Release v1.1.2: Improve UX, restrict HTTP to local networks, fix sync stability

android/app/src/main/java/dev/dettmer/simplenotes/MainActivity.kt

@@ -34,6 +34,7 @@ import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.withContext
 import dev.dettmer.simplenotes.sync.WebDavSyncService
 import androidx.core.splashscreen.SplashScreen.Companion.installSplashScreen
+import androidx.swiperefreshlayout.widget.SwipeRefreshLayout
 
 class MainActivity : AppCompatActivity() {
     
@@ -41,6 +42,7 @@ class MainActivity : AppCompatActivity() {
     private lateinit var emptyStateCard: MaterialCardView
     private lateinit var fabAddNote: FloatingActionButton
     private lateinit var toolbar: MaterialToolbar
+    private lateinit var swipeRefreshLayout: SwipeRefreshLayout
     
     private lateinit var adapter: NotesAdapter
     private val storage by lazy { NotesStorage(this) }
@@ -152,6 +154,12 @@ class MainActivity : AppCompatActivity() {
             try {
                 val syncService = WebDavSyncService(this@MainActivity)
                 
+                // 🔥 v1.1.2: Check if there are unsynced changes first (performance optimization)
+                if (!syncService.hasUnsyncedChanges()) {
+                    Logger.d(TAG, "⏭️ Auto-sync ($source): No unsynced changes - skipping")
+                    return@launch
+                }
+                
                 // ⭐ WICHTIG: Server-Erreichbarkeits-Check VOR Sync (wie in SyncWorker)
                 val isReachable = withContext(Dispatchers.IO) {
                     syncService.isServerReachable()
@@ -220,6 +228,7 @@ class MainActivity : AppCompatActivity() {
         emptyStateCard = findViewById(R.id.emptyStateCard)
         fabAddNote = findViewById(R.id.fabAddNote)
         toolbar = findViewById(R.id.toolbar)
+        swipeRefreshLayout = findViewById<SwipeRefreshLayout>(R.id.swipeRefreshLayout)
     }
     
     private fun setupToolbar() {
@@ -233,10 +242,72 @@ class MainActivity : AppCompatActivity() {
         recyclerViewNotes.adapter = adapter
         recyclerViewNotes.layoutManager = LinearLayoutManager(this)
         
+        // 🔥 v1.1.2: Setup Pull-to-Refresh
+        setupPullToRefresh()
+        
         // Setup Swipe-to-Delete
         setupSwipeToDelete()
     }
     
+    /**
+     * Setup Pull-to-Refresh für manuellen Sync (v1.1.2)
+     */
+    private fun setupPullToRefresh() {
+        swipeRefreshLayout.setOnRefreshListener {
+            Logger.d(TAG, "🔄 Pull-to-Refresh triggered - starting manual sync")
+            
+            lifecycleScope.launch {
+                try {
+                    val prefs = getSharedPreferences(Constants.PREFS_NAME, Context.MODE_PRIVATE)
+                    val serverUrl = prefs.getString(Constants.KEY_SERVER_URL, null)
+                    
+                    if (serverUrl.isNullOrEmpty()) {
+                        showToast("⚠️ Server noch nicht konfiguriert")
+                        swipeRefreshLayout.isRefreshing = false
+                        return@launch
+                    }
+                    
+                    val syncService = WebDavSyncService(this@MainActivity)
+                    
+                    // 🔥 v1.1.2: Check if there are unsynced changes first (performance optimization)
+                    if (!syncService.hasUnsyncedChanges()) {
+                        Logger.d(TAG, "⏭️ No unsynced changes, skipping server reachability check")
+                        showToast("✅ Bereits synchronisiert")
+                        swipeRefreshLayout.isRefreshing = false
+                        return@launch
+                    }
+                    
+                    // Check if server is reachable
+                    if (!syncService.isServerReachable()) {
+                        showToast("⚠️ Server nicht erreichbar")
+                        swipeRefreshLayout.isRefreshing = false
+                        return@launch
+                    }
+                    
+                    // Perform sync
+                    val result = syncService.syncNotes()
+                    
+                    if (result.isSuccess) {
+                        showToast("✅ ${result.syncedCount} Notizen synchronisiert")
+                        loadNotes()
+                    } else {
+                        showToast("❌ Sync fehlgeschlagen: ${result.errorMessage}")
+                    }
+                } catch (e: Exception) {
+                    Logger.e(TAG, "Pull-to-Refresh sync failed", e)
+                    showToast("❌ Fehler: ${e.message}")
+                } finally {
+                    swipeRefreshLayout.isRefreshing = false
+                }
+            }
+        }
+        
+        // Set Material 3 color scheme
+        swipeRefreshLayout.setColorSchemeResources(
+            com.google.android.material.R.color.material_dynamic_primary50
+        )
+    }
+    
     private fun setupSwipeToDelete() {
         val itemTouchHelper = ItemTouchHelper(object : ItemTouchHelper.SimpleCallback(
             0, // No drag
@@ -336,11 +407,18 @@ class MainActivity : AppCompatActivity() {
     private fun triggerManualSync() {
         lifecycleScope.launch {
             try {
-                showToast("Starte Synchronisation...")
-                
                 // Create sync service
                 val syncService = WebDavSyncService(this@MainActivity)
                 
