feat: persist doc/page selection across refreshes via sessionStorage

app/page.js

@@ -50,8 +50,19 @@ export default function Home() {
             .then(data => {
                 setDocuments(data);
                 if (data.length > 0) {
-                    setSelectedDocIndex(data[0].index);
-                    setPageIdx(0);
+                    // Restore saved position from sessionStorage
+                    const savedDoc = sessionStorage.getItem('selectedDocIndex');
+                    const savedPage = sessionStorage.getItem('pageIdx');
+                    const docIdx = savedDoc ? parseInt(savedDoc, 10) : null;
+                    const restoredDoc = docIdx !== null && data.find(d => d.index === docIdx);
+
+                    if (restoredDoc) {
+                        setSelectedDocIndex(docIdx);
+                        setPageIdx(savedPage ? parseInt(savedPage, 10) : 0);
+                    } else {
+                        setSelectedDocIndex(data[0].index);
+                        setPageIdx(0);
+                    }
                 }
                 setLoading(false);
             })
@@ -78,14 +89,20 @@ export default function Home() {
         }
     }, []);
 
-    // Update currentDoc when selection changes
+    // Update currentDoc when selection changes + persist to sessionStorage
     useEffect(() => {
         if (selectedDocIndex !== null) {
             const doc = documents.find(d => d.index === selectedDocIndex);
             setCurrentDoc(doc);
+            sessionStorage.setItem('selectedDocIndex', selectedDocIndex);
         }
     }, [selectedDocIndex, documents]);
 
+    // Persist pageIdx to sessionStorage
+    useEffect(() => {
+        sessionStorage.setItem('pageIdx', pageIdx);
+    }, [pageIdx]);
+
     // Fetch page data (reusable — called on page change and after saving)
     const refreshPageData = useCallback(() => {
         if (selectedDocIndex !== null && currentPageNumber !== null) {