retain virtuoso scroll position

src/components/views/Board.jsx

@@ -43,6 +43,7 @@ import useAnonModeStore from '../../hooks/stores/useAnonModeStore';
 import useGeneralStore from '../../hooks/stores/useGeneralStore';
 import packageJson from '../../../package.json'
 const {version} = packageJson
+let lastVirtuosoStates = {};
 
 
 const Board = () => {
@@ -103,6 +104,7 @@ const Board = () => {
   const quoteRefsMobile = useRef({});
   const postOnHoverRef = useRef(null);
   const selectedThreadCidRef = useRef(null);
+  const virtuosoRef = useRef();
 
   const { feed, hasMore, loadMore } = useFeed({subplebbitAddresses: [`${selectedAddress}`], sortType: 'active'});
   const subplebbit = useSubplebbit({subplebbitAddress: selectedAddress});
@@ -648,7 +650,21 @@ const Board = () => {
   };
 
 
-  
+  useEffect(() => {
+    const setLastVirtuosoState = () => {
+      virtuosoRef.current?.getState((snapshot) => {
+        if (snapshot?.ranges?.length) {
+          lastVirtuosoStates[selectedAddress] = snapshot;
+        }
+      });
+    };
+    window.addEventListener('scroll', setLastVirtuosoState);
+
+    return () => window.removeEventListener('scroll', setLastVirtuosoState);
+  }, [selectedAddress]);
+
+  const lastVirtuosoState = lastVirtuosoStates[selectedAddress];
+
 
   return (
     <>
@@ -1267,7 +1283,7 @@ const Board = () => {
                     </>
                   : null}
                   <Virtuoso
-                  increaseViewportBy={2000}
+                  increaseViewportBy={{bottom: 600, top: 600}}
                   data={selectedFeed}
                   itemContent={(index, thread) => {
                     const { displayedReplies, omittedCount } = filteredRepliesByThread[thread.cid] || {};
@@ -2825,6 +2841,9 @@ const Board = () => {
                       </Fragment>
                     );
                   }}
+                  ref={virtuosoRef}
+                  restoreStateFrom={lastVirtuosoState}
+                  initialScrollTop={lastVirtuosoState?.scrollTop}
                   endReached={tryLoadMore}
                   useWindowScroll={true}
                   components={{ Footer: hasMore && feed.length > 0 ? () => <PostLoader /> : null }}