showSnackbar(
                     message = context.getString(R.string.snackbar_bluetooth_attempting_connection, deviceNameForMessage),
                     duration = SnackbarDuration.Short
@@ -255,13 +248,9 @@ fun determineBluetoothTopBarAction(
                 bluetoothViewModel.connectToSavedDevice()
             }
         )
-            } else {
-                // If really no other condition applies and no device is saved,
-                // and the above cases haven't been met, "Go to settings" is a safe default.
-                // This will likely only be hit if connStatusEnum has an unexpected value
-                // and savedAddr is null, but that should already be covered by "Case 2".
-                // For safety, nonetheless:
-                SharedViewModel.TopBarAction(
+
+        // 5) Fallback
+        else -> SharedViewModel.TopBarAction(
             icon = Icons.Default.Bluetooth,
             contentDescription = context.getString(R.string.bluetooth_action_check_settings_desc),
             onClick = {
@@ -274,8 +263,6 @@ fun determineBluetoothTopBarAction(
         )
     }
 }
-    }
-}
 
 /**
  * The main screen for displaying an overview of measurements, user status, and Bluetooth controls.
@@ -330,6 +317,51 @@ fun OverviewScreen(
     val connectedDeviceAddr by bluetoothViewModel.connectedDeviceAddress.collectAsState()
     val savedDeviceNameString by bluetoothViewModel.savedScaleName.collectAsState()
 
+    val enableBluetoothLauncher = rememberLauncherForActivityResult(
+        contract = ActivityResultContracts.StartActivityForResult()
+    ) { result ->
+        bluetoothViewModel.refreshPermissionsStatus()
+        if (result.resultCode == Activity.RESULT_OK) {
+            if (bluetoothViewModel.permissionsGranted.value) {
+                // Permissions and BT are fine → safe to connect now
+                bluetoothViewModel.connectToSavedDevice()
+            } else {
+                scope.launch {
+                    sharedViewModel.showSnackbar(
+                        message = context.getString(R.string.bluetooth_enabled_permissions_missing),
+                        duration = SnackbarDuration.Long
+                    )
+                }
+            }
+        } else {
+            scope.launch {
+                sharedViewModel.showSnackbar(
+                    message = context.getString(R.string.bt_snackbar_bluetooth_disabled_to_connect_default),
+                    duration = SnackbarDuration.Long
+                )
+            }
+        }
+    }
+
+    val permissionsLauncher = rememberLauncherForActivityResult(
+        ActivityResultContracts.RequestMultiplePermissions()
+    ) { result ->
+        bluetoothViewModel.refreshPermissionsStatus()
+        val allGranted = result.values.all { it }
+        if (allGranted) {
+            if (bluetoothViewModel.isBluetoothEnabled()) {
+                bluetoothViewModel.connectToSavedDevice()
+            } else {
+                val intent = Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE)
+                enableBluetoothLauncher.launch(intent)
+            }
+        } else {
+            sharedViewModel.showSnackbar(R.string.bt_snackbar_permissions_required_to_connect_default)
+        }
+    }
+
+
+
     // Determine the Bluetooth action for the top bar
     val bluetoothTopBarAction = determineBluetoothTopBarAction(
         context = context,
@@ -339,7 +371,9 @@ fun OverviewScreen(
         currentNavController = navController,
         bluetoothViewModel = bluetoothViewModel,
         sharedViewModel = sharedViewModel,
-        currentDeviceName = savedDeviceNameString
+        currentDeviceName = savedDeviceNameString,
+        permissionsLauncher = permissionsLauncher,
+        enableBluetoothLauncher = enableBluetoothLauncher
     )
 
     // LaunchedEffect to configure the top bar based on the current state

android_app/app/src/main/java/com/health/openscale/ui/screen/settings/BluetoothScreen.kt

@@ -56,9 +56,13 @@ import androidx.compose.material3.OutlinedCard
 import androidx.compose.material3.SnackbarDuration
 import androidx.compose.material3.Text
 import androidx.compose.runtime.Composable
+import androidx.compose.runtime.DisposableEffect
 import androidx.compose.runtime.collectAsState
 import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.remember
 import androidx.compose.runtime.rememberCoroutineScope
+import androidx.compose.runtime.setValue
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.graphics.vector.ImageVector
@@ -94,31 +98,15 @@ fun BluetoothScreen(
     val scanError by bluetoothViewModel.scanError.collectAsState()
     val connectionError by bluetoothViewModel.connectionError.collectAsState()
     val hasPermissions by bluetoothViewModel.permissionsGranted.collectAsState()
+    var pendingScan by remember { mutableStateOf(false) }
 
     val savedDeviceAddress by bluetoothViewModel.savedScaleAddress.collectAsState()
     val savedDeviceName by bluetoothViewModel.savedScaleName.collectAsState()
 
-    val permissionsLauncher = rememberLauncherForActivityResult(
-        contract = ActivityResultContracts.RequestMultiplePermissions()
-    ) { permissionsMap ->
-        bluetoothViewModel.refreshPermissionsStatus()
-        val allGranted = permissionsMap.values.all { it }
-        if (allGranted) {
-            if (!bluetoothViewModel.isBluetoothEnabled()) {
-                scope.launch {
-                    sharedViewModel.showSnackbar(
-                        message = context.getString(R.string.bluetooth_enable_for_scan),
-                        duration = SnackbarDuration.Short
-                    )
-                }
-            }
-        } else {
-            scope.launch {
-                sharedViewModel.showSnackbar(
-                    message = context.getString(R.string.bluetooth_permissions_required_for_scan),
-                    duration = SnackbarDuration.Long
-                )
-            }
+    DisposableEffect(Unit) {
+        onDispose {
+            pendingScan = false
+            bluetoothViewModel.requestStopDeviceScan()
         }
     }
 
