diff --git a/components/calendar/calendar-client.tsx b/components/calendar/calendar-client.tsx
index 790f3f8..7e29fd5 100644
--- a/components/calendar/calendar-client.tsx
+++ b/components/calendar/calendar-client.tsx
@@ -994,32 +994,26 @@ export function CalendarClient({ initialCalendars, userId, userProfile }: Calend
       const endDate = new Date(startDate);
       endDate.setHours(startDate.getHours() + 1);
       
-      // If no calendar is selected, use the first available calendar
-      if (!selectedCalendarId && calendars.length > 0) {
-        const firstCalendar = calendars[0];
-        setSelectedCalendarId(firstCalendar.id);
-        
-        setEventForm({
-          title: "",
-          description: null,
-          start: startDate.toISOString(),
-          end: endDate.toISOString(),
-          allDay: false,
-          location: null,
-          calendarId: firstCalendar.id
-        });
-      } else {
-        setEventForm({
-          title: "",
-          description: null,
-          start: startDate.toISOString(),
-          end: endDate.toISOString(),
-          allDay: false,
-          location: null,
-          calendarId: selectedCalendarId
-        });
+      // Get available calendars and use the first one if needed
+      const availableCalendarsList = getAvailableCalendars();
+      const calendarToUse = selectedCalendarId && availableCalendarsList.some(cal => cal.id === selectedCalendarId)
+        ? selectedCalendarId
+        : (availableCalendarsList[0]?.id || calendars[0]?.id);
+      
+      if (calendarToUse && calendarToUse !== selectedCalendarId) {
+        setSelectedCalendarId(calendarToUse);
       }
       
+      setEventForm({
+        title: "",
+        description: null,
+        start: startDate.toISOString(),
+        end: endDate.toISOString(),
+        allDay: false,
+        location: null,
+        calendarId: calendarToUse
+      });
+      
       setIsEventModalOpen(true);
       lastClickDateRef.current = null;
     } else {
@@ -1050,33 +1044,26 @@ export function CalendarClient({ initialCalendars, userId, userProfile }: Calend
     selectDate.setHours(0, 0, 0, 0);
     setSelectedDate(selectDate);
     
-    // If no calendar is selected, use the first available calendar
-    if (!selectedCalendarId && calendars.length > 0) {
-      const firstCalendar = calendars[0];
-      console.log("No calendar selected, selecting first calendar:", firstCalendar);
-      setSelectedCalendarId(firstCalendar.id);
-      
-      setEventForm({
-        title: "",
-        description: null,
-        start: startDate.toISOString(),
-        end: endDate.toISOString(),
-        allDay: selectInfo.allDay,
-        location: null,
-        calendarId: firstCalendar.id
-      });
-    } else {
-      setEventForm({
-        title: "",
-        description: null,
-        start: startDate.toISOString(),
-        end: endDate.toISOString(),
-        allDay: selectInfo.allDay,
-        location: null,
-        calendarId: selectedCalendarId
-      });
+    // Get available calendars and use the first one if needed
+    const availableCalendarsList = getAvailableCalendars();
+    const calendarToUse = selectedCalendarId && availableCalendarsList.some(cal => cal.id === selectedCalendarId)
+      ? selectedCalendarId
+      : (availableCalendarsList[0]?.id || calendars[0]?.id);
+    
+    if (calendarToUse && calendarToUse !== selectedCalendarId) {
+      setSelectedCalendarId(calendarToUse);
     }
     
+    setEventForm({
+      title: "",
+      description: null,
+      start: startDate.toISOString(),
+      end: endDate.toISOString(),
+      allDay: selectInfo.allDay || false,
+      location: null,
+      calendarId: calendarToUse
+    });
+    
     setIsEventModalOpen(true);
   };
 
@@ -1085,6 +1072,15 @@ export function CalendarClient({ initialCalendars, userId, userProfile }: Calend
     const startDate = new Date(event.start);
     const endDate = new Date(event.end || event.start);
 
+    const eventCalendarId = event.extendedProps.calendarId;
+    const availableCalendars = getAvailableCalendars();
+    
+    // Check if the event's calendar is still available for editing
+    const canEditEventCalendar = availableCalendars.some(cal => cal.id === eventCalendarId);
+    
+    // If not available, use the first available calendar instead
+    const calendarIdToUse = canEditEventCalendar ? eventCalendarId : (availableCalendars[0]?.id || eventCalendarId);
+
     setSelectedEvent(event.extendedProps.originalEvent);
     setEventForm({
       title: event.title,
@@ -1093,7 +1089,7 @@ export function CalendarClient({ initialCalendars, userId, userProfile }: Calend
       end: endDate.toISOString().slice(0, 16),
       allDay: event.isAllDay,
       location: event.extendedProps.location,
-      calendarId: event.extendedProps.calendarId,
+      calendarId: calendarIdToUse,
     });
     setIsEventModalOpen(true);
   };
@@ -1248,6 +1244,59 @@ export function CalendarClient({ initialCalendars, userId, userProfile }: Calend
     return calendar.name;
   };
 
