fix: 完成商务迁移复核与接口优化并清理历史资料

internal/data/system/media.go

@@ -125,6 +125,9 @@ func (r *mediaRepo) UpdateMediaName(ctx context.Context, id uint, name string) e
 	// not-found error instead of silently succeeding with RowsAffected=0.
 	var po mediaPO
 	if err := r.data.DB().WithContext(ctx).Where("id = ?", id).First(&po).Error; err != nil {
+		if errors.Is(err, gorm.ErrRecordNotFound) {
+			return system.ErrMediaNotFound
+		}
 		return err
 	}
 	return r.data.DB().WithContext(ctx).Model(&po).Update("name", name).Error
@@ -147,7 +150,7 @@ func (r *mediaRepo) CreateMediaBatch(ctx context.Context, items []*system.MediaF
 func (r *mediaRepo) SaveCategory(ctx context.Context, v *system.AttachmentCategory) error {
 	db := r.data.DB().WithContext(ctx)
 	var count int64
-	query := db.Model(&categoryPO{}).Where("name = ? AND pid = ?", v.Name, v.ParentID)
+	query := db.Model(&categoryPO{}).Where("name = ? AND pid = ? AND id <> ?", v.Name, v.ParentID, v.ID)
 	if err := query.Count(&count).Error; err != nil {
 		return err
 	}

internal/data/system/media_edit_test.go

@@ -0,0 +1,40 @@
+package system
+
+import (
+	"context"
+	"kra/internal/biz/system"
+	"path/filepath"
+	"testing"
+)
+
+func TestMediaEditsKeepUnchangedCategoryNameAndMapMissingFile(t *testing.T) {
+	db, err := openWithDriver("sqlite", filepath.Join(t.TempDir(), "media.db"))
+	if err != nil {
+		t.Fatal(err)
+	}
+	pool, _ := db.DB()
+	t.Cleanup(func() { _ = pool.Close() })
+	if err := db.AutoMigrate(&mediaPO{}, &categoryPO{}); err != nil {
+		t.Fatal(err)
+	}
+	r := NewMediaRepo(&Data{gormDB: newReloadableDB(db, nil)})
+	ctx := context.Background()
+	category := &system.AttachmentCategory{Name: "screenshots"}
+	if err := r.SaveCategory(ctx, category); err != nil {
+		t.Fatal(err)
+	}
+	var row categoryPO
+	if err := db.First(&row).Error; err != nil {
+		t.Fatal(err)
+	}
+	category.ID = row.ID
+	if err := r.SaveCategory(ctx, category); err != nil {
+		t.Fatalf("unchanged category rejected: %v", err)
+	}
+	if err := r.SaveCategory(ctx, &system.AttachmentCategory{Name: "screenshots"}); err == nil {
+		t.Fatal("duplicate category accepted")
+	}
+	if err := r.UpdateMediaName(ctx, 999, "missing"); err != system.ErrMediaNotFound {
+		t.Fatalf("missing file: %v", err)
+	}
+}