refactor: remove legacy assistant compatibility

backend/services/workflow/realtime.py

@@ -123,7 +123,7 @@ class RealtimeWorkflowOutput(WorkflowOutput):
 
 
 class WorkflowRealtimeController:
-    """Run Workflow v3 over one StepFun or Qwen realtime session."""
+    """Run Workflow v4 over one StepFun or Qwen realtime session."""
 
     def __init__(
         self,
@@ -400,9 +400,10 @@ class WorkflowRealtimeController:
         tools = self._build_agent_tools(node_id)
         prompt = self._agent_prompt(node_id)
         await self._runtime.realtime.update_session(prompt, tools)
-        generate = str(
-            self._engine.data(node_id).get("entryMode") or "wait_user"
-        ) == "generate"
+        generate = (
+            str(self._engine.data(node_id).get("entryMode", "wait_user"))
+            == "generate"
+        )
         if generate:
             self._state.status = WorkflowStatus.RUNNING_AGENT
         else:
@@ -1074,9 +1075,7 @@ class WorkflowRealtimeController:
         )
 
     def _message_completion_policy(self, node_id: str) -> str:
-        return str(
-            self._engine.data(node_id).get("completionPolicy") or "playback"
-        )
+        return str(self._engine.data(node_id)["completionPolicy"])
 
     def _set_last_action(self, outcome) -> None:
         self._store.values.update(