Refactor workflow routing and greeting management in Brain classes

- Update WorkflowBrain to handle greeting playback more effectively, ensuring that the initial greeting completes before transitioning to the first node.
- Introduce new methods for managing greeting states and conditions, enhancing the interaction flow for user turns.
- Refactor WorkflowLLMRouter to improve routing logic and ensure proper handling of conditional paths.
- Enhance tests to verify the correct behavior of greeting management and routing under various scenarios, including waiting for audio playback to finish.
- Update frontend components to reflect changes in edge handling and improve user experience in workflow configurations.

backend/services/workflow_router.py

@@ -1,4 +1,4 @@
-"""Pre-response LLM routing for Workflow Agent edges.
+"""Small LLM router for Workflow conditional edges.
 
 The router deliberately uses a separate, short completion.  Its only output is
 a required function choice, so the current Agent cannot speak before the graph
@@ -16,12 +16,14 @@ from models import AssistantConfig
 from openai import AsyncOpenAI
 
 
-STAY_ON_CURRENT_AGENT = "workflow_stay_on_current_agent"
+STAY_ON_CURRENT_NODE = "workflow_stay_on_current_node"
+# Compatibility alias for callers saved before all source nodes supported LLM edges.
+STAY_ON_CURRENT_AGENT = STAY_ON_CURRENT_NODE
 MAX_ROUTING_HISTORY_ENTRIES = 20
 
 
 class WorkflowLLMRouter:
-    """Select one LLM edge before the conversational LLM is allowed to reply."""
+    """Select one LLM edge without allowing the router to speak."""
 
     def __init__(self, cfg: AssistantConfig):
         self._cfg = cfg
@@ -39,10 +41,10 @@ class WorkflowLLMRouter:
     ) -> str | None:
         """Return an edge function name, STAY, or None when routing failed."""
         if not edges:
-            return STAY_ON_CURRENT_AGENT
+            return STAY_ON_CURRENT_NODE
 
         names = {edge_name(edge) for edge in edges}
-        stay_name = STAY_ON_CURRENT_AGENT
+        stay_name = STAY_ON_CURRENT_NODE
         while stay_name in names:
             stay_name = f"_{stay_name}"
 
@@ -62,7 +64,7 @@ class WorkflowLLMRouter:
                 "type": "function",
                 "function": {
                     "name": stay_name,
-                    "description": "所有转移条件都不满足，继续由当前 Agent 处理用户消息。",
+                    "description": "所有转移条件都不满足，留在当前节点。",
                     "parameters": {"type": "object", "properties": {}},
                 },
             }
@@ -76,7 +78,7 @@ class WorkflowLLMRouter:
             "你是工作流路由器，不是对话助手。收到一轮完整用户输入后，"
             "必须且只能调用一个提供的函数，禁止输出任何口头回复。\n"
             "按给出的顺序判断转移条件；选择第一个明确满足的转移函数。"
-            "如果没有条件满足，调用留在当前 Agent 的函数。\n\n"
+            "如果没有条件满足，调用留在当前节点的函数。\n\n"
             f"当前节点：{node_name}\n"
             f"当前节点任务：{node_prompt or '未配置'}\n"
             f"转移条件：\n{ordered_conditions}"
@@ -113,17 +115,17 @@ class WorkflowLLMRouter:
             )
             tool_calls = response.choices[0].message.tool_calls or []
             if not tool_calls:
-                logger.warning("Workflow 路由 LLM 未返回函数调用，留在当前 Agent")
-                return STAY_ON_CURRENT_AGENT
+                logger.warning("Workflow 路由 LLM 未返回函数调用，留在当前节点")
+                return STAY_ON_CURRENT_NODE
             selected = str(tool_calls[0].function.name or "")
             if selected == stay_name:
-                return STAY_ON_CURRENT_AGENT
+                return STAY_ON_CURRENT_NODE
             if selected not in names:
                 logger.warning(f"Workflow 路由 LLM 返回未知函数:{selected}")
-                return STAY_ON_CURRENT_AGENT
+                return STAY_ON_CURRENT_NODE
             return selected
         except Exception as exc:  # noqa: BLE001 - routing failure must not end the call
-            logger.warning(f"Workflow LLM 边判断失败，留在当前 Agent:{exc}")
+            logger.warning(f"Workflow LLM 边判断失败，留在当前节点:{exc}")
             return None
         finally:
             await client.close()