fix(map): attach desktop drawer scroll listener when ref is already set

Previously, the desktop branch of useMapDrawerState only attached the scroll
listener inside the MutationObserver callback. If drawerContentRef.current
was already populated when the effect ran (common on subsequent listing
changes), no DOM mutation fired, the listener never attached, and the sticky
drawer header stayed hidden. Now we attach immediately when the ref is set
and only fall back to the observer when it isn't.

Made-with: Cursor

Author: dnywh

src/features/map/hooks/useMapDrawerState.ts

@@ -112,32 +112,45 @@ export function useMapDrawerState({
     };
   }, [isDesktop, isFullSnap]);
 
-  // Desktop: the drawer is portalled, so it isn't in the tree on first
-  // render. Watch the document for it to mount, then attach once.
+  // Desktop: the drawer is portalled, so it may not be in the tree on the
+  // first render. If the ref is already set by the time this effect runs
+  // (common on subsequent listing changes), attach directly; otherwise fall
+  // back to a MutationObserver that attaches once the portal mounts.
   useEffect(() => {
     if (!isDesktop || !isListingSelected) return;
 
+    let attachedTo: HTMLElement | null = null;
+
     const handleScroll = () => {
-      if (drawerContentRef.current) {
-        setIsDrawerHeaderShown(
-          drawerContentRef.current.scrollTop > SCROLL_THRESHOLD
-        );
+      if (attachedTo) {
+        setIsDrawerHeaderShown(attachedTo.scrollTop > SCROLL_THRESHOLD);
       }
     };
 
-    const observer = new MutationObserver(() => {
-      const drawerContent = drawerContentRef.current;
-      if (drawerContent) {
-        drawerContent.addEventListener("scroll", handleScroll);
-        observer.disconnect();
-      }
-    });
+    const attach = (element: HTMLElement) => {
+      attachedTo = element;
+      element.addEventListener("scroll", handleScroll);
+    };
 
-    observer.observe(document.body, { childList: true, subtree: true });
+    let observer: MutationObserver | null = null;
+
+    if (drawerContentRef.current) {
+      attach(drawerContentRef.current);
+    } else {
+      observer = new MutationObserver(() => {
+        const drawerContent = drawerContentRef.current;
+        if (drawerContent) {
+          attach(drawerContent);
+          observer?.disconnect();
+          observer = null;
+        }
+      });
+      observer.observe(document.body, { childList: true, subtree: true });
+    }
 
     return () => {
-      observer.disconnect();
-      drawerContentRef.current?.removeEventListener("scroll", handleScroll);
+      observer?.disconnect();
+      attachedTo?.removeEventListener("scroll", handleScroll);
     };
   }, [isDesktop, isListingSelected]);