diff --git a/app/(main)/[locale]/calendar/page.tsx b/app/(main)/[locale]/calendar/page.tsx
index 23eaebbd..b39f2796 100644
--- a/app/(main)/[locale]/calendar/page.tsx
+++ b/app/(main)/[locale]/calendar/page.tsx
@@ -71,7 +71,10 @@ type PendingScopeAction =
   | { type: "delete"; event: CalendarEvent; sendScheduling?: boolean };
 
 function isRecurringEvent(event: CalendarEvent): boolean {
-  return (event.recurrenceRules?.length ?? 0) > 0 || event.recurrenceId != null;
+  // Stalwart may return an empty-string `recurrenceId` for non-recurring events
+  // rather than null; treat that as non-recurring so editing doesn't route
+  // through the recurrence-scope flow for a plain single event.
+  return (event.recurrenceRules?.length ?? 0) > 0 || Boolean(event.recurrenceId);
 }
 
 export default function CalendarPage() {