优化

internal/handler/media.go

@@ -123,7 +123,7 @@ func listLibrariesHandler(svc *service.Container) gin.HandlerFunc {
 			for i, l := range libs {
 				libIDs[i] = l.ID
 			}
-			counts, _ := svc.Repo.Media.CountByLibraries(ctx, libIDs, repository.MediaQueryFilter{
+			counts, _ := svc.Media.CountLibrariesCached(ctx, libIDs, repository.MediaQueryFilter{
 				IncludeNSFW:       visibility.IncludeNSFW,
 				AllowedLibraryIDs: visibility.AllowedLibraryIDs,
 				HiddenLibraryIDs:  visibility.HiddenLibraryIDs,

internal/handler/playback.go

@@ -85,6 +85,18 @@ func toggleFavouriteHandler(svc *service.Container) gin.HandlerFunc {
 func listFavouritesHandler(svc *service.Container) gin.HandlerFunc {
 	return func(c *gin.Context) {
 		uid, _ := c.Get(middleware.CtxUserID)
+		if c.Query("ids") == "1" {
+			ids, err := svc.Playback.ListFavouriteIDs(c.Request.Context(), uid.(string))
+			if err != nil {
+				c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
+				return
+			}
+			if ids == nil {
+				ids = []string{}
+			}
+			c.JSON(http.StatusOK, gin.H{"ids": ids})
+			return
+		}
 		items, err := svc.Playback.ListFavourites(c.Request.Context(), uid.(string))
 		if err != nil {
 			c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})

internal/service/emby_compat.go

@@ -21,6 +21,7 @@ import (
 	"github.com/truewhile/MeBox/internal/model"
 	"github.com/truewhile/MeBox/internal/repository"
 	"go.uber.org/zap"
+	"golang.org/x/sync/singleflight"
 )
 
 // 用一个固定的 ServerId 字符串。Emby 客户端会缓存这个 id，第一次见到
@@ -65,6 +66,11 @@ type EmbyService struct {
 	peopleMu    sync.RWMutex
 	peopleCache map[string]embyPeopleCacheEntry
 
+	// latestFlight collapses the homepage stampede: clients request Latest
+	// for every library at once, and a shared expiry used to rebuild each
+	// library in parallel.
+	latestFlight singleflight.Group
+
 	tmdb          *TMDbProvider
 	adult         *AdultProvider
 	personImageMu sync.RWMutex

internal/service/emby_items_detail.go

@@ -8,6 +8,7 @@ import (
 	"os"
 	"path/filepath"
 	"strings"
+	"sync"
 	"time"
 
 	"go.uber.org/zap"
@@ -120,44 +121,87 @@ func (e *EmbyService) Item(ctx context.Context, mediaID, userID string) (map[str
 	return e.itemPayload(e.withPayloadCache(ctx), m, fav, pos, true), nil
 }
 
-// LatestItems 最近添加，全库或指定库。远程媒体库(parentID 带前缀)直接透传远程。
+// LatestItems 最近添加，全库或指定库。远程媒体库(parentID 带前缀)走远程并缓存。
 func (e *EmbyService) LatestItems(ctx context.Context, userID, parentID string, limit int) ([]map[string]any, error) {
+	if e == nil {
+		return nil, nil
+	}
 	if limit <= 0 || limit > 100 {
 		limit = 20
 	}
-	if e.remote != nil && IsEmbyRemoteID(parentID) {
-		mountID, remoteParent, _ := DecodeEmbyRemoteID(parentID)
-		mount, acct, _ := e.remote.ResolveMount(ctx, mountID)
-		if mount == nil || acct == nil {
-			return nil, nil
+	cacheKey := e.embyLatestCacheKey(userID, parentID, limit)
+	if items, ok := e.cachedLatestItems(ctx, cacheKey); ok {
+		return items, nil
+	}
+	// 一个客户端断开不应取消正在为其他客户端填充的共享重建。
+	loadCtx := context.WithoutCancel(ctx)
+	v, err, _ := e.latestFlight.Do(cacheKey, func() (any, error) {
+		if items, ok := e.cachedLatestItems(loadCtx, cacheKey); ok {
+			return embyLatestCacheValue{Items: items}, nil
 		}
-		if !EmbyMountLibraryAllowed(e.mediaVisibility(ctx, userID), mount) {
-			return nil, nil
-		}
-		out, err := e.remote.RemoteLatest(ctx, mount, acct, remoteParent, limit)
+		value, err := e.loadLatestItems(loadCtx, userID, parentID, limit)
 		if err != nil {
 			return nil, err
 		}
-		if err := e.mergeRemoteUserData(ctx, userID, out); err != nil {
-			return nil, err
+		if e.cache != nil {
+			e.cache.SetJSON(loadCtx, cacheKey, value, time.Duration(e.embyLatestCacheTTLSeconds())*time.Second)
 		}
-		return out, nil
+		e.rememberArtworkRefs(value.Artwork)
+		return value, nil
+	})
+	if err != nil {
+		return nil, err
+	}
+	cached, _ := v.(embyLatestCacheValue)
+	if cached.Items == nil {
+		return []map[string]any{}, nil
+	}
+	return cached.Items, nil
+}
+
+func (e *EmbyService) cachedLatestItems(ctx context.Context, cacheKey string) ([]map[string]any, bool) {
+	if e == nil || e.cache == nil {
+		return nil, false
 	}
-	cacheKey := e.embyLatestCacheKey(userID, parentID, limit)
 	var cached embyLatestCacheValue
-	if e.cache != nil && e.cache.GetJSON(ctx, cacheKey, &cached) {
-		e.rememberArtworkRefs(cached.Artwork)
-		return cached.Items, nil
+	if !e.cache.GetJSON(ctx, cacheKey, &cached) {
+		return nil, false
+	}
+	e.rememberArtworkRefs(cached.Artwork)
+	if cached.Items == nil {
+		return []map[string]any{}, true
+	}
+	return cached.Items, true
+}
+
+func (e *EmbyService) loadLatestItems(ctx context.Context, userID, parentID string, limit int) (embyLatestCacheValue, error) {
+	if e.remote != nil && IsEmbyRemoteID(parentID) {
+		mountID, remoteParent, _ := DecodeEmbyRemoteID(parentID)
+		mount, acct, _ := e.remote.ResolveMount(ctx, mountID)
+		if mount == nil || acct == nil || !EmbyMountLibraryAllowed(e.mediaVisibility(ctx, userID), mount) {
+			return embyLatestCacheValue{Items: []map[string]any{}}, nil
+		}
+		out, err := e.remote.RemoteLatest(ctx, mount, acct, remoteParent, limit)
+		if err != nil {
+			return embyLatestCacheValue{}, err
+		}
+		if out == nil {
+			out = []map[string]any{}
+		}
+		if err := e.mergeRemoteUserData(ctx, userID, out); err != nil {
+			return embyLatestCacheValue{}, err
+		}
+		return embyLatestCacheValue{Items: out}, nil
 	}
 	q := e.repo.DB.WithContext(ctx).Model(&model.Media{}).Where("deleted_at IS NULL")
 	q = e.applyUserMediaVisibility(ctx, q, userID)
 	if parentID != "" {
 		if episodic, err := e.libraryIsEpisodic(ctx, parentID); err == nil && episodic {
 			out, artwork, err := e.latestSeriesItemsForLibrary(ctx, userID, parentID, limit)
-			if err == nil && e.cache != nil {
-				e.cache.SetJSON(ctx, cacheKey, embyLatestCacheValue{Items: out, Artwork: artwork}, time.Duration(e.embyLatestCacheTTLSeconds())*time.Second)
+			if err != nil {
+				return embyLatestCacheValue{}, err
 			}
-			return out, err
+			return embyLatestCacheValue{Items: out, Artwork: artwork}, nil
 		}
 		q = q.Where("library_id IN ?", e.mergedLibraryIDs(ctx, parentID))
 	}
@@ -170,7 +214,7 @@ func (e *EmbyService) LatestItems(ctx context.Context, userID, parentID string,
 	}
 	var rows []model.Media
 	if err := q.Order(mediaReleaseOrderSQL(true)).Limit(rowLimit).Find(&rows).Error; err != nil {
-		return nil, err
+		return embyLatestCacheValue{}, err
 	}
 	rows = e.collapseMediaVersionRows(ctx, rows)
 	if len(rows) > limit {
@@ -178,12 +222,9 @@ func (e *EmbyService) LatestItems(ctx context.Context, userID, parentID string,
 	}
 	out, err := e.payloadsForMedia(ctx, rows, userID)
 	if err != nil {
-		return nil, err
+		return embyLatestCacheValue{}, err
 	}
-	if e.cache != nil {
-		e.cache.SetJSON(ctx, cacheKey, embyLatestCacheValue{Items: out}, time.Duration(e.embyLatestCacheTTLSeconds())*time.Second)
-	}
-	return out, nil
+	return embyLatestCacheValue{Items: out}, nil
 }
 
