feat: Add annotations, cache management, and offline feature improvements

- Add annotation creation to API and repository layer (AnnotationsRepository)
- Add DtoMapper for AnnotationDto to domain model conversion
- Extend PAnnotationsRepository protocol with createAnnotation method
- Add cache management to SettingsRepository (getCacheSize, getMaxCacheSize, updateMaxCacheSize, clearCache)
- Extend PSettingsRepository protocol with cache settings methods
- Use localized Highlight label in annotation overlay JavaScript for WebView and NativeWebView
- Improve API error handling with detailed logging for HTTP errors and response data
- Add LocalizedError extension for APIError with human-readable descriptions
- Update localization strings for German and English (Highlight, Synchronization, VPN warning)
- Update RELEASE_NOTES.md with version 2.0.0 offline reading feature details

readeck/Data/API/API.swift

@@ -153,21 +153,26 @@ class API: PAPI {
         }
         
         let (data, response) = try await URLSession.shared.data(for: request)
-        
+
         guard let httpResponse = response as? HTTPURLResponse else {
+            logger.error("Invalid HTTP response for \(endpoint)")
             throw APIError.invalidResponse
         }
-        
+
         guard 200...299 ~= httpResponse.statusCode else {
+            logger.error("Server error for \(endpoint): HTTP \(httpResponse.statusCode)")
+            logger.error("Response data: \(String(data: data, encoding: .utf8) ?? "Unable to decode")")
             handleUnauthorizedResponse(httpResponse.statusCode)
             throw APIError.serverError(httpResponse.statusCode)
         }
-        
+
         // Als String dekodieren statt als JSON
         guard let string = String(data: data, encoding: .utf8) else {
+            logger.error("Unable to decode response as UTF-8 string for \(endpoint)")
+            logger.error("Data size: \(data.count) bytes")
             throw APIError.invalidResponse
         }
-        
+
         return string
     }
     
@@ -540,3 +545,16 @@ enum APIError: Error {
     case invalidResponse
     case serverError(Int)
 }
+
+extension APIError: LocalizedError {
+    var errorDescription: String? {
+        switch self {
+        case .invalidURL:
+            return "Invalid URL"
+        case .invalidResponse:
+            return "Invalid server response"
+        case .serverError(let statusCode):
+            return "Server error: HTTP \(statusCode)"
+        }
+    }
+}

readeck/Data/Mappers/DtoMapper.swift

@@ -0,0 +1,12 @@
+//
+//  DtoMapper.swift
+//  readeck
+//
+//  Created by Ilyas Hallak on 30.11.25.
+//
+
+extension AnnotationDto {
+    func toDomain() -> Annotation {
+        Annotation(id: id, text: text, created: created, startOffset: startOffset, endOffset: endOffset, startSelector: startSelector, endSelector: endSelector)
+    }
+}

readeck/Data/Repository/AnnotationsRepository.swift

@@ -1,11 +1,17 @@
 import Foundation
 
 class AnnotationsRepository: PAnnotationsRepository {
+    
     private let api: PAPI
 
     init(api: PAPI) {
         self.api = api
     }
+    
+    func createAnnotation(bookmarkId: String, color: String, startOffset: Int, endOffset: Int, startSelector: String, endSelector: String) async throws -> Annotation {
+        try await api.createAnnotation(bookmarkId: bookmarkId, color: color, startOffset: startOffset, endOffset: endOffset, startSelector: startSelector, endSelector: endSelector)
+            .toDomain()
+    }
 
     func fetchAnnotations(bookmarkId: String) async throws -> [Annotation] {
         let annotationDtos = try await api.getBookmarkAnnotations(bookmarkId: bookmarkId)
@@ -25,4 +31,6 @@ class AnnotationsRepository: PAnnotationsRepository {
     func deleteAnnotation(bookmarkId: String, annotationId: String) async throws {
         try await api.deleteAnnotation(bookmarkId: bookmarkId, annotationId: annotationId)
     }
+    
+    
 }

readeck/Data/Repository/SettingsRepository.swift

@@ -1,5 +1,6 @@
 import Foundation
 import CoreData
+import Kingfisher
 
 class SettingsRepository: PSettingsRepository {
     private let coreDataManager = CoreDataManager.shared
@@ -329,4 +330,47 @@ class SettingsRepository: PSettingsRepository {
         }
     }
 
