diff --git a/internal/service/local_metadata_adult_test.go b/internal/service/local_metadata_adult_test.go
index cfd9a3b..98cc1a7 100644
--- a/internal/service/local_metadata_adult_test.go
+++ b/internal/service/local_metadata_adult_test.go
@@ -184,6 +184,85 @@ func TestReadAdultMetadataDerivesDMMPosterFromRemoteFanart(t *testing.T) {
 	}
 }
 
+func TestReadAdultArtworkIgnoresLoosePosterInLibraryRoot(t *testing.T) {
+	root := t.TempDir()
+	// 云下载这类库把不同影片平铺在同一个根目录里，根目录中残留的松散海报
+	// 属于别的影片，不能被抓来当作当前影片的封面。
+	if err := os.WriteFile(filepath.Join(root, "AAA-001-poster.jpg"), []byte("jpg"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.WriteFile(filepath.Join(root, "AAA-001-fanart.jpg"), []byte("jpg"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+	mediaPath := filepath.Join(root, "BBB-002.mp4")
+	if err := os.WriteFile(mediaPath, []byte("x"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+
+	got, err := ReadLocalMetadata(mediaPath, root, false)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if got != nil && (got.PosterURL != "" || got.BackdropURL != "") {
+		t.Fatalf("library-root artwork must not be inherited: poster=%q backdrop=%q", got.PosterURL, got.BackdropURL)
+	}
+}
+
+func TestReadAdultArtworkIgnoresLoosePosterInSharedFolder(t *testing.T) {
+	root := t.TempDir()
+	dir := filepath.Join(root, "shared")
+	if err := os.MkdirAll(dir, 0o755); err != nil {
+		t.Fatal(err)
+	}
+	for _, name := range []string{"AAA-001.mp4", "BBB-002.mp4"} {
+		if err := os.WriteFile(filepath.Join(dir, name), []byte("x"), 0o644); err != nil {
+			t.Fatal(err)
+		}
+	}
+	if err := os.WriteFile(filepath.Join(dir, "AAA-001-poster.jpg"), []byte("jpg"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.WriteFile(filepath.Join(dir, "AAA-001-fanart.jpg"), []byte("jpg"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+
+	got, err := ReadLocalMetadata(filepath.Join(dir, "BBB-002.mp4"), root, false)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if got != nil && (got.PosterURL != "" || got.BackdropURL != "") {
+		t.Fatalf("sibling artwork must not be inherited in a shared folder: poster=%q backdrop=%q", got.PosterURL, got.BackdropURL)
+	}
+}
+
+func TestReadAdultArtworkKeepsLooseFallbackInItemFolder(t *testing.T) {
+	root := t.TempDir()
+	dir := filepath.Join(root, "BBB-002")
+	if err := os.MkdirAll(dir, 0o755); err != nil {
+		t.Fatal(err)
+	}
+	mediaPath := filepath.Join(dir, "video.mp4")
+	if err := os.WriteFile(mediaPath, []byte("x"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+	poster := filepath.Join(dir, "japanese-title-cover.jpg")
+	fanart := filepath.Join(dir, "japanese-title-fanart.jpg")
+	if err := os.WriteFile(poster, []byte("jpg"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.WriteFile(fanart, []byte("jpg"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+
+	got, err := ReadLocalMetadata(mediaPath, root, false)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if got == nil || got.PosterURL != poster || got.BackdropURL != fanart {
+		t.Fatalf("single-item folder should keep loose artwork fallback: %+v", got)
+	}
+}
+
 func TestReadAdultArtworkByCodeWithoutNFO(t *testing.T) {
 	root := t.TempDir()
 	mediaPath := filepath.Join(root, "SSIS-001-CD1.mp4")
diff --git a/internal/service/local_metadata_artwork.go b/internal/service/local_metadata_artwork.go
index e31d38a..839e353 100644
--- a/internal/service/local_metadata_artwork.go
+++ b/internal/service/local_metadata_artwork.go
@@ -11,23 +11,23 @@ import (
 	"strings"
 )
 
-func metadataFromArtwork(mediaPath, showBaseDir string) *LocalMetadata {
+func metadataFromArtwork(mediaPath, showBaseDir, libraryRoot string) *LocalMetadata {
 	meta := &LocalMetadata{}
-	mergeArtworkMetadata(meta, mediaPath, showBaseDir)
+	mergeArtworkMetadata(meta, mediaPath, showBaseDir, libraryRoot)
 	if meta.PosterURL == "" && meta.BackdropURL == "" {
 		return nil
 	}
 	return meta
 }
 
