Add agent.py

agent.py

@@ -0,0 +1,45 @@
+"""
+Simple LangChain agent demonstrating Human‑in‑the‑Loop middleware.
+
+The chain:
+1. User prompt is passed to a PromptTemplate.
+2. The template is processed by an LLM (OpenAI).
+3. The output passes through the HIL middleware which prints the assistant’s answer and asks the user to confirm or modify it before returning.
+
+Run with:
+    python agent.py
+Make sure you have OPENAI_API_KEY set in your environment.
+"""
+
+import os
+from langchain.prompts import PromptTemplate
+from langchain.schema import RunnableSequence
+from langchain_openai import ChatOpenAI
+from langchain.middleware.hil import HumanInTheLoopMiddleware
+
+api_key = os.getenv("OPENAI_API_KEY")
+if not api_key:
+    raise RuntimeError("OPENAI_API_KEY environment variable is required.")
+
+llm = OpenAI(api_key=api_key, temperature=0.7)
+
+prompt_template = PromptTemplate(
+    input_variables=["question"],
+    template="You are a helpful assistant. Answer the following question clearly and concisely: {question}"
+)
+
+chain = RunnableSequence([prompt_template, llm])
+hil_chain = HumanInTheLoopMiddleware(chain)
+
+if __name__ == "__main__":
+    while True:
+        try:
+            user_input = input("\nUser: ")
+            if user_input.lower() in {"exit", "quit", "q"}:
+                print("Goodbye!")
+                break
+            result = hil_chain.invoke({"question": user_input})
+            print(f"\nAssistant (confirmed): {result}\n")
+        except KeyboardInterrupt:
+            print("\nInterrupted. Exiting.")
+            break