修复循环推理bug

backend/app/main_graph/nodes/error_handling.py

@@ -0,0 +1,95 @@
+"""
+错误处理节点 - 处理子图/工具调用错误
+"""
+
+from app.main_graph.state import MainGraphState, ErrorSeverity
+from app.logger import info
+
+
+def error_handling_node(state: MainGraphState) -> MainGraphState:
+    """
+    错误处理节点：处理子图/工具调用错误
+
+    返回结构化错误信息，格式如下：
+    {
+        "tool/node": "...",
+        "status": "failed",
+        "error": "...",
+        "retries_exceeded": true/false,
+        "suggestion": "..."
+    }
+    """
+    state.current_phase = "error_handling"
+
+    if not state.current_error:
+        state.current_phase = "react_reasoning"
+        return state
+
+    error = state.current_error
+
+    # 更新错误状态
+    state.error_message = f"{error.error_type}: {error.error_message}"
+
+    # 记录结构化错误信息
+    structured_error = {
+        "tool": error.source,
+        "status": "failed",
+        "error": error.error_message,
+        "retries_exceeded": error.retry_count >= error.max_retries,
+        "retry_count": error.retry_count,
+        "max_retries": error.max_retries
+    }
+
+    # 根据错误类型添加建议
+    if "RAG" in error.error_type:
+        structured_error["suggestion"] = "尝试重新表述问题或直接询问"
+    elif "subgraph" in error.source or "contact" in error.source:
+        structured_error["suggestion"] = "子图执行失败，请尝试简化查询"
+    elif "timeout" in error.error_message.lower():
+        structured_error["suggestion"] = "请求超时，请稍后再试"
+    else:
+        structured_error["suggestion"] = "请尝试其他方式提问"
+
+    state.debug_info["structured_error"] = structured_error
+
+    # 策略1: 检查是否可以重试
+    can_retry = (
+        error.severity in [ErrorSeverity.WARNING, ErrorSeverity.ERROR]
+        and error.retry_count < error.max_retries
+    )
+
+    if can_retry:
+        error.retry_count += 1
+        state.retry_action = error.source
+        state.debug_info["retry_count"] = error.retry_count
+
+        if "RAG" in error.error_type:
+            state.last_action = "RE_RETRIEVE_RAG"
+        elif "subgraph" in error.source:
+            state.last_action = "DIRECT_RESPONSE"
+        else:
+            state.last_action = "REASON"
+
+        state.current_phase = "retrying"
+        return state
+
+    # 策略2: 无法重试，尝试降级方案
+    if error.severity != ErrorSeverity.FATAL:
+        state.final_result = (
+            f"⚠️  遇到一些问题：\n"
+            f"```json\n{structured_error}\n```\n"
+            f"但我会尽力用现有信息回答您。"
+        )
+        state.success = True
+        state.current_phase = "finalizing"
+        return state
+
+    # 策略3: 致命错误
+    state.final_result = (
+        f"❌ 服务暂时不可用，请稍后再试。\n"
+        f"```json\n{structured_error}\n```"
+    )
+    state.success = False
+    state.current_phase = "finalizing"
+
+    return state