fix: Update documentation and add English versions for all guides [skip ci]

.github/workflows/build-production-apk.yml

@@ -6,7 +6,7 @@ on:
   workflow_dispatch:  # Ermöglicht manuellen Trigger
 
 permissions:
-  contents: write  # Für Release-Erstellung erforderlich
+  contents: write  # Fuer Release-Erstellung erforderlich
 
 jobs:
   build:
@@ -25,7 +25,7 @@ jobs:
       
       - name: Semantic Versionsnummer aus build.gradle.kts extrahieren
         run: |
-          # Version aus build.gradle.kts für F-Droid Kompatibilität
+          # Version aus build.gradle.kts fuer F-Droid Kompatibilität
           VERSION_NAME=$(grep "versionName = " android/app/build.gradle.kts | sed 's/.*versionName = "\(.*\)".*/\1/')
           VERSION_CODE=$(grep "versionCode = " android/app/build.gradle.kts | sed 's/.*versionCode = \([0-9]*\).*/\1/')
           
@@ -62,7 +62,7 @@ jobs:
           mkdir -p apk-output
           
           # === Standard Flavor (mit Google Services) ===
-          # Universal APK (funktioniert auf allen Geräten)
+          # Universal APK (funktioniert auf allen Geraeten)
           cp android/app/build/outputs/apk/standard/release/app-standard-universal-release.apk \
              apk-output/simple-notes-sync-v${{ env.VERSION_NAME }}-standard-universal.apk
           
@@ -113,107 +113,41 @@ jobs:
         uses: softprops/action-gh-release@v1
         with:
           tag_name: ${{ env.VERSION_TAG }}
-          name: "📝 Simple Notes Sync v${{ env.VERSION_NAME }} (Produktions-Release)"
+          name: "📝 Simple Notes Sync v${{ env.VERSION_NAME }}"
           files: apk-output/*.apk
           draft: false
           prerelease: false
           generate_release_notes: false
           body: |
-            # 📝 Produktions-Release: Simple Notes Sync v${{ env.VERSION_NAME }}
+            ## 📦 Downloads
             
-            ## Build-Informationen
+            | Variante | Datei | Info |
+            |----------|-------|------|
+            | **🏆 Empfohlen** | `simple-notes-sync-v${{ env.VERSION_NAME }}-standard-universal.apk` | Funktioniert auf allen Android-Geraeten |
+            | Modern (2018+) | `simple-notes-sync-v${{ env.VERSION_NAME }}-standard-arm64-v8a.apk` | Kleinere Dateigröße fuer 64-bit Geräte |
+            | Aelter (<2018) | `simple-notes-sync-v${{ env.VERSION_NAME }}-standard-armeabi-v7a.apk` | Fuer 32-bit ARM Geräte |
+            | F-Droid Universal | `simple-notes-sync-v${{ env.VERSION_NAME }}-fdroid-universal.apk` | Fuer F-Droid Store |
+            | F-Droid ARM64 | `simple-notes-sync-v${{ env.VERSION_NAME }}-fdroid-arm64-v8a.apk` | F-Droid 64-bit |
+            | F-Droid ARMv7 | `simple-notes-sync-v${{ env.VERSION_NAME }}-fdroid-armeabi-v7a.apk` | F-Droid 32-bit |
             
-            - **Version:** ${{ env.VERSION_NAME }}+${{ env.BUILD_NUMBER }}
+            💡 **Nicht sicher?** → Nimm die **Universal** APK!
-            - **Build-Datum:** ${{ env.COMMIT_DATE }}
-            - **Commit:** ${{ env.SHORT_SHA }}
-            - **Umgebung:** 🟢 **PRODUKTION**
             
