Show stale detail blocker while refreshing city data

frontend/components/dashboard/Dashboard.module.css

@@ -774,8 +774,39 @@
 .root :global(.panel-body) {
   overflow-y: auto;
   flex: 1;
+  position: relative;
   padding: 0 20px 24px;
 }
+
+.root :global(.panel-sync-blocker) {
+  position: sticky;
+  top: 0;
+  z-index: 6;
+  display: flex;
+  align-items: center;
+  gap: 10px;
+  margin: 0 0 12px;
+  padding: 12px 14px;
+  border: 1px solid rgba(34, 211, 238, 0.22);
+  border-radius: 8px;
+  background: rgba(8, 16, 30, 0.96);
+  color: var(--text-primary);
+  box-shadow: 0 14px 34px rgba(2, 6, 23, 0.38);
+  backdrop-filter: blur(18px);
+  font-size: 12px;
+  font-weight: 650;
+  line-height: 1.45;
+}
+
+.root :global(.panel-content-stale) {
+  opacity: 0.28;
+  pointer-events: none;
+  user-select: none;
+}
+
+.root :global(.panel-content-stale canvas) {
+  visibility: hidden;
+}
 .root :global(.panel-body::-webkit-scrollbar) {
   width: 4px;
 }

frontend/components/dashboard/DetailPanel.tsx

@@ -196,6 +196,7 @@ export function DetailPanel() {
         (detail.forecast?.daily?.length ?? 0) <= 1),
   );
   const isPanelSyncing = store.loadingState.cityDetail;
+  const isShowingCachedDetailDuringSync = Boolean(detail && isPanelSyncing);
 
   const blurActiveElement = () => {
     if (typeof document === "undefined") return;
@@ -384,7 +385,18 @@ export function DetailPanel() {
         </div>
       </div>
 
-      <div className="panel-body">
+      <div className={clsx("panel-body", isShowingCachedDetailDuringSync && "is-syncing")}>
+        {isShowingCachedDetailDuringSync ? (
+          <div className="panel-sync-blocker" role="status" aria-live="polite">
+            <span className="panel-loading-spinner" aria-hidden="true" />
+            <span>
+              {locale === "en-US"
+                ? `Refreshing ${panelDisplayName}. Current cards are paused until the latest data arrives.`
+                : `正在刷新 ${panelDisplayName}，最新数据返回前暂停展示旧卡片。`}
+            </span>
+          </div>
+        ) : null}
+        <div className={clsx(isShowingCachedDetailDuringSync && "panel-content-stale")}>
         {!hasBasicPanelContent ? (
           <section className="detail-summary-shell detail-empty-state">
             <div className="detail-section-head">
@@ -479,6 +491,7 @@ export function DetailPanel() {
             {heavyContentReady ? <ForecastTable /> : null}
           </>
         )}
+        </div>
       </div>
     </aside>
   );

frontend/hooks/useDashboardStore.tsx

@@ -788,11 +788,7 @@ export function DashboardStoreProvider({
       return;
     }
 
-    const cachedDetail = cityDetailsByName[cityName];
+    const needsDetailRefresh = true;
-    const needsDetailRefresh = hasSparseDetailCoverage(
-      cachedDetail,
-      cachedDetail?.local_date,
-    );
     setLoadingState((current) => ({ ...current, cityDetail: true }));
     const detailPromise = ensureCityDetail(cityName, needsDetailRefresh, "panel");
     void Promise.allSettled([summaryPromise, detailPromise])

frontend/hooks/useLeafletMap.ts

@@ -593,6 +593,13 @@ export function useLeafletMap({
     }
 
     async function maybeAutoShowNearbyStations() {
+      if (selectedCity && isLoadingDetail) {
+        autoNearbyCityRef.current = selectedCity;
+        clearNearbyRefreshTimer();
+        layer.clearLayers();
+        return;
+      }
+
       if (handlingAutoNearbyRef.current) {
         return;
       }
@@ -700,7 +707,7 @@ export function useLeafletMap({
       map.off("zoomend", syncVisibility);
       map.off("moveend", maybeAutoShowNearbyStations);
     };
-  }, [cityDetailsByName, selectedCity, selectedDetail, suspendMotion]);
+  }, [cityDetailsByName, selectedCity, selectedDetail, suspendMotion, isLoadingDetail]);
 
   // Centralized City Selection Zoom Effect
   // Higher level than selection: we only flyTo once the data is loaded (selectedDetail)