+                // 🔥 v1.1.2: Check if there are unsynced changes first (performance optimization)
+                if (!syncService.hasUnsyncedChanges()) {
+                    Logger.d(TAG, "⏭️ Manual Sync: No unsynced changes - skipping")
+                    showToast("✅ Bereits synchronisiert")
+                    return@launch
+                }
+                
+                showToast("Starte Synchronisation...")
+                
                 // ⭐ WICHTIG: Server-Erreichbarkeits-Check VOR Sync (wie in SyncWorker)
                 val isReachable = withContext(Dispatchers.IO) {
                     syncService.isServerReachable()

android/app/src/main/java/dev/dettmer/simplenotes/NoteEditorActivity.kt

@@ -41,7 +41,8 @@ class NoteEditorActivity : AppCompatActivity() {
         setSupportActionBar(toolbar)
         supportActionBar?.apply {
             setDisplayHomeAsUpEnabled(true)
-            setHomeAsUpIndicator(android.R.drawable.ic_menu_close_clear_cancel)
+            // 🔥 v1.1.2: Use default back arrow (Material Design) instead of X icon
+            // Icon is set in XML: app:navigationIcon="?attr/homeAsUpIndicator"
         }
         
         // Find views

android/app/src/main/java/dev/dettmer/simplenotes/SettingsActivity.kt

@@ -10,6 +10,7 @@ import android.util.Log
 import android.view.MenuItem
 import android.widget.Button
 import android.widget.EditText
+import android.widget.RadioButton
 import android.widget.RadioGroup
 import android.widget.TextView
 import androidx.appcompat.app.AlertDialog
@@ -20,14 +21,12 @@ import androidx.lifecycle.lifecycleScope
 import androidx.localbroadcastmanager.content.LocalBroadcastManager
 import com.google.android.material.appbar.MaterialToolbar
 import com.google.android.material.card.MaterialCardView
-import com.google.android.material.chip.Chip
 import com.google.android.material.color.DynamicColors
 import com.google.android.material.switchmaterial.SwitchMaterial
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.Dispatchers
-import kotlinx.coroutines.Job
-import kotlinx.coroutines.delay
 import kotlinx.coroutines.launch
+import dev.dettmer.simplenotes.utils.UrlValidator
 import kotlinx.coroutines.withContext
 import dev.dettmer.simplenotes.sync.WebDavSyncService
 import dev.dettmer.simplenotes.sync.NetworkMonitor
@@ -49,6 +48,7 @@ class SettingsActivity : AppCompatActivity() {
         private const val LICENSE_URL = "https://github.com/inventory69/simple-notes-sync/blob/main/LICENSE"
     }
     
+    private lateinit var textInputLayoutServerUrl: com.google.android.material.textfield.TextInputLayout
     private lateinit var editTextServerUrl: EditText
     private lateinit var editTextUsername: EditText
     private lateinit var editTextPassword: EditText
@@ -57,7 +57,12 @@ class SettingsActivity : AppCompatActivity() {
     private lateinit var buttonSyncNow: Button
     private lateinit var buttonRestoreFromServer: Button
     private lateinit var textViewServerStatus: TextView
-    private lateinit var chipAutoSaveStatus: Chip
+    
+    // Protocol Selection UI
+    private lateinit var protocolRadioGroup: RadioGroup
+    private lateinit var radioHttp: RadioButton
+    private lateinit var radioHttps: RadioButton
+    private lateinit var protocolHintText: TextView
     
     // Sync Interval UI
     private lateinit var radioGroupSyncInterval: RadioGroup
@@ -68,8 +73,6 @@ class SettingsActivity : AppCompatActivity() {
     private lateinit var cardDeveloperProfile: MaterialCardView
     private lateinit var cardLicense: MaterialCardView
     
