重构：移除对 debug_info 的依赖，只使用新的结构化状态字段

backend/app/main_graph/nodes/fast_paths.py

@@ -44,9 +44,6 @@ async def fast_chitchat_node(state: MainGraphState, config: Optional[RunnableCon
     # 标记快速路径成功，但不设置 final_result，让 llm_call 生成回答
     state.success = True
     state.current_phase = "llm_call"
-    state.debug_info["fast_chitchat_success"] = True
-    
-    # 更新新的结构化字段
     state.fast_path.chitchat_success = True
 
     # 发送完成事件
@@ -168,7 +165,7 @@ async def _generate_fast_answer(state: MainGraphState, query: str) -> MainGraphS
         state.final_result = full_content
         state.success = True
         state.current_phase = "finalizing"
-        state.debug_info["fast_rag_success"] = True
+        state.fast_path.rag_success = True
         return state
 
     except Exception as e:
@@ -181,8 +178,8 @@ async def fast_tool_node(state: MainGraphState, config: Optional[RunnableConfig]
     """快速工具节点"""
     state.current_phase = "fast_tool"
 
-    decision = state.debug_info.get("hybrid_decision", {})
-    suggested_tools = decision.get("suggested_tools", [])
+    decision = state.hybrid_router.decision
+    suggested_tools = decision.suggested_tools if (decision and hasattr(decision, 'suggested_tools')) else []
     info(f"[Fast Tool] 开始处理，建议工具: {suggested_tools}")
 
     await dispatch_custom_event("fast_path_start", {"path": "fast_tool", "suggested_tools": suggested_tools}, config)
@@ -197,16 +194,23 @@ async def fast_tool_node(state: MainGraphState, config: Optional[RunnableConfig]
     return _mark_fast_path_failed(state, "快速工具调用暂未完善")
 
 
+# ========== 条件路由函数 ==========
+def check_fast_path_success(state: MainGraphState) -> str:
+    """检查快速路径是否成功 - 使用新的结构化字段"""
+    if state.fast_path.failed:
+        info("[Fast Path Check] 快速路径失败，升级到 React 循环")
+        return "escalate"
+    
+    info("[Fast Path Check] 快速路径成功，进入 llm_call")
+    return "llm_call"
+
+
 # ========== 公共函数 ==========
 def _mark_fast_path_failed(state: MainGraphState, reason: str = "") -> MainGraphState:
-    """标记快速路径失败，准备升级到 React 循环"""
-    state.debug_info["fast_path_failed"] = True
-    state.debug_info["fast_path_fail_reason"] = reason
-    state.success = False
-    
-    # 更新新的结构化字段
+    """标记快速路径失败，准备升级到 React 循环 - 使用新的结构化字段"""
     state.fast_path.failed = True
     state.fast_path.fail_reason = reason
+    state.success = False
     
     info(f"[Fast Path] 标记失败，准备升级: {reason}")
     return state
@@ -217,5 +221,6 @@ __all__ = [
     "fast_chitchat_node",
     "fast_rag_node",
     "fast_tool_node",
+    "check_fast_path_success",
     "_mark_fast_path_failed",
 ]