fix: recurring event display and AI query improvements

- Use occurrenceStart instead of startTime in getEventsInRange so
  recurring events show their actual occurrence date to the AI
- Add lazy CalDAV sync in ChatService (syncOnce before first DB access)
- Add CaldavService.sync() with internal config check (silent no-op)
- Show German recurrence description (e.g. "Jede Woche") instead of
  generic "Wiederkehrend" in EventCardBase via formatRecurrenceRule()
- Move RepeatType and REPEAT_TYPE_LABELS from editEvent to shared
- Separate calendar overlay useFocusEffect from event loading

apps/server/src/ai/utils/toolExecutor.ts

@@ -234,7 +234,7 @@ export async function executeToolCall(
 
       const eventsText = events
         .map((e) => {
-          const start = new Date(e.startTime);
+          const start = new Date(e.occurrenceStart);
           const recurrenceInfo = e.recurrenceRule ? " (wiederkehrend)" : "";
           return `- ${e.title} (ID: ${e.id}) am ${formatDate(start)} um ${formatTime(start)} Uhr${recurrenceInfo}`;
         })

apps/server/src/app.ts

@@ -62,12 +62,13 @@ const aiProvider = new GPTAdapter();
 // Initialize services
 const authService = new AuthService(userRepo);
 const eventService = new EventService(eventRepo);
+const caldavService = new CaldavService(caldavRepo, eventService);
 const chatService = new ChatService(
   chatRepo,
   eventService,
   aiProvider,
+  caldavService,
 );
-const caldavService = new CaldavService(caldavRepo, eventService);
 
 // Initialize controllers
 const authController = new AuthController(authService);

apps/server/src/services/CaldavService.ts

@@ -257,4 +257,14 @@ export class CaldavService {
   async deleteConfig(userId: string) {
     return await this.caldavRepo.deleteByUserId(userId);
   }
+
+  /**
+   * Sync with CalDAV server if config exists. Silent no-op if no config.
+   */
+  async sync(userId: string): Promise<void> {
+    const config = await this.getConfig(userId);
+    if (!config) return;
+    await this.pushAll(userId);
+    await this.pullEvents(userId);
+  }
 }

apps/server/src/services/ChatService.ts

@@ -14,6 +14,7 @@ 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 = {
@@ -543,6 +544,7 @@ export class ChatService {
     private chatRepo: ChatRepository,
     private eventService: EventService,
     private aiProvider: AIProvider,
+    private caldavService: CaldavService,
   ) {}
 
   async processMessage(
@@ -573,17 +575,32 @@ 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);
         },
       });