优化，添加滚动记忆

internal/handler/danmaku_settings_test.go

@@ -112,7 +112,8 @@ func TestGetDanmakuConfigIncludesPerUserMergePreference(t *testing.T) {
 		t.Fatalf("status = %d, want 200", w.Code)
 	}
 	var cfg struct {
-		MergeSources bool `json:"merge_sources"`
+		MergeSources bool    `json:"merge_sources"`
+		PlaybackRate float64 `json:"playback_rate"`
 	}
 	if err := json.Unmarshal(w.Body.Bytes(), &cfg); err != nil {
 		t.Fatalf("decode: %v", err)
@@ -120,6 +121,9 @@ func TestGetDanmakuConfigIncludesPerUserMergePreference(t *testing.T) {
 	if cfg.MergeSources {
 		t.Fatal("default merge preference should be false")
 	}
+	if cfg.PlaybackRate != 1 {
+		t.Fatalf("default playback rate = %v, want 1", cfg.PlaybackRate)
+	}
 
 	if err := svc.Danmaku.SetMergeSources(t.Context(), "user-1", true); err != nil {
 		t.Fatalf("set: %v", err)
@@ -137,7 +141,7 @@ func TestGetDanmakuConfigIncludesPerUserMergePreference(t *testing.T) {
 func TestUpdateDanmakuSettingsPersistsAllPlayerPreferences(t *testing.T) {
 	svc := newDanmakuSettingsService(t)
 
-	body := "{\"enabled\":false,\"opacity\":0.6,\"font_size\":32,\"area\":0.7,\"merge_sources\":true,\"volume\":0.35,\"source\":\"https://dm.example/base/\",\"app_id\":\"my-app-id\",\"app_key\":\"my-app-secret\"}"
+	body := "{\"enabled\":false,\"opacity\":0.6,\"font_size\":32,\"area\":0.7,\"merge_sources\":true,\"volume\":0.35,\"playback_rate\":1.5,\"source\":\"https://dm.example/base/\",\"app_id\":\"my-app-id\",\"app_key\":\"my-app-secret\"}"
 	c, w := newDanmakuSettingsContext(t, svc, http.MethodPut, "/danmaku/settings", body, "user-1")
 	updateDanmakuSettingsHandler(svc)(c)
 
@@ -154,7 +158,7 @@ func TestUpdateDanmakuSettingsPersistsAllPlayerPreferences(t *testing.T) {
 	if cfg.Enabled || cfg.Opacity != "0.6" || cfg.FontSize != "32" || cfg.Area != "0.7" {
 		t.Fatalf("unexpected render config: %+v", cfg)
 	}
-	if !cfg.MergeSources || cfg.Volume != 0.35 {
+	if !cfg.MergeSources || cfg.Volume != 0.35 || cfg.PlaybackRate != 1.5 {
 		t.Fatalf("unexpected user preferences: %+v", cfg)
 	}
 	if cfg.Source != "https://dm.example/base" || cfg.AppID != "my-app-id" || !cfg.AppKeyConfigured {
@@ -165,11 +169,30 @@ func TestUpdateDanmakuSettingsPersistsAllPlayerPreferences(t *testing.T) {
 	if err != nil || user == nil {
 		t.Fatalf("read persisted user: %v", err)
 	}
-	if user.DanmakuAppKey != "my-app-secret" || user.PlayerVolume != 0.35 || user.DanmakuSource != "https://dm.example/base" {
+	if user.DanmakuAppKey != "my-app-secret" || user.PlayerVolume != 0.35 || user.PlayerPlaybackRate != 1.5 || user.DanmakuSource != "https://dm.example/base" {
 		t.Fatalf("preferences not persisted: %+v", user)
 	}
 }
 
+func TestUpdateDanmakuSettingsRejectsInvalidPlaybackRate(t *testing.T) {
+	svc := newDanmakuSettingsService(t)
+
+	c, w := newDanmakuSettingsContext(t, svc, http.MethodPut, "/danmaku/settings",
+		`{"playback_rate":4}`, "user-1")
+	updateDanmakuSettingsHandler(svc)(c)
+
+	if w.Code != http.StatusBadRequest {
+		t.Fatalf("status = %d, want 400 (body=%s)", w.Code, w.Body.String())
+	}
+	user, err := svc.Repo.User.FindByID(t.Context(), "user-1")
+	if err != nil || user == nil {
+		t.Fatalf("read user: %v", err)
+	}
+	if user.PlayerPlaybackRate != 1 {
+		t.Fatalf("invalid playback rate was persisted: %v", user.PlayerPlaybackRate)
+	}
+}
+
 func TestUpdateDanmakuSettingsRejectsInvalidSource(t *testing.T) {
 	svc := newDanmakuSettingsService(t)
 

internal/model/user.go

@@ -33,6 +33,7 @@ type User struct {
 	SubtitleChineseMode string `gorm:"size:16;not null;default:original" json:"subtitle_chinese_mode"`
 	// 网页播放器偏好按用户存储，切换媒体对象后继续沿用。
 	PlayerVolume        float64 `gorm:"not null;default:1" json:"player_volume"`
+	PlayerPlaybackRate  float64 `gorm:"not null;default:1" json:"player_playback_rate"`
 	DanmakuEnabled      bool    `gorm:"not null;default:true" json:"danmaku_enabled"`
 	DanmakuOpacity      float64 `gorm:"not null;default:1" json:"danmaku_opacity"`
 	DanmakuFontSize     int     `gorm:"not null;default:24" json:"danmaku_font_size"`

internal/service/danmaku_service.go

@@ -49,6 +49,12 @@ const (
 // dandanplay protocol (search/episodes + comment/{episodeId}) may be used.
 const DanmakuDefaultSource = "https://api.dandanplay.net"
 
