feat: add recurring event deletion with three modes

Implement three deletion modes for recurring events:
- single: exclude specific occurrence via EXDATE mechanism
- future: set RRULE UNTIL to stop future occurrences
- all: delete entire event series

Changes include:
- Add exceptionDates field to CalendarEvent model
- Add RecurringDeleteMode type and DeleteRecurringEventDTO
- EventService.deleteRecurring() with mode-based logic using rrule library
- EventController DELETE endpoint accepts mode/occurrenceDate query params
- recurrenceExpander filters out exception dates during expansion
- AI tools support deleteMode and occurrenceDate for proposed deletions
- ChatService.confirmEvent() handles recurring delete modes
- New DeleteEventModal component for unified delete confirmation UI
- Calendar screen integrates modal for both recurring and non-recurring events

apps/server/src/services/ChatService.ts

@@ -10,11 +10,16 @@ import {
   UpdateEventDTO,
   EventAction,
   CreateMessageDTO,
+  RecurringDeleteMode,
 } from "@calchat/shared";
 import { ChatRepository, EventRepository, AIProvider } from "./interfaces";
+import { EventService } from "./EventService";
 import { getWeeksOverview, getMonthOverview } from "../utils/eventFormatters";
 
-type TestResponse = { content: string; proposedChanges?: ProposedEventChange[] };
+type TestResponse = {
+  content: string;
+  proposedChanges?: ProposedEventChange[];
+};
 
 // Test response index (cycles through responses)
 let responseIndex = 0;
@@ -25,8 +30,7 @@ const staticResponses: TestResponse[] = [
   // === MULTI-EVENT TEST RESPONSES ===
   // Response 0: 3 Meetings an verschiedenen Tagen
   {
-    content:
-      "Alles klar! Ich erstelle dir 3 Team-Meetings für diese Woche:",
+    content: "Alles klar! Ich erstelle dir 3 Team-Meetings für diese Woche:",
     proposedChanges: [
       {
         id: "multi-1-a",
@@ -62,8 +66,7 @@ const staticResponses: TestResponse[] = [
   },
   // Response 1: 5 Termine für einen Projekttag
   {
-    content:
-      "Ich habe deinen kompletten Projekttag am Dienstag geplant:",
+    content: "Ich habe deinen kompletten Projekttag am Dienstag geplant:",
     proposedChanges: [
       {
         id: "multi-2-a",
@@ -119,8 +122,7 @@ const staticResponses: TestResponse[] = [
   },
   // Response 2: 2 wiederkehrende Termine
   {
-    content:
-      "Ich erstelle dir zwei wiederkehrende Fitness-Termine:",
+    content: "Ich erstelle dir zwei wiederkehrende Fitness-Termine:",
     proposedChanges: [
       {
         id: "multi-3-a",
@@ -209,7 +211,8 @@ const staticResponses: TestResponse[] = [
           title: "Arzttermin Dr. Müller",
           startTime: getDay("Wednesday", 1, 9, 30),
           endTime: getDay("Wednesday", 1, 10, 30),
-          description: "Routineuntersuchung - Versichertenkarte nicht vergessen",
+          description:
+            "Routineuntersuchung - Versichertenkarte nicht vergessen",
         },
       },
     ],
@@ -403,6 +406,7 @@ export class ChatService {
   constructor(
     private chatRepo: ChatRepository,
     private eventRepo: EventRepository,
+    private eventService: EventService,
     private aiProvider: AIProvider,
   ) {}
 
@@ -462,9 +466,15 @@ export class ChatService {
     event?: CreateEventDTO,
     eventId?: string,
     updates?: UpdateEventDTO,
+    deleteMode?: RecurringDeleteMode,
+    occurrenceDate?: string,
   ): Promise<ChatResponse> {
     // Update specific proposal with respondedAction
-    await this.chatRepo.updateProposalResponse(messageId, proposalId, "confirm");
+    await this.chatRepo.updateProposalResponse(
+      messageId,
+      proposalId,
+      "confirm",
+    );
 
     // Perform the actual event operation
     let content: string;
@@ -478,10 +488,25 @@ export class ChatService {
         ? `Der Termin "${updatedEvent.title}" wurde aktualisiert.`
         : "Termin nicht gefunden.";
     } else if (action === "delete" && eventId) {
-      await this.eventRepo.delete(eventId);
+      // Use deleteRecurring for proper handling of recurring events
+      const mode = deleteMode || "all";
+      await this.eventService.deleteRecurring(
+        eventId,
+        userId,
+        mode,
+        occurrenceDate,
+      );
+
+      // Build appropriate response message
+      let deleteDescription = "";
+      if (deleteMode === "single") {
+        deleteDescription = " (dieses Vorkommen)";
+      } else if (deleteMode === "future") {
+        deleteDescription = " (dieses und zukünftige Vorkommen)";
+      }
       content = event?.title
-        ? `Der Termin "${event.title}" wurde gelöscht.`
-        : "Der Termin wurde gelöscht.";
+        ? `Der Termin "${event.title}"${deleteDescription} wurde gelöscht.`
+        : `Der Termin${deleteDescription} wurde gelöscht.`;
     } else {
       content = "Ungültige Aktion.";
     }

