Fix/hardcover api key per user (#1943)

* feat: add hardcover API key and sync settings to KoboSync and KoboUserSettings entities

* feat(hardcover): enhance sync functionality to use per-user API keys

- Updated HardcoverSyncService to utilize user-specific Hardcover API keys for syncing reading progress.
- Modified syncProgressToHardcover method to accept userId, allowing for personalized sync settings.
- Improved logging to include userId in sync operations for better traceability.
- Adjusted KoboReadingStateService to pass userId when triggering sync to Hardcover.

* feat(database): update kobo_location_source column size and add hardcover settings

- Increased the size of the kobo_location_source column to accommodate longer location strings from Kobo devices.
- Added new columns for hardcover API key and sync settings in the kobo_user_settings table to enhance user customization.

* refactor(hardcover): update tests to use user-specific Kobo settings

- Replaced AppSettingService with KoboSettingsService in HardcoverSyncServiceTest to utilize user-specific settings.
- Modified syncProgressToHardcover method calls to include userId for personalized sync operations.
- Added a new test case to handle scenarios where user settings are not found, ensuring robust error handling.

---------

Co-authored-by: akiraslingshot <akiraslingshot@gmail.com>

booklore-api/src/main/java/com/adityachandel/booklore/model/dto/KoboSyncSettings.java

@@ -12,4 +12,6 @@ public class KoboSyncSettings {
     private Float progressMarkAsReadingThreshold;
     private Float progressMarkAsFinishedThreshold;
     private boolean autoAddToShelf;
+    private String hardcoverApiKey;
+    private boolean hardcoverSyncEnabled;
 }

booklore-api/src/main/java/com/adityachandel/booklore/model/entity/KoboUserSettingsEntity.java

@@ -37,4 +37,11 @@ public class KoboUserSettingsEntity {
     @Column(name = "auto_add_to_shelf")
     @Builder.Default
     private boolean autoAddToShelf = false;
+
+    @Column(name = "hardcover_api_key", length = 2048)
+    private String hardcoverApiKey;
+
+    @Column(name = "hardcover_sync_enabled")
+    @Builder.Default
+    private boolean hardcoverSyncEnabled = false;
 }

booklore-api/src/main/java/com/adityachandel/booklore/model/entity/UserBookProgressEntity.java

@@ -69,7 +69,7 @@ public class UserBookProgressEntity {
     @Column(name = "kobo_location_type", length = 50)
     private String koboLocationType;
 
-    @Column(name = "kobo_location_source", length = 50)
+    @Column(name = "kobo_location_source", length = 512)
     private String koboLocationSource;
 
     @Enumerated(EnumType.STRING)

booklore-api/src/main/java/com/adityachandel/booklore/service/hardcover/HardcoverSyncService.java

@@ -1,13 +1,14 @@
 package com.adityachandel.booklore.service.hardcover;
 
-import com.adityachandel.booklore.model.dto.settings.MetadataProviderSettings;
+import com.adityachandel.booklore.model.dto.KoboSyncSettings;
 import com.adityachandel.booklore.model.entity.BookEntity;
 import com.adityachandel.booklore.model.entity.BookMetadataEntity;
 import com.adityachandel.booklore.repository.BookRepository;
-import com.adityachandel.booklore.service.appsettings.AppSettingService;
+import com.adityachandel.booklore.service.kobo.KoboSettingsService;
 import com.adityachandel.booklore.service.metadata.parser.hardcover.GraphQLRequest;
 import lombok.extern.slf4j.Slf4j;
 import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.context.annotation.Lazy;
 import org.springframework.http.HttpHeaders;
 import org.springframework.http.MediaType;
 import org.springframework.scheduling.annotation.Async;
@@ -23,8 +24,8 @@ import java.util.Map;
 
 /**
  * Service to sync reading progress to Hardcover.
- * Uses the global Hardcover API token from Metadata Provider Settings.
+ * Uses per-user Hardcover API tokens for reading progress sync.
- * Sync only activates if the token is configured and Hardcover is enabled.
+ * Each user can configure their own Hardcover API key in Kobo settings.
  */
 @Slf4j
 @Service
@@ -35,12 +36,15 @@ public class HardcoverSyncService {
     private static final int STATUS_READ = 3;
 
     private final RestClient restClient;
-    private final AppSettingService appSettingService;
+    private final KoboSettingsService koboSettingsService;
     private final BookRepository bookRepository;
 
