v0.11.6 added event form rules.

frontend/src/components/MobileEventForm.jsx

@@ -226,6 +226,7 @@ export default function MobileEventForm({ event, eventTypes, userGroups, selecte
     : null;
   // Track previous typeId so we can detect a type change vs start time change
   const prevTypeIdRef = useRef(event?.event_type_id ? String(event.event_type_id) : '');
+  const mountedRef = useRef(false);
   const [allDay, setAllDay] = useState(!!event?.all_day);
   const [track, setTrack] = useState(!!event?.track_availability);
   const [isPrivate, setIsPrivate] = useState(event ? !event.is_public : false);
@@ -262,13 +263,13 @@ export default function MobileEventForm({ event, eventTypes, userGroups, selecte
     finally { setSavingType(false); }
   };
 
-  // Auto-calculate end date/time when start date, start time, or event type changes.
-  // Rules:
-  //   - New event: use eventType duration (default 1hr)
-  //   - Editing + type changed: use new eventType duration
-  //   - Editing + type same: use saved event duration (preserve original length)
-  //   - Always: if end < start, advance end date by 1 day (overnight events)
+  // Mark mounted after first render
+  useEffect(() => { mountedRef.current = true; }, []);
+
+  // Auto-calculate end date/time ONLY when start date, start time, or type actually changes.
+  // Skips initial mount so edit mode fields are never overwritten on open.
   useEffect(() => {
+    if(!mountedRef.current) return; // skip initial mount — never auto-change on open
     if(!sd||!st) return;
     const start = buildISO(sd,st);
     if(!start) return;
@@ -278,11 +279,11 @@ export default function MobileEventForm({ event, eventTypes, userGroups, selecte
 
     let durMins;
     if(!event || typeChanged) {
-      // New event or type change: use eventType duration
+      // New event or explicit type change: use eventType duration
       const typ = localTypes.find(t=>t.id===Number(typeId));
       durMins = (typ?.default_duration_hrs||1) * 60;
     } else {
-      // Editing with same type: preserve the saved event duration
+      // Editing start date/time with same type: preserve saved duration
       durMins = savedDurMins || 60;
     }