-    private var autoSaveIndicatorJob: Job? = null
-    
     private val prefs by lazy {
         getSharedPreferences(Constants.PREFS_NAME, MODE_PRIVATE)
     }
@@ -98,6 +101,7 @@ class SettingsActivity : AppCompatActivity() {
     }
     
     private fun findViews() {
+        textInputLayoutServerUrl = findViewById(R.id.textInputLayoutServerUrl)
         editTextServerUrl = findViewById(R.id.editTextServerUrl)
         editTextUsername = findViewById(R.id.editTextUsername)
         editTextPassword = findViewById(R.id.editTextPassword)
@@ -106,7 +110,12 @@ class SettingsActivity : AppCompatActivity() {
         buttonSyncNow = findViewById(R.id.buttonSyncNow)
         buttonRestoreFromServer = findViewById(R.id.buttonRestoreFromServer)
         textViewServerStatus = findViewById(R.id.textViewServerStatus)
-        chipAutoSaveStatus = findViewById(R.id.chipAutoSaveStatus)
+        
+        // Protocol Selection UI
+        protocolRadioGroup = findViewById(R.id.protocolRadioGroup)
+        radioHttp = findViewById(R.id.radioHttp)
+        radioHttps = findViewById(R.id.radioHttps)
+        protocolHintText = findViewById(R.id.protocolHintText)
         
         // Sync Interval UI
         radioGroupSyncInterval = findViewById(R.id.radioGroupSyncInterval)
@@ -119,16 +128,91 @@ class SettingsActivity : AppCompatActivity() {
     }
     
     private fun loadSettings() {
-        editTextServerUrl.setText(prefs.getString(Constants.KEY_SERVER_URL, ""))
+        val savedUrl = prefs.getString(Constants.KEY_SERVER_URL, "") ?: ""
+        
+        // Parse existing URL to extract protocol and host/path
+        if (savedUrl.isNotEmpty()) {
+            val (protocol, hostPath) = parseUrl(savedUrl)
+            
+            // Set protocol radio button
+            when (protocol) {
+                "http" -> radioHttp.isChecked = true
+                "https" -> radioHttps.isChecked = true
+                else -> radioHttp.isChecked = true // Default to HTTP (most users have local servers)
+            }
+            
+            // Set URL with protocol prefix in the text field
+            editTextServerUrl.setText("$protocol://$hostPath")
+        } else {
+            // Default: HTTP selected (lokale Server sind häufiger), empty URL with prefix
+            radioHttp.isChecked = true
+            editTextServerUrl.setText("http://")
+        }
+        
         editTextUsername.setText(prefs.getString(Constants.KEY_USERNAME, ""))
         editTextPassword.setText(prefs.getString(Constants.KEY_PASSWORD, ""))
         switchAutoSync.isChecked = prefs.getBoolean(Constants.KEY_AUTO_SYNC, false)
         
+        // Update hint text based on selected protocol
+        updateProtocolHint()
+        
         // Server Status prüfen
         checkServerStatus()
     }
     
+    /**
+     * Parse URL into protocol and host/path components
+     * @param url Full URL like "https://example.com:8080/webdav"
+     * @return Pair of (protocol, hostPath) like ("https", "example.com:8080/webdav")
+     */
+    private fun parseUrl(url: String): Pair<String, String> {
+        return when {
+            url.startsWith("https://") -> "https" to url.removePrefix("https://")
+            url.startsWith("http://") -> "http" to url.removePrefix("http://")
+            else -> "http" to url // Default to HTTP if no protocol specified
+        }
+    }
+    
+    /**
+     * Update the hint text below protocol selection based on selected protocol
+     */
+    private fun updateProtocolHint() {
+        protocolHintText.text = if (radioHttp.isChecked) {
+            "HTTP nur für lokale Netzwerke (z.B. 192.168.x.x, 10.x.x.x)"
+        } else {
+            "HTTPS für sichere Verbindungen über das Internet"
+        }
+    }
+    
+    /**
+     * Update protocol prefix in URL field when radio button changes
+     * Keeps the host/path part, only changes http:// <-> https://
+     */
+    private fun updateProtocolInUrl() {
+        val currentText = editTextServerUrl.text.toString()
+        val newProtocol = if (radioHttp.isChecked) "http" else "https"
+        
+        // Extract host/path without protocol
+        val hostPath = when {
+            currentText.startsWith("https://") -> currentText.removePrefix("https://")
+            currentText.startsWith("http://") -> currentText.removePrefix("http://")
+            else -> currentText
+        }
+        
+        // Set new URL with correct protocol
+        editTextServerUrl.setText("$newProtocol://$hostPath")
+        
+        // Move cursor to end
+        editTextServerUrl.setSelection(editTextServerUrl.text?.length ?: 0)
+    }
+    
     private fun setupListeners() {
+        // Protocol selection listener - update URL prefix when radio changes
+        protocolRadioGroup.setOnCheckedChangeListener { _, checkedId ->
+            updateProtocolInUrl()
+            updateProtocolHint()
+        }
+        
         buttonTestConnection.setOnClickListener {
             saveSettings()
             testConnection()
@@ -146,24 +230,23 @@ class SettingsActivity : AppCompatActivity() {
         
         switchAutoSync.setOnCheckedChangeListener { _, isChecked ->
             onAutoSyncToggled(isChecked)
-            showAutoSaveIndicator()
         }
         