             ---
             
-            ## 📋 Änderungen
+            ## 📋 Aenderungen
             
             ${{ env.COMMIT_MSG }}
             
             ---
             
-            ## 📦 Download & Installation
+            ## 📊 Build-Info
             
-            ### Welche APK soll ich herunterladen?
+            - **Version:** ${{ env.VERSION_NAME }} (Code: ${{ env.BUILD_NUMBER }})
-            
+            - **Datum:** ${{ env.COMMIT_DATE }}
-            **Flavor-Wahl (beide identisch, nur für verschiedene Stores):**
+            - **Commit:** ${{ env.SHORT_SHA }}
-            - **Standard**: Für direkten Download / Obtainium / GitHub Releases
-            - **F-Droid**: Für F-Droid Store (identisch, nur andere Kennzeichnung)
-            
-            💡 **Hinweis:** Beide Flavors sind 100% FOSS - keine Google Services, kein Tracking!
-            
-            **Architektur-Wahl:**
-            
-            | Dein Gerät | Standard Flavor | F-Droid Flavor | Größe | Hinweis |
-            |------------|----------------|----------------|-------|---------|
-            | 🤷 Nicht sicher? | `simple-notes-sync-v${{ env.VERSION_NAME }}-standard-universal.apk` | `...-fdroid-universal.apk` | ~5 MB | Funktioniert überall |
-            | Modern (2018+) | `simple-notes-sync-v${{ env.VERSION_NAME }}-standard-arm64-v8a.apk` | `...-fdroid-arm64-v8a.apk` | ~3 MB | Schneller, kleiner |
-            | Ältere Geräte | `simple-notes-sync-v${{ env.VERSION_NAME }}-standard-armeabi-v7a.apk` | `...-fdroid-armeabi-v7a.apk` | ~3 MB | ARM-Chips vor 2018 |
-            
-            💡 **Empfehlung:** Nimm die **Standard Universal** APK!
-            
-            ### Installationsschritte
-            1. Lade die passende APK aus den Assets unten herunter
-            2. Aktiviere "Installation aus unbekannten Quellen" in den Android-Einstellungen
-            3. Öffne die heruntergeladene APK-Datei
-            4. Folge den Installationsanweisungen
-            5. Konfiguriere die WebDAV-Einstellungen in der App
             
             ---
             
-            ## ⚙️ Funktionen
+            **[<5B> Dokumentation](https://github.com/inventory69/simple-notes-sync/blob/main/QUICKSTART.md)** · **[🐛 Issue melden](https://github.com/inventory69/simple-notes-sync/issues)**
-            
-            - ✅ Automatische WebDAV-Synchronisation alle 30 Minuten (~0,4% Akku/Tag)
-            - ✅ Intelligente Gateway-Erkennung (automatische Heimnetzwerk-Erkennung)
-            - ✅ Material Design 3 Oberfläche
-            - ✅ Datenschutzorientiert (kein Tracking, keine Analysen)
-            - ✅ Offline-First Architektur
-            
-            ---
-            
-            ## 🔄 Update von vorheriger Version
-            
-            Installiere diese APK einfach über die bestehende Installation - alle Daten und Einstellungen bleiben erhalten.
-            
-            ---
-            
-            ## 📱 Obtanium - Auto-Update App
-            
-            Erhalte automatische Updates mit [Obtanium](https://github.com/ImranR98/Obtanium/releases/latest).
-            
-            **Einrichtung:**
-            1. Installiere Obtanium über den Link oben
-            2. Füge die App mit dieser URL hinzu: `https://github.com/inentory69/simple-notes-sync`
-            3. Aktiviere Auto-Updates
-            
-            ---
-            
-            ## 🆘 Support
-            
-            Bei Problemen oder Fragen öffne bitte ein Issue auf GitHub.
-            
-            ---
-            
-            ## 🔒 Datenschutz & Sicherheit
-            
-            - Alle Daten werden über deinen eigenen WebDAV-Server synchronisiert (self-hosted)
-            - Keine Drittanbieter-Analysen oder Tracking
-            - Keine Internet-Berechtigungen außer für WebDAV-Sync
-            - Unterstützt HTTP (lokal) und HTTPS (extern) - du entscheidest
-            - Open Source - prüfe den Code selbst
-            
-            ---
-            
-            ## 🛠️ Erstellt mit
-            
-            - **Sprache:** Kotlin
-            - **UI:** Material Design 3
-            - **Sync:** WorkManager + WebDAV
-            - **Target SDK:** Android 16 (API 36)
-            - **Min SDK:** Android 8.0 (API 26)
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}

