Update app.py

app.py

@@ -377,10 +377,24 @@ def increment_tool_count(state: AgentState) -> dict:
 def finish_node(state: AgentState) -> dict:
     last = state["messages"][-1]
     content = last.content
-    # 提取最终答案（纯文本）
     answer = content.strip().split("\n")[-1].strip()
     if "FINAL ANSWER:" in answer:
         answer = answer.split("FINAL ANSWER:")[-1].strip()
+
+    # 若答案仍为空，尝试从历史消息中提取最后一条有内容的 AI 消息
+    if not answer:
+        for m in reversed(state["messages"]):
+            if isinstance(m, AIMessage) and m.content.strip():
+                answer = m.content.strip().split("\n")[-1].strip()
+                break
+
+    # 依然无答案时，输出原因
+    if not answer:
+        if state.get("tool_attempts", 0) >= 5:
+            answer = "Unable to determine answer: reached maximum tool calls without conclusion."
+        else:
+            answer = "Unable to determine answer: insufficient information."
+
     return {"final_answer": answer}
 
 def build_graph():