+        // Clear error when user starts typing again
+        editTextServerUrl.addTextChangedListener(object : android.text.TextWatcher {
+            override fun beforeTextChanged(s: CharSequence?, start: Int, count: Int, after: Int) {}
+            override fun onTextChanged(s: CharSequence?, start: Int, before: Int, count: Int) {
+                textInputLayoutServerUrl.error = null
+            }
+            override fun afterTextChanged(s: android.text.Editable?) {}
+        })
+        
         // Server Status Check bei Settings-Änderung
         editTextServerUrl.setOnFocusChangeListener { _, hasFocus ->
             if (!hasFocus) {
                 checkServerStatus()
-                showAutoSaveIndicator()
             }
         }
-        
-        editTextUsername.setOnFocusChangeListener { _, hasFocus ->
-            if (!hasFocus) showAutoSaveIndicator()
-        }
-        
-        editTextPassword.setOnFocusChangeListener { _, hasFocus ->
-            if (!hasFocus) showAutoSaveIndicator()
-        }
     }
     
     /**
@@ -258,8 +341,26 @@ class SettingsActivity : AppCompatActivity() {
     }
     
     private fun saveSettings() {
+        // URL is already complete with protocol in the text field (http:// or https://)
+        val fullUrl = editTextServerUrl.text.toString().trim()
+        
+        // Clear previous error
+        textInputLayoutServerUrl.error = null
+        textInputLayoutServerUrl.isErrorEnabled = false
+        
+        // 🔥 v1.1.2: Validate HTTP URL (only allow for local networks)
+        if (fullUrl.isNotEmpty()) {
+            val (isValid, errorMessage) = UrlValidator.validateHttpUrl(fullUrl)
+            if (!isValid) {
+                // Only show error in TextField (no Toast)
+                textInputLayoutServerUrl.isErrorEnabled = true
+                textInputLayoutServerUrl.error = errorMessage
+                return
+            }
+        }
+        
         prefs.edit().apply {
-            putString(Constants.KEY_SERVER_URL, editTextServerUrl.text.toString().trim())
+            putString(Constants.KEY_SERVER_URL, fullUrl)
             putString(Constants.KEY_USERNAME, editTextUsername.text.toString().trim())
             putString(Constants.KEY_PASSWORD, editTextPassword.text.toString().trim())
             putBoolean(Constants.KEY_AUTO_SYNC, switchAutoSync.isChecked)
@@ -268,6 +369,24 @@ class SettingsActivity : AppCompatActivity() {
     }
     
     private fun testConnection() {
+        // URL is already complete with protocol in the text field (http:// or https://)
+        val fullUrl = editTextServerUrl.text.toString().trim()
+        
+        // Clear previous error
+        textInputLayoutServerUrl.error = null
+        textInputLayoutServerUrl.isErrorEnabled = false
+        
+        // 🔥 v1.1.2: Validate before testing
+        if (fullUrl.isNotEmpty()) {
+            val (isValid, errorMessage) = UrlValidator.validateHttpUrl(fullUrl)
+            if (!isValid) {
+                // Only show error in TextField (no Toast)
+                textInputLayoutServerUrl.isErrorEnabled = true
+                textInputLayoutServerUrl.error = errorMessage
+                return
+            }
+        }
+        
         lifecycleScope.launch {
             try {
                 showToast("Teste Verbindung...")
@@ -291,8 +410,23 @@ class SettingsActivity : AppCompatActivity() {
     private fun syncNow() {
         lifecycleScope.launch {
             try {
-                showToast("Synchronisiere...")
                 val syncService = WebDavSyncService(this@SettingsActivity)
+                
+                // 🔥 v1.1.2: Check if there are unsynced changes first (performance optimization)
+                if (!syncService.hasUnsyncedChanges()) {
+                    showToast("✅ Bereits synchronisiert")
+                    return@launch
+                }
+                
+                showToast("Synchronisiere...")
+                
+                // ⭐ WICHTIG: Server-Erreichbarkeits-Check VOR Sync (wie in anderen Triggern)
+                if (!syncService.isServerReachable()) {
+                    showToast("⚠️ Server nicht erreichbar")
+                    checkServerStatus() // Server-Status aktualisieren
+                    return@launch
+                }
+                
                 val result = syncService.syncNotes()
                 
                 if (result.isSuccess) {
@@ -420,32 +554,6 @@ class SettingsActivity : AppCompatActivity() {
         }
     }
     
