diff --git a/backend/main.py b/backend/main.py
index 0ede6c1..ad1a5ca 100644
--- a/backend/main.py
+++ b/backend/main.py
@@ -406,7 +406,7 @@ async def serve_media(path: str, request: _Request):
         raise _HE(404, "Nicht gefunden.")
     return _media_response(filepath)
 
-APP_VER = "927"  # muss mit APP_VER in app.js übereinstimmen
+APP_VER = "928"  # muss mit APP_VER in app.js übereinstimmen
 
 @app.get("/.well-known/assetlinks.json")
 async def assetlinks():
diff --git a/backend/routes/dogs.py b/backend/routes/dogs.py
index cc86caf..405856f 100644
--- a/backend/routes/dogs.py
+++ b/backend/routes/dogs.py
@@ -191,23 +191,24 @@ async def get_welcome_dashboard(dog_id: int, user=Depends(get_current_user)):
             raise HTTPException(404, "Hund nicht gefunden.")
 
         # Hintergrundfoto: Querformat-Bilder bevorzugt, tagesweise rotierend
+        # user_id-Filter als zweite Sicherungsebene (dog_id-Ownership bereits oben geprüft)
         photos = conn.execute(
             """SELECT dm.url FROM diary_media dm
                JOIN diary d ON d.id = dm.diary_id
-               WHERE d.dog_id=? AND dm.media_type='image'
+               WHERE d.dog_id=? AND d.user_id=? AND dm.media_type='image'
                  AND dm.img_width IS NOT NULL AND dm.img_width > dm.img_height
                ORDER BY d.datum DESC, d.id DESC, dm.id ASC""",
-            (dog_id,)
+            (dog_id, user["id"])
         ).fetchall()
         # Fallback: Bilder ohne Dimensionsdaten (vor dem Backfill hochgeladen)
         if not photos:
             photos = conn.execute(
                 """SELECT dm.url FROM diary_media dm
                    JOIN diary d ON d.id = dm.diary_id
-                   WHERE d.dog_id=? AND dm.media_type='image'
+                   WHERE d.dog_id=? AND d.user_id=? AND dm.media_type='image'
                      AND dm.img_width IS NULL
                    ORDER BY d.datum DESC, d.id DESC, dm.id ASC""",
-                (dog_id,)
+                (dog_id, user["id"])
             ).fetchall()
         random_photo = None
         if photos:
diff --git a/backend/static/js/app.js b/backend/static/js/app.js
index 6366a57..ba4c022 100644
--- a/backend/static/js/app.js
+++ b/backend/static/js/app.js
@@ -3,7 +3,7 @@
    Router, State-Management, Navigation, Initialisierung.
    ============================================================ */
 
-const APP_VER     = '927'; // ← bei jedem Deploy mit Frontend-Änderungen erhöhen
+const APP_VER     = '928'; // ← bei jedem Deploy mit Frontend-Änderungen erhöhen
 const APP_VERSION = '1.5.1'; // ← semantische Version, wird bei make release gesetzt
 const IS_STAGING  = location.hostname === 'staging.banyaro.app';
 // Cache-Bust-Parameter nach Update-Reload sofort entfernen
diff --git a/backend/static/js/pages/dog-profile.js b/backend/static/js/pages/dog-profile.js
index 9399085..8e18db5 100644
--- a/backend/static/js/pages/dog-profile.js
+++ b/backend/static/js/pages/dog-profile.js
@@ -1388,6 +1388,9 @@ window.Page_dog_profile = (() => {
         // Dog Switcher in Header + Sidebar aktualisieren
         App.renderDogSwitcher?.();
 
+        // Welten neu laden damit HUND-Welt den neuen Hund zeigt
+        window.Worlds?.refresh(_appState);
+
         await _render();
       });
     });
diff --git a/backend/static/js/worlds.js b/backend/static/js/worlds.js
index e032542..b640775 100644
--- a/backend/static/js/worlds.js
+++ b/backend/static/js/worlds.js
@@ -924,7 +924,8 @@ window.Worlds = (() => {
 
   async function _loadDailyImage(dog) {
     if (!dog) return null;
-    const todayKey = 'bg3_' + new Date().toISOString().slice(0, 10);
+    const userId   = _state?.user?.id || 'anon';
+    const todayKey = `bg3_${userId}_` + new Date().toISOString().slice(0, 10);
     const cached = _wLoad(todayKey);
     if (cached?.data) return cached.data;
     try {
@@ -1689,6 +1690,17 @@ window.Worlds = (() => {
     return String(s).replace(/&/g,'&amp;').replace(/</g,'&lt;').replace(/>/g,'&gt;').replace(/"/g,'&quot;');
   }
 
-  return { init, show, hide, navigateTo, openConfig: _openConfigModal, get _visible() { return _visible; } };
+  function refresh(appState) {
+    if (appState) _state = appState;
+    localStorage.removeItem('w3_dogs');
+    _bgUrl = null;
+    if (_visible) {
+      if (_cur === 0) _renderJetzt();
+      else if (_cur === 1) _renderHund();
+      else _renderWelt();
+    }
+  }
+
+  return { init, show, hide, navigateTo, refresh, openConfig: _openConfigModal, get _visible() { return _visible; } };
 
 })();
diff --git a/backend/static/sw.js b/backend/static/sw.js
index aa529d6..1f31d7d 100644
--- a/backend/static/sw.js
+++ b/backend/static/sw.js
@@ -3,7 +3,7 @@
    Offline-Cache + Push Notifications + Tile-Cache
    ============================================================ */
 
-const CACHE_VERSION = 'by-v927';
+const CACHE_VERSION = 'by-v928';
 const CACHE_STATIC  = `${CACHE_VERSION}-static`;
 const CACHE_TILES   = 'ban-yaro-tiles-v1';  // bleibt über SW-Updates erhalten
 const CACHE_API     = 'ban-yaro-api-v1';    // API-Response-Cache