Release v1.2.0 - Local Backup & Markdown Desktop Integration

✨ New Features:
- Local backup/restore system with 3 modes (Merge/Replace/Overwrite)
- Markdown export for desktop access via WebDAV mount
- Dual-format architecture (JSON master + Markdown mirror)
- Settings UI extended with backup & desktop integration sections

📝 Changes:
- Server restore now asks for mode selection (user safety)
- WebDAV mount instructions for Windows/Mac/Linux in README
- Complete CHANGELOG.md with all version history

🔧 Technical:
- BackupManager.kt for complete backup/restore logic
- Note.toMarkdown/fromMarkdown with YAML frontmatter
- ISO8601 timestamps for desktop compatibility
- Last-Write-Wins conflict resolution

📚 Documentation:
- CHANGELOG.md (Keep a Changelog format)
- README updates (removed Joplin/Obsidian, added WebDAV-mount)
- F-Droid changelogs (DE+EN, under 500 chars)
- SYNC_ARCHITECTURE.md in project-docs
- MARKDOWN_DESKTOP_REALITY_CHECK.md strategic plan
- WEB_EDITOR_PLAN_v1.3.0.md for future web editor feature

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

@@ -13,6 +13,7 @@ import android.widget.EditText
 import android.widget.RadioButton
 import android.widget.RadioGroup
 import android.widget.TextView
+import androidx.activity.result.contract.ActivityResultContracts
 import androidx.appcompat.app.AlertDialog
 import androidx.appcompat.app.AppCompatActivity
 import androidx.appcompat.widget.SwitchCompat
@@ -26,6 +27,8 @@ import com.google.android.material.switchmaterial.SwitchMaterial
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.launch
+import dev.dettmer.simplenotes.backup.BackupManager
+import dev.dettmer.simplenotes.backup.RestoreMode
 import dev.dettmer.simplenotes.utils.UrlValidator
 import kotlinx.coroutines.withContext
 import dev.dettmer.simplenotes.sync.WebDavSyncService
@@ -53,9 +56,13 @@ class SettingsActivity : AppCompatActivity() {
     private lateinit var editTextUsername: EditText
     private lateinit var editTextPassword: EditText
     private lateinit var switchAutoSync: SwitchCompat
+    private lateinit var switchMarkdownExport: SwitchCompat
     private lateinit var buttonTestConnection: Button
     private lateinit var buttonSyncNow: Button
+    private lateinit var buttonCreateBackup: Button
+    private lateinit var buttonRestoreFromFile: Button
     private lateinit var buttonRestoreFromServer: Button
+    private lateinit var buttonImportMarkdown: Button
     private lateinit var textViewServerStatus: TextView
     
     // Protocol Selection UI
@@ -73,6 +80,22 @@ class SettingsActivity : AppCompatActivity() {
     private lateinit var cardDeveloperProfile: MaterialCardView
     private lateinit var cardLicense: MaterialCardView
     
+    // Backup Manager
+    private val backupManager by lazy { BackupManager(this) }
+    
+    // Activity Result Launchers
+    private val createBackupLauncher = registerForActivityResult(
+        ActivityResultContracts.CreateDocument("application/json")
+    ) { uri ->
+        uri?.let { createBackup(it) }
+    }
+    
+    private val restoreBackupLauncher = registerForActivityResult(
+        ActivityResultContracts.OpenDocument()
+    ) { uri ->
+        uri?.let { showRestoreDialog(RestoreSource.LOCAL_FILE, it) }
+    }
+    
     private val prefs by lazy {
         getSharedPreferences(Constants.PREFS_NAME, MODE_PRIVATE)
     }
@@ -106,9 +129,13 @@ class SettingsActivity : AppCompatActivity() {
         editTextUsername = findViewById(R.id.editTextUsername)
         editTextPassword = findViewById(R.id.editTextPassword)
         switchAutoSync = findViewById(R.id.switchAutoSync)
+        switchMarkdownExport = findViewById(R.id.switchMarkdownExport)
         buttonTestConnection = findViewById(R.id.buttonTestConnection)
         buttonSyncNow = findViewById(R.id.buttonSyncNow)
+        buttonCreateBackup = findViewById(R.id.buttonCreateBackup)
+        buttonRestoreFromFile = findViewById(R.id.buttonRestoreFromFile)
         buttonRestoreFromServer = findViewById(R.id.buttonRestoreFromServer)
+        buttonImportMarkdown = findViewById(R.id.buttonImportMarkdown)
         textViewServerStatus = findViewById(R.id.textViewServerStatus)
         
         // Protocol Selection UI
@@ -152,6 +179,7 @@ class SettingsActivity : AppCompatActivity() {
         editTextUsername.setText(prefs.getString(Constants.KEY_USERNAME, ""))
         editTextPassword.setText(prefs.getString(Constants.KEY_PASSWORD, ""))
         switchAutoSync.isChecked = prefs.getBoolean(Constants.KEY_AUTO_SYNC, false)
+        switchMarkdownExport.isChecked = prefs.getBoolean(Constants.KEY_MARKDOWN_EXPORT, false)  // Default: disabled (offline-first)
         
         // Update hint text based on selected protocol
         updateProtocolHint()
@@ -223,15 +251,36 @@ class SettingsActivity : AppCompatActivity() {
             syncNow()
         }
         
+        buttonCreateBackup.setOnClickListener {
+            // Dateiname mit Timestamp
+            val timestamp = SimpleDateFormat("yyyy-MM-dd_HHmmss", Locale.US)
+                .format(java.util.Date())
+            val filename = "simplenotes_backup_$timestamp.json"
+            createBackupLauncher.launch(filename)
+        }
+        
+        buttonRestoreFromFile.setOnClickListener {
+            restoreBackupLauncher.launch(arrayOf("application/json"))
+        }
+        
         buttonRestoreFromServer.setOnClickListener {
             saveSettings()
-            showRestoreConfirmation()
+            showRestoreDialog(RestoreSource.WEBDAV_SERVER, null)
+        }
+        
+        buttonImportMarkdown.setOnClickListener {
+            saveSettings()
+            importMarkdownChanges()
         }
         
         switchAutoSync.setOnCheckedChangeListener { _, isChecked ->
             onAutoSyncToggled(isChecked)
         }
         