 func (e *EmbyService) latestSeriesItemsForLibrary(ctx context.Context, userID, libraryID string, limit int) ([]map[string]any, map[string]embyArtworkRef, error) {
@@ -194,7 +235,8 @@ func (e *EmbyService) latestSeriesItemsForLibrary(ctx context.Context, userID, l
 		Where("library_id IN ? AND (season_num > 0 OR episode_num > 0)", e.mergedLibraryIDs(ctx, libraryID))
 	q = e.applyUserMediaVisibility(ctx, q, userID)
 	var rows []model.Media
-	if err := q.Order(mediaReleaseOrderSQL(true)).Limit(embySeriesGroupingLimit).Find(&rows).Error; err != nil {
+	// 只要最近几部剧的卡片，不要把整库 5 万行拉进内存再丢掉。
+	if err := q.Order(mediaReleaseOrderSQL(true)).Limit(embyLatestSeriesRowLimit(limit)).Find(&rows).Error; err != nil {
 		return nil, nil, err
 	}
 	groups := e.seriesGroupsFromMedia(ctx, rows)
@@ -209,6 +251,24 @@ func (e *EmbyService) latestSeriesItemsForLibrary(ctx context.Context, userID, l
 	return items, e.artworkRefsForSeriesGroups(groups), nil
 }
 
+// embyLatestSeriesRowLimit 是 Latest 剧集卡片的候选窗口。按「每部剧最近约 40
+// 集」估，刚好覆盖现有 25 部 × 40 集的分组测试，又不会为了 16 张海报去扫整库。
+// ponytail: 一部长剧如果占满窗口，更老的剧不会出现在 Latest 行；点进媒体库
+// 仍走完整分组。上限 2000 行。
+func embyLatestSeriesRowLimit(limit int) int {
+	if limit < 1 {
+		limit = 20
+	}
+	n := limit * 40
+	if n < 200 {
+		n = 200
+	}
+	if n > 2000 {
+		n = 2000
+	}
+	return n
+}
+
 // ResumeItems 列出有未完成播放进度的媒体。
 func (e *EmbyService) ResumeItems(ctx context.Context, userID string, limit int) (map[string]any, error) {
 	return e.resumableItems(ctx, ItemsParams{UserID: userID, Limit: limit})
@@ -393,7 +453,7 @@ func (e *EmbyService) resumableItems(ctx context.Context, p ItemsParams) (map[st
 	// 总数用候选行数（本地过滤后 + 远程候选），对继续观看行的翻页语义
 	// 足够准确。
 	needed := p.StartIndex + p.Limit
-	items := make([]map[string]any, 0, p.Limit)
+	slots := make([]resumeSlot, 0, len(hist))
 	localTotal, remoteTotal := 0, 0
 	for _, h := range hist {
 		if m, ok := byID[h.MediaID]; ok {
@@ -401,36 +461,77 @@ func (e *EmbyService) resumableItems(ctx context.Context, p ItemsParams) (map[st
 				continue
 			}
 			localTotal++
-			if produced := len(items); produced < needed {
-				items = append(items, e.itemPayload(ctx, m, false, h.PositionMs, false))
-			}
+			slots = append(slots, resumeSlot{item: e.itemPayload(ctx, m, false, h.PositionMs, false)})
 			continue
 		}
 		if e.remote == nil || !IsEmbyRemoteID(h.MediaID) {
 			continue
 		}
 		remoteTotal++
-		if len(items) >= needed {
-			continue
-		}
-		mountID, remoteID, _ := DecodeEmbyRemoteID(h.MediaID)
-		mount, acct, err := e.remote.ResolveMount(ctx, mountID)
-		if err != nil || mount == nil || acct == nil {
-			continue
-		}
-		item, err := e.remote.RemoteItem(ctx, mount, acct, remoteID)
-		if err != nil || item == nil {
-			continue
-		}
-		if p.ParentID != "" {
-			parentID, _ := item["ParentId"].(string)
-			seriesID, _ := item["SeriesId"].(string)
-			if parentID != p.ParentID && seriesID != p.ParentID && mountID != p.ParentID {
+		slots = append(slots, resumeSlot{fetch: &resumeRemoteFetch{hist: h}})
+	}
+	for {
+		filled := 0
+		pending := make([]*resumeRemoteFetch, 0)
+		for i := range slots {
+			if slots[i].item != nil {
+				filled++
+				if filled >= needed {
+					break
+				}
 				continue
 			}
+			f := slots[i].fetch
+			if f == nil || f.done {
+				continue
+			}
+			if f.mount == nil {
+				mountID, remoteID, _ := DecodeEmbyRemoteID(f.hist.MediaID)
+				mount, acct, err := e.remote.ResolveMount(ctx, mountID)
+				if err != nil || mount == nil || acct == nil {
+					f.done = true
+					continue
+				}
+				f.mount, f.acct, f.remoteID = mount, acct, remoteID
+			}
+			pending = append(pending, f)
+			if filled+len(pending) >= needed {
+				break
+			}
 		}
-		item["UserData"] = mergedRemoteUserData(item["UserData"], &h)
-		items = append(items, item)
+		if len(pending) == 0 {
+			break
+		}
+		e.fillResumeRemotes(ctx, pending)
+		for i := range slots {
+			f := slots[i].fetch
+			if f == nil || !pendingContains(pending, f) {
+				continue
+			}
+			f.done = true
+			item := f.item
+			f.item = nil
+			if item == nil {
+				continue
+			}
+			if p.ParentID != "" {
+				parentID, _ := item["ParentId"].(string)
+				seriesID, _ := item["SeriesId"].(string)
+				mountID, _, _ := DecodeEmbyRemoteID(f.hist.MediaID)
+				if parentID != p.ParentID && seriesID != p.ParentID && mountID != p.ParentID {
+					continue
+				}
+			}
+			item["UserData"] = mergedRemoteUserData(item["UserData"], &f.hist)
+			slots[i].item = item
+		}
+	}
+	items := make([]map[string]any, 0, p.Limit)
+	for i := range slots {
+		if slots[i].item == nil {
+			continue
+		}
+		items = append(items, slots[i].item)
 	}
 
