diff --git a/pkg/filemanager/manager/metadata.go b/pkg/filemanager/manager/metadata.go
index 69797fbf..a5293c18 100644
--- a/pkg/filemanager/manager/metadata.go
+++ b/pkg/filemanager/manager/metadata.go
@@ -97,6 +97,15 @@ var (
 			},
 		},
 		"dav": {},
+		// Allow manipulating thumbnail metadata via public PatchMetadata API
+		"thumb": {
+			// Only supported thumb metadata currently is thumb:disabled
+			dbfs.ThumbDisabledKey: func(ctx context.Context, m *manager, patch *fs.MetadataPatch) error {
+				// Presence of this key disables thumbnails; value is ignored.
+				// We allow both setting and removing this key.
+				return nil
+			},
+		},
 		customizeMetadataSuffix: {
 			iconColorMetadataKey: validateColor(false),
 			emojiIconMetadataKey: func(ctx context.Context, m *manager, patch *fs.MetadataPatch) error {
diff --git a/pkg/thumb/builtin.go b/pkg/thumb/builtin.go
index 3a9f2ff4..2081a9c2 100644
--- a/pkg/thumb/builtin.go
+++ b/pkg/thumb/builtin.go
@@ -19,6 +19,10 @@ import (
 
 const thumbTempFolder = "thumb"
 
+// BuiltinSupportedExts lists file extensions supported by the built-in
+// thumbnail generator. Extensions are lowercased and do not include the dot.
+var BuiltinSupportedExts = []string{"jpg", "jpeg", "png", "gif"}
+
 // Thumb 缩略图
 type Thumb struct {
 	src image.Image
diff --git a/routers/router.go b/routers/router.go
index d474ccf3..213a05b4 100644
--- a/routers/router.go
+++ b/routers/router.go
@@ -618,12 +618,13 @@ func initMasterRouter(dep dependency.Dep) *gin.Engine {
 					controllers.ServeEntity,
 				)
 			}
-			// 获取缩略图
+			// get thumb
 			file.GET("thumb",
 				middleware.ContextHint(),
 				controllers.FromQuery[explorer.FileThumbService](explorer.FileThumbParameterCtx{}),
 				controllers.Thumb,
 			)
+			// reset thumb removed; use metadata patch to re-enable thumbnails
 			// Delete files
 			file.DELETE("",
 				controllers.FromJSON[explorer.DeleteFileService](explorer.DeleteFileParameterCtx{}),
diff --git a/service/basic/site.go b/service/basic/site.go
index 287c0ed1..d9383bd6 100644
--- a/service/basic/site.go
+++ b/service/basic/site.go
@@ -1,13 +1,17 @@
 package basic
 
 import (
-	"github.com/cloudreve/Cloudreve/v4/application/dependency"
-	"github.com/cloudreve/Cloudreve/v4/inventory"
-	"github.com/cloudreve/Cloudreve/v4/inventory/types"
-	"github.com/cloudreve/Cloudreve/v4/pkg/setting"
-	"github.com/cloudreve/Cloudreve/v4/service/user"
-	"github.com/gin-gonic/gin"
-	"github.com/mojocn/base64Captcha"
+    "sort"
+    "strings"
+
+    "github.com/cloudreve/Cloudreve/v4/application/dependency"
+    "github.com/cloudreve/Cloudreve/v4/inventory"
+    "github.com/cloudreve/Cloudreve/v4/inventory/types"
+    "github.com/cloudreve/Cloudreve/v4/pkg/setting"
+    "github.com/cloudreve/Cloudreve/v4/pkg/thumb"
+    "github.com/cloudreve/Cloudreve/v4/service/user"
+    "github.com/gin-gonic/gin"
+    "github.com/mojocn/base64Captcha"
 )
 
 // SiteConfig 站点全局设置序列
@@ -47,7 +51,10 @@ type SiteConfig struct {
 	MaxBatchSize      int                       `json:"max_batch_size,omitempty"`
 	ThumbnailWidth    int                       `json:"thumbnail_width,omitempty"`
 	ThumbnailHeight   int                       `json:"thumbnail_height,omitempty"`
-	CustomProps       []types.CustomProps       `json:"custom_props,omitempty"`
+    CustomProps       []types.CustomProps       `json:"custom_props,omitempty"`
+
+    // Thumbnail section
+    ThumbExts []string `json:"thumb_exts,omitempty"`
 
 	// App settings
 	AppPromotion bool `json:"app_promotion,omitempty"`
@@ -71,10 +78,10 @@ type (
 )
 
 func (s *GetSettingService) GetSiteConfig(c *gin.Context) (*SiteConfig, error) {
-	dep := dependency.FromContext(c)
-	settings := dep.SettingProvider()
+    dep := dependency.FromContext(c)
+    settings := dep.SettingProvider()
 
-	switch s.Section {
+    switch s.Section {
 	case "login":
 		legalDocs := settings.LegalDocuments(c)
 		return &SiteConfig{
@@ -115,12 +122,53 @@ func (s *GetSettingService) GetSiteConfig(c *gin.Context) (*SiteConfig, error) {
 		}, nil
 	case "app":
 		appSetting := settings.AppSetting(c)
-		return &SiteConfig{
-			AppPromotion: appSetting.Promotion,
-		}, nil
-	default:
-		break
-	}
+        return &SiteConfig{
+            AppPromotion: appSetting.Promotion,
+        }, nil
+    case "thumb":
+        // Return supported thumbnail extensions from enabled generators.
+        exts := map[string]bool{}
+        if settings.BuiltinThumbGeneratorEnabled(c) {
+            for _, e := range thumb.BuiltinSupportedExts {
+                exts[e] = true
+            }
+        }
+        if settings.FFMpegThumbGeneratorEnabled(c) {
+            for _, e := range settings.FFMpegThumbExts(c) {
+                exts[strings.ToLower(e)] = true
+            }
+        }
+        if settings.VipsThumbGeneratorEnabled(c) {
+            for _, e := range settings.VipsThumbExts(c) {
+                exts[strings.ToLower(e)] = true
+            }
+        }
+        if settings.LibreOfficeThumbGeneratorEnabled(c) {
+            for _, e := range settings.LibreOfficeThumbExts(c) {
+                exts[strings.ToLower(e)] = true
+            }
+        }
+        if settings.MusicCoverThumbGeneratorEnabled(c) {
+            for _, e := range settings.MusicCoverThumbExts(c) {
+                exts[strings.ToLower(e)] = true
+            }
+        }
+        if settings.LibRawThumbGeneratorEnabled(c) {
+            for _, e := range settings.LibRawThumbExts(c) {
+                exts[strings.ToLower(e)] = true
+            }
+        }
+
+        // map -> sorted slice
+        result := make([]string, 0, len(exts))
+        for e := range exts {
+            result = append(result, e)
+        }
+        sort.Strings(result)
+        return &SiteConfig{ThumbExts: result}, nil
+    default:
+        break
+    }
 
 	u := inventory.UserFromContext(c)
 	siteBasic := settings.SiteBasic(c)