+  // Check if user can create/edit events in a mission calendar
+  const canEditMissionCalendar = (calendar: CalendarWithMission): boolean => {
+    // If not a mission calendar, allow
+    if (!calendar.missionId || !calendar.mission) {
+      return true;
+    }
+
+    const mission = calendar.mission;
+    
+    // Check if user is the creator
+    if (mission.creatorId === userId) {
+      return true;
+    }
+
+    // Check if user has one of the guardian roles
+    const guardianRoles = ['gardien-temps', 'gardien-parole', 'gardien-memoire'];
+    const userMissionRole = mission.missionUsers?.find(
+      mu => mu.userId === userId && guardianRoles.includes(mu.role)
+    );
+
+    return !!userMissionRole;
+  };
+
+  // Get available calendars for event creation/editing
+  const getAvailableCalendars = (): CalendarWithMission[] => {
+    return calendars.filter(cal => {
+      const calWithMission = cal as CalendarWithMission;
+      
+      // Always allow "Mon Calendrier"
+      if (cal.name === "Mon Calendrier") {
+        return true;
+      }
+
+      // Always allow Microsoft synced calendars
+      if (calWithMission.syncConfig?.syncEnabled && calWithMission.syncConfig?.mailCredential) {
+        return true;
+      }
+
+      // Always allow group calendars
+      if (cal.name?.startsWith("Groupe:")) {
+        return true;
+      }
+
+      // For mission calendars, check permissions
+      if (cal.name?.startsWith("Mission:")) {
+        return canEditMissionCalendar(calWithMission);
+      }
+
+      // Allow other calendars by default
+      return true;
+    });
+  };
+
   // Update CalendarSelector to handle visibility - displayed as a left column
   const CalendarSelector = () => (
     <div className="flex flex-col gap-2 mb-4">
@@ -1892,45 +1941,51 @@ export function CalendarClient({ initialCalendars, userId, userProfile }: Calend
 
             <div className="space-y-2">
               <Label className="text-base font-semibold text-gray-800">Calendrier</Label>
-              <div className="grid grid-cols-2 gap-2">
-                {calendars.map((cal) => {
-                  const calWithMission = cal as CalendarWithMission;
-                  const label = getCalendarDisplayName(calWithMission);
-                  return (
-                  <button
-                    key={cal.id}
-                    type="button"
-                    onClick={() => {
-                      setEventForm(prev => ({
-                        ...prev,
-                        calendarId: cal.id
-                      }));
-                    }}
-                    className={`flex items-center gap-2 px-3 py-2 rounded-lg transition-all ${
-                      eventForm.calendarId === cal.id
-                        ? 'bg-white ring-2 ring-primary'
-                        : 'bg-white hover:bg-gray-50 border border-gray-200'
-                    }`}
-                  >
-                    <div 
-                      className="w-3 h-3 rounded-full" 
-                      style={{ backgroundColor: cal.color }}
-                    />
-                    <span className={`text-sm ${
-                      eventForm.calendarId === cal.id 
-                        ? 'font-medium text-gray-900' 
-                        : 'text-gray-700'
-                    }`}>
-                      {label}
-                    </span>
-                    {calWithMission.syncConfig?.syncEnabled && (
-                      <Badge variant="outline" className="ml-auto text-[10px] px-1 py-0.5 border-blue-400 text-blue-600">
-                        Sync
-                      </Badge>
-                    )}
-                  </button>
-                );})}
-              </div>
+              <ScrollArea className="max-h-64 border border-gray-200 rounded-lg">
+                <div className="space-y-1 p-2">
+                  {getAvailableCalendars().map((cal) => {
+                    const calWithMission = cal as CalendarWithMission;
+                    const label = getCalendarDisplayName(calWithMission);
+                    return (
+                      <button
+                        key={cal.id}
+                        type="button"
+                        onClick={() => {
+                          setEventForm(prev => ({
+                            ...prev,
+                            calendarId: cal.id
+                          }));
+                        }}
+                        className={`w-full flex items-center gap-3 px-3 py-2.5 rounded-lg transition-all text-left ${
+                          eventForm.calendarId === cal.id
+                            ? 'bg-blue-50 ring-2 ring-blue-500 border border-blue-200'
+                            : 'bg-white hover:bg-gray-50 border border-gray-200'
+                        }`}
+                      >
+                        <div 
+                          className="w-4 h-4 rounded-full flex-shrink-0" 
+                          style={{ backgroundColor: cal.color }}
+                        />
+                        <span className={`text-sm flex-1 ${
+                          eventForm.calendarId === cal.id 
+                            ? 'font-medium text-gray-900' 
+                            : 'text-gray-700'
+                        }`}>
+                          {label}
+                        </span>
+                        {calWithMission.syncConfig?.syncEnabled && (
+                          <Badge variant="outline" className="text-[10px] px-1.5 py-0.5 border-blue-400 text-blue-600 flex-shrink-0">
+                            Sync
+                          </Badge>
+                        )}
+                        {eventForm.calendarId === cal.id && (
+                          <Check className="w-4 h-4 text-blue-600 flex-shrink-0" />
+                        )}
+                      </button>
+                    );
+                  })}
+                </div>
+              </ScrollArea>
             </div>
 
             <div className="grid grid-cols-2 gap-4">