fix: Resolve streaming response issue in case of nested conditions node

api/core/workflow/nodes/answer/base_stream_processor.py

@@ -59,7 +59,7 @@ class StreamProcessor(ABC):
                     # only nodes in the correct logical branch are included.
                     reachable_node_ids.add(edge.target_node_id)
                     ids = self._fetch_node_ids_in_reachable_branch(edge.target_node_id, run_result.edge_source_handle)
-                    reachable_node_ids.update(ids)
+                    reachable_node_ids |= ids
                 else:
                     # if the condition edge in parallel, and the target node is not in parallel, we should not remove it
                     # Issues: #13626
@@ -69,7 +69,10 @@ class StreamProcessor(ABC):
                     ):
                         continue
                     unreachable_first_node_ids.add(edge.target_node_id)
-            unreachable_first_node_ids = unreachable_first_node_ids - reachable_node_ids
+
+            self.rest_node_ids |= reachable_node_ids
+
+            unreachable_first_node_ids -= reachable_node_ids
             for node_id in unreachable_first_node_ids:
                 self._remove_node_ids_in_unreachable_branch(node_id, reachable_node_ids)
 
@@ -85,7 +88,7 @@ class StreamProcessor(ABC):
                     continue
 
             node_ids.add(edge.target_node_id)
-            node_ids.update(self._fetch_node_ids_in_reachable_branch(edge.target_node_id, branch_identify))
+            node_ids |= self._fetch_node_ids_in_reachable_branch(edge.target_node_id, branch_identify)
         return node_ids
 
     def _remove_node_ids_in_unreachable_branch(self, node_id: str, reachable_node_ids: set[str]) -> None:
@@ -95,7 +98,6 @@ class StreamProcessor(ABC):
         if node_id not in self.rest_node_ids:
             return
         self.rest_node_ids.remove(node_id)
-        self.rest_node_ids.update(reachable_node_ids - self.rest_node_ids)
 
         for edge in self.graph.edge_mapping.get(node_id, []):
             if edge.target_node_id in reachable_node_ids: