fix: avoid repeated category organization

internal/service/organizer.go

@@ -7,15 +7,17 @@
 //	movie: {Title} ({Year})/{Title} ({Year}).{Ext}
 //	tv:    {Title}/Season {Season:02d}/{Title} - S{Season:02d}E{Episode:02d}.{Ext}
 //
-// We do NOT delete the source after move — the operator can turn that on
-// via a config flag. This mirrors MediaStation's "organize after download"
-// workflow.
+// Organizing moves the source file. On the same filesystem this is an
+// os.Rename; across filesystems it falls back to streaming copy + source
+// removal, so operators should keep downloads and media on the same volume
+// when they want instant moves and no temporary duplicate disk usage.
 package service
 
 import (
 	"context"
 	"errors"
 	"fmt"
+	"io"
 	"os"
 	"path/filepath"
 	"strings"
@@ -79,10 +81,7 @@ func (o *OrganizerService) OrganizeMedia(ctx context.Context, mediaID string) (s
 		season := fmt.Sprintf("Season %02d", m.SeasonNum)
 		epTag := fmt.Sprintf("S%02dE%02d", m.SeasonNum, m.EpisodeNum)
 		root := o.organizeRoot(lib.Path, lib.Type, category)
-		dir := filepath.Join(root, category, title, season)
-		if category == "" {
-			dir = filepath.Join(root, title, season)
-		}
+		dir := filepath.Join(categoryRoot(root, category), title, season)
 		dst = filepath.Join(dir, fmt.Sprintf("%s - %s%s", title, epTag, ext))
 	} else {
 		// Movie: {lib.Path}/[分类]/{Title} ({Year})/{Title} ({Year}).ext
@@ -91,10 +90,7 @@ func (o *OrganizerService) OrganizeMedia(ctx context.Context, mediaID string) (s
 			folder = fmt.Sprintf("%s (%d)", title, m.Year)
 		}
 		root := o.organizeRoot(lib.Path, lib.Type, category)
-		dir := filepath.Join(root, category, folder)
-		if category == "" {
-			dir = filepath.Join(root, folder)
-		}
+		dir := filepath.Join(categoryRoot(root, category), folder)
 		dst = filepath.Join(dir, folder+ext)
 	}
 
@@ -219,17 +215,20 @@ func moveFile(src, dst string) error {
 	if err := os.Rename(src, dst); err == nil {
 		return nil
 	}
-	// Cross-device: read → write → remove.
-	data, err := os.ReadFile(src)
+	// Cross-device: stream copy → remove. This can temporarily consume the
+	// destination file size while copying, but the source is removed after the
+	// copy succeeds.
+	in, err := os.Open(src)
 	if err != nil {
 		return err
 	}
+	defer in.Close()
 	// O_EXCL 保证不会覆盖已存在的目标。
 	f, err := os.OpenFile(dst, os.O_WRONLY|os.O_CREATE|os.O_EXCL, 0o644)
 	if err != nil {
 		return err
 	}
-	if _, werr := f.Write(data); werr != nil {
+	if _, werr := io.Copy(f, in); werr != nil {
 		f.Close()
 		os.Remove(dst)
 		return werr
@@ -284,6 +283,13 @@ func (o *OrganizerService) organizeRoot(libraryPath, mediaType, category string)
 	return libraryPath
 }
 
+func categoryRoot(root, category string) string {
+	if strings.TrimSpace(category) == "" || pathAlreadyEndsWith(root, category) {
+		return root
+	}
+	return filepath.Join(root, category)
+}
+
 func mediaTypeRootDir(mediaType string) string {
 	switch normalizeMediaType(mediaType, "", "") {
 	case "movie":

internal/service/organizer_test.go

@@ -176,3 +176,59 @@ func TestOrganizeMediaAddsMoviePilotStyleTypeRootForGenericMediaRoot(t *testing.
 		t.Fatalf("organized file missing: %v", err)
 	}
 }
+
+func TestOrganizeMediaDoesNotRepeatCategoryWhenLibraryIsCategoryRoot(t *testing.T) {
+	root := t.TempDir()
+	libraryRoot := filepath.Join(root, "media", "电视剧", "国产剧")
+	sourceDir := filepath.Join(root, "downloads", "国产剧")
+	if err := os.MkdirAll(sourceDir, 0o755); err != nil {
+		t.Fatal(err)
+	}
+	source := filepath.Join(sourceDir, "Some Show S01E02.mkv")
+	if err := os.WriteFile(source, []byte("episode"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+
+	db, err := gorm.Open(sqlite.Open(":memory:"), &gorm.Config{})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err := db.AutoMigrate(&model.Library{}, &model.Media{}, &model.Setting{}); err != nil {
+		t.Fatal(err)
+	}
+	repos := repository.New(db)
+	if err := repos.Setting.Set(t.Context(), "organizer.smart_classify", "true"); err != nil {
+		t.Fatal(err)
+	}
+	lib := model.Library{Name: "国产剧", Path: libraryRoot, Type: "tv", Enabled: true}
+	if err := repos.Library.Create(t.Context(), &lib); err != nil {
+		t.Fatal(err)
+	}
+	media := model.Media{
+		LibraryID:    lib.ID,
+		Title:        "Some Show",
+		Path:         source,
+		Container:    "mkv",
+		Countries:    "CN",
+		SeasonNum:    1,
+		EpisodeNum:   2,
+		ScrapeStatus: "matched",
+	}
+	if err := repos.Media.Upsert(t.Context(), &media); err != nil {
+		t.Fatal(err)
+	}
+
+	organizer := NewOrganizerService(&config.Config{}, zap.NewNop(), repos)
+	dst, err := organizer.OrganizeMedia(t.Context(), media.ID)
+	if err != nil {
+		t.Fatal(err)
+	}
+	want := filepath.Join(libraryRoot, "Some Show", "Season 01", "Some Show - S01E02.mkv")
+	if dst != want {
+		t.Fatalf("dst = %q, want %q", dst, want)
+	}
+	repeated := filepath.Join(libraryRoot, "国产剧", "Some Show", "Season 01", "Some Show - S01E02.mkv")
+	if _, err := os.Stat(repeated); !os.IsNotExist(err) {
+		t.Fatalf("repeated category path exists or stat failed unexpectedly: %v", err)
+	}
+}