diff --git a/backend/app/services/workflow_engine.py b/backend/app/services/workflow_engine.py
index fcd56ad..dfebd0c 100644
--- a/backend/app/services/workflow_engine.py
+++ b/backend/app/services/workflow_engine.py
@@ -5742,8 +5742,11 @@ class WorkflowEngine:
             for nid in ready_nodes:
                 node = self.nodes[nid]
                 node_input = self.get_node_input(nid, self.node_outputs, active_edges)
-                if node.get('type') == 'start' and not node_input:
-                    node_input = input_data
+                # start 节点无条件获取初始输入；非 start 节点无入边时同样需要
+                if not node_input:
+                    incoming = [e for e in active_edges if e["target"] == nid]
+                    if not incoming:
+                        node_input = input_data
                 node_inputs[nid] = node_input
 
             # 预算检查（整批节点）