+        switchMarkdownExport.setOnCheckedChangeListener { _, isChecked ->
+            onMarkdownExportToggled(isChecked)
+        }
+        
         // Clear error when user starts typing again
         editTextServerUrl.addTextChangedListener(object : android.text.TextWatcher {
             override fun beforeTextChanged(s: CharSequence?, start: Int, count: Int, after: Int) {}
@@ -498,6 +547,67 @@ class SettingsActivity : AppCompatActivity() {
         }
     }
     
+    private fun onMarkdownExportToggled(enabled: Boolean) {
+        prefs.edit().putBoolean(Constants.KEY_MARKDOWN_EXPORT, enabled).apply()
+        
+        if (enabled) {
+            showToast("Markdown-Export aktiviert - Notizen werden als .md-Dateien exportiert")
+        } else {
+            showToast("Markdown-Export deaktiviert - nur JSON-Sync aktiv")
+        }
+    }
+    
+    private fun importMarkdownChanges() {
+        // Prüfen ob Server konfiguriert ist
+        val serverUrl = prefs.getString(Constants.KEY_SERVER_URL, "") ?: ""
+        val username = prefs.getString(Constants.KEY_USERNAME, "") ?: ""
+        val password = prefs.getString(Constants.KEY_PASSWORD, "") ?: ""
+        
+        if (serverUrl.isBlank() || username.isBlank() || password.isBlank()) {
+            showToast("Bitte zuerst WebDAV-Server konfigurieren")
+            return
+        }
+        
+        // Import-Dialog mit Warnung
+        AlertDialog.Builder(this)
+            .setTitle("Markdown-Import")
+            .setMessage(
+                "Importiert Änderungen aus .md-Dateien vom Server.\n\n" +
+                "⚠️ Bei Konflikten: Last-Write-Wins (neuere Zeitstempel gewinnen)\n\n" +
+                "Fortfahren?"
+            )
+            .setPositiveButton("Importieren") { _, _ ->
+                performMarkdownImport(serverUrl, username, password)
+            }
+            .setNegativeButton("Abbrechen", null)
+            .show()
+    }
+    
+    private fun performMarkdownImport(serverUrl: String, username: String, password: String) {
+        showToast("Importiere Markdown-Dateien...")
+        
+        lifecycleScope.launch(Dispatchers.IO) {
+            try {
+                val syncService = WebDavSyncService(this@SettingsActivity)
+                val importCount = syncService.syncMarkdownFiles(serverUrl, username, password)
+                
+                withContext(Dispatchers.Main) {
+                    if (importCount > 0) {
+                        showToast("$importCount Notizen aus Markdown importiert")
+                        // Benachrichtige MainActivity zum Neuladen
+                        sendBroadcast(Intent("dev.dettmer.simplenotes.NOTES_CHANGED"))
+                    } else {
+                        showToast("Keine Markdown-Änderungen gefunden")
+                    }
+                }
+            } catch (e: Exception) {
+                withContext(Dispatchers.Main) {
+                    showToast("Import-Fehler: ${e.message}")
+                }
+            }
+        }
+    }
+    
     private fun checkBatteryOptimization() {
         val powerManager = getSystemService(Context.POWER_SERVICE) as PowerManager
         val packageName = packageName
@@ -612,4 +722,231 @@ class SettingsActivity : AppCompatActivity() {
         super.onPause()
         saveSettings()
     }
+    
+    // ========================================
+    // BACKUP & RESTORE FUNCTIONS (v1.2.0)
+    // ========================================
+    
+    /**
+     * Restore-Quelle (Lokale Datei oder WebDAV Server)
+     */
+    private enum class RestoreSource {
+        LOCAL_FILE,
+        WEBDAV_SERVER
+    }
+    
+    /**
+     * Erstellt Backup (Task #1.2.0-04)
+     */
+    private fun createBackup(uri: Uri) {
+        lifecycleScope.launch {
+            try {
+                Logger.d(TAG, "📦 Creating backup...")
+                val result = backupManager.createBackup(uri)
+                
+                if (result.success) {
+                    showToast("✅ ${result.message}")
+                } else {
+                    showErrorDialog("Backup fehlgeschlagen", result.error ?: "Unbekannter Fehler")
+                }
+            } catch (e: Exception) {
+                Logger.e(TAG, "Failed to create backup", e)
+                showErrorDialog("Backup fehlgeschlagen", e.message ?: "Unbekannter Fehler")
+            }
+        }
+    }
+    
+    /**
+     * Universeller Restore-Dialog für beide Quellen (Task #1.2.0-05 + #1.2.0-05b)
+     * 
+     * @param source Lokale Datei oder WebDAV Server
+     * @param fileUri URI der lokalen Datei (nur für LOCAL_FILE)
+     */
+    private fun showRestoreDialog(source: RestoreSource, fileUri: Uri?) {
+        val sourceText = when (source) {
+            RestoreSource.LOCAL_FILE -> "Lokale Datei"
+            RestoreSource.WEBDAV_SERVER -> "WebDAV Server"
+        }
+        
+        // Custom View mit Radio Buttons
+        val dialogView = layoutInflater.inflate(android.R.layout.select_dialog_singlechoice, null)
+        val radioGroup = android.widget.RadioGroup(this).apply {
+            orientation = android.widget.RadioGroup.VERTICAL
+            setPadding(50, 20, 50, 20)
+        }
+        
+        // Radio Buttons erstellen
+        val radioMerge = android.widget.RadioButton(this).apply {
+            text = "⚪ Zusammenführen (Standard)\n   → Neue hinzufügen, Bestehende behalten"
+            id = 0
+            isChecked = true
+            setPadding(10, 10, 10, 10)
+        }
+        
+        val radioReplace = android.widget.RadioButton(this).apply {
+            text = "⚪ Ersetzen\n   → Alle löschen & Backup importieren"
+            id = 1
+            setPadding(10, 10, 10, 10)
+        }
+        
+        val radioOverwrite = android.widget.RadioButton(this).apply {
+            text = "⚪ Duplikate überschreiben\n   → Backup gewinnt bei Konflikten"
+            id = 2
+            setPadding(10, 10, 10, 10)
+        }
+        
+        radioGroup.addView(radioMerge)
+        radioGroup.addView(radioReplace)
+        radioGroup.addView(radioOverwrite)
+        
