diff --git a/internal/handler/emby_playback.go b/internal/handler/emby_playback.go
index b49446b..0450f7a 100644
--- a/internal/handler/emby_playback.go
+++ b/internal/handler/emby_playback.go
@@ -348,12 +348,6 @@ func embyVideoStreamHandler(svc *service.Container, cloudMode string) gin.Handle
 		// 此前这里把所有错误一律吞成 404：云盘 Cookie 过期、直链解析失败、
 		// STRM 播放被关闭……在第三方播放器上全部表现为「404 不存在」，
 		// 无法排查。现在区分：行不存在→404；云盘播放不可用/上游故障→502+原因。
-		//
-		// 网盘直链与换取时的 UA 严格绑定，而 Emby 客户端的 API 层与播放器层 UA
-		// 不保证相同（浏览器一定相同），所以只有浏览器客户端允许服务端短路换链。
-		if !isBrowserLikeUserAgent(c.GetHeader("User-Agent")) {
-			c.Request = c.Request.WithContext(service.WithClientSideSTRMResolve(c.Request.Context()))
-		}
 		err = svc.Stream.ServeFileWithCloudMode(c.Writer, c.Request, c.Param("id"), cloudMode)
 		switch {
 		case err == nil:
@@ -393,25 +387,6 @@ func embyPlaybackRedirectToken(c *gin.Context, svc *service.Container) string {
 	return token
 }
 
-// isBrowserLikeUserAgent 判断请求是否来自浏览器（含 WebView / Electron 客户端）。
-//
-// 只有浏览器能保证「API 请求」与「<video> 拉流」用同一个 User-Agent，因此也只有
-// 浏览器客户端可以安全地接受服务端换链后的 CDN 直链（见
-// service.WithClientSideSTRMResolve 说明）。原生播放器的播放器层与 API 层 UA
-// 不保证一致，必须让客户端自己去同源 strm 端点换链。
-func isBrowserLikeUserAgent(ua string) bool {
-	ua = strings.ToLower(strings.TrimSpace(ua))
-	if ua == "" {
-		return false
-	}
-	for _, marker := range []string{"mozilla/", "applewebkit/", "gecko/"} {
-		if strings.Contains(ua, marker) {
-			return true
-		}
-	}
-	return false
-}
-
 func embyShouldRedirectVideoStreamToSTRM(c *gin.Context, svc *service.Container, mediaID, cloudMode string) bool {
 	if c == nil || svc == nil || svc.Repo == nil || svc.Repo.Media == nil || cloudMode != service.CloudPlaybackModeRedirectProxy {
 		return false
diff --git a/internal/handler/emby_video_stream_resolve_test.go b/internal/handler/emby_video_stream_resolve_test.go
deleted file mode 100644
index 94916b2..0000000
--- a/internal/handler/emby_video_stream_resolve_test.go
+++ /dev/null
@@ -1,138 +0,0 @@
-package handler
-
-import (
-	"context"
-	"net/http"
-	"net/http/httptest"
-	"strings"
-	"testing"
-
-	"github.com/gin-gonic/gin"
-	"github.com/glebarez/sqlite"
-	"go.uber.org/zap"
-	"gorm.io/gorm"
-
-	"github.com/truewhile/MeBox/internal/config"
-	"github.com/truewhile/MeBox/internal/model"
-	"github.com/truewhile/MeBox/internal/repository"
-	"github.com/truewhile/MeBox/internal/service"
-	"github.com/truewhile/MeBox/internal/service/cloud"
-)
-
-// newEmbyStreamResolveTestContainer 造一个最小的 Emby 播放容器：一条云盘 strm 媒体
-// 加一个必定被调用的换链解析器，用于观察服务端是否替客户端换链。
-func newEmbyStreamResolveTestContainer(t *testing.T, resolver *countingStrmResolver) *service.Container {
-	t.Helper()
-	gin.SetMode(gin.TestMode)
-	db, err := gorm.Open(sqlite.Open(":memory:"), &gorm.Config{})
-	if err != nil {
-		t.Fatalf("open db: %v", err)
-	}
-	if err := db.AutoMigrate(&model.Media{}, &model.Setting{}, &model.StrmAccount{}, &model.Library{}, &model.User{}); err != nil {
-		t.Fatalf("migrate: %v", err)
-	}
-	if err := db.Create(&model.Media{
-		Base:      model.Base{ID: "cloud-1"},
-		Title:     "Cloud",