+const (
+	minPlayerPlaybackRate     = 0.5
+	maxPlayerPlaybackRate     = 3.0
+	defaultPlayerPlaybackRate = 1.0
+)
+
 // danmakuOfficialBase is where identification (/api/v2/match) and the
 // comment/search fallback always go, regardless of the configured source.
 // A package var (not a const) so tests can point it at a local server.
@@ -63,6 +69,8 @@ type DanmakuRenderConfig struct {
 	FontSize string  `json:"font_size"`
 	Area     string  `json:"area"`
 	Volume   float64 `json:"volume"`
+	// PlaybackRate 是当前用户的播放倍速偏好（按用户存储）。
+	PlaybackRate float64 `json:"playback_rate"`
 	// MergeSources 是当前用户的弹幕合并偏好（按用户存储）。
 	MergeSources bool `json:"merge_sources"`
 	// AppKeyConfigured 只表明用户是否保存了应用密钥，不回传密钥明文。
@@ -89,6 +97,7 @@ type DanmakuSettingsPatch struct {
 	Area         *float64 `json:"area"`
 	MergeSources *bool    `json:"merge_sources"`
 	Volume       *float64 `json:"volume"`
+	PlaybackRate *float64 `json:"playback_rate"`
 }
 
 type danmakuUserContextKey struct{}
@@ -345,10 +354,11 @@ func cloneDanmakuAnimeList(in []DanmakuAnime) []DanmakuAnime {
 // Config reads danmaku settings from the runtime settings table.
 func (s *DanmakuService) Config(ctx context.Context) DanmakuRenderConfig {
 	cfg := DanmakuRenderConfig{
-		Opacity:  "1",
-		FontSize: "24",
-		Area:     "1",
-		Volume:   1,
+		Opacity:      "1",
+		FontSize:     "24",
+		Area:         "1",
+		Volume:       1,
+		PlaybackRate: defaultPlayerPlaybackRate,
 	}
 	if s == nil || s.repo == nil || s.repo.Setting == nil {
 		return cfg
@@ -399,7 +409,14 @@ func (s *DanmakuService) findUser(ctx context.Context, userID string) (*model.Us
 
 func danmakuConfigFromUser(user *model.User) DanmakuRenderConfig {
 	if user == nil {
-		return DanmakuRenderConfig{Enabled: true, Opacity: "1", FontSize: "24", Area: "1", Volume: 1}
+		return DanmakuRenderConfig{
+			Enabled:      true,
+			Opacity:      "1",
+			FontSize:     "24",
+			Area:         "1",
+			Volume:       1,
+			PlaybackRate: defaultPlayerPlaybackRate,
+		}
 	}
 	opacity := user.DanmakuOpacity
 	if opacity < 0.1 || opacity > 1 {
@@ -417,6 +434,10 @@ func danmakuConfigFromUser(user *model.User) DanmakuRenderConfig {
 	if volume < 0 || volume > 1 {
 		volume = 1
 	}
+	playbackRate := user.PlayerPlaybackRate
+	if playbackRate < minPlayerPlaybackRate || playbackRate > maxPlayerPlaybackRate {
+		playbackRate = defaultPlayerPlaybackRate
+	}
 	return DanmakuRenderConfig{
 		Enabled:          user.DanmakuEnabled,
 		Source:           strings.TrimSpace(user.DanmakuSource),
@@ -425,6 +446,7 @@ func danmakuConfigFromUser(user *model.User) DanmakuRenderConfig {
 		FontSize:         strconv.Itoa(fontSize),
 		Area:             strconv.FormatFloat(area, 'f', -1, 64),
 		Volume:           volume,
+		PlaybackRate:     playbackRate,
 		MergeSources:     user.DanmakuMergeSources,
 		AppKeyConfigured: strings.TrimSpace(user.DanmakuAppKey) != "",
 	}
@@ -495,6 +517,17 @@ func (s *DanmakuService) UpdateUserSettings(ctx context.Context, userID string,
 		}
 		updates["player_volume"] = *patch.Volume
 	}
+	if patch.PlaybackRate != nil {
+		if *patch.PlaybackRate < minPlayerPlaybackRate || *patch.PlaybackRate > maxPlayerPlaybackRate {
+			return DanmakuRenderConfig{}, fmt.Errorf(
+				"%w: playback_rate must be between %.2f and %.2f",
+				ErrInvalidDanmakuSettings,
+				minPlayerPlaybackRate,
+				maxPlayerPlaybackRate,
+			)
+		}
+		updates["player_playback_rate"] = *patch.PlaybackRate
+	}
 	if len(updates) == 0 {
 		return DanmakuRenderConfig{}, ErrNoDanmakuSettings
 	}

internal/service/danmaku_service_test.go

@@ -422,6 +422,7 @@ func TestDanmakuFetchUsesPerUserSourceAndCredentials(t *testing.T) {
 	user.DanmakuFontSize = 30
 	user.DanmakuArea = 0.7
 	user.PlayerVolume = 0.42
+	user.PlayerPlaybackRate = 1.25
 	require.NoError(t, svc.repo.User.Create(ctx, &user))
 	seedDanmakuMedia(t, svc, "per-user-media", "测试动画", "", 0)
 
@@ -430,6 +431,7 @@ func TestDanmakuFetchUsesPerUserSourceAndCredentials(t *testing.T) {
 	require.Contains(t, res.Raw, "弹幕A")
 	require.Equal(t, srv.URL(), res.Source)
 	require.Equal(t, 0.42, res.Volume)
+	require.Equal(t, 1.25, res.PlaybackRate)
 	require.Equal(t, "0.65", res.Opacity)
 	require.Equal(t, "30", res.FontSize)
 	require.Equal(t, srv.lastHeaders.Get("X-AppId"), "user-app-id")