 	total := int64(localTotal + remoteTotal)
@@ -441,6 +542,57 @@ func (e *EmbyService) resumableItems(ctx context.Context, p ItemsParams) (map[st
 	return map[string]any{"Items": items[p.StartIndex:end], "TotalRecordCount": total, "StartIndex": p.StartIndex}, nil
 }
 
+type resumeSlot struct {
+	item  map[string]any
+	fetch *resumeRemoteFetch
+}
+
+type resumeRemoteFetch struct {
+	hist     model.PlaybackHistory
+	mount    *model.EmbyMount
+	acct     *model.StrmAccount
+	remoteID string
+	item     map[string]any
+	done     bool
+}
+
+func pendingContains(rows []*resumeRemoteFetch, target *resumeRemoteFetch) bool {
+	for _, row := range rows {
+		if row == target {
+			return true
+		}
+	}
+	return false
+}
+
+// fillResumeRemotes 并行补齐继续观看里的远程条目。同一页以前是串行 GET，
+// 远程一慢就把整个 Resume 拖到数秒。结果按原播放历史顺序回填。
+func (e *EmbyService) fillResumeRemotes(ctx context.Context, rows []*resumeRemoteFetch) {
+	if e == nil || e.remote == nil || len(rows) == 0 {
+		return
+	}
+	var wg sync.WaitGroup
+	sem := make(chan struct{}, 4)
+	for i := range rows {
+		wg.Add(1)
+		go func(i int) {
+			defer wg.Done()
+			select {
+			case sem <- struct{}{}:
+			case <-ctx.Done():
+				return
+			}
+			defer func() { <-sem }()
+			item, err := e.remote.RemoteItem(ctx, rows[i].mount, rows[i].acct, rows[i].remoteID)
+			if err != nil || item == nil {
+				return
+			}
+			rows[i].item = item
+		}(i)
+	}
+	wg.Wait()
+}
+
 func (e *EmbyService) itemPayload(ctx context.Context, m *model.Media, fav bool, posMs int64, includePeople bool) map[string]any {
 	itemType := "Movie"
 	name := m.Title

internal/service/emby_remote.go

@@ -805,6 +805,15 @@ func (r *EmbyRemoteService) RemoteSearchMount(ctx context.Context, mount *model.
 
 // RemoteItem 拉取远程单条目详情（含响应的重写）。
 func (r *EmbyRemoteService) RemoteItem(ctx context.Context, mount *model.EmbyMount, acct *model.StrmAccount, remoteID string) (map[string]any, error) {
+	cacheKey := ""
+	if r != nil && r.cache != nil && mount != nil && remoteID != "" {
+		cacheKey = r.remoteCacheKey("item", mount.ID, remoteID)
+		var cached map[string]any
+		if r.cache.GetJSON(ctx, cacheKey, &cached) && len(cached) > 0 {
+			r.rememberRemotePeople(mount, cached)
+			return cached, nil
+		}
+	}
 	cfg, err := r.remoteConfigWithToken(ctx, acct)
 	if err != nil {
 		return nil, err
@@ -817,6 +826,9 @@ func (r *EmbyRemoteService) RemoteItem(ctx context.Context, mount *model.EmbyMou
 	}
 	r.rememberRemotePeople(mount, out)
 	RewriteEmbyRemoteIDs(out, mount.ID)
+	if cacheKey != "" && len(out) > 0 {
+		r.cache.SetJSON(ctx, cacheKey, out, r.remoteMediaCacheTTL())
+	}
 	return out, nil
 }
 