+    // Thread-local to hold the current API token for GraphQL requests
+    private final ThreadLocal<String> currentApiToken = new ThreadLocal<>();
+
     @Autowired
-    public HardcoverSyncService(AppSettingService appSettingService, BookRepository bookRepository) {
+    public HardcoverSyncService(@Lazy KoboSettingsService koboSettingsService, BookRepository bookRepository) {
-        this.appSettingService = appSettingService;
+        this.koboSettingsService = koboSettingsService;
         this.bookRepository = bookRepository;
         this.restClient = RestClient.builder()
                 .baseUrl(HARDCOVER_API_URL)
@@ -50,105 +54,116 @@ public class HardcoverSyncService {
     /**
      * Asynchronously sync Kobo reading progress to Hardcover.
      * This method is non-blocking and will not fail the calling process if sync fails.
+     * Uses the user's personal Hardcover API key if configured.
      *
      * @param bookId The book ID to sync progress for
      * @param progressPercent The reading progress as a percentage (0-100)
+     * @param userId The user ID whose reading progress is being synced
      */
     @Async
     @Transactional(readOnly = true)
-    public void syncProgressToHardcover(Long bookId, Float progressPercent) {
+    public void syncProgressToHardcover(Long bookId, Float progressPercent, Long userId) {
         try {
-            if (!isHardcoverSyncEnabled()) {
+            // Get user's Hardcover settings
-                log.trace("Hardcover sync skipped: not enabled or no API token configured");
+            KoboSyncSettings userSettings = koboSettingsService.getSettingsByUserId(userId);
+            
+            if (!isHardcoverSyncEnabledForUser(userSettings)) {
+                log.trace("Hardcover sync skipped for user {}: not enabled or no API token configured", userId);
                 return;
             }
 
-            if (progressPercent == null) {
+            // Set the user's API token for this sync operation
-                log.debug("Hardcover sync skipped: no progress to sync");
+            currentApiToken.set(userSettings.getHardcoverApiKey());
-                return;
-            }
 
-            // Fetch book fresh within the async context to avoid lazy loading issues
+            try {
-            BookEntity book = bookRepository.findById(bookId).orElse(null);
+                if (progressPercent == null) {
-            if (book == null) {
+                    log.debug("Hardcover sync skipped: no progress to sync");
-                log.debug("Hardcover sync skipped: book {} not found", bookId);
-                return;
-            }
-
-            BookMetadataEntity metadata = book.getMetadata();
-            if (metadata == null) {
-                log.debug("Hardcover sync skipped: book {} has no metadata", bookId);
-                return;
-            }
-
-            // Find the book on Hardcover - use stored ID if available
-            HardcoverBookInfo hardcoverBook;
-            if (metadata.getHardcoverBookId() != null) {
-                // Use the stored numeric book ID directly
-                hardcoverBook = new HardcoverBookInfo();
-                hardcoverBook.bookId = metadata.getHardcoverBookId();
-                hardcoverBook.pages = metadata.getPageCount();
-                log.debug("Using stored Hardcover book ID: {}", hardcoverBook.bookId);
-            } else {
-                // Search by ISBN
-                hardcoverBook = findHardcoverBook(metadata);
-                if (hardcoverBook == null) {
-                    log.debug("Hardcover sync skipped: book {} not found on Hardcover", bookId);
                     return;
                 }
-            }
 
-            // Determine the status based on progress
+                // Fetch book fresh within the async context to avoid lazy loading issues
-            int statusId = progressPercent >= 99.0f ? STATUS_READ : STATUS_CURRENTLY_READING;
+                BookEntity book = bookRepository.findById(bookId).orElse(null);
+                if (book == null) {
+                    log.debug("Hardcover sync skipped: book {} not found", bookId);
+                    return;
+                }
 
-            // Calculate progress in pages
+                BookMetadataEntity metadata = book.getMetadata();
-            int progressPages = 0;
+                if (metadata == null) {
-            if (hardcoverBook.pages != null && hardcoverBook.pages > 0) {
+                    log.debug("Hardcover sync skipped: book {} has no metadata", bookId);
-                progressPages = Math.round((progressPercent / 100.0f) * hardcoverBook.pages);
+                    return;
-                progressPages = Math.max(0, Math.min(hardcoverBook.pages, progressPages));
+                }
-            }
-            log.info("Progress calculation: progressPercent={}%, totalPages={}, progressPages={}", 
-                    progressPercent, hardcoverBook.pages, progressPages);
 
