diff --git a/Frontend-Learner/components/classroom/VideoPlayer.vue b/Frontend-Learner/components/classroom/VideoPlayer.vue
index 4147ab09..90d5e531 100644
--- a/Frontend-Learner/components/classroom/VideoPlayer.vue
+++ b/Frontend-Learner/components/classroom/VideoPlayer.vue
@@ -12,7 +12,7 @@ const props = defineProps<{
 const emit = defineEmits<{
     (e: 'timeupdate', currentTime: number, duration: number): void;
     (e: 'ended'): void;
-    (e: 'loadedmetadata'): void;
+    (e: 'loadedmetadata', duration: number): void;
 }>();
 
 const videoRef = ref<HTMLVideoElement | null>(null);
@@ -39,7 +39,115 @@ const formatTime = (time: number) => {
 const currentTimeDisplay = computed(() => formatTime(currentTime.value));
 const durationDisplay = computed(() => formatTime(duration.value || 0));
 
+// YouTube Helper Logic
+const isYoutube = computed(() => {
+    const s = props.src.toLowerCase();
+    return s.includes('youtube.com') || s.includes('youtu.be');
+});
+
+const youtubeEmbedUrl = computed(() => {
+    if (!isYoutube.value) return '';
+    let videoId = '';
+    
+    // Extract Video ID
+    if (props.src.includes('youtu.be')) {
+        videoId = props.src.split('youtu.be/')[1]?.split('?')[0];
+    } else {
+        const urlParams = new URLSearchParams(props.src.split('?')[1]);
+        videoId = urlParams.get('v') || '';
+    }
+
+    // Return Embed URL with enablejsapi=1
+    return `https://www.youtube.com/embed/${videoId}?enablejsapi=1&rel=0`;
+});
+
+// YouTube API Tracking
+let ytPlayer: any = null;
+let ytInterval: any = null;
+
+const initYoutubeAPI = () => {
+    if (!isYoutube.value || typeof window === 'undefined') return;
+
+    // Load API Script if not exists
+    if (!(window as any).YT) {
+        const tag = document.createElement('script');
+        tag.src = "https://www.youtube.com/iframe_api";
+        const firstScriptTag = document.getElementsByTagName('script')[0];
+        firstScriptTag.parentNode?.insertBefore(tag, firstScriptTag);
+    }
+
+    const setupPlayer = () => {
+        ytPlayer = new (window as any).YT.Player('youtube-iframe', {
+            events: {
+                'onReady': (event: any) => {
+                    duration.value = event.target.getDuration();
+                    
+                    // Resume Logic for YouTube
+                    if (props.initialSeekTime && props.initialSeekTime > 0) {
+                        event.target.seekTo(props.initialSeekTime, true);
+                    }
+                    
+                    emit('loadedmetadata', event.target.getDuration());
+                },
+                'onStateChange': (event: any) => {
+                    if (event.data === (window as any).YT.PlayerState.PLAYING) {
+                        startYTTracking();
+                    } else {
+                        stopYTTracking();
+                    }
+                    if (event.data === (window as any).YT.PlayerState.ENDED) {
+                        emit('ended');
+                    }
+                }
+            }
+        });
+    };
+
+    if ((window as any).YT && (window as any).YT.Player) {
+        setupPlayer();
+    } else {
+        (window as any).onYouTubeIframeAPIReady = setupPlayer;
+    }
+};
+
+const startYTTracking = () => {
+    stopYTTracking();
+    ytInterval = setInterval(() => {
+        if (ytPlayer && ytPlayer.getCurrentTime) {
+            currentTime.value = ytPlayer.getCurrentTime();
+            emit('timeupdate', currentTime.value, duration.value);
+        }
+    }, 1000); // Check every second
+};
+
+const stopYTTracking = () => {
+    if (ytInterval) clearInterval(ytInterval);
+};
+
+onMounted(() => {
+    if (isYoutube.value) initYoutubeAPI();
+});
+
+onUnmounted(() => {
+    stopYTTracking();
+});
+
+// Watch for src change to re-init
+watch(() => props.src, () => {
+    if (isYoutube.value) {
+        setTimeout(initYoutubeAPI, 500);
+    }
+});
+
 const togglePlay = () => {
+    if (isYoutube.value) {
+        if (ytPlayer && ytPlayer.getPlayerState) {
+            const state = ytPlayer.getPlayerState();
+            if (state === 1) ytPlayer.pauseVideo();
+            else ytPlayer.playVideo();
+        }
+        return;
+    }
     if (!videoRef.value) return;
     if (isPlaying.value) videoRef.value.pause();
     else videoRef.value.play();
@@ -63,7 +171,7 @@ const handleLoadedMetadata = () => {
              videoRef.value.currentTime = seekTo;
         }
     }
-    emit('loadedmetadata');
+    emit('loadedmetadata', videoRef.value?.duration || 0);
 };
 
 const handleEnded = () => {
@@ -72,7 +180,7 @@ const handleEnded = () => {
 };
 
 const seek = (e: MouseEvent) => {
-    if (!videoRef.value) return;
+    if (!videoRef.value || !isFinite(videoRef.value.duration)) return;
     const rect = (e.currentTarget as HTMLElement).getBoundingClientRect();
     const percent = (e.clientX - rect.left) / rect.width;
     videoRef.value.currentTime = percent * videoRef.value.duration;
@@ -102,38 +210,52 @@ watch([volume, isMuted], () => {
 
