refactor: reduce CalDAV sync to login and manual sync button only

- Remove auto-login sync in AuthGuard
- Remove 10s interval sync and syncAndReload in calendar tab
- Remove lazy syncOnce pattern in ChatService AI callbacks
- Remove CaldavService dependency from ChatService constructor

apps/client/src/app/(tabs)/calendar.tsx

@@ -17,7 +17,6 @@ import { Ionicons } from "@expo/vector-icons";
 import { useThemeStore } from "../../stores/ThemeStore";
 import BaseBackground from "../../components/BaseBackground";
 import { EventService } from "../../services";
-import { CaldavConfigService } from "../../services/CaldavConfigService";
 import { useEventsStore } from "../../stores";
 import { useDropdownPosition } from "../../hooks/useDropdownPosition";
 
@@ -108,25 +107,11 @@ const Calendar = () => {
     }
   }, [monthIndex, currentYear, setEvents]);
 
-  // Sync CalDAV in background, then reload events
+  // Load events from DB on focus
-  const syncAndReload = useCallback(async () => {
-    try {
-      await CaldavConfigService.sync();
-      await loadEvents();
-    } catch {
-      // Sync failed — not critical
-    }
-  }, [loadEvents]);
-
-  // Load events instantly on focus, then sync in background periodically
   useFocusEffect(
     useCallback(() => {
       loadEvents();
-      syncAndReload();
+    }, [loadEvents]),
-
-      const interval = setInterval(syncAndReload, 10_000);
-      return () => clearInterval(interval);
-    }, [loadEvents, syncAndReload]),
   );
 
   // Re-open overlay after back navigation from editEvent

apps/client/src/components/AuthGuard.tsx

@@ -62,11 +62,6 @@ export const AuthGuard = ({ children }: AuthGuardProps) => {
       if (!useAuthStore.getState().isAuthenticated) return;
       await preloadAppData();
       setDataReady(true);
-      try {
-        await CaldavConfigService.sync();
-      } catch {
-        // No CalDAV config or sync failed — not critical
-      }
     };
     init();
   }, [loadStoredUser]);

apps/server/src/app.ts

@@ -63,12 +63,7 @@ const aiProvider = new GPTAdapter();
 const authService = new AuthService(userRepo);
 const eventService = new EventService(eventRepo);
 const caldavService = new CaldavService(caldavRepo, eventService);
-const chatService = new ChatService(
+const chatService = new ChatService(chatRepo, eventService, aiProvider);
-  chatRepo,
-  eventService,
-  aiProvider,
-  caldavService,
-);
 
 // Initialize controllers
 const authController = new AuthController(authService);

apps/server/src/services/ChatService.ts

@@ -14,7 +14,6 @@ import {
 } from "@calchat/shared";
 import { ChatRepository, AIProvider } from "./interfaces";
 import { EventService } from "./EventService";
-import { CaldavService } from "./CaldavService";
 import { getWeeksOverview, getMonthOverview } from "../utils/eventFormatters";
 
 type TestResponse = {
@@ -543,7 +542,6 @@ export class ChatService {
     private chatRepo: ChatRepository,
     private eventService: EventService,
     private aiProvider: AIProvider,
-    private caldavService: CaldavService,
   ) {}
 
   async processMessage(
@@ -578,32 +576,17 @@ export class ChatService {
         limit: 20,
       });
 
-      // Lazy CalDAV sync: only sync once when the AI first accesses event data
-      let hasSynced = false;
-      const syncOnce = async () => {
-        if (hasSynced) return;
-        hasSynced = true;
-        try {
-          await this.caldavService.sync(userId);
-        } catch {
-          // CalDAV sync is not critical for AI responses
-        }
-      };
-
       response = await this.aiProvider.processMessage(data.content, {
         userId,
         conversationHistory: history,
         currentDate: new Date(),
         fetchEventsInRange: async (start, end) => {
-          await syncOnce();
           return this.eventService.getByDateRange(userId, start, end);
         },
         searchEvents: async (query) => {
-          await syncOnce();
           return this.eventService.searchByTitle(userId, query);
         },
         fetchEventById: async (eventId) => {
-          await syncOnce();
           return this.eventService.getById(eventId, userId);
         },
       });