Load calendar data async so slow/failing sources don't block page load

Split loadDashboardData into two phases: core data (settings, widgets,
notes) renders immediately, then calendar events load in the background.
Uses Promise.allSettled so individual calendar source failures don't
affect other sources or the dashboard.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/app/page.tsx

@@ -381,33 +381,21 @@ export default function DashboardPage() {
     }
   }
 
-  async function loadDashboardData() {
-    setDashboardError(null);
-
+  async function loadCalendarData(widgets: Widget[]) {
     try {
-      const [settingsResponse, widgetsResponse, notesResponse] = await Promise.all([
-        fetch("/api/settings", {
-          cache: "no-store"
-        }),
-        fetch("/api/widgets", {
-          cache: "no-store"
-        }),
-        fetch("/api/notes", {
-          cache: "no-store"
-        })
-      ]);
-
-      const settingsData = await parseJsonResponse<{ settings: Settings }>(settingsResponse);
-      const widgetsData = await parseJsonResponse<{ widgets: Widget[] }>(widgetsResponse);
-      const notesData = await parseJsonResponse<{ notes: NoteBoardItem[] }>(notesResponse);
-
       const allSourcesResponse = await fetch("/api/calendar/source", {
         cache: "no-store"
       });
       const allSourcesData = await parseJsonResponse<{ sources: CalendarSource[] }>(allSourcesResponse);
+      setCalendarSources(allSourcesData.sources);
 
-      const calendarWidgets = widgetsData.widgets.filter((widget) => widget.type === "calendar");
-      const calendarLoads = await Promise.all(
+      const calendarWidgets = widgets.filter((widget) => widget.type === "calendar");
+
+      if (calendarWidgets.length === 0) {
+        return;
+      }
+
+      const calendarLoads = await Promise.allSettled(
         calendarWidgets.map(async (widget) => {
           const [configResponse, eventsResponse] = await Promise.all([
             fetch(`/api/calendar/source?widgetId=${encodeURIComponent(widget.id)}`, {
@@ -439,21 +427,49 @@ export default function DashboardPage() {
       const nextSelectionsByWidget: Record<string, string[]> = {};
       const nextEventsCountByWidget: Record<string, number> = {};
 
-      calendarLoads.forEach((calendarLoad) => {
-        nextEventsByWidget[calendarLoad.widgetId] = calendarLoad.events;
-        nextErrorsByWidget[calendarLoad.widgetId] = calendarLoad.error;
-        nextSelectionsByWidget[calendarLoad.widgetId] = calendarLoad.selectedSourceIds;
-        nextEventsCountByWidget[calendarLoad.widgetId] = calendarLoad.nextEventsCount;
+      calendarLoads.forEach((result) => {
+        if (result.status === "fulfilled") {
+          nextEventsByWidget[result.value.widgetId] = result.value.events;
+          nextErrorsByWidget[result.value.widgetId] = result.value.error;
+          nextSelectionsByWidget[result.value.widgetId] = result.value.selectedSourceIds;
+          nextEventsCountByWidget[result.value.widgetId] = result.value.nextEventsCount;
+        }
       });
 
+      setCalendarEventsByWidget(nextEventsByWidget);
+      setCalendarErrorsByWidget(nextErrorsByWidget);
+      setCalendarSelectionsByWidget(nextSelectionsByWidget);
+      setCalendarNextEventsCountByWidget(nextEventsCountByWidget);
+    } catch {
+      // calendar load failure must not block dashboard
+    }
+  }
+
+  async function loadDashboardData() {
+    setDashboardError(null);
+
+    try {
+      const [settingsResponse, widgetsResponse, notesResponse] = await Promise.all([
+        fetch("/api/settings", {
+          cache: "no-store"
+        }),
+        fetch("/api/widgets", {
+          cache: "no-store"
+        }),
+        fetch("/api/notes", {
+          cache: "no-store"
+        })
+      ]);
+
+      const settingsData = await parseJsonResponse<{ settings: Settings }>(settingsResponse);
+      const widgetsData = await parseJsonResponse<{ widgets: Widget[] }>(widgetsResponse);
+      const notesData = await parseJsonResponse<{ notes: NoteBoardItem[] }>(notesResponse);
+
       setSettings(settingsData.settings);
       setWidgets(widgetsData.widgets);
       setNotes(notesData.notes);
-      setCalendarEventsByWidget(nextEventsByWidget);
-      setCalendarErrorsByWidget(nextErrorsByWidget);
-      setCalendarSources(allSourcesData.sources);
-      setCalendarSelectionsByWidget(nextSelectionsByWidget);
-      setCalendarNextEventsCountByWidget(nextEventsCountByWidget);
+
+      void loadCalendarData(widgetsData.widgets);
     } catch (error) {
       setDashboardError(error instanceof Error ? error.message : "Dashboard konnte nicht geladen werden.");
     }