+        // Hauptlayout
+        val mainLayout = android.widget.LinearLayout(this).apply {
+            orientation = android.widget.LinearLayout.VERTICAL
+            setPadding(50, 30, 50, 30)
+        }
+        
+        // Info Text
+        val infoText = android.widget.TextView(this).apply {
+            text = "Quelle: $sourceText\n\nWiederherstellungs-Modus:"
+            textSize = 16f
+            setPadding(0, 0, 0, 20)
+        }
+        
+        // Hinweis Text
+        val hintText = android.widget.TextView(this).apply {
+            text = "\nℹ️ Ein Sicherheits-Backup wird vor dem Wiederherstellen automatisch erstellt."
+            textSize = 14f
+            setTypeface(null, android.graphics.Typeface.ITALIC)
+            setPadding(0, 20, 0, 0)
+        }
+        
+        mainLayout.addView(infoText)
+        mainLayout.addView(radioGroup)
+        mainLayout.addView(hintText)
+        
+        // Dialog erstellen
+        AlertDialog.Builder(this)
+            .setTitle("⚠️ Backup wiederherstellen?")
+            .setView(mainLayout)
+            .setPositiveButton("Wiederherstellen") { _, _ ->
+                val selectedMode = when (radioGroup.checkedRadioButtonId) {
+                    1 -> RestoreMode.REPLACE
+                    2 -> RestoreMode.OVERWRITE_DUPLICATES
+                    else -> RestoreMode.MERGE
+                }
+                
+                when (source) {
+                    RestoreSource.LOCAL_FILE -> fileUri?.let { performRestoreFromFile(it, selectedMode) }
+                    RestoreSource.WEBDAV_SERVER -> performRestoreFromServer(selectedMode)
+                }
+            }
+            .setNegativeButton("Abbrechen", null)
+            .show()
+    }
+    
+    /**
+     * Führt Restore aus lokaler Datei durch (Task #1.2.0-05)
+     */
+    private fun performRestoreFromFile(uri: Uri, mode: RestoreMode) {
+        lifecycleScope.launch {
+            val progressDialog = android.app.ProgressDialog(this@SettingsActivity).apply {
+                setMessage("Wiederherstellen...")
+                setCancelable(false)
+                show()
+            }
+            
+            try {
+                Logger.d(TAG, "📥 Restoring from file: $uri (mode: $mode)")
+                val result = backupManager.restoreBackup(uri, mode)
+                
+                progressDialog.dismiss()
+                
+                if (result.success) {
+                    val message = result.message ?: "Wiederhergestellt: ${result.imported_notes} Notizen"
+                    showToast("✅ $message")
+                    
+                    // Refresh MainActivity's note list
+                    setResult(RESULT_OK)
+                    broadcastNotesChanged()
+                } else {
+                    showErrorDialog("Wiederherstellung fehlgeschlagen", result.error ?: "Unbekannter Fehler")
+                }
+            } catch (e: Exception) {
+                progressDialog.dismiss()
+                Logger.e(TAG, "Failed to restore from file", e)
+                showErrorDialog("Wiederherstellung fehlgeschlagen", e.message ?: "Unbekannter Fehler")
+            }
+        }
+    }
+    
+    /**
+     * Führt Restore vom Server durch (Task #1.2.0-05b)
+     * Nutzt neues universelles Dialog-System mit Restore-Modi
+     * 
+     * HINWEIS: Die alte WebDavSyncService.restoreFromServer() Funktion
+     * unterstützt noch keine Restore-Modi. Aktuell wird immer REPLACE verwendet.
+     * TODO: WebDavSyncService.restoreFromServer() erweitern für v1.2.1+
+     */
+    private fun performRestoreFromServer(mode: RestoreMode) {
+        lifecycleScope.launch {
+            val progressDialog = android.app.ProgressDialog(this@SettingsActivity).apply {
+                setMessage("Wiederherstellen vom Server...")
+                setCancelable(false)
+                show()
+            }
+            
+            try {
+                Logger.d(TAG, "📥 Restoring from server (mode: $mode)")
+                Logger.w(TAG, "⚠️ Server-Restore nutzt aktuell immer REPLACE Mode (TODO: v1.2.1+)")
+                
+                // Auto-Backup erstellen (Sicherheitsnetz)
+                val autoBackupUri = backupManager.createAutoBackup()
+                if (autoBackupUri == null) {
+                    Logger.w(TAG, "⚠️ Auto-backup failed, but continuing with restore")
+                }
+                
+                // Server-Restore durchführen
+                val webdavService = WebDavSyncService(this@SettingsActivity)
+                val result = withContext(Dispatchers.IO) {
+                    // Nutzt alte Funktion (immer REPLACE)
+                    webdavService.restoreFromServer()
+                }
+                
+                progressDialog.dismiss()
+                
+                if (result.isSuccess) {
+                    showToast("✅ Wiederhergestellt: ${result.restoredCount} Notizen")
+                    setResult(RESULT_OK)
+                    broadcastNotesChanged()
+                } else {
+                    showErrorDialog("Wiederherstellung fehlgeschlagen", result.errorMessage ?: "Unbekannter Fehler")
+                }
+            } catch (e: Exception) {
+                progressDialog.dismiss()
+                Logger.e(TAG, "Failed to restore from server", e)
+                showErrorDialog("Wiederherstellung fehlgeschlagen", e.message ?: "Unbekannter Fehler")
+            }
+        }
+    }
+    
+    /**
+     * Sendet Broadcast dass Notizen geändert wurden
+     */
+    private fun broadcastNotesChanged() {
+        val intent = Intent(dev.dettmer.simplenotes.sync.SyncWorker.ACTION_SYNC_COMPLETED)
+        intent.putExtra("success", true)
+        intent.putExtra("syncedCount", 0)
+        LocalBroadcastManager.getInstance(this).sendBroadcast(intent)
+    }
+    
+    /**
+     * Zeigt Error-Dialog an
+     */
+    private fun showErrorDialog(title: String, message: String) {
+        AlertDialog.Builder(this)
+            .setTitle(title)
+            .setMessage(message)
+            .setPositiveButton("OK", null)
+            .show()
+    }
 }

