修复标注数据无记录问题

backend/app/services/annotation_platform_service.py

@@ -308,14 +308,31 @@ def _convert_to_jsonl(file_path: Path) -> Path:
         return jsonl_path
 
     try:
-        # 尝试作为 JSON 数组解析
+        # 尝试作为 JSON 解析
         data = _json.loads(content)
         if isinstance(data, list):
+            # JSON 数组
+            items = data
+        elif isinstance(data, dict):
+            # JSON 对象：查找嵌套的数组字段
+            items = None
+            for key in ("data", "items", "results", "records", "annotations", "samples"):
+                if key in data and isinstance(data[key], list):
+                    items = data[key]
+                    break
+            if items is None:
+                # 单个对象，包装为数组
+                items = [data]
+        else:
+            items = None
+
+        if items is not None:
             with open(jsonl_path, "w", encoding="utf-8") as out:
-                for item in data:
+                for item in items:
                     out.write(_json.dumps(item, ensure_ascii=False) + "\n")
-            # 删除原始 JSON 文件
-            file_path.unlink()
+            # 只有当原始文件与新文件不同时才删除（避免删除刚写入的文件）
+            if jsonl_path != file_path and file_path.exists():
+                file_path.unlink()
             return jsonl_path
     except _json.JSONDecodeError:
         pass
@@ -334,7 +351,8 @@ def _convert_to_jsonl(file_path: Path) -> Path:
 
     with open(jsonl_path, "w", encoding="utf-8") as out:
         out.write("\n".join(valid_lines) + ("\n" if valid_lines else ""))
-    file_path.unlink()
+    if jsonl_path != file_path and file_path.exists():
+        file_path.unlink()
     return jsonl_path