@@ -127,7 +115,19 @@ fun BluetoothScreen(
     ) { result ->
         bluetoothViewModel.refreshPermissionsStatus()
         if (result.resultCode == Activity.RESULT_OK) {
-            if (!bluetoothViewModel.permissionsGranted.value) {
+            if (bluetoothViewModel.permissionsGranted.value) {
+                if (pendingScan) {
+                    bluetoothViewModel.clearAllErrors()
+                    if (!bluetoothViewModel.isScanning.value) {
+                        bluetoothViewModel.requestStartDeviceScan()
+                    }
+                    try {
+                        pendingScan = false
+                    } catch (e: Exception) {
+                        TODO("Not yet implemented")
+                    }
+                }
+            } else {
                 scope.launch {
                     sharedViewModel.showSnackbar(
                         message = context.getString(R.string.bluetooth_enabled_permissions_missing),
@@ -145,6 +145,36 @@ fun BluetoothScreen(
         }
     }
 
+    val permissionsLauncher = rememberLauncherForActivityResult(
+        contract = ActivityResultContracts.RequestMultiplePermissions()
+    ) { permissionsMap ->
+        bluetoothViewModel.refreshPermissionsStatus()
+        val allGranted = permissionsMap.values.all { it }
+        if (allGranted) {
+            if (bluetoothViewModel.isBluetoothEnabled()) {
+                if (pendingScan) {
+                    bluetoothViewModel.clearAllErrors()
+                    if (!bluetoothViewModel.isScanning.value) {
+                        bluetoothViewModel.requestStartDeviceScan()
+                    }
+                    pendingScan = false
+                }
+            } else {
+                val enableBtIntent = Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE)
+                enableBluetoothLauncher.launch(enableBtIntent)
+            }
+        } else {
+            pendingScan = false
+            scope.launch {
+                sharedViewModel.showSnackbar(
+                    message = context.getString(R.string.bluetooth_permissions_required_for_scan),
+                    duration = SnackbarDuration.Long
+                )
+            }
+        }
+    }
+
+
     Column(
         modifier = Modifier
             .fillMaxSize()
@@ -156,6 +186,7 @@ fun BluetoothScreen(
         // Status and action area (Scan button or info cards)
         if (!hasPermissions) {
             PermissionRequestCard(onGrantPermissions = {
+                pendingScan = true
                 permissionsLauncher.launch(
                     arrayOf(Manifest.permission.BLUETOOTH_SCAN, Manifest.permission.BLUETOOTH_CONNECT)
                 )
@@ -203,8 +234,26 @@ fun BluetoothScreen(
                     if (isScanning) {
                         bluetoothViewModel.requestStopDeviceScan()
                     } else {
-                        bluetoothViewModel.clearAllErrors() // Clear previous errors before starting a new scan
+                        pendingScan = true
+                        bluetoothViewModel.clearAllErrors()
+                        when {
+                            !bluetoothViewModel.permissionsGranted.value -> {
+                                permissionsLauncher.launch(
+                                    arrayOf(
+                                        Manifest.permission.BLUETOOTH_SCAN,
+                                        Manifest.permission.BLUETOOTH_CONNECT
+                                    )
+                                )
+                            }
+                            !bluetoothViewModel.isBluetoothEnabled() -> {
+                                val enableBtIntent = Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE)
+                                enableBluetoothLauncher.launch(enableBtIntent)
+                            }
+                            else -> {
                                 bluetoothViewModel.requestStartDeviceScan()
+                                pendingScan = false
+                            }
+                        }
                     }
                 },
                 modifier = Modifier.fillMaxWidth(),
@@ -440,7 +489,7 @@ fun DeviceCardItem(
     onClick: () -> Unit
 ) {
     val supportColor = if (deviceInfo.isSupported) MaterialTheme.colorScheme.primary else MaterialTheme.colorScheme.onSurfaceVariant.copy(alpha = 0.7f)
-    val unknownDeviceName = stringResource(R.string.unknown_device_placeholder)
+    val unknownDeviceName = stringResource(R.string.unknown_device)
 
     ElevatedCard(
         onClick = onClick,

android_app/app/src/main/res/values-de/strings.xml

@@ -190,7 +190,6 @@
     <string name="bluetooth_must_be_enabled_for_scan">Bluetooth muss aktiviert sein, um nach Waagen zu suchen.</string>
     <string name="saved_scale_label">Gespeicherte Waage:</string>
     <string name="unknown_device">Unbekannt</string>
-    <string name="unknown_device_placeholder">Unbekanntes Gerät</string>
     <string name="stop_scan_button">Scan stoppen</string>
     <string name="search_for_scales_button">Nach Waagen suchen</string>
     <string name="search_for_scales_button_desc">Schaltfläche "Nach Waagen suchen"</string>

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

@@ -192,7 +192,6 @@
     <string name="bluetooth_must_be_enabled_for_scan">Bluetooth must be enabled to search for scales.</string>
     <string name="saved_scale_label">Saved Scale:</string>
     <string name="unknown_device">Unknown</string>
-    <string name="unknown_device_placeholder">Unknown Device</string>
     <string name="stop_scan_button">Stop Scan</string>
     <string name="search_for_scales_button">Search for Scales</string>
     <string name="search_for_scales_button_desc">Search for scales button</string>