Update app.py

app.py

@@ -238,7 +238,10 @@ def get_backend_health() -> str:
 # GRADIO INTERFACE
 # ============================================================================
 
-with gr.Blocks(title="ZeroEngine-Backend", theme=gr.themes.Monochrome()) as demo:
+with gr.Blocks(title="ZeroEngine-Backend") as demo:
+    # Apply theme after Blocks creation for Gradio 6.5.0 compatibility
+    if hasattr(demo, 'theme'):
+        demo.theme = gr.themes.Monochrome()
     gr.HTML("""
         <div style='text-align: center; padding: 20px;'>
             <h1>🔧 ZeroEngine-Backend</h1>
@@ -321,4 +324,30 @@ with gr.Blocks(title="ZeroEngine-Backend", theme=gr.themes.Monochrome()) as demo
         health_btn.click(get_backend_health, None, [health_output])
 
 if __name__ == "__main__":
+    import atexit
+    import signal
+    
+    def cleanup_on_exit():
+        """Cleanup function called on application exit"""
+        print("[CLEANUP] Backend shutting down...")
+        # Clear caches
+        global prompt_cache, response_cache, token_ledger
+        prompt_cache.clear()
+        response_cache.clear()
+        token_ledger.clear()
+        print("[CLEANUP] Backend shutdown complete")
+    
+    # Register cleanup functions
+    atexit.register(cleanup_on_exit)
+    
+    def signal_handler(signum, frame):
+        """Handle shutdown signals gracefully"""
+        print(f"[CLEANUP] Received signal {signum}")
+        cleanup_on_exit()
+        import sys
+        sys.exit(0)
+    
+    signal.signal(signal.SIGTERM, signal_handler)
+    signal.signal(signal.SIGINT, signal_handler)
+    
     demo.launch(server_name="0.0.0.0", server_port=7860, ssr_mode=False)