-		Path:      "cloud://cloud115/Movie.mkv",
-		Container: "strm",
-		STRMURL:   "/api/strm/play/cloud115/video.mkv?acct=a1&pickcode=pc1",
-	}).Error; err != nil {
-		t.Fatalf("seed media: %v", err)
-	}
-	repos := repository.New(db)
-	cfg := &config.Config{}
-	log := zap.NewNop()
-	return &service.Container{
-		Cfg:    cfg,
-		Log:    log,
-		Repo:   repos,
-		Emby:   service.NewEmbyService(cfg, log, repos),
-		Stream: service.NewStreamService(cfg, log, repos, nil).SetStrmPlayTargetResolver(resolver.Resolve),
-	}
-}
-
-type countingStrmResolver struct {
-	calls int
-}
-
-func (r *countingStrmResolver) Resolve(context.Context, string, string) (*service.StrmPlayResult, error) {
-	r.calls++
-	link := "https://cdnfhnfile.115cdn.net/637b/Movie.mkv?t=1&k=sig"
-	return &service.StrmPlayResult{
-		RedirectURL: link,
-		Link:        &cloud.DirectLink{URL: link, Headers: map[string]string{"User-Agent": "ua"}},
-	}, nil
-}
-
-func serveEmbyVideoStream(t *testing.T, svc *service.Container, userAgent string) *httptest.ResponseRecorder {
-	t.Helper()
-	rec := httptest.NewRecorder()
-	c, _ := gin.CreateTestContext(rec)
-	c.Request = httptest.NewRequest(http.MethodGet, "/emby/Videos/cloud-1/stream?api_key=jwt123", nil)
-	c.Request.Header.Set("User-Agent", userAgent)
-	c.Params = gin.Params{{Key: "id", Value: "cloud-1"}}
-	embyVideoStreamHandler(svc, service.CloudPlaybackModeRedirectProxy)(c)
-	return rec
-}
-
-// 115 直链与换取时的 User-Agent 严格绑定（换错一个字符 CDN 就 403），而原生
-// 播放器（小幻影视 / RodelPlayer）的 API 层与播放器层 UA 并不一致，因此对非
-// 浏览器客户端绝不能在服务端替它换链，必须让客户端自己去同源端点换链。
-func TestEmbyVideoStreamDoesNotResolveDirectLinkForNativePlayer(t *testing.T) {
-	resolver := &countingStrmResolver{}
-	svc := newEmbyStreamResolveTestContainer(t, resolver)
-
-	w := serveEmbyVideoStream(t, svc, "RodelPlayer/2.2610.2.0 (Windows NT 10.0.26200; x64)")
-
-	if w.Code != http.StatusFound {
-		t.Fatalf("status = %d body=%s, want 302", w.Code, w.Body.String())
-	}
-	if resolver.calls != 0 {
-		t.Fatalf("server-side resolve called %d times, want 0", resolver.calls)
-	}
-	loc := w.Header().Get("Location")
-	if !strings.Contains(loc, "/api/strm/play/cloud115/video.mkv") {
-		t.Fatalf("Location = %q, want the same-origin strm endpoint", loc)
-	}
-	if strings.Contains(loc, "115cdn.net") {
-		t.Fatalf("Location = %q, must not point straight at the CDN for a native player", loc)
-	}
-}
-
-// 浏览器的 XHR 与 <video> 拉流必然是同一个 UA，可以继续享受服务端换链少一跳。
-func TestEmbyVideoStreamResolvesDirectLinkForBrowser(t *testing.T) {
-	resolver := &countingStrmResolver{}
-	svc := newEmbyStreamResolveTestContainer(t, resolver)
-
-	w := serveEmbyVideoStream(t, svc, "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/150.0.0.0 Safari/537.36")
-
-	if w.Code != http.StatusFound {
-		t.Fatalf("status = %d body=%s, want 302", w.Code, w.Body.String())
-	}
-	if resolver.calls != 1 {
-		t.Fatalf("server-side resolve called %d times, want 1", resolver.calls)
-	}
-	if loc := w.Header().Get("Location"); !strings.Contains(loc, "115cdn.net") {
-		t.Fatalf("Location = %q, want the resolved direct link", loc)