-    private fun showAutoSaveIndicator() {
-        // Cancel previous job if still running
-        autoSaveIndicatorJob?.cancel()
-        
-        // Show saving indicator
-        chipAutoSaveStatus.apply {
-            visibility = android.view.View.VISIBLE
-            text = "💾 Speichere..."
-            setChipBackgroundColorResource(android.R.color.darker_gray)
-        }
-        
-        // Save settings
-        saveSettings()
-        
-        // Show saved confirmation after short delay
-        autoSaveIndicatorJob = lifecycleScope.launch {
-            delay(300) // Short delay to show "Speichere..."
-            chipAutoSaveStatus.apply {
-                text = "✓ Gespeichert"
-                setChipBackgroundColorResource(android.R.color.holo_green_light)
-            }
-            delay(2000) // Show for 2 seconds
-            chipAutoSaveStatus.visibility = android.view.View.GONE
-        }
-    }
-    
     private fun showRestoreConfirmation() {
         android.app.AlertDialog.Builder(this)
             .setTitle(R.string.restore_confirmation_title)

android/app/src/main/java/dev/dettmer/simplenotes/sync/SyncWorker.kt

@@ -8,6 +8,7 @@ import androidx.work.WorkerParameters
 import dev.dettmer.simplenotes.BuildConfig
 import dev.dettmer.simplenotes.utils.Logger
 import dev.dettmer.simplenotes.utils.NotificationHelper
+import kotlinx.coroutines.CancellationException
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.withContext
 
@@ -52,7 +53,25 @@ class SyncWorker(
             }
             
             if (BuildConfig.DEBUG) {
-                Logger.d(TAG, "📍 Step 2: Checking server reachability (Pre-Check)")
+                Logger.d(TAG, "📍 Step 2: Checking for unsynced changes (Performance Pre-Check)")
+            }
+            
+            // 🔥 v1.1.2: Performance-Optimierung - Skip Sync wenn keine lokalen Änderungen
+            // Spart Batterie + Netzwerk-Traffic + Server-Last
+            if (!syncService.hasUnsyncedChanges()) {
+                Logger.d(TAG, "⏭️ No local changes - skipping sync (performance optimization)")
+                Logger.d(TAG, "   Saves battery, network traffic, and server load")
+                
+                if (BuildConfig.DEBUG) {
+                    Logger.d(TAG, "✅ SyncWorker.doWork() SUCCESS (no changes to sync)")
+                    Logger.d(TAG, "═══════════════════════════════════════")
+                }
+                
+                return@withContext Result.success()
+            }
+            
+            if (BuildConfig.DEBUG) {
+                Logger.d(TAG, "📍 Step 3: Checking server reachability (Pre-Check)")
             }
             
             // ⭐ KRITISCH: Server-Erreichbarkeits-Check VOR Sync
@@ -63,6 +82,9 @@ class SyncWorker(
                 Logger.d(TAG, "   Reason: Server offline/wrong network/network not ready/not configured")
                 Logger.d(TAG, "   This is normal in foreign WiFi or during network initialization")
                 