DOCS.en.md

@@ -0,0 +1,474 @@
+# Simple Notes Sync - Technical Documentation
+
+This file contains detailed technical information about implementation, architecture, and advanced features.
+
+**🌍 Languages:** [Deutsch](DOCS.md) · **English**
+
+---
+
+## 📐 Architecture
+
+### Overall Overview
+
+```
+┌─────────────────┐
+│  Android App    │
+│  (Kotlin)       │
+└────────┬────────┘
+         │ WebDAV/HTTP
+         │
+┌────────▼────────┐
+│  WebDAV Server  │
+│  (Docker)       │
+└─────────────────┘
+```
+
+### Android App Architecture
+
+```
+app/
+├── models/
+│   ├── Note.kt              # Data class for notes
+│   └── SyncStatus.kt        # Sync status enum
+├── storage/
+│   └── NotesStorage.kt      # Local JSON file storage
+├── sync/
+│   ├── WebDavSyncService.kt # WebDAV sync logic
+│   ├── NetworkMonitor.kt    # WiFi detection
+│   ├── SyncWorker.kt        # WorkManager background worker
+│   └── BootReceiver.kt      # Device reboot handler
+├── adapters/
+│   └── NotesAdapter.kt      # RecyclerView adapter
+├── utils/
+│   ├── Constants.kt         # App constants
+│   ├── NotificationHelper.kt# Notification management
+│   └── Logger.kt            # Debug/release logging
+└── activities/
+    ├── MainActivity.kt      # Main view with list
+    ├── NoteEditorActivity.kt# Note editor
+    └── SettingsActivity.kt  # Server configuration
+```
+
+---
+
+## 🔄 Auto-Sync Implementation
+
+### WorkManager Periodic Task
+
+Auto-sync is based on **WorkManager** with the following configuration:
+
+```kotlin
+val constraints = Constraints.Builder()
+    .setRequiredNetworkType(NetworkType.UNMETERED)  // WiFi only
+    .build()
+
+val syncRequest = PeriodicWorkRequestBuilder<SyncWorker>(
+    30, TimeUnit.MINUTES,  // Every 30 minutes
+    10, TimeUnit.MINUTES   // Flex interval
+)
+    .setConstraints(constraints)
+    .build()
+```
+
+**Why WorkManager?**
+- ✅ Runs even when app is closed
+- ✅ Automatic restart after device reboot
+- ✅ Battery-efficient (Android managed)
+- ✅ Guaranteed execution when constraints are met
+
+### Network Detection
+
+Instead of SSID-based detection (Android 13+ privacy issues), we use **Gateway IP Comparison**:
+
+```kotlin
+fun isInHomeNetwork(): Boolean {
+    val gatewayIP = getGatewayIP()         // e.g. 192.168.0.1
+    val serverIP = extractIPFromUrl(serverUrl)  // e.g. 192.168.0.188
+    
+    return isSameNetwork(gatewayIP, serverIP)  // Checks /24 network
+}
+```
+
+**Advantages:**
+- ✅ No location permissions needed
+- ✅ Works with all Android versions
+- ✅ Reliable and fast
+
+### Sync Flow
+
+```
+1. WorkManager wakes up (every 30 min)
+   ↓
+2. Check: WiFi connected?
+   ↓
+3. Check: Same network as server?
+   ↓
+4. Load local notes
+   ↓
+5. Upload new/changed notes → Server
+   ↓
+6. Download remote notes ← Server
+   ↓
+7. Merge & resolve conflicts
+   ↓
+8. Update local storage
+   ↓
+9. Show notification (if changes)
+```
+
+---
+
+## 🔋 Battery Optimization
+
+### Usage Analysis
+
+| Component | Frequency | Usage | Details |
+|------------|----------|-----------|---------|
+| WorkManager Wakeup | Every 30 min | ~0.15 mAh | System wakes up |
+| Network Check | 48x/day | ~0.03 mAh | Gateway IP check |
+| WebDAV Sync | 2-3x/day | ~1.5 mAh | Only when changes |
+| **Total** | - | **~12 mAh/day** | **~0.4%** at 3000mAh |
+
+### Optimizations
+
+1. **IP Caching**
+   ```kotlin
+   private var cachedServerIP: String? = null
+   // DNS lookup only once at start, not every check
+   ```
+
+2. **Throttling**
+   ```kotlin
+   private var lastSyncTime = 0L
+   private const val MIN_SYNC_INTERVAL_MS = 60_000L  // Max 1 sync/min
+   ```
+
+3. **Conditional Logging**
+   ```kotlin
+   object Logger {
+       fun d(tag: String, msg: String) {
+           if (BuildConfig.DEBUG) Log.d(tag, msg)
+       }
+   }
+   ```
+