-	}
-}
-
-func TestIsBrowserLikeUserAgent(t *testing.T) {
-	cases := []struct {
-		ua   string
-		want bool
-	}{
-		{"Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/150.0.0.0 Safari/537.36", true},
-		{"Mozilla/5.0 (iPhone; CPU iPhone OS 18_0 like Mac OS X) AppleWebKit/605.1.15", true},
-		{"RodelPlayer/2.2610.2.0 (Windows NT 10.0.26200; x64)", false},
-		{"Yamby/2.0.5.5(Android", false},
-		{"Infuse-Direct/8.0", false},
-		{"", false},
-	}
-	for _, tc := range cases {
-		if got := isBrowserLikeUserAgent(tc.ua); got != tc.want {
-			t.Fatalf("isBrowserLikeUserAgent(%q) = %v, want %v", tc.ua, got, tc.want)
-		}
-	}
-}
diff --git a/internal/service/emby_item_payload_empty_ids_test.go b/internal/service/emby_item_payload_empty_ids_test.go
new file mode 100644
index 0000000..381e84d
--- /dev/null
+++ b/internal/service/emby_item_payload_empty_ids_test.go
@@ -0,0 +1,92 @@
+package service
+
+import (
+	"testing"
+
+	"github.com/truewhile/MeBox/internal/model"
+)
+
+// Emby/Jellyfin 对「不适用」的字段不下发（JSON 里没有该键），而不是下发空串。
+// 小幻影视（RodelPlayer）2.2610 会把电影条目的 "SeasonId": "" 原样传进播放准备
+// 逻辑并抛 ArgumentException（Parameter 'seasonId'），导致整个起播失败。
+func TestEmbyMovieItemOmitsEmptySeasonAndSeriesFields(t *testing.T) {
+	svc := newTestEmbyService(t)
+	lib := model.Library{Name: "小姐姐", Path: `/media/小姐姐`, Type: "movie", Enabled: true}
+	if err := svc.repo.Library.Create(t.Context(), &lib); err != nil {
+		t.Fatalf("create library: %v", err)
+	}
+	movie := model.Media{
+		Base:      model.Base{ID: "movie-strm"},
+		LibraryID: lib.ID,
+		Title:     "SNIS-919",
+		Path:      `/media/小姐姐/三上悠亚/SNIS-919/SNIS-919.strm`,
+		Container: "strm",
+		STRMURL:   "/api/strm/play/cloud115/video.mkv?acct=a1&pickcode=pc1",
+	}
+	if err := svc.repo.DB.Create(&movie).Error; err != nil {
+		t.Fatalf("create media: %v", err)
+	}
+
+	item := svc.itemPayload(t.Context(), &movie, false, 0, false)
+	if item["Type"] != "Movie" {
+		t.Fatalf("Type = %#v, want Movie", item["Type"])
+	}
+	for _, key := range []string{"SeasonId", "SeriesId", "SeasonName", "SeriesName"} {
+		if value, ok := item[key]; ok {
+			t.Fatalf("%s must be omitted for a movie, got %#v", key, value)
+		}
+	}
+}
+
+// 剧集的季/剧归属是真实存在的，不能被一起删掉。
+func TestEmbyEpisodeItemKeepsSeasonAndSeriesFields(t *testing.T) {
+	svc := newTestEmbyService(t)
+	lib := model.Library{Name: "剧集", Path: `/media/tv`, Type: "tv", Enabled: true}
+	if err := svc.repo.Library.Create(t.Context(), &lib); err != nil {
+		t.Fatalf("create library: %v", err)
+	}
+	episode := model.Media{
+		Base:       model.Base{ID: "ep-1"},
+		LibraryID:  lib.ID,
+		Title:      "命运石之门",
+		Path:       `/media/tv/命运石之门/Season 01/命运石之门 - S01E01.mkv`,
+		SeasonNum:  1,
+		EpisodeNum: 1,
+	}
+	if err := svc.repo.DB.Create(&episode).Error; err != nil {
+		t.Fatalf("create media: %v", err)
+	}
+
+	item := svc.itemPayload(t.Context(), &episode, false, 0, false)
+	if item["Type"] != "Episode" {
+		t.Fatalf("Type = %#v, want Episode", item["Type"])
+	}
+	for _, key := range []string{"SeasonId", "SeriesId", "SeasonName", "SeriesName"} {