+    // MARK: - Cache Settings
+
+    private let maxCacheSizeKey = "KingfisherMaxCacheSize"
+
+    func getCacheSize() async throws -> UInt {
+        return try await withCheckedThrowingContinuation { continuation in
+            KingfisherManager.shared.cache.calculateDiskStorageSize { result in
+                switch result {
+                case .success(let size):
+                    continuation.resume(returning: size)
+                case .failure(let error):
+                    continuation.resume(throwing: error)
+                }
+            }
+        }
+    }
+
+    func getMaxCacheSize() async throws -> UInt {
+        if let savedSize = userDefault.object(forKey: maxCacheSizeKey) as? UInt {
+            return savedSize
+        } else {
+            // Default: 200 MB
+            let defaultBytes = UInt(200 * 1024 * 1024)
+            userDefault.set(defaultBytes, forKey: maxCacheSizeKey)
+            return defaultBytes
+        }
+    }
+
+    func updateMaxCacheSize(_ sizeInBytes: UInt) async throws {
+        KingfisherManager.shared.cache.diskStorage.config.sizeLimit = sizeInBytes
+        userDefault.set(sizeInBytes, forKey: maxCacheSizeKey)
+        logger.info("Updated max cache size to \(sizeInBytes) bytes")
+    }
+
+    func clearCache() async throws {
+        return try await withCheckedThrowingContinuation { continuation in
+            KingfisherManager.shared.cache.clearDiskCache {
+                KingfisherManager.shared.cache.clearMemoryCache()
+                self.logger.info("Cache cleared successfully")
+                continuation.resume()
+            }
+        }
+    }
 }

readeck/Domain/Protocols/PAnnotationsRepository.swift

@@ -1,4 +1,5 @@
 protocol PAnnotationsRepository {
     func fetchAnnotations(bookmarkId: String) async throws -> [Annotation]
     func deleteAnnotation(bookmarkId: String, annotationId: String) async throws
+    func createAnnotation(bookmarkId: String, color: String, startOffset: Int, endOffset: Int, startSelector: String, endSelector: String) async throws -> Annotation
 }

readeck/Domain/Protocols/PSettingsRepository.swift

@@ -26,4 +26,10 @@ protocol PSettingsRepository {
     // Offline Settings methods
     func loadOfflineSettings() async throws -> OfflineSettings
     func saveOfflineSettings(_ settings: OfflineSettings) async throws
+
+    // Cache Settings methods
+    func getCacheSize() async throws -> UInt
+    func getMaxCacheSize() async throws -> UInt
+    func updateMaxCacheSize(_ sizeInBytes: UInt) async throws
+    func clearCache() async throws
 }

readeck/Localizations/de.lproj/Localizable.strings

@@ -82,6 +82,7 @@
 "Favorite" = "Favorit";
 "Finished reading?" = "Fertig gelesen?";
 "Font" = "Schrift";
+"Highlight" = "Markierung";
 "Font family" = "Schriftart";
 "Font Settings" = "Schrift";
 "Font size" = "Schriftgröße";
@@ -148,6 +149,8 @@
 "Settings" = "Einstellungen";
 "Show Performance Logs" = "Performance-Logs anzeigen";
 "Show Timestamps" = "Zeitstempel anzeigen";
+"Synchronization" = "Synchronisation";
+"VPN connections are detected as active internet connections." = "VPN-Verbindungen werden als aktive Internetverbindungen erkannt.";
 "Speed" = "Geschwindigkeit";
 "Syncing with server..." = "Synchronisiere mit Server...";
 "Theme" = "Design";