-            // Step 1: Add/update the book in user's library
+                // Find the book on Hardcover - use stored ID if available
-            Integer userBookId = insertOrGetUserBook(hardcoverBook.bookId, hardcoverBook.editionId, statusId);
+                HardcoverBookInfo hardcoverBook;
-            if (userBookId == null) {
+                if (metadata.getHardcoverBookId() != null) {
-                log.warn("Hardcover sync failed: could not get user_book_id for book {}", bookId);
+                    // Use the stored numeric book ID directly
-                return;
+                    hardcoverBook = new HardcoverBookInfo();
-            }
+                    hardcoverBook.bookId = metadata.getHardcoverBookId();
+                    hardcoverBook.pages = metadata.getPageCount();
+                    log.debug("Using stored Hardcover book ID: {}", hardcoverBook.bookId);
+                } else {
+                    // Search by ISBN
+                    hardcoverBook = findHardcoverBook(metadata);
+                    if (hardcoverBook == null) {
+                        log.debug("Hardcover sync skipped: book {} not found on Hardcover", bookId);
+                        return;
+                    }
+                }
 
-            // Step 2: Create or update the reading progress
+                // Determine the status based on progress
-            boolean success = upsertReadingProgress(userBookId, hardcoverBook.editionId, progressPages);
+                int statusId = progressPercent >= 99.0f ? STATUS_READ : STATUS_CURRENTLY_READING;
-            
+
-            if (success) {
+                // Calculate progress in pages
-                log.info("Synced progress to Hardcover: book={}, hardcoverBookId={}, progress={}% ({}pages)", 
+                int progressPages = 0;
-                        bookId, hardcoverBook.bookId, Math.round(progressPercent), progressPages);
+                if (hardcoverBook.pages != null && hardcoverBook.pages > 0) {
+                    progressPages = Math.round((progressPercent / 100.0f) * hardcoverBook.pages);
+                    progressPages = Math.max(0, Math.min(hardcoverBook.pages, progressPages));
+                }
+                log.info("Progress calculation: userId={}, progressPercent={}%, totalPages={}, progressPages={}", 
+                        userId, progressPercent, hardcoverBook.pages, progressPages);
+
+                // Step 1: Add/update the book in user's library
+                Integer userBookId = insertOrGetUserBook(hardcoverBook.bookId, hardcoverBook.editionId, statusId);
+                if (userBookId == null) {
+                    log.warn("Hardcover sync failed: could not get user_book_id for book {}", bookId);
+                    return;
+                }
+
+                // Step 2: Create or update the reading progress
+                boolean success = upsertReadingProgress(userBookId, hardcoverBook.editionId, progressPages);
+                
+                if (success) {
+                    log.info("Synced progress to Hardcover: userId={}, book={}, hardcoverBookId={}, progress={}% ({}pages)", 
+                            userId, bookId, hardcoverBook.bookId, Math.round(progressPercent), progressPages);
+                }
+
+            } finally {
+                // Clean up thread-local
+                currentApiToken.remove();
             }
 
         } catch (Exception e) {
-            log.error("Failed to sync progress to Hardcover for book {}: {}", 
+            log.error("Failed to sync progress to Hardcover for book {} (user {}): {}", 
-                    bookId, e.getMessage());
+                    bookId, userId, e.getMessage());
         }
     }
 
-    private boolean isHardcoverSyncEnabled() {
+    /**
-        MetadataProviderSettings.Hardcover hardcoverSettings = 
+     * Check if Hardcover sync is enabled for a specific user.
-                appSettingService.getAppSettings().getMetadataProviderSettings().getHardcover();
+     */
-        
+    private boolean isHardcoverSyncEnabledForUser(KoboSyncSettings userSettings) {
-        if (hardcoverSettings == null) {
+        if (userSettings == null) {
             return false;
         }
 
-        return hardcoverSettings.isEnabled() 
+        return userSettings.isHardcoverSyncEnabled() 
-                && hardcoverSettings.getApiKey() != null 
+                && userSettings.getHardcoverApiKey() != null 
-                && !hardcoverSettings.getApiKey().isBlank();
+                && !userSettings.getHardcoverApiKey().isBlank();
     }
 
     private String getApiToken() {
-        return appSettingService.getAppSettings()
+        return currentApiToken.get();
-                .getMetadataProviderSettings()
-                .getHardcover()
-                .getApiKey();
     }
 