+		value, _ := item[key].(string)
+		if value == "" {
+			t.Fatalf("%s = %#v, want a non-empty value for an episode", key, item[key])
+		}
+	}
+}
+
+func TestDropEmptyStringFields(t *testing.T) {
+	item := map[string]any{
+		"SeasonId":  "",
+		"SeriesId":  "   ",
+		"SeriesName": "命运石之门",
+		"IndexNumber": 0,
+	}
+	dropEmptyStringFields(item, "SeasonId", "SeriesId", "SeriesName")
+	if _, ok := item["SeasonId"]; ok {
+		t.Fatalf("empty SeasonId must be removed")
+	}
+	if _, ok := item["SeriesId"]; ok {
+		t.Fatalf("whitespace-only SeriesId must be removed")
+	}
+	if item["SeriesName"] != "命运石之门" {
+		t.Fatalf("non-empty SeriesName must be kept, got %#v", item["SeriesName"])
+	}
+	if item["IndexNumber"] != 0 {
+		t.Fatalf("non-string fields must be left alone, got %#v", item["IndexNumber"])
+	}
+}
diff --git a/internal/service/emby_items_detail.go b/internal/service/emby_items_detail.go
index 16b56d4..040745e 100644
--- a/internal/service/emby_items_detail.go
+++ b/internal/service/emby_items_detail.go
@@ -787,9 +787,34 @@ func (e *EmbyService) itemPayload(ctx context.Context, m *model.Media, fav bool,
 	if includePeople {
 		item["People"] = e.resolveMediaPeople(ctx, m)
 	}
+	// Emby/Jellyfin 对「不适用」的字段是直接不下发（JSON 里没有该键），而不是下发
+	// 空串或占位值。电影等非剧集条目没有季/剧归属，小幻影视（RodelPlayer）2.2610
+	// 会把 "SeasonId": "" 原样传进播放准备逻辑并抛 ArgumentException
+	// （Parameter 'seasonId'），起播直接失败；"SeasonName": "特别篇" 也会让客户端
+	// 把电影当成特别篇展示。剧集则保留真实的季/剧信息，只清掉空值。
+	seasonKeys := []string{"SeasonId", "SeriesId", "SeasonName", "SeriesName"}
+	if itemType == "Episode" {
+		dropEmptyStringFields(item, seasonKeys...)
+	} else {
+		for _, key := range seasonKeys {
+			delete(item, key)
+		}
+	}
 	return item
 }
 
+// dropEmptyStringFields 删除值为空串（或全空白）的字符串字段。
+//
+// 用于对齐 Emby/Jellyfin 的序列化行为：这些字段在没有值时是「不存在」，
+// 而不是空串。客户端普遍把空串当合法值使用，收到空串会当成非法参数。
+func dropEmptyStringFields(item map[string]any, keys ...string) {
+	for _, key := range keys {
+		if value, ok := item[key].(string); ok && strings.TrimSpace(value) == "" {
+			delete(item, key)
+		}
+	}
+}
+
 func (e *EmbyService) resolveMediaPeople(ctx context.Context, m *model.Media) []map[string]any {
 	if m == nil {
 		return []map[string]any{}
diff --git a/internal/service/stream_direct_redirect_test.go b/internal/service/stream_direct_redirect_test.go
index 6a03110..c1fefd2 100644
--- a/internal/service/stream_direct_redirect_test.go
+++ b/internal/service/stream_direct_redirect_test.go
@@ -145,43 +145,6 @@ func TestServeFileFallsBackWhenDirectResolveUnavailable(t *testing.T) {
 	}
 }
 
-// 客户端 API 层与播放器层 UA 不一致时（原生播放器普遍如此）不能由服务端换链后
-// 直接 302 到 CDN：115 直链绑定换取时的 UA，换错就是 403。此时必须回退到同源的
-// strm 端点跳转，让播放器用自己的 UA 换链。
-func TestServeFileWithClientSideResolveKeepsSTRMEndpoint(t *testing.T) {
-	repos := directRedirectTestRepo(t)
-	seedCloudSTRMMedia(t, repos, "cloud-client-side", "/api/strm/play/cloud115/video.mkv?acct=a1&pickcode=pc1")
-	direct := "https://cdnfhnfile.115cdn.net/637b/Movie.mkv?t=1&k=sig"
-	resolveCalls := 0
-	svc := NewStreamService(&config.Config{}, zap.NewNop(), repos, nil).
