Add BookDate card stack animations and thumbnail caching

Implements pure CSS card stack animations for BookDate recommendations, including smooth exit and advance transitions. Adds local caching of library cover thumbnails during scans, updates database schema and API to serve cached covers, and enhances BookDate to support 'favorites' scope with a book picker modal. Updates admin settings validation logic for Prowlarr, improves indexer state management, and documents new features and backend changes.

src/lib/bookdate/helpers.ts

@@ -232,12 +232,12 @@ async function enrichWithUserRatings(
 /**
  * Get user's Plex library books based on scope
  * @param userId - User ID
- * @param scope - 'full' | 'listened' | 'rated'
+ * @param scope - 'full' | 'listened' | 'rated' | 'favorites'
  * @returns Array of library books (max 40)
  */
 export async function getUserLibraryBooks(
   userId: string,
-  scope: 'full' | 'listened' | 'rated'
+  scope: 'full' | 'listened' | 'rated' | 'favorites'
 ): Promise<LibraryBook[]> {
   try {
     const configService = getConfigService();
@@ -249,6 +249,74 @@ export async function getUserLibraryBooks(
       scope = 'full';
     }
 
+    // Handle favorites scope
+    if (scope === 'favorites') {
+      const user = await prisma.user.findUnique({
+        where: { id: userId },
+        select: { bookDateFavoriteBookIds: true },
+      });
+
+      const favoriteIds = user?.bookDateFavoriteBookIds
+        ? JSON.parse(user.bookDateFavoriteBookIds)
+        : [];
+
+      if (favoriteIds.length === 0) {
+        logger.warn('Favorites scope selected but no favorites stored, falling back to full library');
+        scope = 'full';
+      } else {
+        // Get library ID for filtering
+        let libraryId: string;
+        if (backendMode === 'audiobookshelf') {
+          const absLibraryId = await configService.get('audiobookshelf.library_id');
+          if (!absLibraryId) {
+            logger.warn('No Audiobookshelf library ID configured');
+            return [];
+          }
+          libraryId = absLibraryId;
+        } else {
+          const plexConfig = await configService.getPlexConfig();
+          if (!plexConfig.libraryId) {
+            logger.warn('No Plex library ID configured');
+            return [];
+          }
+          libraryId = plexConfig.libraryId;
+        }
+
+        // Query favorite books
+        const cachedBooks = await prisma.plexLibrary.findMany({
+          where: {
+            id: { in: favoriteIds },
+            plexLibraryId: libraryId, // Ensure books are from current library
+          },
+          select: {
+            title: true,
+            author: true,
+            narrator: true,
+            plexGuid: true,
+            plexRatingKey: true,
+            userRating: true,
+          },
+          orderBy: { addedAt: 'desc' },
+        });
+
+        logger.info(`Fetched ${cachedBooks.length} favorite books for user ${userId}`);
+
+        // For Plex: Enrich with user's personal ratings
+        // For Audiobookshelf: Skip enrichment (no rating support)
+        if (backendMode === 'plex') {
+          return await enrichWithUserRatings(userId, cachedBooks);
+        } else {
+          // Audiobookshelf: Map to LibraryBook without ratings
+          return cachedBooks.map(book => ({
+            title: book.title,
+            author: book.author,
+            narrator: book.narrator || undefined,
+            rating: undefined,
+          }));
+        }
+      }
+    }
+
     // Get library ID based on backend mode
     let libraryId: string;
     if (backendMode === 'audiobookshelf') {
@@ -422,7 +490,7 @@ export async function buildAIPrompt(
 ): Promise<string> {
   const libraryBooks = await getUserLibraryBooks(
     userId,
-    config.libraryScope as 'full' | 'listened' | 'rated'
+    config.libraryScope as 'full' | 'listened' | 'rated' | 'favorites'
   );
 
   const swipeHistory = await getUserRecentSwipes(userId, 10);
@@ -434,6 +502,27 @@ export async function buildAIPrompt(
     libraryScope: config.libraryScope,
   });
 
+  let instructions =
+    'Recommend 15-20 audiobooks the user would enjoy based on their library and swipe history. ' +
+    'CRITICAL RULES:\n' +
+    '1. DO NOT recommend any books already in the user\'s library (check titles carefully)\n' +
+    '2. DO NOT recommend any books from the swipe history (whether requested, rejected, dismissed, or marked_as_liked)\n' +
+    '3. You must provide 15-20 diverse recommendations, not just 3-5\n' +
+    '4. Focus on variety across genres, authors, and styles\n' +
+    '5. Consider user ratings if available (0-10 scale, higher = liked more)\n' +
+    '6. Learn from rejected books to avoid similar recommendations\n' +
+    '7. Learn from requested books to find similar ones\n' +
+    '8. Pay special attention to "marked_as_liked" books - these are books the user has already read/listened to elsewhere and enjoyed. Find similar books to these.\n' +
+    '9. Each recommendation should be a NEW book not mentioned anywhere in the user context';
+
+  // Add special instruction for favorites scope
+  if (config.libraryScope === 'favorites') {
+    instructions += '\n\n' +
+      'IMPORTANT: The user has specifically handpicked these ' + libraryBooks.length + ' books as their personal favorites. ' +
+      'These represent their preferred genres, authors, themes, and styles. Use these as PRIMARY INSPIRATION for your recommendations. ' +
+      'Find books that capture the essence of what makes these favorites special to the user.';
+  }
+
   const prompt = {
     task: 'recommend_audiobooks',
     user_context: {
@@ -447,18 +536,7 @@ export async function buildAIPrompt(
       })),
       custom_preferences: config.customPrompt || null,
     },
-    instructions:
-      'Recommend 15-20 audiobooks the user would enjoy based on their library and swipe history. ' +
-      'CRITICAL RULES:\n' +
-      '1. DO NOT recommend any books already in the user\'s library (check titles carefully)\n' +
-      '2. DO NOT recommend any books from the swipe history (whether requested, rejected, dismissed, or marked_as_liked)\n' +
-      '3. You must provide 15-20 diverse recommendations, not just 3-5\n' +
-      '4. Focus on variety across genres, authors, and styles\n' +
-      '5. Consider user ratings if available (0-10 scale, higher = liked more)\n' +
-      '6. Learn from rejected books to avoid similar recommendations\n' +
-      '7. Learn from requested books to find similar ones\n' +
-      '8. Pay special attention to "marked_as_liked" books - these are books the user has already read/listened to elsewhere and enjoyed. Find similar books to these.\n' +
-      '9. Each recommendation should be a NEW book not mentioned anywhere in the user context',
+    instructions,
   };
 
   const promptString = JSON.stringify(prompt);