     /**

booklore-api/src/main/java/com/adityachandel/booklore/service/kobo/KoboReadingStateService.java

@@ -154,6 +154,9 @@ public class KoboReadingStateService {
                 
                 KoboReadingState.CurrentBookmark.Location location = bookmark.getLocation();
                 if (location != null) {
+                    log.debug("Kobo location data: value={}, type={}, source={} (length={})", 
+                            location.getValue(), location.getType(), location.getSource(),
+                            location.getSource() != null ? location.getSource().length() : 0);
                     progress.setKoboLocation(location.getValue());
                     progress.setKoboLocationType(location.getType());
                     progress.setKoboLocationSource(location.getSource());
@@ -171,8 +174,8 @@ public class KoboReadingStateService {
             progressRepository.save(progress);
             log.debug("Synced Kobo progress: bookId={}, progress={}%", bookId, progress.getKoboProgressPercent());
             
-            // Sync progress to Hardcover asynchronously (if enabled)
+            // Sync progress to Hardcover asynchronously (if enabled for this user)
-            hardcoverSyncService.syncProgressToHardcover(book.getId(), progress.getKoboProgressPercent());
+            hardcoverSyncService.syncProgressToHardcover(book.getId(), progress.getKoboProgressPercent(), userId);
         } catch (NumberFormatException e) {
             log.warn("Invalid entitlement ID format: {}", readingState.getEntitlementId());
         }

booklore-api/src/main/java/com/adityachandel/booklore/service/kobo/KoboSettingsService.java

@@ -82,6 +82,10 @@ public class KoboSettingsService {
 
         entity.setAutoAddToShelf(settings.isAutoAddToShelf());
 
+        // Update Hardcover settings
+        entity.setHardcoverApiKey(settings.getHardcoverApiKey());
+        entity.setHardcoverSyncEnabled(settings.isHardcoverSyncEnabled());
+
         repository.save(entity);
         return mapToDto(entity);
     }
@@ -122,6 +126,19 @@ public class KoboSettingsService {
         dto.setProgressMarkAsReadingThreshold(entity.getProgressMarkAsReadingThreshold());
         dto.setProgressMarkAsFinishedThreshold(entity.getProgressMarkAsFinishedThreshold());
         dto.setAutoAddToShelf(entity.isAutoAddToShelf());
+        dto.setHardcoverApiKey(entity.getHardcoverApiKey());
+        dto.setHardcoverSyncEnabled(entity.isHardcoverSyncEnabled());
         return dto;
     }
+
+    /**
+     * Get Hardcover settings for a specific user by ID.
+     * Used by HardcoverSyncService to get user-specific API key.
+     */
+    @Transactional(readOnly = true)
+    public KoboSyncSettings getSettingsByUserId(Long userId) {
+        return repository.findByUserId(userId)
+                .map(this::mapToDto)
+                .orElse(null);
+    }
 }

booklore-api/src/main/resources/db/migration/V76__Add_user_hardcover_settings.sql

@@ -0,0 +1,6 @@
+-- Add per-user Hardcover settings to kobo_user_settings table
+ALTER TABLE kobo_user_settings ADD COLUMN hardcover_api_key VARCHAR(2048);
+ALTER TABLE kobo_user_settings ADD COLUMN hardcover_sync_enabled BOOLEAN DEFAULT FALSE;
+
+-- Fix kobo_location_source column size (Kobo devices can send longer location strings)
+ALTER TABLE user_book_progress MODIFY COLUMN kobo_location_source VARCHAR(512);

booklore-api/src/test/java/com/adityachandel/booklore/service/hardcover/HardcoverSyncServiceTest.java

@@ -1,11 +1,10 @@
 package com.adityachandel.booklore.service.hardcover;
 
-import com.adityachandel.booklore.model.dto.settings.AppSettings;
+import com.adityachandel.booklore.model.dto.KoboSyncSettings;
-import com.adityachandel.booklore.model.dto.settings.MetadataProviderSettings;
 import com.adityachandel.booklore.model.entity.BookEntity;
 import com.adityachandel.booklore.model.entity.BookMetadataEntity;
 import com.adityachandel.booklore.repository.BookRepository;
-import com.adityachandel.booklore.service.appsettings.AppSettingService;
+import com.adityachandel.booklore.service.kobo.KoboSettingsService;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.DisplayName;
 import org.junit.jupiter.api.Test;
@@ -31,7 +30,7 @@ import static org.mockito.Mockito.*;
 class HardcoverSyncServiceTest {
 