+4. **Network Constraints**
+   - WiFi only (not mobile data)
+   - Only when server is reachable
+   - No permanent listeners
+
+---
+
+## 📦 WebDAV Sync Details
+
+### Upload Flow
+
+```kotlin
+suspend fun uploadNotes(): Int {
+    val localNotes = storage.loadAllNotes()
+    var uploadedCount = 0
+    
+    for (note in localNotes) {
+        if (note.syncStatus == SyncStatus.PENDING) {
+            val jsonContent = note.toJson()
+            val remotePath = "$serverUrl/${note.id}.json"
+            
+            sardine.put(remotePath, jsonContent.toByteArray())
+            
+            note.syncStatus = SyncStatus.SYNCED
+            storage.saveNote(note)
+            uploadedCount++
+        }
+    }
+    
+    return uploadedCount
+}
+```
+
+### Download Flow
+
+```kotlin
+suspend fun downloadNotes(): DownloadResult {
+    val remoteFiles = sardine.list(serverUrl)
+    var downloadedCount = 0
+    var conflictCount = 0
+    
+    for (file in remoteFiles) {
+        if (!file.name.endsWith(".json")) continue
+        
+        val content = sardine.get(file.href)
+        val remoteNote = Note.fromJson(content)
+        val localNote = storage.loadNote(remoteNote.id)
+        
+        if (localNote == null) {
+            // New note from server
+            storage.saveNote(remoteNote)
+            downloadedCount++
+        } else if (localNote.modifiedAt < remoteNote.modifiedAt) {
+            // Server has newer version
+            storage.saveNote(remoteNote)
+            downloadedCount++
+        } else if (localNote.modifiedAt > remoteNote.modifiedAt) {
+            // Local version is newer → Conflict
+            resolveConflict(localNote, remoteNote)
+            conflictCount++
+        }
+    }
+    
+    return DownloadResult(downloadedCount, conflictCount)
+}
+```
+
+### Conflict Resolution
+
+Strategy: **Last-Write-Wins** with **Conflict Copy**
+
+```kotlin
+fun resolveConflict(local: Note, remote: Note) {
+    // Rename remote note (conflict copy)
+    val conflictNote = remote.copy(
+        id = "${remote.id}_conflict_${System.currentTimeMillis()}",
+        title = "${remote.title} (Conflict)"
+    )
+    
+    storage.saveNote(conflictNote)
+    
+    // Local note remains
+    local.syncStatus = SyncStatus.SYNCED
+    storage.saveNote(local)
+}
+```
+
+---
+
+## 🔔 Notifications
+
+### Notification Channels
+
+```kotlin
+val channel = NotificationChannel(
+    "notes_sync_channel",
+    "Notes Synchronization",
+    NotificationManager.IMPORTANCE_DEFAULT
+)
+```
+
+### Success Notification
+
+```kotlin
+fun showSyncSuccess(context: Context, count: Int) {
+    val intent = Intent(context, MainActivity::class.java)
+    val pendingIntent = PendingIntent.getActivity(context, 0, intent, FLAGS)
+    
+    val notification = NotificationCompat.Builder(context, CHANNEL_ID)
+        .setContentTitle("Sync successful")
+        .setContentText("$count notes synchronized")
+        .setContentIntent(pendingIntent)  // Click opens app
+        .setAutoCancel(true)              // Dismiss on click
+        .build()
+    
+    notificationManager.notify(NOTIFICATION_ID, notification)
+}
+```
+
+---
+
+## 🛡️ Permissions
+
+The app requires **minimal permissions**:
+
+```xml
+<!-- Network -->
+<uses-permission android:name="android.permission.INTERNET" />
+<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
+<uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />
+<uses-permission android:name="android.permission.CHANGE_WIFI_STATE" />
+
+<!-- Notifications -->
+<uses-permission android:name="android.permission.POST_NOTIFICATIONS" />
+
+<!-- Boot Receiver -->
+<uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED" />
+
+<!-- Battery Optimization (optional) -->
+<uses-permission android:name="android.permission.REQUEST_IGNORE_BATTERY_OPTIMIZATIONS" />