-func mergeArtworkMetadata(meta *LocalMetadata, mediaPath, showBaseDir string) {
+func mergeArtworkMetadata(meta *LocalMetadata, mediaPath, showBaseDir, libraryRoot string) {
 	if meta == nil {
 		return
 	}
 	mediaDir := filepath.Dir(mediaPath)
 	if localPoster := firstLocalPoster(mediaPath, showBaseDir); localPoster != "" {
 		meta.PosterURL = localPoster
-	} else if meta.PosterURL == "" {
+	} else if meta.PosterURL == "" && looseArtworkFallbackAllowed(mediaDir, libraryRoot) {
 		meta.PosterURL = firstAdultLooseImage(mediaDir, "poster")
 	}
 	dirs := []string{mediaDir, showBaseDir}
@@ -39,7 +39,7 @@ func mergeArtworkMetadata(meta *LocalMetadata, mediaPath, showBaseDir string) {
 			meta.BackdropURL = img
 			break
 		}
-		if meta.BackdropURL == "" {
+		if meta.BackdropURL == "" && looseArtworkFallbackAllowed(dir, libraryRoot) {
 			meta.BackdropURL = firstAdultLooseImage(dir, "backdrop")
 		}
 	}
@@ -245,6 +245,48 @@ func firstExistingPosterImage(dir string, names ...string) string {
 	return ""
 }
 
+// looseArtworkFallbackAllowed reports whether an unmatched image sitting in dir
+// can be attributed to mediaPath. Such an image carries no filename relation to
+// a specific video, so it is only trustworthy when the folder holds a single
+// media file and that folder is not the library root. Download tools routinely
+// drop unrelated titles flat into one directory (a 115 cloud-download library,
+// for example); claiming the first "*-poster.jpg" there made every item show the
+// same artwork. Mirrors the root-level guard findMovieNFO already applies to
+// loose NFO files.
+func looseArtworkFallbackAllowed(dir, libraryRoot string) bool {
+	if dir == "" {
+		return false
+	}
+	if libraryRoot != "" && samePath(dir, libraryRoot) {
+		return false
+	}
+	return countMediaFilesInDir(dir) <= 1
+}
+
+// countMediaFilesInDir counts the video files directly inside dir, stopping once
+// more than one is found. It walks the real directory rather than reusing the
+// loose-image glob because a shared folder may contain no images at all.
+func countMediaFilesInDir(dir string) int {
+	entries, err := os.ReadDir(dir)
+	if err != nil {
+		return 0
+	}
+	count := 0
+	for _, entry := range entries {
+		if entry.IsDir() {
+			continue
+		}
+		if _, ok := videoExtensions[strings.ToLower(filepath.Ext(entry.Name()))]; !ok {
+			continue
+		}
+		count++
+		if count > 1 {
+			return count
+		}
+	}
+	return count
+}
+
 func firstAdultLooseImage(dir, kind string) string {
 	if dir == "" {
 		return ""
diff --git a/internal/service/local_metadata_read.go b/internal/service/local_metadata_read.go
index 032d70c..c835a19 100644
--- a/internal/service/local_metadata_read.go
+++ b/internal/service/local_metadata_read.go
@@ -17,12 +17,12 @@ func ReadLocalMetadata(mediaPath, libraryRoot string, seriesLike bool) (*LocalMe
 	doc, path, err := findMovieNFO(mediaPath, libraryRoot)
 	if err != nil {
 		if errors.Is(err, os.ErrNotExist) {
-			return metadataFromArtwork(mediaPath, ""), nil
+			return metadataFromArtwork(mediaPath, "", libraryRoot), nil
 		}
 		return nil, err
 	}
 	meta := metadataFromDoc(doc, filepath.Dir(path), false)
-	mergeArtworkMetadata(meta, mediaPath, filepath.Dir(path))
+	mergeArtworkMetadata(meta, mediaPath, filepath.Dir(path), libraryRoot)
 	// A sidecar written while resolution tokens were misread as SxxExx must not
 	// reintroduce the bogus season/episode on rescan.
 	dropResolutionArtifactEpisodeIdentity(meta, mediaPath)
@@ -115,9 +115,9 @@ func readSeriesMetadata(mediaPath, libraryRoot string) (*LocalMetadata, error) {
 		}
 	}
 	if meta == nil {
-		meta = metadataFromArtwork(mediaPath, showBaseDir)
+		meta = metadataFromArtwork(mediaPath, showBaseDir, libraryRoot)
 	} else {
-		mergeArtworkMetadata(meta, mediaPath, showBaseDir)
+		mergeArtworkMetadata(meta, mediaPath, showBaseDir, libraryRoot)
 	}
 	// A sidecar written while resolution tokens were misread as SxxExx must not
 	// reintroduce the bogus season/episode on rescan.