fix(annotation): fix use_new_version to support files without annotation

Problem:
use_new_version returned 404 annotation not found for files without
annotation, preventing users from switching to new versions.

Solution:
1. Query latest file by logical_path
2. Update LabelingProjectFile to point to latest version
3. If annotation exists: clear it and update file_id
4. If no annotation: just update project file snapshot
5. Return new file_id in response

runtime/datamate-python/app/module/annotation/service/editor.py

@@ -1723,16 +1723,19 @@ class AnnotationEditorService:
         """
         使用文件新版本并清空标注
 
+        如果文件有多个版本（通过 logical_path 关联），将标注切换到最新版本。
+        如果存在标注记录，会清空标注内容。
+
         Args:
             project_id: 标注项目ID
-            file_id: 文件ID
+            file_id: 文件ID（当前关联的文件ID）
 
         Returns:
             操作结果
         """
         project = await self._get_project_or_404(project_id)
 
-        # 获取文件信息
+        # 获取当前文件信息
         file_result = await self.db.execute(
             select(DatasetFiles)
             .join(LabelingProjectFile, LabelingProjectFile.file_id == DatasetFiles.id)
@@ -1748,7 +1751,46 @@ class AnnotationEditorService:
                 status_code=404, detail=f"文件不存在或不属于该项目: {file_id}"
             )
 
-        # 获取标注信息
+        # 获取同一逻辑路径下的最新版本文件
+        logical_path = file_record.logical_path
+        latest_file_result = await self.db.execute(
+            select(DatasetFiles)
+            .where(
+                DatasetFiles.dataset_id == project.dataset_id,
+                DatasetFiles.logical_path == logical_path,
+                DatasetFiles.status == "ACTIVE",
+            )
+            .order_by(DatasetFiles.version.desc())
+            .limit(1)
+        )
+        latest_file = latest_file_result.scalar_one_or_none()
+
+        if not latest_file:
+            raise HTTPException(
+                status_code=404, detail=f"找不到该文件的最新版本: {logical_path}"
+            )
+
+        # 如果当前文件已经是最新版本，无需更新
+        if latest_file.id == file_id:
+            return {
+                "fileId": file_id,
+                "previousFileVersion": file_record.version,
+                "currentFileVersion": latest_file.version,
+                "message": "当前文件已是最新版本，无需切换",
+            }
+
+        # 更新 LabelingProjectFile 指向最新版本
+        project_file_result = await self.db.execute(
+            select(LabelingProjectFile).where(
+                LabelingProjectFile.project_id == project.id,
+                LabelingProjectFile.file_id == file_id,
+            )
+        )
+        project_file = project_file_result.scalar_one_or_none()
+        if project_file:
+            project_file.file_id = str(latest_file.id)
+
+        # 获取标注信息（基于原 file_id）
         annotation_result = await self.db.execute(
             select(AnnotationResult)
             .where(
@@ -1759,22 +1801,12 @@ class AnnotationEditorService:
         )
         annotation = annotation_result.scalar_one_or_none()
 
-        current_file_version = file_record.version
+        now = datetime.utcnow()
-
-        if not annotation:
-            raise HTTPException(status_code=404, detail=f"标注不存在: {file_id}")
 
+        if annotation:
+            # 存在标注记录：清空标注并更新文件版本
             previous_file_version = annotation.file_version
 
-        if annotation.file_version is not None:
-            if current_file_version <= annotation.file_version:
-                raise HTTPException(
-                    status_code=400,
-                    detail=f"文件版本（{current_file_version}）未更新或低于标注版本（{annotation.file_version}）",
-                )
-
-        # 清空标注并更新版本号
-        now = datetime.utcnow()
             cleared_payload: Dict[str, Any] = {}
             if isinstance(annotation.annotation, dict) and self._is_segmented_annotation(
                 annotation.annotation
@@ -1799,9 +1831,11 @@ class AnnotationEditorService:
                     SEGMENT_TOTAL_KEY: total_segments,
                 }
 
+            # 更新标注记录指向新文件
+            annotation.file_id = str(latest_file.id)
             annotation.annotation = cleared_payload
             annotation.annotation_status = ANNOTATION_STATUS_NO_ANNOTATION
-        annotation.file_version = current_file_version
+            annotation.file_version = latest_file.version
             annotation.updated_at = now
 
             await self.db.commit()
@@ -1809,14 +1843,24 @@ class AnnotationEditorService:
 
             await self._sync_annotation_to_knowledge(
                 project,
-            file_record,
+                latest_file,
                 cleared_payload,
                 annotation.updated_at or now,
             )
 
             return {
-            "fileId": file_id,
+                "fileId": str(latest_file.id),
                 "previousFileVersion": previous_file_version,
-            "currentFileVersion": current_file_version,
+                "currentFileVersion": latest_file.version,
-            "message": "已使用新版本并清空标注",
+                "message": "已切换到新版本并清空标注",
+            }
+        else:
+            # 不存在标注记录：只需更新项目文件快照
+            await self.db.commit()
+
+            return {
+                "fileId": str(latest_file.id),
+                "previousFileVersion": file_record.version,
+                "currentFileVersion": latest_file.version,
+                "message": "已切换到新版本",
             }