+```
+
+**No Location Permissions!**  
+Earlier versions required `ACCESS_FINE_LOCATION` for SSID detection. Now we use Gateway IP Comparison.
+
+---
+
+## 🧪 Testing
+
+### Test Server
+
+```bash
+# WebDAV server reachable?
+curl -u noteuser:password http://192.168.0.188:8080/
+
+# Upload file
+echo '{"test":"data"}' > test.json
+curl -u noteuser:password -T test.json http://192.168.0.188:8080/test.json
+
+# Download file
+curl -u noteuser:password http://192.168.0.188:8080/test.json
+```
+
+### Test Android App
+
+**Unit Tests:**
+```bash
+cd android
+./gradlew test
+```
+
+**Instrumented Tests:**
+```bash
+./gradlew connectedAndroidTest
+```
+
+**Manual Testing Checklist:**
+
+- [ ] Create note → visible in list
+- [ ] Edit note → changes saved
+- [ ] Delete note → removed from list
+- [ ] Manual sync → server status "Reachable"
+- [ ] Auto-sync → notification after ~30 min
+- [ ] Close app → auto-sync continues
+- [ ] Device reboot → auto-sync starts automatically
+- [ ] Server offline → error notification
+- [ ] Notification click → app opens
+
+---
+
+## 🚀 Build & Deployment
+
+### Debug Build
+
+```bash
+cd android
+./gradlew assembleDebug
+# APK: app/build/outputs/apk/debug/app-debug.apk
+```
+
+### Release Build
+
+```bash
+./gradlew assembleRelease
+# APK: app/build/outputs/apk/release/app-release-unsigned.apk
+```
+
+### Sign (for Distribution)
+
+```bash
+# Create keystore
+keytool -genkey -v -keystore my-release-key.jks -keyalg RSA -keysize 2048 -validity 10000 -alias my-alias
+
+# Sign APK
+jarsigner -verbose -sigalg SHA256withRSA -digestalg SHA-256 \
+  -keystore my-release-key.jks \
+  app-release-unsigned.apk my-alias
+
+# Optimize
+zipalign -v 4 app-release-unsigned.apk app-release.apk
+```
+
+---
+
+## 🐛 Debugging
+
+### LogCat Filter
+
+```bash
+# Only app logs
+adb logcat -s SimpleNotesApp NetworkMonitor SyncWorker WebDavSyncService
+
+# With timestamps
+adb logcat -v time -s SyncWorker
+
+# Save to file
+adb logcat -s SyncWorker > sync_debug.log
+```
+
+### Common Issues
+
+**Problem: Auto-sync not working**
+```
+Solution: Disable battery optimization
+Settings → Apps → Simple Notes → Battery → Don't optimize
+```
+
+**Problem: Server not reachable**
+```
+Check: 
+1. Server running? → docker-compose ps
+2. IP correct? → ip addr show
+3. Port open? → telnet 192.168.0.188 8080
+4. Firewall? → sudo ufw allow 8080
+```
+
+**Problem: Notifications not appearing**
+```
+Check:
+1. Notification permission granted?
+2. Do Not Disturb active?
+3. App in background? → Force stop & restart
+```
+
+---
+
+## 📚 Dependencies
+
+```gradle
+// Core
+androidx.core:core-ktx:1.12.0
+androidx.appcompat:appcompat:1.6.1
+com.google.android.material:material:1.11.0
+
+// Lifecycle
+androidx.lifecycle:lifecycle-runtime-ktx:2.7.0
+
+// RecyclerView
+androidx.recyclerview:recyclerview:1.3.2
+
+// Coroutines
+org.jetbrains.kotlinx:kotlinx-coroutines-android:1.7.3
+
+// WorkManager
+androidx.work:work-runtime-ktx:2.9.0
+
+// WebDAV Client
+com.github.thegrizzlylabs:sardine-android:0.8
+
+// Broadcast (deprecated but working)
+androidx.localbroadcastmanager:localbroadcastmanager:1.1.0
+```
+
+---
+
+## 🔮 Roadmap
+
+### v1.1
+- [ ] Search & Filter
+- [ ] Dark Mode
+- [ ] Tags/Categories
+- [ ] Markdown Preview
+
+### v2.0
+- [ ] Desktop Client (Flutter)
+- [ ] End-to-End Encryption
+- [ ] Shared Notes (Collaboration)
+- [ ] Attachment Support
+
+---
+
+## 📖 Further Documentation
+
+- [Project Docs](https://github.com/inventory69/project-docs/tree/main/simple-notes-sync)
+- [Android Guide](https://github.com/inventory69/project-docs/blob/main/simple-notes-sync/ANDROID_GUIDE.md)
+- [Bugfix Documentation](https://github.com/inventory69/project-docs/blob/main/simple-notes-sync/BUGFIX_SYNC_SPAM_AND_NOTIFICATIONS.md)
+
+---
+
+**Last updated:** December 21, 2025

