diff --git a/app/agenda/page.tsx b/app/agenda/page.tsx
index 6642c10..f48885c 100644
--- a/app/agenda/page.tsx
+++ b/app/agenda/page.tsx
@@ -63,7 +63,8 @@ export default async function CalendarPage() {
             { name: { in: ["Privée", "Default"] } },
             { 
               syncConfig: { 
-                isNot: null
+                isNot: null,
+                syncEnabled: true  // Also check that sync is enabled
               } 
             }
           ]
@@ -140,6 +141,19 @@ export default async function CalendarPage() {
   // Extract mission calendars
   const missionCalendars = missionUserRelations.flatMap(mu => mu.mission.calendars);
   
+  // Debug: Log calendar filtering
+  console.log('[AGENDA] Calendar filtering:', {
+    personalCalendarsCount: personalCalendars.length,
+    personalCalendars: personalCalendars.map(cal => ({
+      id: cal.id,
+      name: cal.name,
+      hasSyncConfig: !!cal.syncConfig,
+      syncEnabled: cal.syncConfig?.syncEnabled,
+      provider: cal.syncConfig?.provider,
+    })),
+    missionCalendarsCount: missionCalendars.length,
+  });
+  
   // Combine personal and mission calendars
   let calendars = [...personalCalendars, ...missionCalendars];
 
diff --git a/app/api/events/route.ts b/app/api/events/route.ts
index 212d4b5..52488d8 100644
--- a/app/api/events/route.ts
+++ b/app/api/events/route.ts
@@ -2,6 +2,8 @@ import { NextRequest, NextResponse } from "next/server";
 import { getServerSession } from "next-auth/next";
 import { authOptions } from "@/app/api/auth/options";
 import { prisma } from "@/lib/prisma";
+import { updateMicrosoftEvent } from "@/lib/services/microsoft-calendar-sync";
+import { logger } from "@/lib/logger";
 
 // Helper function to check if user can manage events in a mission calendar
 async function canManageMissionCalendar(userId: string, calendarId: string): Promise<boolean> {
@@ -130,7 +132,7 @@ export async function PUT(req: NextRequest) {
       );
     }
 
-    // Verify calendar ownership
+    // Verify calendar ownership and get event with sync config
     const calendar = await prisma.calendar.findFirst({
       where: {
         id: calendarId,
@@ -141,6 +143,11 @@ export async function PUT(req: NextRequest) {
           where: {
             id
           }
+        },
+        syncConfig: {
+          include: {
+            mailCredential: true
+          }
         }
       }
     });
@@ -169,6 +176,9 @@ export async function PUT(req: NextRequest) {
       }
     }
 
+    const existingEvent = calendar.events[0];
+    
+    // Update event in local database
     const event = await prisma.event.update({
       where: { id },
       data: {
@@ -182,6 +192,86 @@ export async function PUT(req: NextRequest) {
       },
     });
 