internal/service/emby_remote_web.go

@@ -388,6 +388,17 @@ func (r *EmbyRemoteService) RemoteMediaDetail(ctx context.Context, mount *model.
 // remoteMediaDetailRaw 拉取远程条目详情，同时返回原始载荷（ID 已伪装），
 // 供调用方免二次请求读取 Type / SeriesId 等字段。
 func (r *EmbyRemoteService) remoteMediaDetailRaw(ctx context.Context, mount *model.EmbyMount, acct *model.StrmAccount, remoteID string) (*model.Media, map[string]any, error) {
+	cacheKey := ""
+	if r != nil && r.cache != nil && mount != nil && remoteID != "" {
+		cacheKey = r.remoteCacheKey("detail", mount.ID, remoteID)
+		var cached struct {
+			Media *model.Media   `json:"media"`
+			Raw   map[string]any `json:"raw"`
+		}
+		if r.cache.GetJSON(ctx, cacheKey, &cached) && cached.Media != nil {
+			return cached.Media, cached.Raw, nil
+		}
+	}
 	cfg, err := r.remoteConfigWithToken(ctx, acct)
 	if err != nil {
 		return nil, nil, err
@@ -400,6 +411,12 @@ func (r *EmbyRemoteService) remoteMediaDetailRaw(ctx context.Context, mount *mod
 	}
 	RewriteEmbyRemoteIDs(out, mount.ID)
 	m := r.MapRemoteItemToMedia(ctx, mount, acct, cfg, out)
+	if cacheKey != "" {
+		r.cache.SetJSON(ctx, cacheKey, struct {
+			Media *model.Media   `json:"media"`
+			Raw   map[string]any `json:"raw"`
+		}{Media: &m, Raw: out}, r.remoteMediaCacheTTL())
+	}
 	return &m, out, nil
 }
 

internal/service/emby_series_hierarchy_test.go

@@ -156,6 +156,12 @@ func TestEmbySeriesGroupingPaginatesAfterFullLibraryGrouping(t *testing.T) {
 	}
 }
 
+func TestEmbyLatestSeriesRowLimitCoversGroupedFixture(t *testing.T) {
+	if got := embyLatestSeriesRowLimit(25); got < 25*40 {
+		t.Fatalf("latest window %d is smaller than the 25x40 fixture", got)
+	}
+}
+
 func TestEmbyItemsKeepSpecialsInSeasonZero(t *testing.T) {
 	svc := newTestEmbyService(t)
 	lib := model.Library{Name: "番剧", Path: `F:\downloads\日番`, Type: "anime", Enabled: true}

internal/service/image_resize.go

@@ -226,6 +226,34 @@ func (p *ImageProxy) acquireResizeSlot(ctx context.Context) (func(), bool) {
 	}
 }
 
+// tryAcquireResizeSlot 不等待。槽位忙时返回 false，调用方应改出原图。
+func (p *ImageProxy) tryAcquireResizeSlot() (func(), bool) {
+	if p == nil {
+		return func() {}, true
+	}
+	p.resizeSemMu.Lock()
+	if p.resizeSem == nil {
+		p.resizeSem = make(chan struct{}, imageResizeConcurrency())
+	}
+	sem := p.resizeSem
+	p.resizeSemMu.Unlock()
+	select {
+	case sem <- struct{}{}:
+		return func() { <-sem }, true
+	default:
+		return nil, false
+	}
+}
+
+// acquireResizeSlotFor 对中等体积的图只尝试一次槽位。忙则放弃缩放，
+// 避免背景图墙在 2 核机器上排成数秒。超大原图仍等待，以免直出多兆字节。
+func (p *ImageProxy) acquireResizeSlotFor(ctx context.Context, size int64) (func(), bool) {
+	if size > 0 && size <= resizeQueueBypassBytes {
+		return p.tryAcquireResizeSlot()
+	}
+	return p.acquireResizeSlot(ctx)
+}
+
 // serveResizedFromFile 从 srcPath 读取图片，按选项缩放后写出，并把结果缓存
 // 到磁盘以免每次请求都重新解码。原图已满足目标尺寸时直接输出原文件。
 // 返回 false 表示缩放不可用，调用方应回退到原图直出。
@@ -241,8 +269,13 @@ func (p *ImageProxy) serveResizedFromFile(w http.ResponseWriter, r *http.Request
 	if serveCachedImageFile(w, r, key, cachePath) {
 		return true
 	}
+	// 本地海报大多已经是一百多 KB 的 JPEG。先解码再缩放会把 2 核机器的
+	// 并发槽（2）堵成数秒队列。体积已经适合直接下发时，不要排队。
+	if serveCompactOriginal(w, r, srcPath, stat) {
+		return true
+	}
 
-	release, ok := p.acquireResizeSlot(r.Context())
+	release, ok := p.acquireResizeSlotFor(r.Context(), stat.Size())
 	if !ok {
 		return false
 	}
@@ -273,6 +306,43 @@ func (p *ImageProxy) serveResizedFromFile(w http.ResponseWriter, r *http.Request
 	return true
 }
 
+// compactImageSkipBytes 是“直接出原图”的体积上限。超过它的原图（多兆字节
+// 的剧照、未压缩 sidecar）仍然走缩放，避免把大文件直接塞给电视端。
+// ponytail: 200KB 覆盖这台机器上的典型海报（平均约 100KB）；更大的图仍尝试缩放。
+const compactImageSkipBytes = 200 * 1024
+
+// resizeQueueBypassBytes 是“槽位忙就放弃缩放”的上限。超过它的原图继续排队，
+// 以免把未压缩的剧照直接发给客户端。
+const resizeQueueBypassBytes = 1536 * 1024
+
+// serveCompactOriginal 在源文件已经很小且是浏览器可直接显示的 JPEG/WebP 时
+// 跳过解码。返回 false 表示仍应走缩放路径。
+func serveCompactOriginal(w http.ResponseWriter, r *http.Request, srcPath string, stat os.FileInfo) bool {
+	if stat == nil || stat.Size() <= 0 || stat.Size() > compactImageSkipBytes {
+		return false
+	}
+	file, err := os.Open(srcPath) // #nosec G304 -- srcPath is an allowed local path or a SHA-derived cache path.
+	if err != nil {
+		return false
+	}
+	var header [12]byte
+	n, _ := file.Read(header[:])
+	_ = file.Close()
+	if !isCompactWebImage(header[:n]) {
+		return false
+	}
+	return serveImageFile(w, r, filepath.Base(srcPath), srcPath, imageBrowserCacheControl)
+}
+
+func isCompactWebImage(header []byte) bool {
+	if len(header) >= 3 && header[0] == 0xff && header[1] == 0xd8 && header[2] == 0xff {
+		return true
+	}
+	return len(header) >= 12 &&
+		string(header[0:4]) == "RIFF" &&
+		string(header[8:12]) == "WEBP"
+}
+
 // writeResizeCache 原子写入缩放结果；失败只记日志，不影响本次响应。
 func (p *ImageProxy) writeResizeCache(cachePath string, data []byte) {
 	dir := filepath.Dir(cachePath)

internal/service/image_resize_test.go

@@ -2,12 +2,15 @@ package service
 
 import (
 	"bytes"
+	"context"
 	"image"
 	"image/color"
+	"image/jpeg"
 	"image/png"
 	"net/http/httptest"
 	"os"
 	"testing"
+	"time"
 )
 
