update: app.py to start chat on button press

app.py

@@ -7,19 +7,26 @@ from guardrails_genie.llm import OpenAIModel
 load_dotenv()
 weave.init(project_name="guardrails-genie")
 
-
 openai_model = st.sidebar.selectbox("OpenAI LLM", ["", "gpt-4o-mini", "gpt-4o"])
 chat_condition = openai_model != ""
 
+# Use session state to track if the chat has started
+if "chat_started" not in st.session_state:
+    st.session_state.chat_started = False
+
+# Start chat when button is pressed
+if st.sidebar.button("Start Chat") and chat_condition:
+    st.session_state.chat_started = True
 
-if chat_condition:
+# Display chat UI if chat has started
+if st.session_state.chat_started:
     st.title("Guardrails Genie")
 
     # Initialize chat history
     if "messages" not in st.session_state:
         st.session_state.messages = []
 
-    llm_model = OpenAIModel(model_name="gpt-4o-mini")
+    llm_model = OpenAIModel(model_name=openai_model)
 
     # Display chat messages from history on app rerun
     for message in st.session_state.messages:
@@ -37,9 +44,9 @@ if chat_condition:
             llm_model, user_prompts=prompt, messages=st.session_state.messages
         )
         response = response.choices[0].message.content
-        response += f"\n\n---\n[Explore in Weave]({call.ui_url})"
+
         # Display assistant response in chat message container
         with st.chat_message("assistant"):
-            st.markdown(response)
+            st.markdown(response + f"\n\n---\n[Explore in Weave]({call.ui_url})")
         # Add assistant response to chat history
         st.session_state.messages.append({"role": "assistant", "content": response})