DOCS.md

@@ -2,6 +2,8 @@
 
 Diese Datei enthält detaillierte technische Informationen über die Implementierung, Architektur und erweiterte Funktionen.
 
+**🌍 Sprachen:** **Deutsch** · [English](DOCS.en.md)
+
 ---
 
 ## 📐 Architektur

QUICKSTART.en.md

@@ -0,0 +1,269 @@
+# Quick Start Guide - Simple Notes Sync 📝
+
+> Step-by-step installation and setup guide
+
+**🌍 Languages:** [Deutsch](QUICKSTART.md) · **English**
+
+---
+
+## Prerequisites
+
+- ✅ Android 8.0+ smartphone/tablet
+- ✅ WiFi connection
+- ✅ Own server with Docker (optional - for self-hosting)
+
+---
+
+## Option 1: With own server (Self-Hosted) 🏠
+
+### Step 1: Setup WebDAV Server
+
+On your server (e.g. Raspberry Pi, NAS, VPS):
+
+```bash
+# Clone repository
+git clone https://github.com/inventory69/simple-notes-sync.git
+cd simple-notes-sync/server
+
+# Configure environment variables
+cp .env.example .env
+nano .env
+```
+
+**Adjust in `.env`:**
+```env
+WEBDAV_PASSWORD=your-secure-password-here
+```
+
+**Start server:**
+```bash
+docker compose up -d
+```
+
+**Find IP address:**
+```bash
+ip addr show | grep "inet " | grep -v 127.0.0.1
+```
+
+➡️ **Note down:** `http://YOUR-SERVER-IP:8080/`
+
+---
+
+### Step 2: Install App
+
+1. **Download APK:** [Latest version](https://github.com/inventory69/simple-notes-sync/releases/latest)
+   - Choose: `simple-notes-sync-vX.X.X-standard-universal.apk`
+   
+2. **Allow installation:**
+   - Android: Settings → Security → Enable "Unknown sources" for your browser
+   
+3. **Open and install APK**
+
+---
+
+### Step 3: Configure App
+
+1. **Open app**
+
+2. **Open settings** (⚙️ icon top right)
+
+3. **Configure server settings:**
+   
+   | Field | Value |
+   |------|------|
+   | **WebDAV Server URL** | `http://YOUR-SERVER-IP:8080/` |
+   | **Username** | `noteuser` |
+   | **Password** | (your password from `.env`) |
+   | **Gateway SSID** | Name of your WiFi network |
+
+4. **Press "Test connection"**
+   - ✅ Success? → Continue to step 4
+   - ❌ Error? → See [Troubleshooting](#troubleshooting)
+
+5. **Enable auto-sync** (toggle switch)
+
+6. **Choose sync interval:**
+   - **15 min** - Maximum currency (~0.8% battery/day)
+   - **30 min** - Recommended (~0.4% battery/day) ⭐
+   - **60 min** - Maximum battery life (~0.2% battery/day)
+
+---
+
+### Step 4: Create First Note
+
+1. Back to main view (← arrow)
+
+2. **"Add note"** (+ icon)
+
+3. Enter title and text
+
+4. **Save** (💾 icon)
+
+5. **Wait for auto-sync** (or manually: ⚙️ → "Sync now")
+
+🎉 **Done!** Your notes will be automatically synchronized!
+
+---
+
+## Option 2: Local notes only (no server) 📱
+
+You can also use Simple Notes **without a server**:
+
+1. **Install app** (see step 2 above)
+
+2. **Use without server configuration:**
+   - Notes are only stored locally
+   - No auto-sync
+   - Perfect for offline-only use
+
+---
+
+## 🔋 Disable Battery Optimization
+
+For reliable auto-sync:
+
+1. **Settings** → **Apps** → **Simple Notes Sync**
+
+2. **Battery** → **Battery usage**
+
+3. Select: **"Don't optimize"** or **"Unrestricted"**
+
+💡 **Note:** Android Doze Mode may still delay sync in standby (~60 min). This is normal and affects all apps.
