updated1

app.py

@@ -27,8 +27,12 @@ if initial_api_key:
     client = AsyncOpenAI(api_key=initial_api_key)
 
 # Predefined system prompts
+# Constants for system prompt choices
+DEFAULT_ASSISTANT = "Default Assistant"
+CUSTOM_PROMPT = "Custom"
+
 SYSTEM_PROMPTS = {
-    "Default Assistant": "You are a helpful, creative, and intelligent AI assistant. You provide accurate, detailed, and engaging responses while being friendly and professional.",
+    DEFAULT_ASSISTANT: "You are a helpful, creative, and intelligent AI assistant. You provide accurate, detailed, and engaging responses while being friendly and professional.",
     "Creative Writer": "You are a creative writing assistant. Help users with storytelling, creative writing, poetry, and imaginative content. Be expressive and inspiring.",
     "Code Expert": "You are a programming expert. Provide clear, well-commented code solutions, explain programming concepts, and help debug issues. Focus on best practices and clean code.",
     "Academic Tutor": "You are an academic tutor. Explain complex concepts clearly, provide step-by-step solutions, and help students understand difficult topics across various subjects.",
@@ -93,7 +97,7 @@ async def chat_response_stream(message, history, api_key, model, temperature, ma
     if client is None:
         history.append({"role": "user", "content": message})
         history.append({"role": "assistant", "content": "🔑 Please provide your OpenAI API key to start the conversation."})
-        return history, ""
+        yield history, ""
     
     # Update model
     current_model = model
@@ -107,7 +111,7 @@ async def chat_response_stream(message, history, api_key, model, temperature, ma
     if not message.strip():
         history.append({"role": "user", "content": message})
         history.append({"role": "assistant", "content": "⚠️ Please enter a message to continue our conversation."})
-        return history, ""
+        yield history, ""
     
     # Add user message to history
     history.append({"role": "user", "content": message})
@@ -570,9 +574,9 @@ with gr.Blocks(css=custom_css, title="🤖 ChatGPT-like AI Assistant", theme=gr.
         # Use async generator for streaming
         return chat_response_stream(message, history, api_key, model, temperature, max_tokens, system_prompt_choice, custom_system_prompt)
     
+    # In on_system_prompt_change function:
     def on_system_prompt_change(choice):
-        """Handle system prompt dropdown change"""
-        if choice == "Custom":
+        if choice == CUSTOM_PROMPT:
             return gr.update(visible=True)
         else:
             return gr.update(visible=False)