diff --git a/frontend/src/pages/constructor.tsx b/frontend/src/pages/constructor.tsx
index dc268a6..40796d5 100644
--- a/frontend/src/pages/constructor.tsx
+++ b/frontend/src/pages/constructor.tsx
@@ -392,7 +392,18 @@ const resolveDurationWithFallback = async (
   }
 
   try {
-    const response = await axios.get(playbackUrl, { responseType: 'blob' });
+    const requestUrl =
+      playbackUrl.startsWith('http://') || playbackUrl.startsWith('https://')
+        ? playbackUrl
+        : playbackUrl.replace(/^\/api(?=\/)/, '');
+
+    const token =
+      typeof window !== 'undefined' ? localStorage.getItem('token') || '' : '';
+    const response = await axios.get(requestUrl, {
+      responseType: 'blob',
+      headers: token ? { Authorization: `Bearer ${token}` } : undefined,
+    });
+
     const blobUrl = URL.createObjectURL(response.data);
     try {
       const blobDuration = await readMediaDuration(blobUrl, mediaType);
@@ -538,7 +549,6 @@ const createDefaultElement = (
       navType: getNavigationButtonKind(type),
       iconUrl: '',
       transitionReverseMode: 'auto_reverse',
-      transitionDurationSec: 0.7,
     };
   }
 
@@ -739,6 +749,7 @@ const ConstructorPage = ({ mode = 'constructor' }: ConstructorPageProps) => {
     useState<EditorMenuItem>('none');
   const [transitionPreview, setTransitionPreview] =
     useState<TransitionPreviewState | null>(null);
+  const [pendingNavigationPageId, setPendingNavigationPageId] = useState('');
 
   const [isLoading, setIsLoading] = useState(true);
   const [isSaving, setIsSaving] = useState(false);
@@ -748,7 +759,6 @@ const ConstructorPage = ({ mode = 'constructor' }: ConstructorPageProps) => {
   const [newTransitionVideoUrl, setNewTransitionVideoUrl] = useState('');
   const [newTransitionSupportsReverse, setNewTransitionSupportsReverse] =
     useState(true);
-  const [newTransitionDurationSec, setNewTransitionDurationSec] = useState(0.7);
   const [errorMessage, setErrorMessage] = useState('');
   const [successMessage, setSuccessMessage] = useState('');
   const [resolvedDurationBySource, setResolvedDurationBySource] = useState<
@@ -984,8 +994,28 @@ const ConstructorPage = ({ mode = 'constructor' }: ConstructorPageProps) => {
       });
     }
 
+    if (newTransitionVideoUrl) {
+      targets.push({ source: newTransitionVideoUrl, mediaType: 'video' });
+    }
+
+    elements.forEach((element) => {
+      if (!isNavigationElementType(element.type)) return;
+      if (element.transitionVideoUrl) {
+        targets.push({ source: element.transitionVideoUrl, mediaType: 'video' });
+      }
+      if (element.reverseVideoUrl) {
+        targets.push({ source: element.reverseVideoUrl, mediaType: 'video' });
+      }
+    });
+
     return targets;
-  }, [backgroundAudioUrl, backgroundVideoUrl, selectedElement]);
+  }, [
+    backgroundAudioUrl,
+    backgroundVideoUrl,
+    elements,
+    newTransitionVideoUrl,
+    selectedElement,
+  ]);
 
   useEffect(() => {
     let isCancelled = false;
@@ -1050,6 +1080,19 @@ const ConstructorPage = ({ mode = 'constructor' }: ConstructorPageProps) => {
       getKnownDurationForSource(selectedElement.mediaUrl || ''),
     );
   }, [getKnownDurationForSource, selectedElement]);
+  const newTransitionDurationNote = useMemo(
+    () => formatDurationNote(getKnownDurationForSource(newTransitionVideoUrl)),
+    [getKnownDurationForSource, newTransitionVideoUrl],
+  );
+  const selectedTransitionDurationNote = useMemo(() => {
+    if (!selectedElement || !isNavigationElementType(selectedElement.type)) {
+      return 'Duration: unknown';
+    }
+
+    return formatDurationNote(
+      getKnownDurationForSource(selectedElement.transitionVideoUrl || ''),
+    );
+  }, [getKnownDurationForSource, selectedElement]);
 
   useEffect(() => {
     if (newTransitionVideoUrl) return;
@@ -1057,6 +1100,32 @@ const ConstructorPage = ({ mode = 'constructor' }: ConstructorPageProps) => {
     setNewTransitionVideoUrl(transitionVideoAssetOptions[0].value);
   }, [newTransitionVideoUrl, transitionVideoAssetOptions]);
 