 // encodeTestPNG 生成一张结构规则、易于压缩的测试用 PNG。
@@ -274,3 +277,60 @@ func TestServeResizedFromFileUsesCacheBeforeDecodingSource(t *testing.T) {
 		t.Fatal("expected cached thumbnail to be reused without decoding the source")
 	}
 }
+
+func TestServeResizedFromFileSkipsDecodeForCompactJPEG(t *testing.T) {
+	dir := t.TempDir()
+	src := dir + string(os.PathSeparator) + "poster.jpg"
+	var buf bytes.Buffer
+	if err := jpeg.Encode(&buf, image.NewRGBA(image.Rect(0, 0, 800, 1200)), &jpeg.Options{Quality: 40}); err != nil {
+		t.Fatalf("encode jpeg: %v", err)
+	}
+	if buf.Len() == 0 || buf.Len() > compactImageSkipBytes {
+		t.Fatalf("test jpeg is %d bytes, want a compact poster", buf.Len())
+	}
+	if err := os.WriteFile(src, buf.Bytes(), 0o644); err != nil {
+		t.Fatalf("write source: %v", err)
+	}
+
+	proxy := &ImageProxy{cacheDir: dir + string(os.PathSeparator) + "cache"}
+	rec := httptest.NewRecorder()
+	if !proxy.serveResizedFromFile(rec, httptest.NewRequest("GET", "/x?maxWidth=120", nil), src, imageResizeOptions{MaxWidth: 120}) {
+		t.Fatal("expected compact jpeg to be served")
+	}
+	if !bytes.Equal(rec.Body.Bytes(), buf.Bytes()) {
+		t.Fatal("expected the original jpeg, not a decoded thumbnail")
+	}
+}
+
+func TestServeResizedFromFileDoesNotQueueWhenResizeBusy(t *testing.T) {
+	dir := t.TempDir()
+	src := dir + string(os.PathSeparator) + "backdrop.jpg"
+	data := make([]byte, compactImageSkipBytes+1024)
+	data[0], data[1], data[2] = 0xff, 0xd8, 0xff
+	if err := os.WriteFile(src, data, 0o644); err != nil {
+		t.Fatalf("write source: %v", err)
+	}
+	proxy := &ImageProxy{cacheDir: dir + string(os.PathSeparator) + "cache"}
+	var releases []func()
+	for i := 0; i < imageResizeConcurrency(); i++ {
+		release, ok := proxy.acquireResizeSlot(context.Background())
+		if !ok {
+			t.Fatal("expected a resize slot")
+		}
+		releases = append(releases, release)
+	}
+	defer func() {
+		for _, release := range releases {
+			release()
+		}
+	}()
+
+	start := time.Now()
+	handled := proxy.serveResizedFromFile(httptest.NewRecorder(), httptest.NewRequest("GET", "/x?maxWidth=480", nil), src, imageResizeOptions{MaxWidth: 480})
+	if time.Since(start) > 200*time.Millisecond {
+		t.Fatal("resize slot was busy but the request still waited in the queue")
+	}
+	if handled {
+		t.Fatal("expected a busy resize slot to fall back so the caller can serve the original")
+	}
+}

internal/service/media_cache.go

@@ -69,6 +69,23 @@ func (s *MediaService) seriesCardsCacheKey(libraryID string, visibility MediaVis
 	return "media:series-cards:" + hex.EncodeToString(sum[:])
 }
 
+func (s *MediaService) libraryCountCacheKey(libraryIDs []string, filter repository.MediaQueryFilter) string {
+	ids := append([]string(nil), libraryIDs...)
+	allowed := append([]string(nil), filter.AllowedLibraryIDs...)
+	hidden := append([]string(nil), filter.HiddenLibraryIDs...)
+	sort.Strings(ids)
+	sort.Strings(allowed)
+	sort.Strings(hidden)
+	sum := sha1.Sum([]byte(strings.Join([]string{
+		"counts",
+		strings.Join(ids, ","),
+		fmt.Sprintf("%t", filter.IncludeNSFW),
+		strings.Join(allowed, ","),
+		strings.Join(hidden, ","),
+	}, "|")))
+	return "media:lib-counts:" + hex.EncodeToString(sum[:])
+}
+
 func (s *MediaService) mediaCacheTTLSeconds() int {
 	if s == nil || s.cfg == nil || s.cfg.Cache.MediaTTLSeconds < 1 {
 		return 90
@@ -82,6 +99,18 @@ func (s *MediaService) mediaObjectTTL() time.Duration {
 	return time.Duration(s.mediaCacheTTLSeconds()) * time.Second
 }
 
+// derivedReadCacheTTL 给首页预览、剧集分组、库计数这类派生读缓存一个更长的
+// 下限。扫描/刮削/删改都会走 invalidateMediaCache 清掉 media: 前缀，所以
+// 拉长 TTL 不会在写入后继续吐旧卡片。配置里的 TTL 更长时仍以配置为准。
+func (s *MediaService) derivedReadCacheTTL() time.Duration {
+	ttl := s.mediaObjectTTL()
+	const floor = 10 * time.Minute
+	if ttl < floor {
+		return floor
+	}
+	return ttl
+}
+
 func hashObjectCacheKey(parts []string) string {
 	sum := sha1.Sum([]byte(strings.Join(parts, "|")))
 	return hex.EncodeToString(sum[:])

internal/service/media_library.go

@@ -2,7 +2,6 @@ package service
 
 import (
 	"context"
-	"time"
 
 	"github.com/truewhile/MeBox/internal/model"
 	"github.com/truewhile/MeBox/internal/repository"
@@ -24,6 +23,31 @@ func (s *MediaService) ListLibraries(ctx context.Context) ([]model.Library, erro
 	return s.repo.Library.List(ctx)
 }
 
