Update app.py

app.py

@@ -29,6 +29,7 @@ from langchain.agents import create_tool_calling_agent, AgentExecutor
 from langchain_core.prompts import ChatPromptTemplate
 
 # LangChain OpenAI imports
+from langchain_openai import ChatOpenAI
 from langchain_openai import AzureOpenAIEmbeddings, AzureChatOpenAI  # OpenAI embeddings and models
 from langchain.embeddings.openai import OpenAIEmbeddings  # OpenAI embeddings for text vectors