+                // 🔥 v1.1.2: Check if we should show warning (server unreachable for >24h)
+                checkAndShowSyncWarning(syncService)
+                
                 if (BuildConfig.DEBUG) {
                     Logger.d(TAG, "✅ SyncWorker.doWork() SUCCESS (silent skip)")
                     Logger.d(TAG, "═══════════════════════════════════════")
@@ -147,6 +169,32 @@ class SyncWorker(
                 }
                 Result.failure()
             }
+        } catch (e: CancellationException) {
+            // ⭐ Job wurde gecancelt - KEIN FEHLER!
+            // Gründe: App-Update, Doze Mode, Battery Optimization, Network Constraint, etc.
+            if (BuildConfig.DEBUG) {
+                Logger.d(TAG, "═══════════════════════════════════════")
+            }
+            Logger.d(TAG, "⏹️ Job was cancelled (normal - update/doze/constraints)")
+            Logger.d(TAG, "   Reason could be: App update, Doze mode, Battery opt, Network disconnect")
+            Logger.d(TAG, "   This is expected Android behavior - not an error!")
+            
+            try {
+                // UI-Refresh trotzdem triggern (falls MainActivity geöffnet)
+                broadcastSyncCompleted(false, 0)
+            } catch (broadcastError: Exception) {
+                Logger.e(TAG, "Failed to broadcast after cancellation", broadcastError)
+            }
+            
+            if (BuildConfig.DEBUG) {
+                Logger.d(TAG, "✅ SyncWorker.doWork() SUCCESS (cancelled, no error)")
+                Logger.d(TAG, "═══════════════════════════════════════")
+            }
+            
+            // ⚠️ WICHTIG: Result.success() zurückgeben!
+            // Cancellation ist KEIN Fehler, WorkManager soll nicht retries machen
+            Result.success()
+            
         } catch (e: Exception) {
             if (BuildConfig.DEBUG) {
                 Logger.d(TAG, "═══════════════════════════════════════")
@@ -189,4 +237,69 @@ class SyncWorker(
         LocalBroadcastManager.getInstance(applicationContext).sendBroadcast(intent)
         Logger.d(TAG, "📡 Broadcast sent: success=$success, count=$count")
     }
+    
+    /**
+     * Prüft ob Server längere Zeit unreachable und zeigt ggf. Warnung (v1.1.2)
+     * - Nur wenn Auto-Sync aktiviert
+     * - Nur wenn schon mal erfolgreich gesynct
+     * - Nur wenn >24h seit letztem erfolgreichen Sync
+     * - Throttling: Max. 1 Warnung pro 24h
+     */
+    private fun checkAndShowSyncWarning(syncService: WebDavSyncService) {
+        try {
+            val prefs = applicationContext.getSharedPreferences(
+                dev.dettmer.simplenotes.utils.Constants.PREFS_NAME,
+                android.content.Context.MODE_PRIVATE
+            )
+            
+            // Check 1: Auto-Sync aktiviert?
+            val autoSyncEnabled = prefs.getBoolean(
+                dev.dettmer.simplenotes.utils.Constants.KEY_AUTO_SYNC,
+                false
+            )
+            if (!autoSyncEnabled) {
+                Logger.d(TAG, "⏭️ Auto-Sync disabled - no warning needed")
+                return
+            }
+            
+            // Check 2: Schon mal erfolgreich gesynct?
+            val lastSuccessfulSync = syncService.getLastSuccessfulSyncTimestamp()
+            if (lastSuccessfulSync == 0L) {
+                Logger.d(TAG, "⏭️ Never synced successfully - no warning needed")
+                return
+            }
+            
+            // Check 3: >24h seit letztem erfolgreichen Sync?
+            val now = System.currentTimeMillis()
+            val timeSinceLastSync = now - lastSuccessfulSync
+            if (timeSinceLastSync < dev.dettmer.simplenotes.utils.Constants.SYNC_WARNING_THRESHOLD_MS) {
+                Logger.d(TAG, "⏭️ Last successful sync <24h ago - no warning needed")
+                return
+            }
+            
+            // Check 4: Throttling - schon Warnung in letzten 24h gezeigt?
+            val lastWarningShown = prefs.getLong(
+                dev.dettmer.simplenotes.utils.Constants.KEY_LAST_SYNC_WARNING_SHOWN,
+                0L
+            )
+            if (now - lastWarningShown < dev.dettmer.simplenotes.utils.Constants.SYNC_WARNING_THRESHOLD_MS) {
+                Logger.d(TAG, "⏭️ Warning already shown in last 24h - throttling")
+                return
+            }
+            
+            // Zeige Warnung
+            val hoursSinceLastSync = timeSinceLastSync / (1000 * 60 * 60)
+            NotificationHelper.showSyncWarning(applicationContext, hoursSinceLastSync)
+            
+            // Speichere Zeitpunkt der Warnung
+            prefs.edit()
+                .putLong(dev.dettmer.simplenotes.utils.Constants.KEY_LAST_SYNC_WARNING_SHOWN, now)
+                .apply()
+            
+            Logger.d(TAG, "⚠️ Sync warning shown: Server unreachable for ${hoursSinceLastSync}h")
+            
+        } catch (e: Exception) {
+            Logger.e(TAG, "Failed to check/show sync warning", e)
+        }
+    }
 }

android/app/src/main/java/dev/dettmer/simplenotes/sync/WebDavSyncService.kt

@@ -189,6 +189,44 @@ class WebDavSyncService(private val context: Context) {
         return prefs.getString(Constants.KEY_SERVER_URL, null)
     }
     