+  useEffect(() => {
+    setElements((prev) => {
+      let hasChanges = false;
+      const next = prev.map((element) => {
+        if (!isNavigationElementType(element.type)) return element;
+
+        const resolvedDuration = getKnownDurationForSource(
+          element.transitionVideoUrl || '',
+        );
+        const nextDuration =
+          Number.isFinite(resolvedDuration) && Number(resolvedDuration) > 0
+            ? Number(resolvedDuration)
+            : undefined;
+        if (element.transitionDurationSec === nextDuration) return element;
+
+        hasChanges = true;
+        return {
+          ...element,
+          transitionDurationSec: nextDuration,
+        };
+      });
+
+      return hasChanges ? next : prev;
+    });
+  }, [getKnownDurationForSource]);
+
   const loadData = useCallback(async () => {
     if (!projectId || !router.isReady || !isAuthReady) return;
 
@@ -1643,7 +1712,13 @@ const ConstructorPage = ({ mode = 'constructor' }: ConstructorPageProps) => {
     const sanitizedName =
       String(newTransitionName || '').trim() ||
       `Transition ${Date.now().toString().slice(-4)}`;
-    const parsedDuration = Number(newTransitionDurationSec);
+    const resolvedDurationSec = getKnownDurationForSource(sanitizedVideoUrl);
+    if (!resolvedDurationSec) {
+      setErrorMessage(
+        'Could not resolve transition video duration yet. Please wait a moment and try again.',
+      );
+      return;
+    }
 
     try {
       setIsCreatingTransition(true);
@@ -1659,10 +1734,7 @@ const ConstructorPage = ({ mode = 'constructor' }: ConstructorPageProps) => {
         video_url: sanitizedVideoUrl,
         audio_url: '',
         supports_reverse: Boolean(newTransitionSupportsReverse),
-        duration_sec:
-          Number.isFinite(parsedDuration) && parsedDuration > 0
-            ? parsedDuration
-            : 0.7,
+        duration_sec: resolvedDurationSec,
       };
 
       await axios.post('/transitions', { data: payload });
@@ -1680,7 +1752,7 @@ const ConstructorPage = ({ mode = 'constructor' }: ConstructorPageProps) => {
     }
   }, [
     activePage?.environment,
-    newTransitionDurationSec,
+    getKnownDurationForSource,
     newTransitionName,
     newTransitionSupportsReverse,
     newTransitionVideoUrl,
@@ -1924,6 +1996,44 @@ const ConstructorPage = ({ mode = 'constructor' }: ConstructorPageProps) => {
           element.navType === 'back' || element.type === 'navigation_prev'
             ? 'back'
             : 'forward';
+        const configuredTargetId = String(element.targetPageId || '').trim();
+        const fallbackTargetId = (() => {
+          const currentPageIndex = pages.findIndex(
+            (page) => page.id === activePageId,
+          );
+          if (currentPageIndex < 0) return '';
+
+          const nextPageIndex =
+            direction === 'back' ? currentPageIndex - 1 : currentPageIndex + 1;
+          const nextPage = pages[nextPageIndex];
+          return nextPage ? String(nextPage.id || '').trim() : '';
+        })();
+        const targetPageId = configuredTargetId || fallbackTargetId;
+
+        if (!targetPageId) {
+          setErrorMessage('No target page available for this navigation button.');
+          return;
+        }
+
+        const hasPlayableTransition =
+          Boolean(element.transitionVideoUrl) &&
+          !(
+            direction === 'back' &&
+            element.transitionReverseMode === 'separate_video' &&
+            !element.reverseVideoUrl
+          );
+
+        if (!hasPlayableTransition) {
+          setPendingNavigationPageId('');
+          setTransitionPreview(null);
+          setActivePageId(targetPageId);
+          setSelectedElementId('');
+          setSelectedMenuItem('none');
+          setErrorMessage('');
+          return;
+        }
+
+        setPendingNavigationPageId(targetPageId);
         openTransitionPreviewForElement(element, direction);
       }
       return;
@@ -2266,6 +2376,16 @@ const ConstructorPage = ({ mode = 'constructor' }: ConstructorPageProps) => {
     const finishPreview = () => {
       cleanupReverseFrame();
       setTransitionPreview(null);
+      setPendingNavigationPageId((pendingPageId) => {
+        const nextPageId = String(pendingPageId || '').trim();
+        if (nextPageId) {
+          setActivePageId(nextPageId);
+          setSelectedElementId('');
+          setSelectedMenuItem('none');
+          setErrorMessage('');
+        }
+        return '';
+      });
     };
 
