diff --git a/api/playback/handler.go b/api/playback/handler.go
index 670efb8..9a75bb5 100644
--- a/api/playback/handler.go
+++ b/api/playback/handler.go
@@ -232,11 +232,6 @@ func (h *Handler) HandleProxy(w http.ResponseWriter, r *http.Request) {
 }
 
 func (h *Handler) HandleSaveProgress(w http.ResponseWriter, r *http.Request) {
-	if r.Method != http.MethodPost {
-		http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
-		return
-	}
-
 	user := middleware.GetUser(r.Context())
 	if user == nil {
 		http.Error(w, "Unauthorized", http.StatusUnauthorized)
@@ -333,6 +328,106 @@ func (h *Handler) HandleCompleteAnime(w http.ResponseWriter, r *http.Request) {
 	w.WriteHeader(http.StatusNoContent)
 }
 
+// HandleEpisodeData returns JSON for episode data (for in-player transitions)
+func (h *Handler) HandleEpisodeData(w http.ResponseWriter, r *http.Request) {
+	if r.Method != http.MethodGet {
+		http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
+		return
+	}
+
+	path := strings.TrimPrefix(r.URL.Path, "/api/watch/episode/")
+	path = strings.Trim(path, "/")
+	if path == "" {
+		http.Error(w, "Missing anime ID", http.StatusBadRequest)
+		return
+	}
+
+	parts := strings.Split(path, "/")
+	malID, err := strconv.Atoi(parts[0])
+	if err != nil || malID <= 0 {
+		http.Error(w, "Invalid anime ID", http.StatusBadRequest)
+		return
+	}
+
+	episode := "1"
+	if len(parts) >= 2 {
+		episode = strings.TrimSpace(parts[1])
+	}
+	if episode == "" {
+		episode = r.URL.Query().Get("ep")
+	}
+	if episode == "" {
+		episode = "1"
+	}
+
+	mode := strings.TrimSpace(r.URL.Query().Get("mode"))
+
+	ctx, cancel := context.WithTimeout(r.Context(), 30*time.Second)
+	defer cancel()
+
+	anime, err := h.jikanClient.GetAnimeByID(ctx, malID)
+	if err != nil {
+		log.Printf("failed to fetch anime %d: %v", malID, err)
+		http.Error(w, "Failed to fetch anime details", http.StatusInternalServerError)
+		return
+	}
+
+	titleCandidates := playbackTitleCandidates(anime)
+	userID := watchlistUserIDFromRequest(r)
+	data, err := h.svc.BuildWatchPageData(ctx, malID, titleCandidates, episode, mode, userID)
+	if err != nil {
+		log.Printf("episode data error for mal_id=%d ep=%s: %v", malID, episode, err)
+		http.Error(w, "Failed to load episode data", http.StatusBadGateway)
+		return
+	}
+
+	clientModeSources := convertModeSources(data.ModeSources)
+	initialMode := data.InitialMode
+	token := ""
+	if source, ok := clientModeSources[initialMode]; ok {
+		token = source.Token
+	}
+
+response := struct {
+		MalID           int                       `json:"mal_id"`
+		Title          string                   `json:"title"`
+		CurrentEpisode string                  `json:"current_episode"`
+		TotalEpisodes int                     `json:"total_episodes"`
+		InitialMode   string                  `json:"initial_mode"`
+		Token         string                  `json:"token"`
+		AvailableModes []string               `json:"available_modes"`
+		ModeSources  map[string]shared.ModeSource `json:"mode_sources"`
+		Segments     []shared.SkipSegment     `json:"segments"`
+	}{
+		MalID:           malID,
+		Title:          data.Title,
+		CurrentEpisode: data.CurrentEpisode,
+		TotalEpisodes: anime.Episodes,
+		InitialMode:    initialMode,
+		Token:          token,
+		AvailableModes: data.AvailableModes,
+		ModeSources:    clientModeSources,
+		Segments:       convertToSharedSegments(data.Segments),
+	}
+
+	w.Header().Set("Content-Type", "application/json")
+	if err := json.NewEncoder(w).Encode(response); err != nil {
+		log.Printf("failed to encode episode data: %v", err)
+	}
+}
+
+func convertToSharedSegments(segments []SkipSegment) []shared.SkipSegment {
+	result := make([]shared.SkipSegment, len(segments))
+	for i, s := range segments {
+		result[i] = shared.SkipSegment{
+			Type:  s.Type,
+			Start: s.Start,
+			End:   s.End,
+		}
+	}
+	return result
+}
+
 func (h *Handler) ensureAnimeSeed(ctx context.Context, malID int) (*database.UpsertAnimeParams, error) {
 	animeID := int64(malID)
 	if _, err := h.svc.db.GetAnime(ctx, animeID); err == nil {
diff --git a/internal/server/routes.go b/internal/server/routes.go
index 5f00829..9c10dca 100644
--- a/internal/server/routes.go
+++ b/internal/server/routes.go
@@ -81,6 +81,7 @@ func NewRouter(cfg Config) http.Handler {
 	mux.HandleFunc("/watch/proxy/subtitle", playbackHandler.HandleProxy)
 	mux.HandleFunc("/api/watch-progress", playbackHandler.HandleSaveProgress)
 	mux.HandleFunc("/api/watch-complete", playbackHandler.HandleCompleteAnime)
+	mux.HandleFunc("/api/watch/episode/", playbackHandler.HandleEpisodeData)
 
 	// Auth Endpoints
 	mux.HandleFunc("/login", func(w http.ResponseWriter, r *http.Request) {
diff --git a/static/player.ts b/static/player.ts
index 778e3dc..480e7af 100644
--- a/static/player.ts
+++ b/static/player.ts
@@ -20,6 +20,18 @@ interface SkipSegment {
   end: number
 }
 