     @Mock
-    private AppSettingService appSettingService;
+    private KoboSettingsService koboSettingsService;
 
     @Mock
     private BookRepository bookRepository;
@@ -52,15 +51,15 @@ class HardcoverSyncServiceTest {
 
     private BookEntity testBook;
     private BookMetadataEntity testMetadata;
-    private AppSettings appSettings;
+    private KoboSyncSettings koboSyncSettings;
-    private MetadataProviderSettings.Hardcover hardcoverSettings;
 
     private static final Long TEST_BOOK_ID = 100L;
+    private static final Long TEST_USER_ID = 1L;
 
     @BeforeEach
     void setUp() throws Exception {
         // Create service with mocked dependencies
-        service = new HardcoverSyncService(appSettingService, bookRepository);
+        service = new HardcoverSyncService(koboSettingsService, bookRepository);
         
         // Inject our mocked restClient using reflection
         Field restClientField = HardcoverSyncService.class.getDeclaredField("restClient");
@@ -75,15 +74,12 @@ class HardcoverSyncServiceTest {
         testMetadata.setPageCount(300);
         testBook.setMetadata(testMetadata);
 
-        appSettings = new AppSettings();
+        // Setup Kobo sync settings with Hardcover enabled
-        MetadataProviderSettings metadataSettings = new MetadataProviderSettings();
+        koboSyncSettings = new KoboSyncSettings();
-        hardcoverSettings = new MetadataProviderSettings.Hardcover();
+        koboSyncSettings.setHardcoverSyncEnabled(true);
-        hardcoverSettings.setEnabled(true);
+        koboSyncSettings.setHardcoverApiKey("test-api-key");
-        hardcoverSettings.setApiKey("test-api-key");
-        metadataSettings.setHardcover(hardcoverSettings);
-        appSettings.setMetadataProviderSettings(metadataSettings);
 
-        when(appSettingService.getAppSettings()).thenReturn(appSettings);
+        when(koboSettingsService.getSettingsByUserId(TEST_USER_ID)).thenReturn(koboSyncSettings);
         when(bookRepository.findById(TEST_BOOK_ID)).thenReturn(Optional.of(testBook));
         
         // Setup RestClient mock chain - handles multiple calls
@@ -97,11 +93,11 @@ class HardcoverSyncServiceTest {
     // === Tests for skipping sync (no API calls should be made) ===
 
     @Test
-    @DisplayName("Should skip sync when Hardcover is not enabled")
+    @DisplayName("Should skip sync when Hardcover sync is not enabled for user")
     void syncProgressToHardcover_whenHardcoverDisabled_shouldSkip() {
-        hardcoverSettings.setEnabled(false);
+        koboSyncSettings.setHardcoverSyncEnabled(false);
 
-        service.syncProgressToHardcover(TEST_BOOK_ID, 50.0f);
+        service.syncProgressToHardcover(TEST_BOOK_ID, 50.0f, TEST_USER_ID);
 
         verify(restClient, never()).post();
     }
@@ -109,9 +105,9 @@ class HardcoverSyncServiceTest {
     @Test
     @DisplayName("Should skip sync when API key is missing")
     void syncProgressToHardcover_whenApiKeyMissing_shouldSkip() {
-        hardcoverSettings.setApiKey(null);
+        koboSyncSettings.setHardcoverApiKey(null);
 
-        service.syncProgressToHardcover(TEST_BOOK_ID, 50.0f);
+        service.syncProgressToHardcover(TEST_BOOK_ID, 50.0f, TEST_USER_ID);
 
         verify(restClient, never()).post();
     }
@@ -119,9 +115,9 @@ class HardcoverSyncServiceTest {
     @Test
     @DisplayName("Should skip sync when API key is blank")
     void syncProgressToHardcover_whenApiKeyBlank_shouldSkip() {
-        hardcoverSettings.setApiKey("   ");
+        koboSyncSettings.setHardcoverApiKey("   ");
 