+// CountLibrariesCached returns per-library media totals. The homepage metadata
+// request asks for every library, and the underlying COUNT is repeated on each
+// refresh. Writes already drop the media: prefix, so a longer TTL is safe.
+func (s *MediaService) CountLibrariesCached(ctx context.Context, libraryIDs []string, filter repository.MediaQueryFilter) (map[string]int64, error) {
+	if len(libraryIDs) == 0 {
+		return map[string]int64{}, nil
+	}
+	cacheKey := s.libraryCountCacheKey(libraryIDs, filter)
+	var cached map[string]int64
+	if s.cache != nil && s.cache.GetJSON(ctx, cacheKey, &cached) && cached != nil {
+		return cached, nil
+	}
+	counts, err := s.repo.Media.CountByLibraries(ctx, libraryIDs, filter)
+	if err != nil {
+		return nil, err
+	}
+	if counts == nil {
+		counts = map[string]int64{}
+	}
+	if s.cache != nil {
+		s.cache.SetJSON(ctx, cacheKey, counts, s.derivedReadCacheTTL())
+	}
+	return counts, nil
+}
+
 // ListLibrariesWithPreview returns libraries populated with item counts and latest preview cards.
 func (s *MediaService) ListLibrariesWithPreview(ctx context.Context, libraries []model.Library, visibility MediaVisibility, cardLimit int) ([]LibraryPreviewItem, error) {
 	return s.listLibrariesWithPreview(ctx, libraries, visibility, cardLimit, true)
@@ -120,7 +144,7 @@ func (s *MediaService) listLibrariesWithPreview(ctx context.Context, libraries [
 	}
 
 	if s.cache != nil {
-		s.cache.SetJSON(ctx, cacheKey, libraryPreviewCacheValue{Items: out}, time.Duration(s.mediaCacheTTLSeconds())*time.Second)
+		s.cache.SetJSON(ctx, cacheKey, libraryPreviewCacheValue{Items: out}, s.derivedReadCacheTTL())
 	}
 
 	return out, nil

internal/service/media_series.go

@@ -70,7 +70,7 @@ func (s *MediaService) libraryRowsWithIndex(ctx context.Context, libraryID strin
 	cards := groupMediaSeriesCardsByKeys(rows, keys)
 	value := &libraryRowsCacheValue{Rows: rows, Resolver: resolver, Episodes: episodes, Cards: cards}
 	if s.cache != nil {
-		s.cache.SetObject(cacheKey, value, s.mediaObjectTTL())
+		s.cache.SetObject(cacheKey, value, s.derivedReadCacheTTL())
 	}
 	return value, nil
 }
@@ -99,7 +99,7 @@ func (s *MediaService) ListLibrarySeriesCards(ctx context.Context, libraryID str
 	}
 	total := int64(len(cards))
 	if s.cache != nil {
-		s.cache.SetObject(cacheKey, &seriesCardsCacheValue{Cards: cards, Total: total}, s.mediaObjectTTL())
+		s.cache.SetObject(cacheKey, &seriesCardsCacheValue{Cards: cards, Total: total}, s.derivedReadCacheTTL())
 	}
 	return cards, total, nil
 }

internal/service/playback.go

@@ -265,6 +265,23 @@ func (p *PlaybackService) ListFavourites(ctx context.Context, userID string) ([]
 	return out, nil
 }
 
+// ListFavouriteIDs returns the user's favourite media IDs without hydrating
+// remote Emby items. Heart-icon state only needs the IDs; fetching each remote
+// detail on every library open adds a few hundred milliseconds.
+func (p *PlaybackService) ListFavouriteIDs(ctx context.Context, userID string) ([]string, error) {
+	favs, err := p.repo.Favorite.ListByUser(ctx, userID)
+	if err != nil {
+		return nil, err
+	}
+	ids := make([]string, 0, len(favs))
+	for _, fav := range favs {
+		if fav.MediaID != "" {
+			ids = append(ids, fav.MediaID)
+		}
+	}
+	return ids, nil
+}
+
 // ─── Playlists ──────────────────────────────────────────────────────────────
 
 // CreatePlaylist persists a new playlist owned by userID.

web/src/api/playback.ts

@@ -61,6 +61,9 @@ export const playbackAPI = {
   listFavourites: () =>
     api.get<{ items: Media[] }>('/favourites').then((r) => r.data.items),
 
+  listFavouriteIDs: () =>
+    api.get<{ ids: string[] }>('/favourites', { params: { ids: 1 } }).then((r) => r.data.ids ?? []),
+
   listPlaylists: () =>
     api.get<{ items: Playlist[] }>('/playlists').then((r) => r.data.items),
 

web/src/components/PlayerControls.tsx

@@ -1,7 +1,9 @@
 import { useCallback, useEffect, useRef, useState } from 'react'
+import { createPortal } from 'react-dom'
 import {
   Captions,
   CaptionsOff,
+  FastForward,
   ListVideo,
   Maximize,
   MessageSquareText,
@@ -9,6 +11,7 @@ import {
   Pause,
   PictureInPicture,
   Play,
+  Rewind,
   SkipBack,
   SkipForward,
   Volume2,
@@ -35,6 +38,24 @@ function formatTime(s: number): string {
   return `${m}:${String(sec).padStart(2, '0')}`
 }
 
+const SEEK_STEP_SEC = 10
+const SEEK_REPEAT_MS = 160
+const SEEK_APPLY_MS = 220
+const SEEK_HINT_MS = 700
+
+type SeekHint = {
+  dir: 'back' | 'forward'
+  seconds: number
+}
+
+function isEditableTarget(target: EventTarget | null): boolean {
+  if (!(target instanceof HTMLElement)) return false
+  return Boolean(
+    target.closest('input, textarea, select, [contenteditable="true"]') ||
+      target.isContentEditable,
+  )
+}
+
 type PlayerControlsProps = {
   videoRef: React.RefObject<HTMLVideoElement>
   uiVisible: boolean
@@ -123,6 +144,14 @@ export function PlayerControls({
   const danmakuOpenRef = useRef(false)
   const playlistOpenRef = useRef(false)
   const pendingSeekRef = useRef<number | null>(null)
+  const applySeekRef = useRef<(absolute: number) => void>(() => undefined)
+  const durationRef = useRef(0)
+  const seekBurstRef = useRef<{ base: number; delta: number } | null>(null)
+  const seekApplyTimerRef = useRef<ReturnType<typeof setTimeout> | null>(null)
+  const seekHintTimerRef = useRef<ReturnType<typeof setTimeout> | null>(null)
+  const lastSeekAtRef = useRef(0)
+  const [seekHint, setSeekHint] = useState<SeekHint | null>(null)
+  const [stageEl, setStageEl] = useState<HTMLElement | null>(null)
 
   useEffect(() => {
     controlsHoveredRef.current = controlsHovered
@@ -144,6 +173,14 @@ export function PlayerControls({
     playlistOpenRef.current = playlistOpen
   }, [playlistOpen])
 
