update tambah reset_session, tidak bisa ganti model di tengah chat

app.py

@@ -447,6 +447,7 @@ def create_gradio_interface():
     with gr.Blocks(title="Chat with CSV using AI Models") as interface:
         session_id = gr.State(lambda: str(uuid.uuid4()))
         chatbot_state = gr.State(lambda: None)
+        model_selected = gr.State(lambda: False)  # Track if model is already in use
         
         # Get model choices
         model_choices = list(MODEL_CONFIG.keys())
@@ -457,25 +458,27 @@ def create_gradio_interface():
 
         with gr.Row():
             with gr.Column(scale=1):
-                file_input = gr.File(
-                    label="Upload CSV Anda",
-                    file_types=[".csv"]
-                )
-                
-                # Model selection accordion BEFORE process button
-                with gr.Accordion("Pilih Model AI", open=True):
+                with gr.Box():
+                    gr.Markdown("### Langkah 1: Pilih Model AI")
                     model_dropdown = gr.Dropdown(
                         label="Model",
                         choices=model_choices,
-                        value=default_model
+                        value=default_model,
+                        interactive=True
                     )
                     model_info = gr.Markdown(
                         value=f"**{default_model}**: {MODEL_CONFIG[default_model]['description']}"
                     )
-                    change_model_button = gr.Button("Terapkan Perubahan Model")
                 
-                # Process button AFTER the accordion
-                process_button = gr.Button("Proses CSV")
+                with gr.Box():
+                    gr.Markdown("### Langkah 2: Unggah dan Proses CSV")
+                    file_input = gr.File(
+                        label="Upload CSV Anda",
+                        file_types=[".csv"]
+                    )
+                    process_button = gr.Button("Proses CSV")
+                
+                reset_button = gr.Button("Reset Sesi (Untuk Ganti Model)")
 
             with gr.Column(scale=2):
                 chatbot_interface = gr.Chatbot(
@@ -500,16 +503,34 @@ def create_gradio_interface():
             outputs=[model_info]
         )
         
-        # Process file handler
+        # Process file handler - disables model selection after file is processed
         def handle_process_file(file, model_key, sess_id):
+            if file is None:
+                return None, None, False, "Mohon upload file CSV terlebih dahulu."
+                
             chatbot = ChatBot(sess_id, model_key)
             result = chatbot.process_file(file)
-            return chatbot, [(None, result)]
+            return chatbot, True, [(None, result)]
 
         process_button.click(
             fn=handle_process_file,
             inputs=[file_input, model_dropdown, session_id],
-            outputs=[chatbot_state, chatbot_interface]
+            outputs=[chatbot_state, model_selected, chatbot_interface]
+        ).then(
+            # Disable model dropdown after processing file
+            fn=lambda selected: gr.update(interactive=not selected),
+            inputs=[model_selected],
+            outputs=[model_dropdown]
+        )
+
+        # Reset handler - enables model selection again
+        def reset_session():
+            return None, False, [], gr.update(interactive=True)
+            
+        reset_button.click(
+            fn=reset_session,
+            inputs=[],
+            outputs=[chatbot_state, model_selected, chatbot_interface, model_dropdown]
         )
 
         # Change model handler