fix(workflow): 1. List operation node；2.Add space error message；3.File session variable handling

api/app/core/workflow/adapters/dify/converter.py

@@ -496,7 +496,23 @@ class DifyConverter(BaseConverter):
     def convert_assigner_node_config(self, node: dict) -> dict:
         node_data = node["data"]
         assignments = []
-        for assignment in node_data["items"]:
+
+        # Support both formats:
+        # 1. New format: node_data["items"] list
+        # 2. Flat format: assigned_variable_selector + input_variable_selector + write_mode
+        if "items" in node_data:
+            raw_items = node_data["items"]
+        elif "assigned_variable_selector" in node_data and "input_variable_selector" in node_data:
+            raw_items = [{
+                "variable_selector": node_data["assigned_variable_selector"],
+                "value": node_data["input_variable_selector"],
+                "input_type": ValueInputType.VARIABLE,
+                "operation": node_data.get("write_mode", "over-write"),
+            }]
+        else:
+            raw_items = []
+
+        for assignment in raw_items:
             if assignment.get("operation") is None or assignment.get("value") is None:
                 continue
             assignments.append(

api/app/core/workflow/nodes/list_operator/config.py

@@ -1,5 +1,5 @@
 from typing import Any
-from pydantic import BaseModel, Field
+from pydantic import BaseModel, Field, field_validator
 
 from app.core.workflow.nodes.base_config import BaseNodeConfig
 from app.core.workflow.nodes.enums import ComparisonOperator
@@ -31,6 +31,11 @@ class ExtractConfig(BaseModel):
     enabled: bool = False
     serial: str = "1"  # 1-based index string, e.g. "1" = first
 
+    @field_validator("serial", mode="before")
+    @classmethod
+    def coerce_serial(cls, v):
+        return str(v)
+
 
 class ListOperatorNodeConfig(BaseNodeConfig):
     """

api/app/core/workflow/utils/file_processor.py

@@ -91,7 +91,7 @@ async def fetch_remote_file_meta(
     """
     import httpx
 
-    name = size = mime_type = extension = None
+    name = extension = None
     try:
         async with httpx.AsyncClient(timeout=10.0) as client:
             resp = await client.head(url, follow_redirects=True)