Switch from Groq to OpenAI gpt-4o-mini

Better tool calling support, no daily token limits.
Requires OPENAI_API_KEY secret in HF Space.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

app.py

@@ -3,7 +3,7 @@ import gradio as gr
 import requests
 import pandas as pd
 from io import BytesIO
-from langchain_groq import ChatGroq
+from langchain_openai import ChatOpenAI
 from langchain_community.tools import DuckDuckGoSearchRun
 from langchain_experimental.tools import PythonREPLTool
 from langchain_core.tools import tool
@@ -66,7 +66,7 @@ def fetch_task_file(task_id: str) -> str:
 
 class BasicAgent:
     def __init__(self):
-        self.llm = ChatGroq(model="llama-3.3-70b-versatile", temperature=0)
+        self.llm = ChatOpenAI(model="gpt-4o-mini", temperature=0)
         self.tools = [
             DuckDuckGoSearchRun(),
             PythonREPLTool(),
@@ -74,7 +74,7 @@ class BasicAgent:
         ]
         self.tools_map = {t.name: t for t in self.tools}
         self.llm_with_tools = self.llm.bind_tools(self.tools)
-        print("BasicAgent initialized with Groq (llama-3.3-70b-versatile).")
+        print("BasicAgent initialized with OpenAI (gpt-4o-mini).")
 
     def __call__(self, question: str, task_id: str = "") -> str:
         full_question = f"[Task ID: {task_id}]\n\n{question}" if task_id else question
@@ -241,7 +241,7 @@ with gr.Blocks() as demo:
         1. Log in to your Hugging Face account using the button below.
         2. Click 'Run Evaluation & Submit All Answers' to fetch questions, run the agent, and submit.
 
-        **Agent:** Custom ReAct loop — Groq llama-3.3-70b-versatile
+        **Agent:** Custom ReAct loop — OpenAI gpt-4o-mini
         **Tools:** DuckDuckGo search, Python REPL, File fetcher (text + Excel)
 
         ---

requirements.txt

@@ -1,7 +1,7 @@
 gradio
 requests
 pandas
-langchain-groq
+langchain-openai
 langgraph
 langchain-community
 langchain-experimental