 <template>
     <div class="bg-black rounded-xl overflow-hidden shadow-2xl mb-6 aspect-video relative group ring-1 ring-white/10">
-        <video
-            ref="videoRef"
-            :src="src"
-            class="w-full h-full object-contain"
-            @click="togglePlay"
-            @timeupdate="handleTimeUpdate"
-            @loadedmetadata="handleLoadedMetadata"
-            @ended="handleEnded"
-        />
-       
-        <!-- Custom Controls Overlay -->
-        <div class="absolute bottom-0 left-0 right-0 p-4 bg-gradient-to-t from-black/80 via-black/40 to-transparent transition-opacity opacity-0 group-hover:opacity-100">
-            <div class="flex items-center gap-4 text-white">
-                <q-btn flat round dense :icon="isPlaying ? 'pause' : 'play_arrow'" @click.stop="togglePlay" />
-                <div class="relative flex-grow h-1.5 bg-white/20 rounded-full cursor-pointer group/progress overflow-hidden" @click="seek">
-                    <div class="absolute top-0 left-0 h-full bg-blue-500 rounded-full group-hover/progress:bg-blue-400 transition-all shadow-[0_0_10px_rgba(59,130,246,0.5)]" :style="{ width: videoProgress + '%' }"></div>
-                </div>
-                <span class="text-xs font-mono font-medium opacity-90">{{ currentTimeDisplay }} / {{ durationDisplay }}</span>
-                
-                <!-- Volume Control -->
-                <div class="flex items-center gap-2 group/volume">
-                    <q-btn flat round dense :icon="volumeIcon" @click.stop="handleToggleMute" color="white" />
-                    <div class="w-0 group-hover/volume:w-20 overflow-hidden transition-all duration-300 flex items-center">
-                        <input 
-                            type="range" 
-                            min="0" 
-                            max="1" 
-                            step="0.1" 
-                            :value="volume" 
-                            @input="handleVolumeChange"
-                            class="w-20 h-1 bg-white/30 rounded-lg appearance-none cursor-pointer accent-blue-500"
-                        />
+        <!-- 1. YouTube Player -->
+        <iframe
+            v-if="isYoutube"
+            id="youtube-iframe"
+            :src="youtubeEmbedUrl"
+            class="w-full h-full"
+            frameborder="0"
+            allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture"
+            allowfullscreen
+        ></iframe>
+
+        <!-- 2. Standard HTML5 Video Player -->
+        <div v-else class="w-full h-full relative">
+            <video
+                ref="videoRef"
+                :src="src"
+                class="w-full h-full object-contain"
+                @click="togglePlay"
+                @timeupdate="handleTimeUpdate"
+                @loadedmetadata="handleLoadedMetadata"
+                @ended="handleEnded"
+            />
+        
+            <!-- Custom Controls Overlay (Only for HTML5 Video) -->
+            <div class="absolute bottom-0 left-0 right-0 p-4 bg-gradient-to-t from-black/80 via-black/40 to-transparent transition-opacity opacity-0 group-hover:opacity-100">
+                <div class="flex items-center gap-4 text-white">
+                    <q-btn flat round dense :icon="isPlaying ? 'pause' : 'play_arrow'" @click.stop="togglePlay" />
+                    <div class="relative flex-grow h-1.5 bg-white/20 rounded-full cursor-pointer group/progress overflow-hidden" @click="seek">
+                        <div class="absolute top-0 left-0 h-full bg-blue-500 rounded-full group-hover/progress:bg-blue-400 transition-all shadow-[0_0_10px_rgba(59,130,246,0.5)]" :style="{ width: videoProgress + '%' }"></div>
+                    </div>
+                    <span class="text-xs font-mono font-medium opacity-90">{{ currentTimeDisplay }} / {{ durationDisplay }}</span>
+                    
+                    <!-- Volume Control -->
+                    <div class="flex items-center gap-2 group/volume">
+                        <q-btn flat round dense :icon="volumeIcon" @click.stop="handleToggleMute" color="white" />
+                        <div class="w-0 group-hover/volume:w-20 overflow-hidden transition-all duration-300 flex items-center">
+                            <input 
+                                type="range" 
+                                min="0" 
+                                max="1" 
+                                step="0.1" 
+                                :value="volume" 
+                                @input="handleVolumeChange"
+                                class="w-20 h-1 bg-white/30 rounded-lg appearance-none cursor-pointer accent-blue-500"
+                            />
+                        </div>
                     </div>
                 </div>
             </div>
diff --git a/Frontend-Learner/composables/useAuth.ts b/Frontend-Learner/composables/useAuth.ts
index b3337b87..2ad6eebc 100644
--- a/Frontend-Learner/composables/useAuth.ts
+++ b/Frontend-Learner/composables/useAuth.ts
@@ -451,6 +451,12 @@ export const useAuth = () => {
     token.value = null
     refreshToken.value = null // ลบ Refresh Token
     user.value = null
+    
+    // Reset client-side storage
+    if (import.meta.client) {
+      localStorage.clear()
+    }
+
     const router = useRouter()
     router.push('/auth/login')
   }
diff --git a/Frontend-Learner/composables/useCourse.ts b/Frontend-Learner/composables/useCourse.ts
index 6b6a6a69..6ca36b73 100644
--- a/Frontend-Learner/composables/useCourse.ts
+++ b/Frontend-Learner/composables/useCourse.ts
@@ -419,14 +419,7 @@ export const useCourse = () => {
             const data = await $fetch<{ code: number; message: string; data: any }>(`${API_BASE_URL}/students/lessons/${lessonId}/progress`, {
                 method: 'POST',
                 headers: token.value ? {
-                    // User Request: "Backend รับ header แบบ Authorization: <token> (ยังไม่ใช้ Bearer)"
-                    // Checking existing usage, most use Bearer. I will stick to existing Bearer for consistency unless it fails,
-                    // BUT user explicitly said "not using Bearer" in this specific prompt.
-                    // To be safe and minimal, I will keep using `Bearer ${token}` if that's what the codebase uses globally,
-                    // UNLESS I see strong evidence otherwise.
-                    // The user's curl example in Step 209 DOES NOT have "Bearer".
-                    // So I will remove it for these 2 functions as requested.
-                    Authorization: `${token.value}` 
+                    Authorization: `Bearer ${token.value}`
                 } : {},
                 body: {
                     video_progress_seconds: progressSeconds,
diff --git a/Frontend-Learner/pages/classroom/learning.vue b/Frontend-Learner/pages/classroom/learning.vue
index cca36da2..35c4b615 100644
--- a/Frontend-Learner/pages/classroom/learning.vue
+++ b/Frontend-Learner/pages/classroom/learning.vue
@@ -20,7 +20,7 @@ const route = useRoute()
 const router = useRouter()
 const { t } = useI18n()
 const { user } = useAuth()
-const { fetchCourseLearningInfo, fetchLessonContent, saveVideoProgress, checkLessonAccess, fetchVideoProgress, fetchCourseAnnouncements } = useCourse()
+const { fetchCourseLearningInfo, fetchLessonContent, saveVideoProgress, checkLessonAccess, fetchVideoProgress, fetchCourseAnnouncements, markLessonComplete } = useCourse()
 // Media Prefs (Global Volume)
 const { volume, muted: isMuted, setVolume, setMuted, applyTo } = useMediaPrefs()
 