+  useEffect(() => {
+    durationRef.current = duration
+  }, [duration])
+
+  useEffect(() => {
+    setStageEl(container())
+  }, [container])
+
   // 点击控制栏外部时关闭字幕菜单
   useEffect(() => {
     if (!subtitleMenuOpen) return
@@ -311,6 +348,7 @@ export function PlayerControls({
     el.currentTime = local
     setCurrentTime(streamOffset + local)
   }
+  applySeekRef.current = applyAbsoluteSeek
 
   const handleSeekChange = (v: number) => {
     setScrubValue(v)
@@ -321,6 +359,11 @@ export function PlayerControls({
   }
 
   const handleSeekStart = () => {
+    if (seekApplyTimerRef.current) {
+      clearTimeout(seekApplyTimerRef.current)
+      seekApplyTimerRef.current = null
+    }
+    seekBurstRef.current = null
     setIsScrubbing(true)
     onUiVisibleChange(true)
     if (hideTimerRef.current) clearTimeout(hideTimerRef.current)
@@ -332,6 +375,102 @@ export function PlayerControls({
     setScrubValue(null)
   }
 
+  const revealControls = useCallback(() => {
+    onUiVisibleChange(true)
+    if (hideTimerRef.current) clearTimeout(hideTimerRef.current)
+    const el = video()
+    if (
+      !el ||
+      el.paused ||
+      controlsHoveredRef.current ||
+      isScrubbingRef.current ||
+      subtitleMenuOpenRef.current ||
+      danmakuOpenRef.current ||
+      playlistOpenRef.current
+    ) {
+      return
+    }
+    hideTimerRef.current = setTimeout(() => {
+      if (
+        !controlsHoveredRef.current &&
+        !isScrubbingRef.current &&
+        !subtitleMenuOpenRef.current &&
+        !danmakuOpenRef.current &&
+        !playlistOpenRef.current
+      ) {
+        onUiVisibleChange(false)
+      }
+    }, 3000)
+  }, [onUiVisibleChange, video])
+
+  const queueRelativeSeek = useCallback((delta: number) => {
+    const el = video()
+    if (!el) return
+    if (!seekBurstRef.current) {
+      const base = pendingSeekRef.current ?? streamOffset + (el.currentTime || 0)
+      seekBurstRef.current = { base, delta: 0 }
+    }
+    seekBurstRef.current.delta += delta
+    const max = durationRef.current > 0 ? durationRef.current : Number.POSITIVE_INFINITY
+    const target = Math.min(max, Math.max(0, seekBurstRef.current.base + seekBurstRef.current.delta))
+    const applied = target - seekBurstRef.current.base
+    seekBurstRef.current.delta = applied
+    if (applied === 0) {
+      if (!seekApplyTimerRef.current) {
+        seekBurstRef.current = null
+        setSeekHint({
+          dir: delta < 0 ? 'back' : 'forward',
+          seconds: 0,
+        })
+        if (seekHintTimerRef.current) clearTimeout(seekHintTimerRef.current)
+        seekHintTimerRef.current = setTimeout(() => setSeekHint(null), SEEK_HINT_MS)
+      }
+      return
+    }
+
+    pendingSeekRef.current = target
+    setCurrentTime(target)
+    setSeekHint({
+      dir: applied < 0 ? 'back' : 'forward',
+      seconds: Math.abs(Math.round(applied)),
+    })
+    revealControls()
+
+    if (seekHintTimerRef.current) clearTimeout(seekHintTimerRef.current)
+    seekHintTimerRef.current = setTimeout(() => setSeekHint(null), SEEK_HINT_MS)
+    if (seekApplyTimerRef.current) clearTimeout(seekApplyTimerRef.current)
+    seekApplyTimerRef.current = setTimeout(() => {
+      const burst = seekBurstRef.current
+      seekBurstRef.current = null
+      seekApplyTimerRef.current = null
+      if (!burst) return
+      applySeekRef.current(burst.base + burst.delta)
+    }, SEEK_APPLY_MS)
+  }, [revealControls, streamOffset, video])
+
+  useEffect(() => {
+    const onKey = (e: KeyboardEvent) => {
+      if (e.altKey || e.ctrlKey || e.metaKey || e.shiftKey) return
+      if (isEditableTarget(e.target)) return
+      if (e.key !== 'ArrowLeft' && e.key !== 'ArrowRight') return
+      e.preventDefault()
+      const now = Date.now()
+      if (e.repeat && now - lastSeekAtRef.current < SEEK_REPEAT_MS) return
+      lastSeekAtRef.current = now
+      e.preventDefault()
+      queueRelativeSeek(e.key === 'ArrowLeft' ? -SEEK_STEP_SEC : SEEK_STEP_SEC)
+    }
+    window.addEventListener('keydown', onKey)
+    return () => window.removeEventListener('keydown', onKey)
+  }, [queueRelativeSeek])
+
+  useEffect(() => {
+    return () => {
+      if (seekApplyTimerRef.current) clearTimeout(seekApplyTimerRef.current)
+      if (seekHintTimerRef.current) clearTimeout(seekHintTimerRef.current)
+    }
+  }, [])
+
   const changeVolume = (v: number) => {
     const el = video()
     if (!el) return
@@ -380,7 +519,39 @@ export function PlayerControls({
   const canAdjustSelectedSubtitle = selectedSubtitle?.delivery === 'webvtt'
   const usesOriginalASS = selectedSubtitle?.delivery === 'ass'
 