-        service.syncProgressToHardcover(TEST_BOOK_ID, 50.0f);
+        service.syncProgressToHardcover(TEST_BOOK_ID, 50.0f, TEST_USER_ID);
 
         verify(restClient, never()).post();
     }
@@ -129,7 +125,7 @@ class HardcoverSyncServiceTest {
     @Test
     @DisplayName("Should skip sync when progress is null")
     void syncProgressToHardcover_whenProgressNull_shouldSkip() {
-        service.syncProgressToHardcover(TEST_BOOK_ID, null);
+        service.syncProgressToHardcover(TEST_BOOK_ID, null, TEST_USER_ID);
 
         verify(restClient, never()).post();
     }
@@ -139,7 +135,7 @@ class HardcoverSyncServiceTest {
     void syncProgressToHardcover_whenBookNotFound_shouldSkip() {
         when(bookRepository.findById(TEST_BOOK_ID)).thenReturn(Optional.empty());
 
-        service.syncProgressToHardcover(TEST_BOOK_ID, 50.0f);
+        service.syncProgressToHardcover(TEST_BOOK_ID, 50.0f, TEST_USER_ID);
 
         verify(restClient, never()).post();
     }
@@ -149,7 +145,7 @@ class HardcoverSyncServiceTest {
     void syncProgressToHardcover_whenNoMetadata_shouldSkip() {
         testBook.setMetadata(null);
 
-        service.syncProgressToHardcover(TEST_BOOK_ID, 50.0f);
+        service.syncProgressToHardcover(TEST_BOOK_ID, 50.0f, TEST_USER_ID);
 
         verify(restClient, never()).post();
     }
@@ -160,7 +156,7 @@ class HardcoverSyncServiceTest {
         testMetadata.setIsbn13(null);
         testMetadata.setIsbn10(null);
 
-        service.syncProgressToHardcover(TEST_BOOK_ID, 50.0f);
+        service.syncProgressToHardcover(TEST_BOOK_ID, 50.0f, TEST_USER_ID);
 
         verify(restClient, never()).post();
     }
@@ -179,7 +175,7 @@ class HardcoverSyncServiceTest {
                 .thenReturn(createEmptyUserBookReadsResponse())
                 .thenReturn(createInsertUserBookReadResponse());
 
-        service.syncProgressToHardcover(TEST_BOOK_ID, 50.0f);
+        service.syncProgressToHardcover(TEST_BOOK_ID, 50.0f, TEST_USER_ID);
 
         // Verify API was called at least once (using stored ID, no search needed)
         verify(restClient, atLeastOnce()).post();
@@ -195,7 +191,7 @@ class HardcoverSyncServiceTest {
                 .thenReturn(createEmptyUserBookReadsResponse())
                 .thenReturn(createInsertUserBookReadResponse());
 
-        service.syncProgressToHardcover(TEST_BOOK_ID, 50.0f);
+        service.syncProgressToHardcover(TEST_BOOK_ID, 50.0f, TEST_USER_ID);
 
         // Verify API was called at least once
         verify(restClient, atLeastOnce()).post();
@@ -207,7 +203,7 @@ class HardcoverSyncServiceTest {
         // Mock: search returns empty results
         when(responseSpec.body(Map.class)).thenReturn(createEmptySearchResponse());
 
-        service.syncProgressToHardcover(TEST_BOOK_ID, 50.0f);
+        service.syncProgressToHardcover(TEST_BOOK_ID, 50.0f, TEST_USER_ID);
 
         // Should call search only
         verify(restClient, times(1)).post();
@@ -224,7 +220,7 @@ class HardcoverSyncServiceTest {
                 .thenReturn(createEmptyUserBookReadsResponse())
                 .thenReturn(createInsertUserBookReadResponse());
 
-        service.syncProgressToHardcover(TEST_BOOK_ID, 99.0f);
+        service.syncProgressToHardcover(TEST_BOOK_ID, 99.0f, TEST_USER_ID);
 
         verify(restClient, atLeastOnce()).post();
     }
@@ -240,7 +236,7 @@ class HardcoverSyncServiceTest {
                 .thenReturn(createEmptyUserBookReadsResponse())
                 .thenReturn(createInsertUserBookReadResponse());
 
-        service.syncProgressToHardcover(TEST_BOOK_ID, 50.0f);
+        service.syncProgressToHardcover(TEST_BOOK_ID, 50.0f, TEST_USER_ID);
 
         verify(restClient, atLeastOnce()).post();
     }
@@ -257,7 +253,7 @@ class HardcoverSyncServiceTest {
                 .thenReturn(createEmptyUserBookReadsResponse())
                 .thenReturn(createInsertUserBookReadResponse());
 