     const configuredDurationMs =
@@ -2700,6 +2820,10 @@ const ConstructorPage = ({ mode = 'constructor' }: ConstructorPageProps) => {
                         </option>
                       ))}
                     </select>
+                    <p className='text-[11px] text-gray-500'>
+                      Transition duration is automatic from video metadata.{' '}
+                      {newTransitionDurationNote}
+                    </p>
                     <label className='flex items-center gap-2 text-[11px] text-gray-700'>
                       <input
                         type='checkbox'
@@ -2710,18 +2834,6 @@ const ConstructorPage = ({ mode = 'constructor' }: ConstructorPageProps) => {
                       />
                       Supports reverse playback
                     </label>
-                    <input
-                      className='w-full rounded border border-gray-300 px-2 py-1 text-xs'
-                      type='number'
-                      min='0.2'
-                      step='0.1'
-                      value={newTransitionDurationSec}
-                      onChange={(event) =>
-                        setNewTransitionDurationSec(
-                          Number(event.target.value || 0.7),
-                        )
-                      }
-                    />
                     <button
                       type='button'
                       className='menu-action-btn'
@@ -2888,6 +3000,9 @@ const ConstructorPage = ({ mode = 'constructor' }: ConstructorPageProps) => {
                             </option>
                           ))}
                         </select>
+                        <p className='mt-1 text-[11px] text-gray-500'>
+                          {selectedMediaDurationNote}
+                        </p>
                       </div>
                       <div>
                         <label className='mb-1 block text-[11px] font-semibold text-gray-600'>
@@ -2919,11 +3034,15 @@ const ConstructorPage = ({ mode = 'constructor' }: ConstructorPageProps) => {
                         <select
                           className='w-full rounded border border-gray-300 px-2 py-1 text-xs'
                           value={selectedElement.transitionVideoUrl || ''}
-                          onChange={(event) =>
+                          onChange={(event) => {
+                            const nextVideoUrl = event.target.value;
+                            const resolvedDuration =
+                              getKnownDurationForSource(nextVideoUrl);
                             updateSelectedElement({
-                              transitionVideoUrl: event.target.value,
-                            })
-                          }
+                              transitionVideoUrl: nextVideoUrl,
+                              transitionDurationSec: resolvedDuration || undefined,
+                            });
+                          }}
                         >
                           <option value=''>Not selected</option>
                           {addFallbackAssetOption(
@@ -2937,7 +3056,7 @@ const ConstructorPage = ({ mode = 'constructor' }: ConstructorPageProps) => {
                           ))}
                         </select>
                         <p className='mt-1 text-[11px] text-gray-500'>
-                          {selectedMediaDurationNote}
+                          {selectedTransitionDurationNote}
                         </p>
                       </div>
                       <div>
@@ -2995,25 +3114,10 @@ const ConstructorPage = ({ mode = 'constructor' }: ConstructorPageProps) => {
                           </select>
                         </div>
                       )}
-                      <div>
-                        <label className='mb-1 block text-[11px] font-semibold text-gray-600'>
-                          Transition duration (sec)
-                        </label>
-                        <input
-                          className='w-full rounded border border-gray-300 px-2 py-1 text-xs'
-                          type='number'
-                          min='0.2'
-                          step='0.1'
-                          value={selectedElement.transitionDurationSec ?? 0.7}
-                          onChange={(event) =>
-                            updateSelectedElement({
-                              transitionDurationSec: Number(
-                                event.target.value || 0.7,
-                              ),
-                            })
-                          }
-                        />
-                      </div>
+                      <p className='text-[11px] text-gray-500'>
+                        Transition duration is set automatically from the selected
+                        video. {selectedTransitionDurationNote}
+                      </p>
                       <div className='flex gap-2 pt-1'>
                         <BaseButton
                           small
@@ -3584,7 +3688,19 @@ const ConstructorPage = ({ mode = 'constructor' }: ConstructorPageProps) => {
           <button
             type='button'
             className='absolute top-4 right-4 rounded bg-white/20 px-3 py-1 text-xs text-white hover:bg-white/30'
-            onClick={() => setTransitionPreview(null)}
+            onClick={() => {
+              setTransitionPreview(null);
+              setPendingNavigationPageId((pendingPageId) => {
+                const nextPageId = String(pendingPageId || '').trim();
+                if (nextPageId) {
+                  setActivePageId(nextPageId);
+                  setSelectedElementId('');
+                  setSelectedMenuItem('none');
+                  setErrorMessage('');
+                }
+                return '';
+              });
+            }}
           >
             Close
           </button>