+  const seekOverlay = seekHint && stageEl
+    ? createPortal(
+        <div className="pointer-events-none absolute inset-0 z-30">
+          <div
+            className={`absolute top-1/2 flex w-36 -translate-y-1/2 flex-col items-center justify-center rounded-full bg-black/55 px-3 py-5 text-white shadow-lg backdrop-blur-sm ${
+              seekHint.dir === 'back' ? 'left-[8%] sm:left-[12%]' : 'right-[8%] sm:right-[12%]'
+            }`}
+          >
+            {seekHint.dir === 'back' ? <Rewind size={28} /> : <FastForward size={28} />}
+            <span className="mt-1 text-center text-sm font-medium leading-tight">
+              {seekHint.seconds > 0
+                ? seekHint.dir === 'back'
+                  ? '回退'
+                  : '快进'
+                : seekHint.dir === 'back'
+                  ? '已到开头'
+                  : '已到结尾'}
+              {seekHint.seconds > 0 && (
+                <>
+                  <br />
+                  <span className="tabular-nums">{seekHint.seconds} 秒</span>
+                </>
+              )}
+            </span>
+          </div>
+        </div>,
+        stageEl,
+      )
+    : null
+
   return (
+    <>
+    {seekOverlay}
     <div
       className={`pointer-events-auto absolute inset-x-0 bottom-0 z-20 bg-gradient-to-t from-black/80 via-black/40 to-transparent px-3 pb-3 pt-14 transition-opacity duration-300 ${
         uiVisible ? 'opacity-100' : 'pointer-events-none opacity-0'
@@ -645,5 +816,6 @@ export function PlayerControls({
         </button>
       </div>
     </div>
+    </>
   )
 }

web/src/hooks/useFavourites.ts

@@ -10,10 +10,10 @@ export function useFavourites() {
   useEffect(() => {
     let cancelled = false
     playbackAPI
-      .listFavourites()
+      .listFavouriteIDs()
       .then((items) => {
         if (!cancelled) {
-          setFavouriteIDs(new Set((items ?? []).map((item) => item.id)))
+          setFavouriteIDs(new Set(items ?? []))
         }
       })
       .catch(() => {

web/src/pages/HomePage.tsx

@@ -8,6 +8,7 @@ import type { SeriesCard } from '../utils/groupSeries'
 import { fetchLibraries, peekLibraries } from '../utils/libraryCache'
 import { usePinnedLibraries } from '../hooks/usePinnedLibraries'
 import { sortByPinnedIds } from '../utils/pinnedLibraries'
+import { partitionPreviewIDs } from '../utils/remoteEmby'
 import {
   ContinueWatchingSection,
   ContinueWatchingSkeleton,
@@ -18,7 +19,6 @@ import {
   HomeLoadingState,
 } from './HomePageSections'
 
-const PREVIEW_BATCH_SIZE = 4
 const hasArtwork = (media?: Media | null) => !!(media?.poster_url || media?.backdrop_url)
 
 export function HomePage() {
@@ -102,12 +102,10 @@ export function HomePage() {
     if (targets.length === 0) return
     targets.forEach((id) => fetchingPreviewLimitsRef.current.set(id, limit))
 
-    const batches: string[][] = []
-    for (let i = 0; i < targets.length; i += PREVIEW_BATCH_SIZE) {
-      batches.push(targets.slice(i, i + PREVIEW_BATCH_SIZE))
-    }
+    // 本地库一次拉完（同一条窗口查询、缓存键稳定）。远程库单独一批，
+    // 避免一个慢的 Emby 挂载拖住整页预览。
+    const batches = partitionPreviewIDs(targets)
 
-    // 分批并发：一个慢库不再阻塞整页预览，先返回的批次立即渲染。
     await Promise.allSettled(
       batches.map(async (batch) => {
         let loaded = false

web/src/pages/LibrariesPage.tsx

@@ -15,6 +15,7 @@ import type { Library } from '../types'
 import type { SeriesCard } from '../utils/groupSeries'
 import { fetchLibraries, invalidateLibraries, peekLibraries } from '../utils/libraryCache'
 import { sortLibraryPreviews } from '../utils/pinnedLibraries'
+import { partitionPreviewIDs } from '../utils/remoteEmby'
 
 export function LibrariesPage() {
   const [libraries, setLibraries] = useState<Library[]>([])
@@ -33,30 +34,33 @@ export function LibrariesPage() {
     if (targets.length === 0) return
     targets.forEach((id) => fetchingRef.current.add(id))
 
-    let loaded = false
-    try {
-      const rows = await libraryAPI.listPreviews(targets, 10)
-      loaded = true
-      setLibraryData((prev) => {
-        const next = { ...prev }
-        for (const row of rows) {
-          next[row.id] = {
-            cards: row.cards ?? [],
-            total: row.total ?? 0,
-          }
+    const batches = partitionPreviewIDs(targets)
+    await Promise.allSettled(
+      batches.map(async (batch) => {
+        let loaded = false
+        try {
+          const rows = await libraryAPI.listPreviews(batch, 10)
+          loaded = true
+          setLibraryData((prev) => {
+            const next = { ...prev }
+            for (const row of rows) {
+              next[row.id] = {
+                cards: row.cards ?? [],
+                total: row.total ?? 0,
+              }
+            }
+            return next
+          })
+        } catch {
+          // 单个批次失败不影响其他批次。
+        } finally {
+          batch.forEach((id) => {
+            if (loaded) fetchedLibIdsRef.current.add(id)
+            fetchingRef.current.delete(id)
+          })
         }
-        return next
-      })
-    } catch {
-      // 容错
-    } finally {
-      targets.forEach((id) => {
-        if (loaded) {
-          fetchedLibIdsRef.current.add(id)
-        }
-        fetchingRef.current.delete(id)
-      })
-    }
+      }),
+    )
   }, [])
 
   const loadLibraries = useCallback(async (options?: { force?: boolean }) => {

web/src/pages/PlayerPage.tsx

@@ -783,7 +783,8 @@ export function PlayerPage() {
     }
   }, [nextEpisode, nextEpisodeTitle, playEpisode])
 
-  // ESC = back 或关闭浮层，[ / ] 或 Shift+P / Shift+N 切换上一集/下一集
+  // ESC = back 或关闭浮层，[ / ] 或 Shift+P / Shift+N 切换上一集/下一集。
+  // 左右方向键的回退/快进在播放器控制栏里处理。
   useEffect(() => {
     const onKey = (e: KeyboardEvent) => {
       const target = e.target as HTMLElement | null

web/src/utils/remoteEmby.ts

@@ -3,4 +3,19 @@
 // embyremote~{accountID}~{remoteID}。
 export function isRemoteEmbyID(id?: string | null): boolean {
   return Boolean(id && id.startsWith('embyremote~'))
+}
+
+// partitionPreviewIDs 把本地库和远程库拆开。混在一个预览请求里时，本地 SQL
+// 会等最慢的远程 Emby 回来才一起返回。
+export function partitionPreviewIDs(ids: string[]): string[][] {
+  const local: string[] = []
+  const remote: string[] = []
+  for (const id of ids) {
+    if (isRemoteEmbyID(id)) remote.push(id)
+    else local.push(id)
+  }
+  const batches: string[][] = []
+  if (local.length > 0) batches.push(local)
+  if (remote.length > 0) batches.push(remote)
+  return batches
 }