+    /**
+     * Prüft ob lokale Änderungen seit letztem Sync vorhanden sind (v1.1.2)
+     * Performance-Optimierung: Vermeidet unnötige Sync-Operationen
+     * 
+     * @return true wenn unsynced changes vorhanden, false sonst
+     */
+    suspend fun hasUnsyncedChanges(): Boolean = withContext(Dispatchers.IO) {
+        return@withContext try {
+            val lastSyncTime = getLastSyncTimestamp()
+            
+            // Wenn noch nie gesynct, dann haben wir Änderungen
+            if (lastSyncTime == 0L) {
+                Logger.d(TAG, "📝 Never synced - assuming changes exist")
+                return@withContext true
+            }
+            
+            // Prüfe ob Notizen existieren die neuer sind als letzter Sync
+            val storage = dev.dettmer.simplenotes.storage.NotesStorage(context)
+            val allNotes = storage.loadAllNotes()
+            
+            val hasChanges = allNotes.any { note ->
+                note.updatedAt > lastSyncTime
+            }
+            
+            Logger.d(TAG, "📊 Unsynced changes check: $hasChanges (${allNotes.size} notes total)")
+            if (hasChanges) {
+                val unsyncedCount = allNotes.count { note -> note.updatedAt > lastSyncTime }
+                Logger.d(TAG, "   → $unsyncedCount notes modified since last sync")
+            }
+            
+            hasChanges
+        } catch (e: Exception) {
+            Logger.e(TAG, "Failed to check for unsynced changes - assuming changes exist", e)
+            // Bei Fehler lieber sync durchführen (safe default)
+            true
+        }
+    }
+    
     /**
      * Prüft ob WebDAV-Server erreichbar ist (ohne Sync zu starten)
      * Verwendet Socket-Check für schnelle Erreichbarkeitsprüfung
@@ -481,8 +519,10 @@ class WebDavSyncService(private val context: Context) {
     }
     
     private fun saveLastSyncTimestamp() {
+        val now = System.currentTimeMillis()
         prefs.edit()
-            .putLong(Constants.KEY_LAST_SYNC, System.currentTimeMillis())
+            .putLong(Constants.KEY_LAST_SYNC, now)
+            .putLong(Constants.KEY_LAST_SUCCESSFUL_SYNC, now)  // 🔥 v1.1.2: Track successful sync
             .apply()
     }
     
@@ -490,6 +530,10 @@ class WebDavSyncService(private val context: Context) {
         return prefs.getLong(Constants.KEY_LAST_SYNC, 0)
     }
     
+    fun getLastSuccessfulSyncTimestamp(): Long {
+        return prefs.getLong(Constants.KEY_LAST_SUCCESSFUL_SYNC, 0)
+    }
+    
     /**
      * Restore all notes from server - overwrites local storage
      * @return RestoreResult with count of restored notes

android/app/src/main/java/dev/dettmer/simplenotes/utils/Constants.kt

@@ -10,6 +10,11 @@ object Constants {
     const val KEY_AUTO_SYNC = "auto_sync_enabled"
     const val KEY_LAST_SYNC = "last_sync_timestamp"
     
+    // 🔥 v1.1.2: Last Successful Sync Monitoring
+    const val KEY_LAST_SUCCESSFUL_SYNC = "last_successful_sync_time"
+    const val KEY_LAST_SYNC_WARNING_SHOWN = "last_sync_warning_shown_time"
+    const val SYNC_WARNING_THRESHOLD_MS = 24 * 60 * 60 * 1000L  // 24h
+    
     // 🔥 NEU: Sync Interval Configuration
     const val PREF_SYNC_INTERVAL_MINUTES = "sync_interval_minutes"
     const val DEFAULT_SYNC_INTERVAL_MINUTES = 30L

android/app/src/main/java/dev/dettmer/simplenotes/utils/NotificationHelper.kt

@@ -288,4 +288,40 @@ object NotificationHelper {
             Logger.d(TAG, "🗑️ Auto-cancelled error notification after 30s timeout")
         }, 30_000)
     }
+    
+    /**
+     * Zeigt Warnung wenn Server längere Zeit nicht erreichbar (v1.1.2)
+     * Throttling: Max. 1 Warnung pro 24h
+     */
+    fun showSyncWarning(context: Context, hoursSinceLastSync: Long) {
+        // PendingIntent für App-Öffnung
+        val intent = Intent(context, MainActivity::class.java).apply {
+            flags = Intent.FLAG_ACTIVITY_NEW_TASK or Intent.FLAG_ACTIVITY_CLEAR_TOP
+        }
+        val pendingIntent = PendingIntent.getActivity(
+            context,
+            0,
+            intent,
+            PendingIntent.FLAG_IMMUTABLE or PendingIntent.FLAG_UPDATE_CURRENT
+        )
+        
+        val notification = NotificationCompat.Builder(context, CHANNEL_ID)
+            .setSmallIcon(android.R.drawable.stat_notify_error)
+            .setContentTitle("⚠️ Sync-Warnung")
+            .setContentText("Server seit ${hoursSinceLastSync}h nicht erreichbar")
+            .setStyle(NotificationCompat.BigTextStyle()
+                .bigText("Der WebDAV-Server ist seit ${hoursSinceLastSync} Stunden nicht erreichbar. " +
+                        "Bitte prüfe deine Netzwerkverbindung oder Server-Einstellungen."))
+            .setPriority(NotificationCompat.PRIORITY_DEFAULT)
+            .setCategory(NotificationCompat.CATEGORY_STATUS)
+            .setContentIntent(pendingIntent)
+            .setAutoCancel(true)
+            .build()
+        
+        val manager = context.getSystemService(Context.NOTIFICATION_SERVICE) 
+            as NotificationManager
+        manager.notify(SYNC_NOTIFICATION_ID, notification)
+        
+        Logger.d(TAG, "⚠️ Showed sync warning: Server unreachable for ${hoursSinceLastSync}h")
+    }
 }