android/app/src/main/java/dev/dettmer/simplenotes/backup/BackupManager.kt

@@ -0,0 +1,361 @@
+package dev.dettmer.simplenotes.backup
+
+import android.content.Context
+import android.net.Uri
+import com.google.gson.Gson
+import com.google.gson.GsonBuilder
+import dev.dettmer.simplenotes.BuildConfig
+import dev.dettmer.simplenotes.models.Note
+import dev.dettmer.simplenotes.storage.NotesStorage
+import dev.dettmer.simplenotes.utils.Logger
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.withContext
+import java.io.File
+import java.text.SimpleDateFormat
+import java.util.*
+
+/**
+ * BackupManager: Lokale Backup & Restore Funktionalität
+ * 
+ * Features:
+ * - Backup aller Notizen in JSON-Datei
+ * - Restore mit 3 Modi (Merge, Replace, Overwrite Duplicates)
+ * - Auto-Backup vor Restore (Sicherheitsnetz)
+ * - Backup-Validierung
+ */
+class BackupManager(private val context: Context) {
+    
+    companion object {
+        private const val TAG = "BackupManager"
+        private const val BACKUP_VERSION = 1
+        private const val AUTO_BACKUP_DIR = "auto_backups"
+        private const val AUTO_BACKUP_RETENTION_DAYS = 7
+    }
+    
+    private val storage = NotesStorage(context)
+    private val gson: Gson = GsonBuilder().setPrettyPrinting().create()
+    
+    /**
+     * Erstellt Backup aller Notizen
+     * 
+     * @param uri Output-URI (via Storage Access Framework)
+     * @return BackupResult mit Erfolg/Fehler Info
+     */
+    suspend fun createBackup(uri: Uri): BackupResult = withContext(Dispatchers.IO) {
+        return@withContext try {
+            Logger.d(TAG, "📦 Creating backup to: $uri")
+            
+            val allNotes = storage.loadAllNotes()
+            Logger.d(TAG, "   Found ${allNotes.size} notes to backup")
+            
+            val backupData = BackupData(
+                backup_version = BACKUP_VERSION,
+                created_at = System.currentTimeMillis(),
+                notes_count = allNotes.size,
+                app_version = BuildConfig.VERSION_NAME,
+                notes = allNotes
+            )
+            
+            val jsonString = gson.toJson(backupData)
+            
+            context.contentResolver.openOutputStream(uri)?.use { outputStream ->
+                outputStream.write(jsonString.toByteArray())
+                Logger.d(TAG, "✅ Backup created successfully")
+            }
+            
+            BackupResult(
+                success = true,
+                notes_count = allNotes.size,
+                message = "Backup erstellt: ${allNotes.size} Notizen"
+            )
+            
+        } catch (e: Exception) {
+            Logger.e(TAG, "Failed to create backup", e)
+            BackupResult(
+                success = false,
+                error = "Backup fehlgeschlagen: ${e.message}"
+            )
+        }
+    }
+    
+    /**
+     * Erstellt automatisches Backup (vor Restore)
+     * Gespeichert in app-internem Storage
+     * 
+     * @return Uri des Auto-Backups oder null bei Fehler
+     */
+    suspend fun createAutoBackup(): Uri? = withContext(Dispatchers.IO) {
+        return@withContext try {
+            val autoBackupDir = File(context.filesDir, AUTO_BACKUP_DIR).apply {
+                if (!exists()) mkdirs()
+            }
+            
+            val timestamp = SimpleDateFormat("yyyy-MM-dd_HHmmss", Locale.US)
+                .format(Date())
+            val filename = "auto_backup_before_restore_$timestamp.json"
+            val file = File(autoBackupDir, filename)
+            
+            Logger.d(TAG, "📦 Creating auto-backup: ${file.absolutePath}")
+            
+            val allNotes = storage.loadAllNotes()
+            val backupData = BackupData(
+                backup_version = BACKUP_VERSION,
+                created_at = System.currentTimeMillis(),
+                notes_count = allNotes.size,
+                app_version = BuildConfig.VERSION_NAME,
+                notes = allNotes
+            )
+            
+            file.writeText(gson.toJson(backupData))
+            
+            // Cleanup alte Auto-Backups
+            cleanupOldAutoBackups(autoBackupDir)
+            
+            Logger.d(TAG, "✅ Auto-backup created: ${file.absolutePath}")
+            Uri.fromFile(file)
+            
+        } catch (e: Exception) {
+            Logger.e(TAG, "Failed to create auto-backup", e)
+            null
+        }
+    }
+    
+    /**
+     * Stellt Notizen aus Backup wieder her
+     * 
+     * @param uri Backup-Datei URI
+     * @param mode Wiederherstellungs-Modus (Merge/Replace/Overwrite)
+     * @return RestoreResult mit Details
+     */
+    suspend fun restoreBackup(uri: Uri, mode: RestoreMode): RestoreResult = withContext(Dispatchers.IO) {
+        return@withContext try {
+            Logger.d(TAG, "📥 Restoring backup from: $uri (mode: $mode)")
+            
+            // 1. Backup-Datei lesen
+            val jsonString = context.contentResolver.openInputStream(uri)?.use { inputStream ->
+                inputStream.bufferedReader().use { it.readText() }
+            } ?: return@withContext RestoreResult(
+                success = false,
+                error = "Datei konnte nicht gelesen werden"
+            )
+            
+            // 2. Backup validieren & parsen
+            val validationResult = validateBackup(jsonString)
+            if (!validationResult.isValid) {
+                return@withContext RestoreResult(
+                    success = false,
+                    error = validationResult.errorMessage ?: "Ungültige Backup-Datei"
+                )
+            }
+            
+            val backupData = gson.fromJson(jsonString, BackupData::class.java)
+            Logger.d(TAG, "   Backup valid: ${backupData.notes_count} notes, version ${backupData.backup_version}")
+            
+            // 3. Auto-Backup erstellen (Sicherheitsnetz)
+            val autoBackupUri = createAutoBackup()
+            if (autoBackupUri == null) {
+                Logger.w(TAG, "⚠️ Auto-backup failed, but continuing with restore")
+            }
+            
+            // 4. Restore durchführen (je nach Modus)
+            val result = when (mode) {
+                RestoreMode.MERGE -> restoreMerge(backupData.notes)
+                RestoreMode.REPLACE -> restoreReplace(backupData.notes)
+                RestoreMode.OVERWRITE_DUPLICATES -> restoreOverwriteDuplicates(backupData.notes)
+            }
+            