@@ -196,6 +196,11 @@ const loadLesson = async (lessonId: number) => {
     if (res.success) {
       currentLesson.value = res.data
       
+      // Initialize progress object if missing (Critical for New Users)
+      if (!currentLesson.value.progress) {
+          currentLesson.value.progress = {}
+      }
+      
       // Update Lesson Completion UI status safely
       if (currentLesson.value?.progress?.is_completed && courseData.value) {
           for (const chapter of courseData.value.chapters) {
@@ -307,8 +312,10 @@ const handleVideoTimeUpdate = (cTime: number, dur: number) => {
   }
 }
 
-const onVideoMetadataLoaded = () => {
-    // Component handles seek and volume
+const onVideoMetadataLoaded = (duration: number) => {
+    if (duration > 0) {
+        currentDuration.value = duration
+    }
 }
 
 const isCompleting = ref(false) // Flag to prevent race conditions during completion
@@ -321,7 +328,9 @@ const isCompleting = ref(false) // Flag to prevent race conditions during comple
 const performSaveProgress = async (force: boolean = false, keepalive: boolean = false) => {
     const lesson = currentLesson.value
     if (!lesson || lesson.type !== 'VIDEO') return
-    if (!lesson.progress) return
+    
+    // Ensure progress object exists
+    if (!lesson.progress) lesson.progress = {}
 