-        service.syncProgressToHardcover(TEST_BOOK_ID, 50.0f);
+        service.syncProgressToHardcover(TEST_BOOK_ID, 50.0f, TEST_USER_ID);
 
         verify(restClient, atLeastOnce()).post();
     }
@@ -273,7 +269,7 @@ class HardcoverSyncServiceTest {
                 .thenReturn(createFindUserBookReadResponse(6001))
                 .thenReturn(createUpdateUserBookReadResponse());
 
-        service.syncProgressToHardcover(TEST_BOOK_ID, 50.0f);
+        service.syncProgressToHardcover(TEST_BOOK_ID, 50.0f, TEST_USER_ID);
 
         verify(restClient, atLeastOnce()).post();
     }
@@ -290,7 +286,7 @@ class HardcoverSyncServiceTest {
                 .thenReturn(createEmptyUserBookReadsResponse())
                 .thenReturn(createInsertUserBookReadResponse());
 
-        service.syncProgressToHardcover(TEST_BOOK_ID, 50.0f);
+        service.syncProgressToHardcover(TEST_BOOK_ID, 50.0f, TEST_USER_ID);
 
         verify(restClient, atLeastOnce()).post();
     }
@@ -304,7 +300,7 @@ class HardcoverSyncServiceTest {
 
         when(responseSpec.body(Map.class)).thenReturn(Map.of("errors", List.of(Map.of("message", "Unauthorized"))));
 
-        assertDoesNotThrow(() -> service.syncProgressToHardcover(TEST_BOOK_ID, 50.0f));
+        assertDoesNotThrow(() -> service.syncProgressToHardcover(TEST_BOOK_ID, 50.0f, TEST_USER_ID));
     }
 
     @Test
@@ -314,7 +310,17 @@ class HardcoverSyncServiceTest {
 
         when(responseSpec.body(Map.class)).thenReturn(null);
 
-        assertDoesNotThrow(() -> service.syncProgressToHardcover(TEST_BOOK_ID, 50.0f));
+        assertDoesNotThrow(() -> service.syncProgressToHardcover(TEST_BOOK_ID, 50.0f, TEST_USER_ID));
+    }
+
+    @Test
+    @DisplayName("Should skip sync when user settings not found")
+    void syncProgressToHardcover_whenUserSettingsNotFound_shouldSkip() {
+        when(koboSettingsService.getSettingsByUserId(TEST_USER_ID)).thenReturn(null);
+
+        service.syncProgressToHardcover(TEST_BOOK_ID, 50.0f, TEST_USER_ID);
+
+        verify(restClient, never()).post();
     }
 
     // === Helper methods to create mock responses ===

booklore-ui/src/app/features/settings/device-settings/component/kobo-sync-settings/kobo-sync-settings-component.html