+            Logger.d(TAG, "✅ Restore completed: ${result.imported_notes} imported, ${result.skipped_notes} skipped")
+            result
+            
+        } catch (e: Exception) {
+            Logger.e(TAG, "Failed to restore backup", e)
+            RestoreResult(
+                success = false,
+                error = "Wiederherstellung fehlgeschlagen: ${e.message}"
+            )
+        }
+    }
+    
+    /**
+     * Validiert Backup-Datei
+     */
+    private fun validateBackup(jsonString: String): ValidationResult {
+        return try {
+            val backupData = gson.fromJson(jsonString, BackupData::class.java)
+            
+            // Version kompatibel?
+            if (backupData.backup_version > BACKUP_VERSION) {
+                return ValidationResult(
+                    isValid = false,
+                    errorMessage = "Backup-Version nicht unterstützt (v${backupData.backup_version} benötigt v${BACKUP_VERSION}+)"
+                )
+            }
+            
+            // Notizen-Array vorhanden?
+            if (backupData.notes.isEmpty()) {
+                return ValidationResult(
+                    isValid = false,
+                    errorMessage = "Backup enthält keine Notizen"
+                )
+            }
+            
+            // Alle Notizen haben ID, title, content?
+            val invalidNotes = backupData.notes.filter { note ->
+                note.id.isBlank() || note.title.isBlank()
+            }
+            
+            if (invalidNotes.isNotEmpty()) {
+                return ValidationResult(
+                    isValid = false,
+                    errorMessage = "Backup enthält ${invalidNotes.size} ungültige Notizen"
+                )
+            }
+            
+            ValidationResult(isValid = true)
+            
+        } catch (e: Exception) {
+            ValidationResult(
+                isValid = false,
+                errorMessage = "Backup-Datei beschädigt oder ungültig: ${e.message}"
+            )
+        }
+    }
+    
+    /**
+     * Restore-Modus: MERGE
+     * Fügt neue Notizen hinzu, behält bestehende
+     */
+    private fun restoreMerge(backupNotes: List<Note>): RestoreResult {
+        val existingNotes = storage.loadAllNotes()
+        val existingIds = existingNotes.map { it.id }.toSet()
+        
+        val newNotes = backupNotes.filter { it.id !in existingIds }
+        val skippedNotes = backupNotes.size - newNotes.size
+        
+        newNotes.forEach { note ->
+            storage.saveNote(note)
+        }
+        
+        return RestoreResult(
+            success = true,
+            imported_notes = newNotes.size,
+            skipped_notes = skippedNotes,
+            message = "${newNotes.size} neue Notizen importiert, $skippedNotes übersprungen"
+        )
+    }
+    
+    /**
+     * Restore-Modus: REPLACE
+     * Löscht alle bestehenden Notizen, importiert Backup
+     */
+    private fun restoreReplace(backupNotes: List<Note>): RestoreResult {
+        // Alle bestehenden Notizen löschen
+        storage.deleteAllNotes()
+        
+        // Backup-Notizen importieren
+        backupNotes.forEach { note ->
+            storage.saveNote(note)
+        }
+        
+        return RestoreResult(
+            success = true,
+            imported_notes = backupNotes.size,
+            skipped_notes = 0,
+            message = "Alle Notizen ersetzt: ${backupNotes.size} importiert"
+        )
+    }
+    
+    /**
+     * Restore-Modus: OVERWRITE_DUPLICATES
+     * Backup überschreibt bei ID-Konflikten
+     */
+    private fun restoreOverwriteDuplicates(backupNotes: List<Note>): RestoreResult {
+        val existingNotes = storage.loadAllNotes()
+        val existingIds = existingNotes.map { it.id }.toSet()
+        
+        val newNotes = backupNotes.filter { it.id !in existingIds }
+        val overwrittenNotes = backupNotes.filter { it.id in existingIds }
+        
+        // Alle Backup-Notizen speichern (überschreibt automatisch)
+        backupNotes.forEach { note ->
+            storage.saveNote(note)
+        }
+        
+        return RestoreResult(
+            success = true,
+            imported_notes = newNotes.size,
+            skipped_notes = 0,
+            overwritten_notes = overwrittenNotes.size,
+            message = "${newNotes.size} neu, ${overwrittenNotes.size} überschrieben"
+        )
+    }
+    
+    /**
+     * Löscht Auto-Backups älter als RETENTION_DAYS
+     */
+    private fun cleanupOldAutoBackups(autoBackupDir: File) {
+        try {
+            val retentionTimeMs = AUTO_BACKUP_RETENTION_DAYS * 24 * 60 * 60 * 1000L
+            val cutoffTime = System.currentTimeMillis() - retentionTimeMs
+            
+            autoBackupDir.listFiles()?.forEach { file ->
+                if (file.lastModified() < cutoffTime) {
+                    Logger.d(TAG, "🗑️ Deleting old auto-backup: ${file.name}")
+                    file.delete()
+                }
+            }
+        } catch (e: Exception) {
+            Logger.e(TAG, "Failed to cleanup old backups", e)
+        }
+    }
+}
+
+/**
+ * Backup-Daten Struktur (JSON)
+ */
+data class BackupData(
+    val backup_version: Int,
+    val created_at: Long,
+    val notes_count: Int,
+    val app_version: String,
+    val notes: List<Note>
+)
+
+/**
+ * Wiederherstellungs-Modi
+ */
+enum class RestoreMode {
+    MERGE,                  // Bestehende + Neue (Standard)
+    REPLACE,                // Alles löschen + Importieren
+    OVERWRITE_DUPLICATES    // Backup überschreibt bei ID-Konflikten
+}
+
+/**
+ * Backup-Ergebnis
+ */
+data class BackupResult(
+    val success: Boolean,
+    val notes_count: Int = 0,
+    val message: String? = null,
+    val error: String? = null
+)
+
+/**
+ * Restore-Ergebnis
+ */
+data class RestoreResult(
+    val success: Boolean,
+    val imported_notes: Int = 0,
+    val skipped_notes: Int = 0,
+    val overwritten_notes: Int = 0,
+    val message: String? = null,
+    val error: String? = null
+)
+
+/**
+ * Validierungs-Ergebnis
+ */
+data class ValidationResult(
+    val isValid: Boolean,
+    val errorMessage: String? = null
+)

android/app/src/main/java/dev/dettmer/simplenotes/models/Note.kt

@@ -1,5 +1,9 @@
 package dev.dettmer.simplenotes.models
 
+import java.text.SimpleDateFormat
+import java.util.Date
+import java.util.Locale
+import java.util.TimeZone
 import java.util.UUID
 
 data class Note(
@@ -25,6 +29,25 @@ data class Note(
         """.trimIndent()
     }
     