+interface EpisodeData {
+  mal_id: number
+  title: string
+  current_episode: string
+  total_episodes: number
+  initial_mode: string
+  token: string
+  available_modes: string[]
+  mode_sources: Record<string, ModeSource>
+  segments: SkipSegment[]
+}
+
 let playerInitialized = false
 
 const initPlayer = (): void => {
@@ -57,9 +69,9 @@ const initPlayer = (): void => {
 
   const streamURL = container.getAttribute('data-stream-url') || '/watch/proxy/stream'
   const initialStreamToken = container.getAttribute('data-stream-token') || ''
-  const currentEpisode = container.getAttribute('data-current-episode') || '1'
+  let currentEpisode = container.getAttribute('data-current-episode') || '1'
   const malID = Number.parseInt(container.getAttribute('data-mal-id') || '', 10)
-  const totalEpisodes = Number.parseInt(container.getAttribute('data-total-episodes') || '0', 10)
+  let totalEpisodes = Number.parseInt(container.getAttribute('data-total-episodes') || '0', 10)
   const animeTitle = container.getAttribute('data-anime-title') || ''
   const animeTitleEnglish = container.getAttribute('data-anime-title-english') || ''
   const animeTitleJapanese = container.getAttribute('data-anime-title-japanese') || ''
@@ -84,7 +96,7 @@ const initPlayer = (): void => {
   const minSegmentDurationSeconds = 20
   const maxSegmentDurationSeconds = 240
 
-  const parsedSegments = segments
+  let parsedSegments = segments
     .map((segment: SkipSegment) => {
       const start = Number(segment.start || 0)
       const end = Number(segment.end || 0)
@@ -765,12 +777,89 @@ const goToNextEpisode = (): void => {
 
   const nextEpisode = currentEpisodeNumber + 1
   markEpisodeTransition(nextEpisode)
-  const nextUrl = `/watch/${animeID}/${nextEpisode}`
 
+  if (document.fullscreenElement) {
+    loadNextEpisodeInPlace(Number(animeID), nextEpisode)
+    return
+  }
+
+  const nextUrl = `/watch/${animeID}/${nextEpisode}`
   sessionStorage.setItem('mal:autoplay-next', 'true')
   window.location.href = nextUrl
 }
 
+const loadNextEpisodeInPlace = async (animeID: number, nextEpisode: number): Promise<void> => {
+  if (!Number.isInteger(animeID) || animeID <= 0) return
+
+  const url = `/api/watch/episode/${animeID}/${nextEpisode}`
+  let data: EpisodeData | null = null
+
+  try {
+    const resp = await fetch(url)
+    if (!resp.ok) return
+    data = await resp.json() as EpisodeData
+  } catch {
+    return
+  }
+
+  if (!data) return
+
+  const container = document.querySelector('[data-video-player]') as HTMLElement | null
+  if (!container) return
+
+  const video = container.querySelector('video') as HTMLVideoElement | null
+  if (!video) return
+
+  container.setAttribute('data-current-episode', String(nextEpisode))
+  container.setAttribute('data-mal-id', String(animeID))
+  container.setAttribute('data-total-episodes', String(data.total_episodes))
+  container.setAttribute('data-start-time-seconds', '0')
+  container.setAttribute('data-initial-mode', data.initial_mode)
+  container.setAttribute('data-stream-token', data.token)
+  container.setAttribute('data-available-modes', JSON.stringify(data.available_modes))
+  container.setAttribute('data-mode-sources', JSON.stringify(data.mode_sources))
+  container.setAttribute('data-segments', JSON.stringify(data.segments))
+
+  currentEpisode = String(nextEpisode)
+  totalEpisodes = data.total_episodes
+
+  const newStreamURL = container.getAttribute('data-stream-url') || '/watch/proxy/stream'
+  const streamMode = data.initial_mode
+  const modeSource = data.mode_sources[streamMode]
+
+  if (modeSource?.token) {
+    video.src = `${newStreamURL}?mode=${encodeURIComponent(streamMode)}&token=${encodeURIComponent(modeSource.token)}`
+  } else if (data.token) {
+    video.src = `${newStreamURL}?mode=${encodeURIComponent(streamMode)}&token=${encodeURIComponent(data.token)}`
+  }
+
+  video.load()
+  video.play().catch(() => {})
+
+  parsedSegments = (data.segments || [])
+    .map((segment: SkipSegment) => {
+      const start = Number(segment.start || 0)
+      const end = Number(segment.end || 0)
+      if (!Number.isFinite(start) || !Number.isFinite(end) || end <= start) {
+        return null
+      }
+      const rawType = String(segment.type || '').toLowerCase()
+      const type = rawType === 'ed' || rawType === 'outro' ? 'ed' : 'op'
+      return { type, start: Math.max(0, start), end: Math.max(0, end) }
+    })
+    .filter((s: unknown): s is { type: string, start: number, end: number } => s !== null)
+    .sort((a: { start: number }, b: { start: number }) => a.start - b.start)
+
+  activeSegments = []
+  resolveActiveSegments()
+  renderSegments()
+  updateSubtitleOptions()
+  updateModeButtons(data.initial_mode)
+
+  const nextUrl = `/watch/${animeID}/${nextEpisode}`
+  window.history.replaceState(null, '', nextUrl)
+}
+
   const completeAnime = async (episodeNumber: number): Promise<void> => {
     if (completionSent) return
     if (!Number.isInteger(malID) || malID <= 0) return