diff --git a/backend/caldav_client.py b/backend/caldav_client.py
index d7a8db2..dc43b9e 100644
--- a/backend/caldav_client.py
+++ b/backend/caldav_client.py
@@ -237,31 +237,43 @@ def update_event(
             continue
 
         if "title" in data or "summary" in data:
-            component["SUMMARY"] = data.get("title", data.get("summary", ""))
+            if "SUMMARY" in component:
+                del component["SUMMARY"]
+            component.add("summary", data.get("title", data.get("summary", "")))
 
         if "start" in data:
+            if "DTSTART" in component:
+                del component["DTSTART"]
             if data.get("allDay"):
-                component["DTSTART"] = date.fromisoformat(data["start"][:10])
+                component.add("dtstart", date.fromisoformat(data["start"][:10]))
             else:
-                component["DTSTART"] = _parse_dt(data["start"])
+                component.add("dtstart", _parse_dt(data["start"]))
 
         if "end" in data:
+            if "DTEND" in component:
+                del component["DTEND"]
             if data.get("allDay"):
-                component["DTEND"] = date.fromisoformat(data["end"][:10])
+                component.add("dtend", date.fromisoformat(data["end"][:10]))
             else:
-                component["DTEND"] = _parse_dt(data["end"])
+                component.add("dtend", _parse_dt(data["end"]))
 
         if "location" in data:
-            component["LOCATION"] = data["location"]
+            if "LOCATION" in component:
+                del component["LOCATION"]
+            component.add("location", data["location"])
         if "description" in data:
-            component["DESCRIPTION"] = data["description"]
+            if "DESCRIPTION" in component:
+                del component["DESCRIPTION"]
+            component.add("description", data["description"])
         if "color" in data:
-            component["X-CALENDARR-COLOR"] = data["color"]
+            if "X-CALENDARR-COLOR" in component:
+                del component["X-CALENDARR-COLOR"]
+            component.add("x-calendarr-color", data["color"])
         if "rrule" in data:
-            if data["rrule"]:
-                component["RRULE"] = _parse_rrule_str(data["rrule"])
-            elif "RRULE" in component:
+            if "RRULE" in component:
                 del component["RRULE"]
+            if data["rrule"]:
+                component.add("rrule", _parse_rrule_str(data["rrule"]))
 
         if "exdate" in data and data["exdate"]:
             # Parse YYYYMMDD string into a proper EXDATE
diff --git a/frontend/js/calendar.js b/frontend/js/calendar.js
index a1e49f7..b2f8caf 100644
--- a/frontend/js/calendar.js
+++ b/frontend/js/calendar.js
@@ -994,8 +994,8 @@ function showEventPopup(ev, anchor) {
   popup.style.left = Math.max(8, left) + 'px';
   popup.style.top  = Math.max(8, top)  + 'px';
 
-  // Hide edit/delete for read-only iCal subscription events
-  const isReadOnly = (ev.source === 'ical');
+  // Hide edit/delete for read-only sources (iCal subscriptions, Home Assistant)
+  const isReadOnly = (ev.source === 'ical' || ev.source === 'homeassistant');
   document.getElementById('popup-edit').style.display = isReadOnly ? 'none' : '';
   document.getElementById('popup-delete').style.display = isReadOnly ? 'none' : '';
 
@@ -1134,7 +1134,7 @@ function openNewEventModal(date) {
 }
 
 function openEditEventModal(ev) {
-  if (ev.source === 'ical') { showToast(t('event_readonly'), true); return; }
+  if (ev.source === 'ical' || ev.source === 'homeassistant') { showToast(t('event_readonly'), true); return; }
   state.editingEvent = ev;
   state.selectedEventColor = ev.color || '';
 
@@ -1426,11 +1426,9 @@ function bindEventModal() {
           await api.put(`/local/events/${encodeURIComponent(ev.id)}`,
             { title, start, end, allDay, location: loc, description: desc, color: color || null, rrule: rrule || '' }
           );
-        } else if (ev.source === 'ical') {
-          const subId = ev.calendar_id.replace('ical-', '');
-          await api.put(`/ical/events/${subId}/${encodeURIComponent(ev.id)}`,
-            { title, start, end, allDay, location: loc, description: desc, color: color || null }
-          );
+        } else if (ev.source === 'ical' || ev.source === 'homeassistant') {
+          showToast(t('event_readonly'), true);
+          return;
         } else {
           await api.put(
             `/caldav/events/${encodeURIComponent(ev.id)}?event_url=${encodeURIComponent(ev.url)}&calendar_id=${ev.calendar_id}`,