fix(calendar): send invitation emails client-side via iMIP

stores/calendar-store.ts

@@ -487,9 +487,16 @@ export const useCalendarStore = create<CalendarStore>()(
           }
 
           set((state) => ({ events: [...state.events, mappedCreated] }));
-          // Invitation emails are sent by the server: `sendSchedulingMessages`
-          // on CalendarEvent/set makes Stalwart queue the iTIP REQUEST itself.
-          // Sending a client-side iMIP copy here produced duplicate emails.
+          // Send invitation emails (iTIP REQUEST) to participants. Stalwart
+          // 0.16 does not reliably queue these server-side via
+          // `sendSchedulingMessages`, so fall back to a client-side iMIP send.
+          if (sendSchedulingMessages && created.participants) {
+            try {
+              await client.sendImipInvitation(created);
+            } catch (e) {
+              debug.error('Failed to send invitation emails:', e);
+            }
+          }
           return mappedCreated;
         } catch (error) {
           debug.error('Failed to create event:', error);
@@ -559,9 +566,23 @@ export const useCalendarStore = create<CalendarStore>()(
               return merged;
             }),
           }));
-          // Update emails (iTIP REQUEST/REPLY) are sent by the server via the
-          // `sendSchedulingMessages` argument already passed above - a manual
-          // iMIP send here produced duplicate emails.
+          // Send invitation emails (iTIP REQUEST) when scheduling is requested.
+          if (sendSchedulingMessages) {
+            const mergedParticipants = cleanUpdates.participants ?? storeEvent?.participants;
+            if (mergedParticipants) {
+              const eventForInvitation = {
+                ...(storeEvent ?? {}),
+                ...cleanUpdates,
+                id: realId,
+                participants: mergedParticipants,
+              } as CalendarEvent;
+              try {
+                await client.sendImipInvitation(eventForInvitation);
+              } catch (e) {
+                debug.error('Failed to send invitation emails:', e);
+              }
+            }
+          }
         } catch (error) {
           debug.error('Failed to update event:', error);
           if (isNetworkError(error)) {
@@ -808,9 +829,6 @@ export const useCalendarStore = create<CalendarStore>()(
         try {
           // Resolve shared event IDs and client-side expanded occurrence IDs
           client = resolveAccountClient(client, storeEvent?.localAccountId);
-          // Cancellation emails (iTIP CANCEL) are sent by the server via the
-          // `sendSchedulingMessages` argument on the destroy below - a manual
-          // iMIP send here produced duplicate emails.
           debug.log('calendar', 'Calendar deleteEvent', {
             storeId: id,
             realId,
@@ -823,6 +841,14 @@ export const useCalendarStore = create<CalendarStore>()(
             events: state.events.filter(e => e.id !== id),
             selectedEventId: state.selectedEventId === id ? null : state.selectedEventId,
           }));
+          // Send cancellation emails (iTIP CANCEL) to participants.
+          if (sendSchedulingMessages && storeEvent?.participants) {
+            try {
+              await client.sendImipCancellation(storeEvent);
+            } catch (e) {
+              debug.error('Failed to send cancellation emails:', e);
+            }
+          }
         } catch (error) {
           debug.error('Failed to delete event:', error);
           if (isNetworkError(error)) {