main.py

from telegram import Update
from telegram.ext import ApplicationBuilder, CommandHandler, MessageHandler, ContextTypes, filters
import os

TOKEN = os.environ.get("TELEGRAM_TOKEN")


async def responder(update: Update, context: ContextTypes.DEFAULT_TYPE):
    msg = update.message.text.lower()

    if msg == "oi":
        await update.message.reply_text("Oi! Tudo bem?")
    else:
        await update.message.reply_text("Não entendi, mas estou funcionando!")

app = ApplicationBuilder().token(TOKEN).build()
app.add_handler(MessageHandler(filters.TEXT & ~filters.COMMAND, responder))

app.run_polling()