+
+---
+
+## 📊 Sync Intervals in Detail
+
+| Interval | Syncs/day | Battery/day | Battery/sync | Use case |
+|-----------|-----------|----------|-----------|----------------|
+| **15 min** | ~96 | ~0.8% (~23 mAh) | ~0.008% | ⚡ Maximum currency (multiple devices) |
+| **30 min** | ~48 | ~0.4% (~12 mAh) | ~0.008% | ✓ **Recommended** - balanced |
+| **60 min** | ~24 | ~0.2% (~6 mAh) | ~0.008% | 🔋 Maximum battery life |
+
+---
+
+## 🐛 Troubleshooting
+
+### Connection test fails
+
+**Problem:** "Connection failed" during test
+
+**Solutions:**
+
+1. **Server running?**
+   ```bash
+   docker compose ps
+   # Should show "Up"
+   ```
+
+2. **Same WiFi?**
+   - Smartphone and server must be on same network
+   - Check SSID in app settings
+
+3. **IP address correct?**
+   ```bash
+   ip addr show | grep "inet "
+   # Check if IP in URL matches
+   ```
+
+4. **Firewall?**
+   ```bash
+   # Open port 8080 (if firewall active)
+   sudo ufw allow 8080/tcp
+   ```
+
+5. **Check server logs:**
+   ```bash
+   docker compose logs -f
+   ```
+
+---
+
+### Auto-sync not working
+
+**Problem:** Notes are not automatically synchronized
+
+**Solutions:**
+
+1. **Auto-sync enabled?**
+   - ⚙️ Settings → Toggle "Auto-sync" must be **ON**
+
+2. **Battery optimization disabled?**
+   - See [Disable Battery Optimization](#-disable-battery-optimization)
+
+3. **On correct WiFi?**
+   - Sync only works when SSID = Gateway SSID
+   - Check current SSID in Android settings
+
+4. **Test manually:**
+   - ⚙️ Settings → "Sync now"
+   - Works? → Auto-sync should work too
+
+---
+
+### Notes not showing up
+
+**Problem:** After installation, no notes visible even though they exist on server
+
+**Solution:**
+
+1. **Manually sync once:**
+   - ⚙️ Settings → "Sync now"
+
+2. **Check server data:**
+   ```bash
+   docker compose exec webdav ls -la /data/
+   # Should show .json files
+   ```
+
+---
+
+### Sync errors
+
+**Problem:** Error message during sync
+
+**Solutions:**
+
+1. **"401 Unauthorized"** → Wrong password
+   - Check password in app settings
+   - Compare with `.env` on server
+
+2. **"404 Not Found"** → Wrong URL
+   - Should end with `/` (e.g. `http://192.168.1.100:8080/`)
+
+3. **"Network error"** → No connection
+   - See [Connection test fails](#connection-test-fails)
+
+---
+
+## 📱 Updates
+
+### Automatic with Obtainium (recommended)
+
+1. **[Install Obtainium](https://github.com/ImranR98/Obtanium/releases/latest)**
+
+2. **Add app:**
+   - URL: `https://github.com/inventory69/simple-notes-sync`
+   - Enable auto-update
+
+3. **Done!** Obtainium notifies you of new versions
+
+### Manual
+
+1. Download new APK from [Releases](https://github.com/inventory69/simple-notes-sync/releases/latest)
+
+2. Install (overwrites old version)
+
+3. All data remains intact!
+
+---
+
+## 🆘 Further Help
+
+- **GitHub Issues:** [Report problem](https://github.com/inventory69/simple-notes-sync/issues)
+- **Complete docs:** [DOCS.en.md](DOCS.en.md)
+- **Server setup details:** [server/README.en.md](server/README.en.md)
+
+---
+
+**Version:** 1.1.0 · **Created:** December 2025