@@ -174,6 +174,82 @@
         </div>
       </div>
 
+      @if (koboSyncSettings.syncEnabled) {
+        <div class="preferences-section">
+          <div class="section-header">
+            <h3 class="section-title">
+              <i class="pi pi-book"></i>
+              Hardcover Integration
+            </h3>
+            <p class="section-description">
+              Sync your Kobo reading progress to your personal Hardcover account.
+            </p>
+          </div>
+
+          <div class="settings-card">
+            <div class="setting-item">
+              <div class="setting-info">
+                <div class="setting-label-row">
+                  <label class="setting-label">Sync Reading Progress to Hardcover</label>
+                  <p-toggle-switch
+                    id="hardcoverSyncEnabled"
+                    name="hardcoverSyncEnabled"
+                    [(ngModel)]="koboSyncSettings.hardcoverSyncEnabled"
+                    (ngModelChange)="onHardcoverSyncToggle()">
+                  </p-toggle-switch>
+                </div>
+                <p class="setting-description">
+                  When enabled, your reading progress from Kobo will be automatically synced to your Hardcover account.
+                  Each user can configure their own Hardcover account.
+                </p>
+              </div>
+            </div>
+
+            @if (koboSyncSettings.hardcoverSyncEnabled) {
+              <div class="setting-item">
+                <div class="setting-info">
+                  <div class="setting-label-row">
+                    <label class="setting-label">Hardcover API Key</label>
+                    <div class="token-input-group">
+                      <input
+                        pInputText
+                        id="hardcoverApiKey"
+                        [(ngModel)]="koboSyncSettings.hardcoverApiKey"
+                        [type]="showHardcoverApiKey ? 'text' : 'password'"
+                        name="hardcoverApiKey"
+                        class="token-input"
+                        placeholder="Enter your Hardcover API key"
+                        (blur)="onHardcoverApiKeyChange()"
+                      />
+                      <p-button
+                        icon="pi pi-copy"
+                        outlined="true"
+                        severity="info"
+                        size="small"
+                        (onClick)="copyText(koboSyncSettings.hardcoverApiKey ?? '', 'API Key')"
+                        [disabled]="!koboSyncSettings.hardcoverApiKey">
+                      </p-button>
+                      <p-button
+                        [icon]="showHardcoverApiKey ? 'pi pi-eye-slash' : 'pi pi-eye'"
+                        outlined="true"
+                        severity="info"
+                        size="small"
+                        (onClick)="toggleShowHardcoverApiKey()">
+                      </p-button>
+                    </div>
+                  </div>
+                  <p class="setting-description">
+                    Your personal Hardcover API key. Get it from
+                    <a href="https://hardcover.app/account/api" target="_blank" rel="noopener">hardcover.app/account/api</a>.
+                    This key is used only for syncing your reading progress and is not shared with other users.
+                  </p>
+                </div>
+              </div>
+            }
+          </div>
+        </div>
+      }
+
       @if (isAdmin) {
         <div class="preferences-section">
           <div class="section-header">

booklore-ui/src/app/features/settings/device-settings/component/kobo-sync-settings/kobo-sync-settings-component.ts

@@ -43,6 +43,7 @@ export class KoboSyncSettingsComponent implements OnInit, OnDestroy {
   isAdmin = false;
   credentialsSaved = false;
   showToken = false;
+  showHardcoverApiKey = false;
 
   koboSettings: KoboSettings = {
     convertToKepub: false,
@@ -58,7 +59,9 @@ export class KoboSyncSettingsComponent implements OnInit, OnDestroy {
     syncEnabled: false,
     progressMarkAsReadingThreshold: 1,
     progressMarkAsFinishedThreshold: 99,
-    autoAddToShelf: true
+    autoAddToShelf: true,
+    hardcoverApiKey: '',
+    hardcoverSyncEnabled: false
   }
 
   ngOnInit() {
@@ -119,6 +122,8 @@ export class KoboSyncSettingsComponent implements OnInit, OnDestroy {
         this.koboSyncSettings.progressMarkAsReadingThreshold = settings.progressMarkAsReadingThreshold ?? 1;
         this.koboSyncSettings.progressMarkAsFinishedThreshold = settings.progressMarkAsFinishedThreshold ?? 99;
         this.koboSyncSettings.autoAddToShelf = settings.autoAddToShelf ?? false;
+        this.koboSyncSettings.hardcoverApiKey = settings.hardcoverApiKey ?? '';
+        this.koboSyncSettings.hardcoverSyncEnabled = settings.hardcoverSyncEnabled ?? false;
         this.credentialsSaved = !!settings.token;
       },
       error: () => {
@@ -167,6 +172,21 @@ export class KoboSyncSettingsComponent implements OnInit, OnDestroy {
     this.showToken = !this.showToken;
   }
 
+  toggleShowHardcoverApiKey() {
+    this.showHardcoverApiKey = !this.showHardcoverApiKey;
+  }
+
+  onHardcoverSyncToggle() {
+    const message = this.koboSyncSettings.hardcoverSyncEnabled
+      ? 'Hardcover sync enabled'
+      : 'Hardcover sync disabled';
+    this.updateKoboSettings(message);
+  }
+
+  onHardcoverApiKeyChange() {
+    this.updateKoboSettings('Hardcover API key updated');
+  }
+
   confirmRegenerateToken() {
     this.confirmationService.confirm({
       message: 'This will generate a new token and invalidate the previous one. Continue?',

booklore-ui/src/app/features/settings/device-settings/component/kobo-sync-settings/kobo.service.ts

@@ -9,6 +9,8 @@ export interface KoboSyncSettings {
   progressMarkAsReadingThreshold?: number;
   progressMarkAsFinishedThreshold?: number;
   autoAddToShelf: boolean;
+  hardcoverApiKey?: string;
+  hardcoverSyncEnabled?: boolean;
 }
 
 @Injectable({