Fix metadata.json download and handle missing duration property

- Replace URL.createObjectURL with data URL in metadata writer
  (blob URLs not available in Manifest V3 service workers)
- Add fallback for missing audio-duration property in chapter extraction
- Handle cases where BIF structure may not include duration metadata

Author: pdugan20

chrome-extension/background/metadata-writer.js

@@ -17,26 +17,18 @@ export class MetadataWriter {
     console.log('[Metadata Writer] Saving metadata file');
 
     const metadataContent = JSON.stringify({ metadata, chapters }, null, 2);
-    const blob = new Blob([metadataContent], { type: 'application/json' });
-    const url = URL.createObjectURL(blob);
 
-    try {
-      const downloadId = await chrome.downloads.download({
-        url: url,
-        filename: `libby-downloads/${sanitizeFilename(bookTitle)}/metadata.json`,
-        saveAs: false,
-      });
+    // Use data URL instead of blob URL (blob URLs don't work in service workers)
+    const dataUrl = 'data:application/json;charset=utf-8,' + encodeURIComponent(metadataContent);
 
-      console.log('[Metadata Writer] Metadata file download started');
+    const downloadId = await chrome.downloads.download({
+      url: dataUrl,
+      filename: `libby-downloads/${sanitizeFilename(bookTitle)}/metadata.json`,
+      saveAs: false,
+    });
 
-      // Revoke blob URL after 30 seconds
-      setTimeout(() => URL.revokeObjectURL(url), 30000);
+    console.log('[Metadata Writer] Metadata file download started');
 
-      return downloadId;
-    } catch (error) {
-      // Clean up blob URL on error
-      URL.revokeObjectURL(url);
-      throw error;
-    }
+    return downloadId;
   }
 }

chrome-extension/iframe/iframe-extractor.js

@@ -102,15 +102,18 @@ async function extractBookData() {
     const url =
       location.origin + '/' + spine.meta.path + '?' + odreadCmptParams[spine.spinePosition];
 
+    // Try different possible duration properties (fallback to 0 if not available)
+    const duration = spine.meta['audio-duration'] || spine.meta.duration || spine.duration || 0;
+
     chapters.push({
       index: spine.meta['-odread-spine-position'],
       title: `Part ${spine.meta['-odread-spine-position'] + 1}`,
       url: url,
-      duration: spine.meta['audio-duration'],
+      duration: duration,
       startTime: cumulativeTime,
     });
 
-    cumulativeTime += spine.meta['audio-duration'];
+    cumulativeTime += duration;
   }
 
   // Get chapter titles from TOC