-		SetStrmPlayTargetResolver(func(_ context.Context, raw, userAgent string) (*StrmPlayResult, error) {
-			resolveCalls++
-			return &StrmPlayResult{
-				RedirectURL: direct,
-				Link:        &cloud.DirectLink{URL: direct, Headers: map[string]string{"User-Agent": userAgent}},
-			}, nil
-		})
-
-	req := httptest.NewRequest(http.MethodGet, "http://nas.local:18080/emby/Videos/cloud-client-side/stream?api_key=jwt123", nil)
-	req.Header.Set("User-Agent", "RodelPlayer/2.2610.2.0 (Windows NT 10.0.26200; x64)")
-	req = req.WithContext(WithClientSideSTRMResolve(req.Context()))
-	w := httptest.NewRecorder()
-
-	if err := svc.ServeFileWithCloudMode(w, req, "cloud-client-side", CloudPlaybackModeRedirectProxy); err != nil {
-		t.Fatalf("ServeFileWithCloudMode: %v", err)
-	}
-	if resolveCalls != 0 {
-		t.Fatalf("resolver called %d times, want 0", resolveCalls)
-	}
-	loc := w.Header().Get("Location")
-	if !strings.Contains(loc, "/api/strm/play/cloud115/video.mkv") {
-		t.Fatalf("Location = %q, want the same-origin strm endpoint", loc)
-	}
-	if strings.Contains(loc, "cdnfhnfile") {
-		t.Fatalf("Location = %q, must not point straight at the CDN", loc)
-	}
-}
-
 // 没有注入解析器（测试/精简部署）时保持原有跳转，不受本次优化影响。
 func TestServeFileKeepsSTRMEndpointWithoutResolver(t *testing.T) {
 	repos := directRedirectTestRepo(t)
diff --git a/internal/service/stream_file.go b/internal/service/stream_file.go
index 76df34b..570c904 100644
--- a/internal/service/stream_file.go
+++ b/internal/service/stream_file.go
@@ -86,36 +86,6 @@ func setCloudRedirectNoStore(w http.ResponseWriter) {
 // 由 /api/strm/play 再去换链，最坏情况只是回到改动前的行为。
 const directPlayResolveTimeout = 10 * time.Second
 
-// clientSideSTRMResolveKey 标记「本次播放由客户端自己换取 strm 直链」。
-type clientSideSTRMResolveKey struct{}
-
-// WithClientSideSTRMResolve 让本次播放跳过「服务端换链后直接 302 到 CDN」的短路，
-// 改为 302 到同源的 strm 播放端点，由客户端自己的请求去换取直链。
-//
-// 为什么需要它：115 等网盘的直链与「换取直链时提交的 User-Agent」逐个字符严格
-// 绑定，换错一个字符 CDN 一律 403。服务端短路换链用的是当前请求的 UA，而真正
-// 拉流的是客户端的播放器组件；当客户端的 API 层与播放器层 UA 不一致时
-// （例如小幻影视 / RodelPlayer：API 请求带 "(Windows NT 10.0.26200; x64)" 后缀、
-// 播放器拉流仍是裸 UA），客户端会拿到与自身 UA 不匹配的直链，CDN 返回 403，
-// 表现为「播放失败」。交给客户端自己请求同源端点换链，换链用的就是播放器真实 UA。
-//
-// 浏览器（含 WebView / Electron）的 XHR 与 <video> 拉流必然是同一个 UA，
-// 不需要走这条路径。
-func WithClientSideSTRMResolve(ctx context.Context) context.Context {
-	if ctx == nil {
-		return nil
-	}
-	return context.WithValue(ctx, clientSideSTRMResolveKey{}, true)
-}
-
-func clientSideSTRMResolve(ctx context.Context) bool {
-	if ctx == nil {
-		return false
-	}
-	enabled, _ := ctx.Value(clientSideSTRMResolveKey{}).(bool)
-	return enabled
-}
-
 // resolveDirectPlayTargetURL 尝试在服务端把 strm 目标解析成客户端可直接拉取的
 // 最终直链，供调用方直接 302。
 //
@@ -126,11 +96,6 @@ func (s *StreamService) resolveDirectPlayTargetURL(r *http.Request, raw string)
 	if s == nil || s.strmResolve == nil || r == nil {
 		return "", false
 	}
-	// 调用方声明该客户端的拉流 UA 与本次请求 UA 不保证一致（见
-	// WithClientSideSTRMResolve）：服务端换出来的直链会绑定错误的 UA，必须放弃短路。
-	if clientSideSTRMResolve(r.Context()) {
-		return "", false
-	}
 	ctx, cancel := context.WithTimeout(r.Context(), directPlayResolveTimeout)
 	defer cancel()
 	// 必须带播放器 UA：115 直链绑定换取时的 UA，且按 UA 分键缓存，换错会拿到