+    // If event has externalEventId and calendar has Microsoft sync, update Microsoft too
+    if (existingEvent.externalEventId && calendar.syncConfig && calendar.syncConfig.provider === 'microsoft' && calendar.syncConfig.syncEnabled) {
+      const syncConfig = calendar.syncConfig;
+      const mailCredential = syncConfig.mailCredential;
+      
+      if (mailCredential && mailCredential.use_oauth && mailCredential.refresh_token) {
+        try {
+          // Prepare Microsoft event data
+          const startDate = new Date(start);
+          const endDate = new Date(end);
+          
+          // Microsoft Graph API expects timezone-aware dates
+          const timeZone = Intl.DateTimeFormat().resolvedOptions().timeZone;
+          
+          const microsoftEventData: any = {
+            subject: title,
+          };
+          
+          if (allDay) {
+            // For all-day events, Microsoft uses date format
+            microsoftEventData.isAllDay = true;
+            microsoftEventData.start = {
+              date: startDate.toISOString().split('T')[0],
+              timeZone: 'UTC'
+            };
+            microsoftEventData.end = {
+              date: endDate.toISOString().split('T')[0],
+              timeZone: 'UTC'
+            };
+          } else {
+            // For timed events, use dateTime
+            microsoftEventData.isAllDay = false;
+            microsoftEventData.start = {
+              dateTime: startDate.toISOString(),
+              timeZone: timeZone
+            };
+            microsoftEventData.end = {
+              dateTime: endDate.toISOString(),
+              timeZone: timeZone
+            };
+          }
+          
+          if (description) {
+            microsoftEventData.body = {
+              contentType: 'HTML',
+              content: description
+            };
+          }
+          
+          if (location) {
+            microsoftEventData.location = {
+              displayName: location
+            };
+          }
+          
+          // Update Microsoft event
+          await updateMicrosoftEvent(
+            session.user.id,
+            mailCredential.email,
+            syncConfig.externalCalendarId || '',
+            existingEvent.externalEventId,
+            microsoftEventData
+          );
+          
+          logger.info('Successfully synced event update to Microsoft', {
+            eventId: id,
+            externalEventId: existingEvent.externalEventId,
+            email: mailCredential.email,
+          });
+        } catch (syncError: any) {
+          // Log error but don't fail the request - local update succeeded
+          logger.error('Failed to sync event update to Microsoft', {
+            eventId: id,
+            externalEventId: existingEvent.externalEventId,
+            error: syncError instanceof Error ? syncError.message : String(syncError),
+          });
+        }
+      }
+    }
+
     console.log("Updated event:", event);
     return NextResponse.json(event);
   } catch (error) {
diff --git a/lib/services/microsoft-calendar-sync.ts b/lib/services/microsoft-calendar-sync.ts
index 6f9bf3b..e230b7f 100644
--- a/lib/services/microsoft-calendar-sync.ts
+++ b/lib/services/microsoft-calendar-sync.ts
@@ -377,6 +377,77 @@ export function convertMicrosoftEventToCalDAV(microsoftEvent: MicrosoftEvent): {
   };
 }
 
+/**
+ * Update a Microsoft calendar event via Graph API
+ */
+export async function updateMicrosoftEvent(
+  userId: string,
+  email: string,
+  calendarId: string,
+  eventId: string,
+  eventData: {
+    subject?: string;
+    body?: string;
+    start?: { dateTime: string; timeZone: string };
+    end?: { dateTime: string; timeZone: string };
+    location?: { displayName: string };
+    isAllDay?: boolean;
+  }
+): Promise<void> {
+  try {
+    const accessToken = await getMicrosoftGraphClient(userId, email);
+    
+    // Build the update payload
+    const payload: any = {};
+    if (eventData.subject !== undefined) payload.subject = eventData.subject;
+    if (eventData.body !== undefined) {
+      payload.body = {
+        contentType: 'HTML',
+        content: eventData.body,
+      };
+    }
+    if (eventData.start) payload.start = eventData.start;
+    if (eventData.end) payload.end = eventData.end;
+    if (eventData.location) payload.location = eventData.location;
+    if (eventData.isAllDay !== undefined) payload.isAllDay = eventData.isAllDay;
+    
+    const url = `https://graph.microsoft.com/v1.0/me/calendars/${calendarId}/events/${eventId}`;
+    
+    logger.info('Updating Microsoft event', {
+      userId,
+      email,
+      calendarId,
+      eventId,
+      url,
+      payload: JSON.stringify(payload),
+    });
+    
+    await axios.patch(url, payload, {
+      headers: {
+        Authorization: `Bearer ${accessToken}`,
+        'Content-Type': 'application/json',
+      },
+    });
+    
+    logger.info('Successfully updated Microsoft event', {
+      userId,
+      email,
+      eventId,
+    });
+  } catch (error: any) {
+    logger.error('Error updating Microsoft event', {
+      userId,
+      email,
+      calendarId,
+      eventId,
+      error: error instanceof Error ? error.message : String(error),
+      responseStatus: error.response?.status,
+      responseData: error.response?.data,
+    });
+    throw error;
+  }
+}
+
 /**
  * Sync events from Microsoft calendar to local Prisma calendar
  */