Refactor respond function to improve message handling and clarity

app.py

@@ -1,6 +1,6 @@
 import gradio as gr
 from langchain.chat_models import init_chat_model
-from langchain_core.messages import HumanMessage
+from langchain_core.messages import HumanMessage, AIMessage
 
 model = init_chat_model("gemini-2.0-flash", model_provider="google_genai")
 
@@ -16,9 +16,16 @@ def respond(
     """
     Respond to user input using the model.
     """
-    response = model.invoke(
-        dialog_history + [HumanMessage(content=user_input)],
-    )
+    history_langchain_format = []
+    for msg in dialog_history:
+        if msg['role'] == "user":
+            history_langchain_format.append(
+                HumanMessage(content=msg['content']))
+        elif msg['role'] == "assistant":
+            history_langchain_format.append(AIMessage(content=msg['content']))
+    history_langchain_format.append(HumanMessage(content=user_input))
+    response = model.invoke(history_langchain_format)
+    print(history_langchain_format)
     return response.content