readeck/Localizations/en.lproj/Localizable.strings

@@ -78,6 +78,7 @@
 "Favorite" = "Favorite";
 "Finished reading?" = "Finished reading?";
 "Font" = "Font";
+"Highlight" = "Highlight";
 "Font family" = "Font family";
 "Font Settings" = "Font Settings";
 "Font size" = "Font size";
@@ -144,6 +145,8 @@
 "Settings" = "Settings";
 "Show Performance Logs" = "Show Performance Logs";
 "Show Timestamps" = "Show Timestamps";
+"Synchronization" = "Synchronization";
+"VPN connections are detected as active internet connections." = "VPN connections are detected as active internet connections.";
 "Speed" = "Speed";
 "Syncing with server..." = "Syncing with server...";
 "Theme" = "Theme";

readeck/UI/Components/NativeWebView.swift

@@ -402,6 +402,8 @@ struct NativeWebView: View {
     }
 
     private func generateAnnotationOverlayJS(isDarkMode: Bool) -> String {
+        let highlightLabel = NSLocalizedString("Highlight", comment: "")
+
         return """
         // Create annotation color overlay
         (function() {
@@ -456,9 +458,9 @@ struct NativeWebView: View {
             `;
             overlay.appendChild(content);
 
-            // Add "Markierung" label
+            // Add localized label
             const label = document.createElement('span');
-            label.textContent = 'Markierung';
+            label.textContent = '\(highlightLabel)';
             label.style.cssText = `
                 color: black;
                 font-size: 16px;

readeck/UI/Components/WebView.swift

@@ -410,6 +410,7 @@ struct WebView: UIViewRepresentable {
         let greenColor = AnnotationColor.green.cssColor(isDark: isDarkMode)
         let blueColor = AnnotationColor.blue.cssColor(isDark: isDarkMode)
         let redColor = AnnotationColor.red.cssColor(isDark: isDarkMode)
+        let highlightLabel = NSLocalizedString("Highlight", comment: "")
 
         return """
         // Create annotation color overlay
@@ -465,9 +466,9 @@ struct WebView: UIViewRepresentable {
             `;
             overlay.appendChild(content);
 
-            // Add "Markierung" label
+            // Add localized label
             const label = document.createElement('span');
-            label.textContent = 'Markierung';
+            label.textContent = '\(highlightLabel)';
             label.style.cssText = `
                 color: black;
                 font-size: 16px;

readeck/UI/Resources/RELEASE_NOTES.md

@@ -4,6 +4,53 @@ Thanks for using the Readeck iOS app! Below are the release notes for each versi
 
 **AppStore:** The App is now in the App Store! [Get it here](https://apps.apple.com/de/app/readeck/id6748764703) for all TestFlight users. If you wish a more stable Version, please download it from there. Or you can continue using TestFlight for the latest features.
 
+## Version 2.0.0
+
+### Offline Reading
+
+- **Read your articles without internet connection** - the feature you've been waiting for!
+- Automatic background sync keeps your favorite articles cached
+- Choose how many articles to cache (up to 200)
+- Cache syncs automatically every 4 hours
+- Manual sync button for instant updates
+- Smart FIFO cleanup automatically removes old cached articles
+- Article images are pre-downloaded for offline viewing
+- Cached articles load instantly, even without network
+
+### Smart Network Monitoring
+
+- **Automatic offline detection** with reliable network monitoring
+- Visual indicator shows when you're offline
+- App automatically loads cached articles when offline
+- Cache-first loading for instant article access
+- Improved VPN handling without false-positives
+- Network status checks interface availability for accuracy
+
+### Offline Settings
+
+- **New dedicated offline settings screen**
+- Enable or disable offline mode
+- Adjust number of cached articles with slider
+- View last sync timestamp
+- Manual sync button
+- Toggle settings work instantly
+
+### Performance & Architecture
+
+- Clean architecture with dedicated cache repository layer
+- Efficient CoreData integration for cached content
+- Kingfisher image prefetching for smooth offline experience
+- Background sync doesn't block app startup
+- Reactive updates with Combine framework
+
+### Developer Features (DEBUG)
+
+- Offline mode simulation toggle for testing
+- Detailed sync logging for troubleshooting
+- Visual debug banner (green=online, red=offline)
+
+---
+
 ## Version 1.2.0
 
 ### Annotations & Highlighting