+    /**
+     * Konvertiert Note zu Markdown mit YAML Frontmatter (Task #1.2.0-08)
+     * Format kompatibel mit Obsidian, Joplin, Typora
+     */
+    fun toMarkdown(): String {
+        return """
+---
+id: $id
+created: ${formatISO8601(createdAt)}
+updated: ${formatISO8601(updatedAt)}
+device: $deviceId
+---
+
+# $title
+
+$content
+        """.trimIndent()
+    }
+    
     companion object {
         fun fromJson(json: String): Note? {
             return try {
@@ -34,6 +57,78 @@ data class Note(
                 null
             }
         }
+        
+        /**
+         * Parst Markdown zurück zu Note-Objekt (Task #1.2.0-09)
+         * 
+         * @param md Markdown-String mit YAML Frontmatter
+         * @return Note-Objekt oder null bei Parse-Fehler
+         */
+        fun fromMarkdown(md: String): Note? {
+            return try {
+                // Parse YAML Frontmatter + Markdown Content
+                val frontmatterRegex = Regex("^---\\n(.+?)\\n---\\n(.*)$", RegexOption.DOT_MATCHES_ALL)
+                val match = frontmatterRegex.find(md) ?: return null
+                
+                val yamlBlock = match.groupValues[1]
+                val contentBlock = match.groupValues[2]
+                
+                // Parse YAML (einfach per String-Split für MVP)
+                val metadata = yamlBlock.lines()
+                    .mapNotNull { line ->
+                        val parts = line.split(":", limit = 2)
+                        if (parts.size == 2) {
+                            parts[0].trim() to parts[1].trim()
+                        } else null
+                    }.toMap()
+                
+                // Extract title from first # heading
+                val title = contentBlock.lines()
+                    .firstOrNull { it.startsWith("# ") }
+                    ?.removePrefix("# ")?.trim() ?: "Untitled"
+                
+                // Extract content (everything after heading)
+                val content = contentBlock
+                    .substringAfter("# $title\n\n", "")
+                    .trim()
+                
+                Note(
+                    id = metadata["id"] ?: UUID.randomUUID().toString(),
+                    title = title,
+                    content = content,
+                    createdAt = parseISO8601(metadata["created"] ?: ""),
+                    updatedAt = parseISO8601(metadata["updated"] ?: ""),
+                    deviceId = metadata["device"] ?: "desktop",
+                    syncStatus = SyncStatus.SYNCED  // Annahme: Vom Server importiert
+                )
+            } catch (e: Exception) {
+                null
+            }
+        }
+        
+        /**
+         * Formatiert Timestamp zu ISO8601 (Task #1.2.0-10)
+         * Format: 2024-12-21T18:00:00Z (UTC)
+         */
+        private fun formatISO8601(timestamp: Long): String {
+            val sdf = SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss'Z'", Locale.US)
+            sdf.timeZone = TimeZone.getTimeZone("UTC")
+            return sdf.format(Date(timestamp))
+        }
+        
+        /**
+         * Parst ISO8601 zurück zu Timestamp (Task #1.2.0-10)
+         * Fallback: Aktueller Timestamp bei Fehler
+         */
+        private fun parseISO8601(dateString: String): Long {
+            return try {
+                val sdf = SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss'Z'", Locale.US)
+                sdf.timeZone = TimeZone.getTimeZone("UTC")
+                sdf.parse(dateString)?.time ?: System.currentTimeMillis()
+            } catch (e: Exception) {
+                System.currentTimeMillis()  // Fallback
+            }
+        }
     }
 }
 

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

@@ -444,9 +444,11 @@ class WebDavSyncService(private val context: Context) {
     private fun uploadLocalNotes(sardine: Sardine, serverUrl: String): Int {
         var uploadedCount = 0
         val localNotes = storage.loadAllNotes()
+        val markdownExportEnabled = prefs.getBoolean(Constants.KEY_MARKDOWN_EXPORT, false)
         
         for (note in localNotes) {
             try {
+                // 1. JSON-Upload (bestehend, unverändert)
                 if (note.syncStatus == SyncStatus.LOCAL_ONLY || note.syncStatus == SyncStatus.PENDING) {
                     val noteUrl = "$serverUrl/${note.id}.json"
                     val jsonBytes = note.toJson().toByteArray()
@@ -457,6 +459,18 @@ class WebDavSyncService(private val context: Context) {
                     val updatedNote = note.copy(syncStatus = SyncStatus.SYNCED)
                     storage.saveNote(updatedNote)
                     uploadedCount++
+                    
+                    // 2. Markdown-Export (NEU in v1.2.0)
+                    // Läuft NACH erfolgreichem JSON-Upload
+                    if (markdownExportEnabled) {
+                        try {
+                            exportToMarkdown(sardine, serverUrl, note)
+                            Logger.d(TAG, "   📝 MD exported: ${note.title}")
+                        } catch (e: Exception) {
+                            Logger.e(TAG, "MD-Export failed for ${note.id}: ${e.message}")
+                            // Kein throw! JSON-Sync darf nicht blockiert werden
+                        }
+                    }
                 }
             } catch (e: Exception) {
                 // Mark as pending for retry
@@ -468,6 +482,49 @@ class WebDavSyncService(private val context: Context) {
         return uploadedCount
     }
     
