Fix: Restore fallback to check recent downloads

When the persistent queue is empty (e.g., after extension reload),
fall back to checking recent downloads from Chrome downloads API.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/popup/popup.ts

@@ -164,7 +164,6 @@ async function loadPDFQueue() {
     const exists = pdfQueue.some(p => p.url === currentTabPDF.url);
     if (!exists) {
       console.log('[Popup] Adding current tab PDF to queue:', currentTabPDF.filename);
-      // Add to queue (will be added to persistent queue when user interacts)
       const entry: PDFQueueEntry = {
         ...currentTabPDF,
         status: 'pending'
@@ -173,10 +172,71 @@ async function loadPDFQueue() {
     }
   }
 
+  // Fallback: check recent downloads if queue is still empty
+  if (pdfQueue.length === 0) {
+    console.log('[Popup] Queue empty, checking recent downloads...');
+    const recentPDFs = await checkRecentDownloads();
+    for (const pdf of recentPDFs) {
+      const exists = pdfQueue.some(p => p.url === pdf.url);
+      if (!exists) {
+        pdfQueue.push({
+          ...pdf,
+          status: 'pending'
+        });
+      }
+    }
+  }
+
   // Render the list
   renderPDFList();
 }
 
+/**
+ * Check recent downloads for PDFs (fallback mechanism)
+ */
+async function checkRecentDownloads(): Promise<DetectedPDF[]> {
+  return new Promise((resolve) => {
+    chrome.downloads.search(
+      {
+        limit: 20,
+        orderBy: ['-startTime']
+      },
+      (items) => {
+        console.log('[Popup] Checked recent downloads:', items.length, 'items');
+
+        const pdfs: DetectedPDF[] = [];
+
+        for (const item of items) {
+          if (
+            item.state === 'complete' &&
+            (item.filename.toLowerCase().endsWith('.pdf') || item.mime === 'application/pdf')
+          ) {
+            let domain = 'unknown';
+            try {
+              const urlObj = new URL(item.url);
+              domain = urlObj.hostname;
+            } catch (e) {
+              // Keep default
+            }
+
+            pdfs.push({
+              id: `download-${item.id}`,
+              filename: item.filename.split('/').pop() || item.filename,
+              url: item.url,
+              size: item.fileSize,
+              timestamp: new Date(item.startTime).getTime(),
+              sourceDomain: domain
+            });
+          }
+        }
+
+        console.log('[Popup] Found', pdfs.length, 'PDF downloads');
+        resolve(pdfs);
+      }
+    );
+  });
+}
+
 /**
  * Render the PDF list
  */