     // 1. Completed Guard: Stop everything if already completed
     if (lesson.progress.is_completed) return
@@ -333,8 +342,16 @@ const performSaveProgress = async (force: boolean = false, keepalive: boolean =
     const maxSec = Math.floor(maxWatchedTime.value) // Use max watched time
     const durationSec = Math.floor(currentDuration.value || 0)
 
-    // 3. Monotonic Check: Don't save if progress hasn't increased (unless forced)
-    if (!force && maxSec <= lastSavedTime.value) return
+    // 3. Monotonic Check: Allow saving 0 if it's the very first save (lastSavedTime is -1)
+    if (!force) {
+        if (lastSavedTime.value === -1) {
+            // First time save: allow 0 or more
+            if (maxSec < 0) return 
+        } else if (maxSec <= lastSavedTime.value) {
+            // Subsequent saves: must be greater than last saved
+            return
+        }
+    }
     
     // 4. Throttle Check: Server Throttle (15 seconds)
     if (!force && (now - lastSavedTimestamp.value < 15000)) return
@@ -343,8 +360,8 @@ const performSaveProgress = async (force: boolean = false, keepalive: boolean =
     lastSavedTime.value = maxSec 
     lastSavedTimestamp.value = now
 
-    // Check if this save might complete the lesson (e.g. > 90% or forced end)
-    const isFinishing = force || (durationSec > 0 && maxSec >= durationSec * 0.9)
+    // Check if this save might complete the lesson (e.g. 100% or forced end)
+    const isFinishing = force || (durationSec > 0 && maxSec >= durationSec)
     
     if (isFinishing) {
         isCompleting.value = true
@@ -353,7 +370,7 @@ const performSaveProgress = async (force: boolean = false, keepalive: boolean =
     try {
         const res = await saveVideoProgress(lesson.id, maxSec, durationSec, keepalive)
         
-        // Handle Completion Response
+        // Handle Completion (Rely on Backend's auto-complete response)
         if (res.success && res.data?.is_completed) {
              markLessonAsCompletedLocally(lesson.id)
              if (lesson.progress) lesson.progress.is_completed = true
@@ -385,15 +402,29 @@ const markLessonAsCompletedLocally = (lessonId: number) => {
 
 const videoSrc = computed(() => {
   if (!currentLesson.value) return ''
-  // Use explicit video_url from API first
-  if (currentLesson.value.video_url) return currentLesson.value.video_url
+  let url = ''
   
-  // Fallback (deprecated logic, but keeping just in case)
-  const content = getLocalizedText(currentLesson.value.content)
-  if (content && (content.startsWith('http') || content.startsWith('/')) && !content.includes(' ')) {
-    return content
+  // Use explicit video_url from API first
+  if (currentLesson.value.video_url) {
+    url = currentLesson.value.video_url
+  } else {
+    // Fallback (deprecated logic)
+    const content = getLocalizedText(currentLesson.value.content)
+    if (content && (content.startsWith('http') || content.startsWith('/')) && !content.includes(' ')) {
+      url = content
+    }
   }
-  return ''
+
+  if (!url) return ''
+
+  // Support Resume for YouTube
+  const isYoutube = url.toLowerCase().includes('youtube.com') || url.toLowerCase().includes('youtu.be')
+  if (isYoutube && initialSeekTime.value > 0) {
+      const separator = url.includes('?') ? '&' : '?'
+      return `${url}${separator}t=${Math.floor(initialSeekTime.value)}`
+  }
+  
+  return url
 })
 
 // เมื่อวิดีโอจบ ให้บันทึกว่าเรียนจบ (Complete)
@@ -402,12 +433,15 @@ const onVideoEnded = async () => {
     const lesson = currentLesson.value
     if (!lesson || !lesson.progress || lesson.progress.is_completed || isCompleting.value) return
 
-    // Force save progress at 100%
-    await performSaveProgress(true, false)
-    
-    // Double check completion state
-    if (currentLesson.value && !currentLesson.value.progress?.is_completed) {
-         markLessonAsCompletedLocally(currentLesson.value.id)
+    isCompleting.value = true
+    try {
+        // 1. Force save progress at 100%
+        // This will trigger the backend's auto-complete logic
+        await performSaveProgress(true, false)
+    } catch (err) {
+        console.error('Failed to save progress on end:', err)
+    } finally {
+        isCompleting.value = false
     }
 }
 
@@ -471,7 +505,7 @@ onBeforeUnmount(() => {
                :initialSeekTime="initialSeekTime"
                @timeupdate="handleVideoTimeUpdate"
                @ended="onVideoEnded"
-               @loadedmetadata="onVideoMetadataLoaded"
+               @loadedmetadata="(d: number) => onVideoMetadataLoaded(d)"
             />
             
              <!-- Lesson Info -->