+    /**
+     * Exportiert einzelne Note als Markdown (Task #1.2.0-11)
+     * 
+     * @param sardine Sardine-Client
+     * @param serverUrl Server-URL (notes/ Ordner)
+     * @param note Note zum Exportieren
+     */
+    private fun exportToMarkdown(sardine: Sardine, serverUrl: String, note: Note) {
+        val mdUrl = serverUrl.replace("/notes", "/notes-md")
+        
+        // Erstelle notes-md/ Ordner falls nicht vorhanden
+        if (!sardine.exists(mdUrl)) {
+            sardine.createDirectory(mdUrl)
+            Logger.d(TAG, "📁 Created notes-md/ directory")
+        }
+        
+        // Sanitize Filename (Task #1.2.0-12)
+        val filename = sanitizeFilename(note.title) + ".md"
+        val noteUrl = "$mdUrl/$filename"
+        
+        // Konvertiere zu Markdown
+        val mdContent = note.toMarkdown().toByteArray()
+        
+        // Upload
+        sardine.put(noteUrl, mdContent, "text/markdown")
+    }
+    
+    /**
+     * Sanitize Filename für sichere Dateinamen (Task #1.2.0-12)
+     * 
+     * Entfernt Windows/Linux-verbotene Zeichen, begrenzt Länge
+     * 
+     * @param title Original-Titel
+     * @return Sicherer Filename
+     */
+    private fun sanitizeFilename(title: String): String {
+        return title
+            .replace(Regex("[<>:\"/\\\\|?*]"), "_")  // Ersetze verbotene Zeichen
+            .replace(Regex("\\s+"), " ")              // Normalisiere Whitespace
+            .take(200)                                 // Max 200 Zeichen (Reserve für .md)
+            .trim('_', ' ')                            // Trim Underscores/Spaces
+    }
+    
     private data class DownloadResult(
         val downloadedCount: Int,
         val conflictCount: Int
@@ -618,6 +675,86 @@ class WebDavSyncService(private val context: Context) {
             )
         }
     }
+    
+    /**
+     * Synchronisiert Markdown-Dateien (Import von Desktop-Programmen) (Task #1.2.0-14)
+     * 
+     * Last-Write-Wins Konfliktauflösung basierend auf updatedAt Timestamp
+     * 
+     * @param serverUrl WebDAV Server-URL (notes/ Ordner)
+     * @param username WebDAV Username
+     * @param password WebDAV Password
+     * @return Anzahl importierter Notizen
+     */
+    suspend fun syncMarkdownFiles(
+        serverUrl: String, 
+        username: String, 
+        password: String
+    ): Int = withContext(Dispatchers.IO) {
+        return@withContext try {
+            Logger.d(TAG, "📝 Starting Markdown sync...")
+            
+            val sardine = OkHttpSardine()
+            sardine.setCredentials(username, password)
+            
+            val mdUrl = serverUrl.replace("/notes", "/notes-md")
+            
+            // Check if notes-md/ exists
+            if (!sardine.exists(mdUrl)) {
+                Logger.d(TAG, "⚠️ notes-md/ directory not found - skipping MD import")
+                return@withContext 0
+            }
+            
+            val localNotes = storage.loadAllNotes()
+            val mdResources = sardine.list(mdUrl).filter { it.name.endsWith(".md") }
+            var importedCount = 0
+            
+            Logger.d(TAG, "📂 Found ${mdResources.size} markdown files")
+            
+            for (resource in mdResources) {
+                try {
+                    // Download MD-File
+                    val mdContent = sardine.get(resource.href.toString())
+                        .bufferedReader().use { it.readText() }
+                    
+                    // Parse zu Note
+                    val mdNote = Note.fromMarkdown(mdContent) ?: continue
+                    
+                    val localNote = localNotes.find { it.id == mdNote.id }
+                    
+                    // Konfliktauflösung: Last-Write-Wins
+                    when {
+                        localNote == null -> {
+                            // Neue Notiz vom Desktop
+                            storage.saveNote(mdNote)
+                            importedCount++
+                            Logger.d(TAG, "   ✅ Imported new: ${mdNote.title}")
+                        }
+                        mdNote.updatedAt > localNote.updatedAt -> {
+                            // Desktop-Version ist neuer (Last-Write-Wins)
+                            storage.saveNote(mdNote)
+                            importedCount++
+                            Logger.d(TAG, "   ✅ Updated from MD: ${mdNote.title}")
+                        }
+                        // Sonst: Lokale Version behalten
+                        else -> {
+                            Logger.d(TAG, "   ⏭️ Local newer, skipping: ${mdNote.title}")
+                        }
+                    }
+                } catch (e: Exception) {
+                    Logger.e(TAG, "Failed to import ${resource.name}", e)
+                    // Continue with other files
+                }
+            }
+            
+            Logger.d(TAG, "✅ Markdown sync completed: $importedCount imported")
+            importedCount
+            
+        } catch (e: Exception) {
+            Logger.e(TAG, "Markdown sync failed", e)
+            0
+        }
+    }
 }
 
 data class RestoreResult(

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

@@ -19,6 +19,10 @@ object Constants {
     const val PREF_SYNC_INTERVAL_MINUTES = "sync_interval_minutes"
     const val DEFAULT_SYNC_INTERVAL_MINUTES = 30L
     
+    // 🔥 v1.2.0: Markdown Export/Import
+    const val KEY_MARKDOWN_EXPORT = "markdown_export_enabled"
+    const val KEY_MARKDOWN_AUTO_IMPORT = "markdown_auto_import_enabled"
+    
     // WorkManager
     const val SYNC_WORK_TAG = "notes_sync"
     const val SYNC_DELAY_SECONDS = 5L

