refactor(storage): use unstorage for session state

src/app/chat/components/chat-area.tsx

@@ -81,35 +81,49 @@ export function ChatArea({
     if (restoredScrollRef.current || messages.length === 0) return;
 
     const scrollNode = scrollRef.current;
-    const snapshot = consumeChatScrollSnapshot();
-    if (!scrollNode || snapshot === null) return;
+    if (!scrollNode) return;
 
-    restoredScrollRef.current = true;
+    let cancelled = false;
+    let frame: number | null = null;
+    let timer: number | null = null;
+    let observerTimer: number | null = null;
+    let lateRestoreTimer: number | null = null;
+    let resizeObserver: ResizeObserver | null = null;
 
-    const restoreScroll = () => {
-      scrollNode.scrollTop = getChatScrollRestoreTop(scrollNode, snapshot);
+    const restore = async () => {
+      const snapshot = await consumeChatScrollSnapshot();
+      if (cancelled || snapshot === null) return;
+
+      restoredScrollRef.current = true;
+
+      const restoreScroll = () => {
+        scrollNode.scrollTop = getChatScrollRestoreTop(scrollNode, snapshot);
+      };
+
+      restoreScroll();
+      frame = window.requestAnimationFrame(restoreScroll);
+      timer = window.setTimeout(restoreScroll, 120);
+      resizeObserver =
+        typeof ResizeObserver === "undefined"
+          ? null
+          : new ResizeObserver(restoreScroll);
+      Array.from(scrollNode.children).forEach((child) => {
+        resizeObserver?.observe(child);
+      });
+      observerTimer = window.setTimeout(() => {
+        resizeObserver?.disconnect();
+      }, 800);
+      lateRestoreTimer = window.setTimeout(restoreScroll, 600);
     };
 
-    restoreScroll();
-    const frame = window.requestAnimationFrame(restoreScroll);
-    const timer = window.setTimeout(restoreScroll, 120);
-    const resizeObserver =
-      typeof ResizeObserver === "undefined"
-        ? null
-        : new ResizeObserver(restoreScroll);
-    Array.from(scrollNode.children).forEach((child) => {
-      resizeObserver?.observe(child);
-    });
-    const observerTimer = window.setTimeout(() => {
-      resizeObserver?.disconnect();
-    }, 800);
-    const lateRestoreTimer = window.setTimeout(restoreScroll, 600);
+    void restore();
 
     return () => {
-      window.cancelAnimationFrame(frame);
-      window.clearTimeout(timer);
-      window.clearTimeout(observerTimer);
-      window.clearTimeout(lateRestoreTimer);
+      cancelled = true;
+      if (frame !== null) window.cancelAnimationFrame(frame);
+      if (timer !== null) window.clearTimeout(timer);
+      if (observerTimer !== null) window.clearTimeout(observerTimer);
+      if (lateRestoreTimer !== null) window.clearTimeout(lateRestoreTimer);
       resizeObserver?.disconnect();
     };
   }, [messages.length]);