android/app/src/main/java/dev/dettmer/simplenotes/utils/UrlValidator.kt

@@ -0,0 +1,107 @@
+package dev.dettmer.simplenotes.utils
+
+import java.net.URL
+
+/**
+ * URL Validator für Network Security (v1.1.2)
+ * Erlaubt HTTP nur für lokale Netzwerke (RFC 1918 Private IPs)
+ */
+object UrlValidator {
+    
+    /**
+     * Prüft ob eine URL eine lokale/private Adresse ist
+     * Erlaubt:
+     * - 192.168.x.x (Class C private)
+     * - 10.x.x.x (Class A private)
+     * - 172.16.x.x - 172.31.x.x (Class B private)
+     * - 127.x.x.x (Localhost)
+     * - .local domains (mDNS/Bonjour)
+     */
+    fun isLocalUrl(url: String): Boolean {
+        return try {
+            val parsedUrl = URL(url)
+            val host = parsedUrl.host.lowercase()
+            
+            // Check for .local domains (e.g., nas.local)
+            if (host.endsWith(".local")) {
+                return true
+            }
+            
+            // Check for localhost
+            if (host == "localhost" || host == "127.0.0.1") {
+                return true
+            }
+            
+            // Parse IP address if it's numeric
+            val ipPattern = """^(\d{1,3})\.(\d{1,3})\.(\d{1,3})\.(\d{1,3})$""".toRegex()
+            val match = ipPattern.find(host)
+            
+            if (match != null) {
+                val octets = match.groupValues.drop(1).map { it.toInt() }
+                
+                // Validate octets are in range 0-255
+                if (octets.any { it > 255 }) {
+                    return false
+                }
+                
+                val (o1, o2, o3, o4) = octets
+                
+                // Check RFC 1918 private IP ranges
+                return when {
+                    // 10.0.0.0/8 (10.0.0.0 - 10.255.255.255)
+                    o1 == 10 -> true
+                    
+                    // 172.16.0.0/12 (172.16.0.0 - 172.31.255.255)
+                    o1 == 172 && o2 in 16..31 -> true
+                    
+                    // 192.168.0.0/16 (192.168.0.0 - 192.168.255.255)
+                    o1 == 192 && o2 == 168 -> true
+                    
+                    // 127.0.0.0/8 (Localhost)
+                    o1 == 127 -> true
+                    
+                    else -> false
+                }
+            }
+            
+            // Not a recognized local address
+            false
+        } catch (e: Exception) {
+            // Invalid URL format
+            false
+        }
+    }
+    
+    /**
+     * Validiert ob HTTP URL erlaubt ist
+     * @return Pair<Boolean, String?> - (isValid, errorMessage)
+     */
+    fun validateHttpUrl(url: String): Pair<Boolean, String?> {
+        return try {
+            val parsedUrl = URL(url)
+            
+            // HTTPS ist immer erlaubt
+            if (parsedUrl.protocol.equals("https", ignoreCase = true)) {
+                return Pair(true, null)
+            }
+            
+            // HTTP nur für lokale URLs erlaubt
+            if (parsedUrl.protocol.equals("http", ignoreCase = true)) {
+                if (isLocalUrl(url)) {
+                    return Pair(true, null)
+                } else {
+                    return Pair(
+                        false,
+                        "HTTP ist nur für lokale Server erlaubt (z.B. 192.168.x.x, 10.x.x.x, nas.local). " +
+                        "Für öffentliche Server verwende bitte HTTPS."
+                    )
+                }
+            }
+            
+            // Anderes Protokoll
+            Pair(false, "Ungültiges Protokoll: ${parsedUrl.protocol}. Bitte verwende HTTP oder HTTPS.")
+        } catch (e: Exception) {
+            Pair(false, "Ungültige URL: ${e.message}")
+        }
+    }
+}