android/app/src/main/res/layout/activity_settings.xml

@@ -387,6 +387,92 @@
 
             </com.google.android.material.card.MaterialCardView>
 
+            <!-- Material 3 Card: Markdown Desktop-Integration (v1.2.0) -->
+            <com.google.android.material.card.MaterialCardView
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                android:layout_marginBottom="16dp"
+                style="@style/Widget.Material3.CardView.Elevated"
+                app:cardCornerRadius="16dp">
+
+                <LinearLayout
+                    android:layout_width="match_parent"
+                    android:layout_height="wrap_content"
+                    android:orientation="vertical"
+                    android:padding="20dp">
+
+                    <!-- Section Header -->
+                    <TextView
+                        android:layout_width="match_parent"
+                        android:layout_height="wrap_content"
+                        android:text="Markdown Desktop-Integration"
+                        android:textAppearance="@style/TextAppearance.Material3.TitleMedium"
+                        android:layout_marginBottom="12dp" />
+
+                    <!-- Info Card -->
+                    <com.google.android.material.card.MaterialCardView
+                        android:layout_width="match_parent"
+                        android:layout_height="wrap_content"
+                        android:layout_marginBottom="16dp"
+                        app:cardBackgroundColor="?attr/colorPrimaryContainer"
+                        app:cardCornerRadius="12dp"
+                        app:cardElevation="0dp">
+
+                        <TextView
+                            android:layout_width="match_parent"
+                            android:layout_height="wrap_content"
+                            android:padding="16dp"
+                            android:text="ℹ️ Exportiert Notizen zusätzlich als .md Dateien. Mounte WebDAV als Netzlaufwerk um mit VS Code, Typora oder jedem Markdown-Editor zu bearbeiten. JSON-Sync bleibt primäres Format."
+                            android:textAppearance="@style/TextAppearance.Material3.BodySmall"
+                            android:textColor="?attr/colorOnPrimaryContainer"
+                            android:lineSpacingMultiplier="1.3" />
+
+                    </com.google.android.material.card.MaterialCardView>
+
+                    <!-- Markdown Export Toggle -->
+                    <LinearLayout
+                        android:layout_width="match_parent"
+                        android:layout_height="wrap_content"
+                        android:layout_marginBottom="16dp"
+                        android:orientation="horizontal"
+                        android:gravity="center_vertical">
+
+                        <TextView
+                            android:layout_width="0dp"
+                            android:layout_height="wrap_content"
+                            android:layout_weight="1"
+                            android:text="📝 Markdown Export (Desktop-Zugriff)"
+                            android:textAppearance="@style/TextAppearance.Material3.BodyLarge" />
+
+                        <androidx.appcompat.widget.SwitchCompat
+                            android:id="@+id/switchMarkdownExport"
+                            android:layout_width="wrap_content"
+                            android:layout_height="wrap_content"
+                            android:checked="true" />
+
+                    </LinearLayout>
+
+                    <!-- Import Markdown Button -->
+                    <Button
+                        android:id="@+id/buttonImportMarkdown"
+                        android:layout_width="match_parent"
+                        android:layout_height="wrap_content"
+                        android:text="📥 Markdown-Änderungen importieren"
+                        style="@style/Widget.Material3.Button.TonalButton" />
+
+                    <!-- Import Info Text -->
+                    <TextView
+                        android:layout_width="match_parent"
+                        android:layout_height="wrap_content"
+                        android:layout_marginTop="8dp"
+                        android:text="Importiert manuelle Änderungen von Desktop-Apps (.md Dateien vom Server)"
+                        android:textAppearance="@style/TextAppearance.Material3.BodySmall"
+                        android:textColor="?attr/colorOnSurfaceVariant" />
+
+                </LinearLayout>
+
+            </com.google.android.material.card.MaterialCardView>
+
             <!-- Material 3 Card: Backup & Restore -->
             <com.google.android.material.card.MaterialCardView
                 android:layout_width="match_parent"
@@ -409,12 +495,12 @@
                         android:textAppearance="@style/TextAppearance.Material3.TitleMedium"
                         android:layout_marginBottom="12dp" />
 
-                    <!-- Warning Info Card -->
+                    <!-- Info Card (anstatt Warning) -->
                     <com.google.android.material.card.MaterialCardView
                         android:layout_width="match_parent"
                         android:layout_height="wrap_content"
                         android:layout_marginBottom="16dp"
-                        app:cardBackgroundColor="?attr/colorErrorContainer"
+                        app:cardBackgroundColor="?attr/colorPrimaryContainer"
                         app:cardCornerRadius="12dp"
                         app:cardElevation="0dp">
 
@@ -422,19 +508,61 @@
                             android:layout_width="match_parent"
                             android:layout_height="wrap_content"
                             android:padding="16dp"
-                            android:text="@string/backup_restore_warning"
+                            android:text="ℹ️ Bei jeder Wiederherstellung wird automatisch ein Sicherheits-Backup erstellt."
                             android:textAppearance="@style/TextAppearance.Material3.BodySmall"
-                            android:textColor="?attr/colorOnErrorContainer"
+                            android:textColor="?attr/colorOnPrimaryContainer"
                             android:lineSpacingMultiplier="1.3" />
 
                     </com.google.android.material.card.MaterialCardView>
 
-                    <!-- Restore Button -->
+                    <!-- Lokales Backup Sektion -->
+                    <TextView
+                        android:layout_width="match_parent"
+                        android:layout_height="wrap_content"
+                        android:text="Lokales Backup"
+                        android:textAppearance="@style/TextAppearance.Material3.LabelLarge"
+                        android:layout_marginBottom="12dp" />
+
+                    <!-- Backup erstellen Button -->
+                    <Button
+                        android:id="@+id/buttonCreateBackup"
+                        android:layout_width="match_parent"
+                        android:layout_height="wrap_content"
+                        android:text="📥 Backup erstellen"
+                        android:layout_marginBottom="8dp"
+                        style="@style/Widget.Material3.Button.TonalButton" />
+
+                    <!-- Aus Datei wiederherstellen Button -->
+                    <Button
+                        android:id="@+id/buttonRestoreFromFile"
+                        android:layout_width="match_parent"
+                        android:layout_height="wrap_content"
+                        android:text="📤 Aus Datei wiederherstellen"
+                        android:layout_marginBottom="16dp"
+                        style="@style/Widget.Material3.Button.TonalButton" />
+
+                    <!-- Divider -->
+                    <View
+                        android:layout_width="match_parent"
+                        android:layout_height="1dp"
+                        android:background="?attr/colorOutline"
+                        android:layout_marginTop="8dp"
+                        android:layout_marginBottom="16dp" />
+
+                    <!-- Server-Backup Sektion -->
+                    <TextView
+                        android:layout_width="match_parent"
+                        android:layout_height="wrap_content"
+                        android:text="Server-Backup"
+                        android:textAppearance="@style/TextAppearance.Material3.LabelLarge"
+                        android:layout_marginBottom="12dp" />
+
+                    <!-- Vom Server wiederherstellen Button -->
                     <Button
                         android:id="@+id/buttonRestoreFromServer"
                         android:layout_width="match_parent"
                         android:layout_height="wrap_content"
-                        android:text="@string/restore_from_server"
+                        android:text="🔄 Vom Server wiederherstellen"
                         style="@style/Widget.Material3.Button.TonalButton" />
 
                 </LinearLayout>