QUICKSTART.md

@@ -2,6 +2,8 @@
 
 > Schritt-für-Schritt Anleitung zur Installation und Einrichtung
 
+**🌍 Sprachen:** **Deutsch** · [English](QUICKSTART.en.md)
+
 ---
 
 ## Voraussetzungen

README.en.md

@@ -0,0 +1,72 @@
+# Simple Notes Sync 📝
+
+> Minimalist offline notes with auto-sync to your own server
+
+[![Android](https://img.shields.io/badge/Android-8.0%2B-green.svg)](https://www.android.com/)
+[![Material Design 3](https://img.shields.io/badge/Material-Design%203-green.svg)](https://m3.material.io/)
+[![License](https://img.shields.io/badge/License-MIT-yellow.svg)](LICENSE)
+
+**📱 [APK Download](https://github.com/inventory69/simple-notes-sync/releases/latest)** · **📖 [Documentation](DOCS.en.md)** · **🚀 [Quick Start](QUICKSTART.en.md)**
+
+**🌍 Languages:** [Deutsch](README.md) · **English**
+
+---
+
+## Features
+
+- 📝 Offline-First - Notes always available
+- 🔄 Auto-Sync - Configurable intervals (15/30/60 min)
+- 🏠 Self-Hosted - WebDAV on your server
+- 🔐 Privacy-First - No cloud, no tracking
+- 🔋 Battery-friendly - ~0.2-0.8% per day
+
+---
+
+## 🚀 Quick Start
+
+### 1. Server Setup
+
+```bash
+cd server
+cp .env.example .env
+# Set password in .env
+docker compose up -d
+```
+
+➡️ **Details:** [Server Setup Guide](server/README.en.md)
+
+### 2. App Installation
+
+1. [Download APK](https://github.com/inventory69/simple-notes-sync/releases/latest)
+2. Install & open
+3. ⚙️ Settings → Configure server
+4. Enable auto-sync
+
+➡️ **Details:** [Complete guide](QUICKSTART.en.md)
+
+---
+
+## 📚 Documentation
+
+- **[Quick Start Guide](QUICKSTART.en.md)** - Step-by-step guide for end users
+- **[Server Setup](server/README.en.md)** - Configure WebDAV server
+- **[Complete Docs](DOCS.en.md)** - Features, troubleshooting, build instructions
+
+---
+
+## 🛠️ Development
+
+```bash
+cd android
+./gradlew assembleStandardRelease
+```
+
+➡️ **Details:** [Build instructions in DOCS.en.md](DOCS.en.md)
+
+---
+
+## 📄 License
+
+MIT License - see [LICENSE](LICENSE)
+
+**v1.1.0** · Built with Kotlin + Material Design 3

README.md

@@ -8,6 +8,8 @@
 
 **📱 [APK Download](https://github.com/inventory69/simple-notes-sync/releases/latest)** · **📖 [Dokumentation](DOCS.md)** · **🚀 [Quick Start](QUICKSTART.md)**
 
+**🌍 Sprachen:** **Deutsch** · [English](README.en.md)
+
 ---
 
 ## Features

server/README.en.md

@@ -0,0 +1,86 @@
+# WebDAV Server - Simple Notes Sync
+
+**🌍 Languages:** [Deutsch](README.md) · **English**
+
+---
+
+## Quick Start
+
+```bash
+# 1. Adjust environment variables
+cp .env.example .env
+nano .env
+
+# 2. Start server
+docker-compose up -d
+
+# 3. Check logs
+docker-compose logs -f
+
+# 4. Test
+curl -u noteuser:your_password http://localhost:8080/
+```
+
+## Server URL
+
+**Local:** `http://localhost:8080/`
+
+**On network:** `http://YOUR_IP:8080/` (e.g. `http://192.168.1.100:8080/`)
+
+Find IP address:
+```bash
+ip addr show | grep "inet " | grep -v 127.0.0.1
+```
+
+## Credentials
+
+Default (see `.env`):
+- Username: `noteuser`
+- Password: See `.env` file
+
+## Management
+
+```bash
+# Check status
+docker-compose ps
+
+# View logs
+docker-compose logs -f
+
+# Restart
+docker-compose restart
+
+# Stop
+docker-compose down
+
+# Update
+docker-compose pull
+docker-compose up -d
+```
+
+## Data Location
+
+Your notes are stored in: `./data/`
+
+**Backup:**
+```bash
+# Create backup
+tar -czf notes-backup-$(date +%Y%m%d).tar.gz data/
+
+# Restore backup
+tar -xzf notes-backup-YYYYMMDD.tar.gz
+```
+
+## External Access (HTTPS)
+
+For access from outside your home network, use a reverse proxy like Caddy or nginx:
+
+**Example with Caddy:**
+
+```Caddyfile
+notes.yourdomain.com {
+    reverse_proxy localhost:8080
+}
+```
+
+**Important:** Always use HTTPS for external access to protect your credentials!

server/README.md

@@ -1,5 +1,9 @@
 # WebDAV Server - Simple Notes Sync
 
+**🌍 Sprachen:** **Deutsch** · [English](README.en.md)
+
+---
+
 ## Quick Start
 
 ```bash