I tried letting AI build a complete app overnight while I slept, providing the project specifications and tracking task progress as if it were a traditional team. The result was better than I expected. In this talk, I will show you the method I use every day to create complex projects with AI—from prototyping and design to actual development and validation—while avoiding security loopholes. We will explore this through real-world examples from professional app developers to understand why "Vibe Coding" today is much more than just asking an AI to "build me an app."