apps/server/src/services/EventService.ts

@@ -3,7 +3,9 @@ import {
   CreateEventDTO,
   UpdateEventDTO,
   ExpandedEvent,
+  RecurringDeleteMode,
 } from "@calchat/shared";
+import { RRule, rrulestr } from "rrule";
 import { EventRepository } from "./interfaces";
 import { expandRecurringEvents } from "../utils/recurrenceExpander";
 
@@ -67,4 +69,96 @@ export class EventService {
     }
     return this.eventRepo.delete(id);
   }
+
+  /**
+   * Delete a recurring event with different modes:
+   * - 'all': Delete the entire event (all occurrences)
+   * - 'single': Add the occurrence date to exception list (EXDATE)
+   * - 'future': Set UNTIL in RRULE to stop future occurrences
+   *
+   * @returns Updated event for 'single'/'future' modes, null for 'all' mode or if not found
+   */
+  async deleteRecurring(
+    id: string,
+    userId: string,
+    mode: RecurringDeleteMode,
+    occurrenceDate?: string,
+  ): Promise<CalendarEvent | null> {
+    const event = await this.eventRepo.findById(id);
+    if (!event || event.userId !== userId) {
+      return null;
+    }
+
+    // For non-recurring events, always delete completely
+    if (!event.isRecurring || !event.recurrenceRule) {
+      await this.eventRepo.delete(id);
+      return null;
+    }
+
+    switch (mode) {
+      case "all":
+        await this.eventRepo.delete(id);
+        return null;
+
+      case "single":
+        if (!occurrenceDate) {
+          throw new Error("occurrenceDate required for single delete mode");
+        }
+        // Add to exception dates
+        return this.eventRepo.addExceptionDate(id, occurrenceDate);
+
+      case "future":
+        if (!occurrenceDate) {
+          throw new Error("occurrenceDate required for future delete mode");
+        }
+        // Check if this is the first occurrence
+        const startDateKey = this.formatDateKey(new Date(event.startTime));
+        if (occurrenceDate <= startDateKey) {
+          // Deleting from first occurrence = delete all
+          await this.eventRepo.delete(id);
+          return null;
+        }
+        // Set UNTIL to the day before the occurrence
+        const updatedRule = this.addUntilToRRule(
+          event.recurrenceRule,
+          occurrenceDate,
+        );
+        return this.eventRepo.update(id, { recurrenceRule: updatedRule });
+
+      default:
+        throw new Error(`Unknown delete mode: ${mode}`);
+    }
+  }
+
+  /**
+   * Add or replace UNTIL clause in an RRULE string.
+   * The UNTIL is set to 23:59:59 of the day before the occurrence date.
+   */
+  private addUntilToRRule(ruleString: string, occurrenceDate: string): string {
+    // Normalize: ensure we have RRULE: prefix for parsing
+    const normalizedRule = ruleString.replace(/^RRULE:/i, "");
+    const parsedRule = rrulestr(`RRULE:${normalizedRule}`);
+
+    // Calculate the day before the occurrence at 23:59:59
+    const untilDate = new Date(occurrenceDate);
+    untilDate.setDate(untilDate.getDate() - 1);
+    untilDate.setHours(23, 59, 59, 0);
+
+    // Create new rule with UNTIL, removing COUNT (they're mutually exclusive)
+    const newRule = new RRule({
+      ...parsedRule.options,
+      count: undefined,
+      until: untilDate,
+    });
+
+    // toString() returns "RRULE:...", we store without prefix
+    return newRule.toString().replace(/^RRULE:/, "");
+  }
+
+  private formatDateKey(date: Date): string {
+    const year = date.getFullYear();
+    const month = String(date.getMonth() + 1).padStart(2, "0");
+    const day = String(date.getDate()).padStart(2, "0");
+    return `${year}-${month}-${day}`;
+  }
 }

apps/server/src/services/interfaces/EventRepository.ts

@@ -11,4 +11,5 @@ export interface EventRepository {
   create(userId: string, data: CreateEventDTO): Promise<CalendarEvent>;
   update(id: string, data: UpdateEventDTO): Promise<CalendarEvent | null>;
   delete(id: string): Promise<boolean>;
+  addExceptionDate(id: string, date: string): Promise<CalendarEvent | null>;
 }