diff --git a/api/core/app/apps/workflow_app_runner.py b/api/core/app/apps/workflow_app_runner.py
index c1372e6f4d..dc6c381e86 100644
--- a/api/core/app/apps/workflow_app_runner.py
+++ b/api/core/app/apps/workflow_app_runner.py
@@ -733,6 +733,7 @@ class WorkflowBasedAppRunner(AppRunner):
                 node_type=event.node_type,
                 # FIXME(QuantumGhost): rely on private state of queue_manager is not ideal.
                 invoke_from=self.queue_manager._invoke_from,
+                node_execution_id=event.id,
                 enclosing_node_id=event.in_loop_id or event.in_iteration_id or None,
             )
             draft_var_saver.save(process_data=process_data, outputs=outputs)
diff --git a/api/models/workflow.py b/api/models/workflow.py
index 9cb6968914..b11f9b89ff 100644
--- a/api/models/workflow.py
+++ b/api/models/workflow.py
@@ -867,6 +867,16 @@ def _naive_utc_datetime():
 
 
 class WorkflowDraftVariable(Base):
+    """`WorkflowDraftVariable` record variables and outputs generated during
+    debugging worfklow or chatflow.
+
+    IMPORTANT: This model maintains multiple invariant rules that must be preserved.
+    Do not instantiate this class directly with the constructor.
+
+    Instead, use the factory methods (`new_conversation_variable`, `new_sys_variable`,
+    `new_node_variable`) defined below to ensure all invariants are properly maintained.
+    """
+
     @staticmethod
     def unique_app_id_node_id_name() -> list[str]:
         return [
@@ -956,6 +966,7 @@ class WorkflowDraftVariable(Base):
     # Use double underscore prefix for better encapsulation,
     # making this attribute harder to access from outside the class.
     __value: Segment | None
+    node_execution_id: str | None  # pretend this field exists.
 
     def __init__(self, *args, **kwargs):
         """
@@ -1062,6 +1073,7 @@ class WorkflowDraftVariable(Base):
         node_id: str,
         name: str,
         value: Segment,
+        node_execution_id: str | None = None,
         description: str = "",
     ) -> "WorkflowDraftVariable":
         variable = WorkflowDraftVariable()
@@ -1073,6 +1085,7 @@ class WorkflowDraftVariable(Base):
         variable.name = name
         variable.set_value(value)
         variable._set_selector(list(variable_utils.to_selector(node_id, name)))
+        variable.node_execution_id = node_execution_id
         return variable
 
     @classmethod
@@ -1100,9 +1113,16 @@ class WorkflowDraftVariable(Base):
         app_id: str,
         name: str,
         value: Segment,
+        node_execution_id: str,
         editable: bool = False,
     ) -> "WorkflowDraftVariable":
-        variable = cls._new(app_id=app_id, node_id=SYSTEM_VARIABLE_NODE_ID, name=name, value=value)
+        variable = cls._new(
+            app_id=app_id,
+            node_id=SYSTEM_VARIABLE_NODE_ID,
+            name=name,
+            node_execution_id=node_execution_id,
+            value=value,
+        )
         variable.editable = editable
         return variable
 
@@ -1114,10 +1134,17 @@ class WorkflowDraftVariable(Base):
         node_id: str,
         name: str,
         value: Segment,
+        node_execution_id: str,
         visible: bool = True,
         editable: bool = True,
     ) -> "WorkflowDraftVariable":
-        variable = cls._new(app_id=app_id, node_id=node_id, name=name, value=value)
+        variable = cls._new(
+            app_id=app_id,
+            node_id=node_id,
+            name=name,
+            node_execution_id=node_execution_id,
+            value=value,
+        )
         variable.visible = visible
         variable.editable = editable
         return variable
diff --git a/api/services/workflow_draft_variable_service.py b/api/services/workflow_draft_variable_service.py
index 0e99e20f06..befffc3347 100644
--- a/api/services/workflow_draft_variable_service.py
+++ b/api/services/workflow_draft_variable_service.py
@@ -460,6 +460,9 @@ class DraftVariableSaver:
     # Indicates how the workflow execution was triggered (see InvokeFrom).
     _invoke_from: InvokeFrom
 
+    #
+    _node_execution_id: str
+
     # _enclosing_node_id identifies the container node that the current node belongs to.
     # For example, if the current node is an LLM node inside an Iteration node
     # or Loop node, then `_enclosing_node_id` refers to the ID of
@@ -476,6 +479,7 @@ class DraftVariableSaver:
         node_id: str,
         node_type: NodeType,
         invoke_from: InvokeFrom,
+        node_execution_id: str,
         enclosing_node_id: str | None = None,
     ):
         self._session = session
@@ -483,6 +487,7 @@ class DraftVariableSaver:
         self._node_id = node_id
         self._node_type = node_type
         self._invoke_from = invoke_from
+        self._node_execution_id = node_execution_id
         self._enclosing_node_id = enclosing_node_id
 
     def _should_save_output_variables_for_draft(self) -> bool:
@@ -512,6 +517,7 @@ class DraftVariableSaver:
                 WorkflowDraftVariable.new_conversation_variable(
                     app_id=self._app_id,
                     name=item.name,
+                    node_execution_id=self._node_execution_id,
                     value=segment,
                 )
             )
@@ -531,6 +537,7 @@ class DraftVariableSaver:
                         app_id=self._app_id,
                         node_id=self._node_id,
                         name=name,
+                        node_execution_id=self._node_execution_id,
                         value=value_seg,
                         visible=True,
                         editable=True,
@@ -551,6 +558,7 @@ class DraftVariableSaver:
                     WorkflowDraftVariable.new_sys_variable(
                         app_id=self._app_id,
                         name=name,
+                        node_execution_id=self._node_execution_id,
                         value=value_seg,
                         editable=self._should_variable_be_editable(node_id, name),
                     )
@@ -561,6 +569,7 @@ class DraftVariableSaver:
                     app_id=self._app_id,
                     node_id=self._node_id,
                     name=self._DUMMY_OUTPUT_IDENTITY,
+                    node_execution_id=self._node_execution_id,
                     value=_build_segment_for_value(self._DUMMY_OUTPUT_VALUE),
                     visible=False,
                     editable=False,
@@ -583,6 +592,7 @@ class DraftVariableSaver:
                     app_id=self._app_id,
                     node_id=self._node_id,
                     name=name,
+                    node_execution_id=self._node_execution_id,
                     value=value_seg,
                     visible=self._should_variable_be_visible(self._node_id, self._node_type, name),
                 )