Software applications are facing a new intermediary in the form of AI agents that sit between users and applications. The competition is heating up between Application AI Agents, like ChatGPT and Google Gemini, and Operating System AI Agents, such as Apple Intelligence and Google’s Gemini Android integration. These AI agents aim to create seamless user experiences, with OS AI taking a more integrated approach by utilizing system-level access. This access allows them to operate across multiple apps, manage personal data, and streamline transactions, which individual apps cannot match. The article highlights Amazon's historical response to the rising importance of mobile traffic and its eventual creation of the Fire Phone, which aimed to circumvent the App Store tax imposed by Apple. However, despite Amazon's attempts to control its ecosystem, the tech landscape is evolving. Operating systems are better positioned to dominate this new layer due to their comprehensive system access and ability to push updates directly to devices. Meanwhile, the emergence of Chinese companies like ByteDance, with their Doubao Phone Assistant, introduces new competition. This assistant uses a more flexible approach by simulating user interactions across apps without needing developers’ cooperation, potentially reshaping how OS AI operates. As companies in the application layer, such as Uber and DoorDash, face this new challenge, they remain confident in their existing advantages. However, they may underestimate the potential disruption from these AI intermediaries. The competitive dynamics resemble those in the automotive industry, where legacy manufacturers initially dismissed Chinese EVs, only to find them gaining significant market share. The future of AI in applications hinges on how these players adapt to the changing tech landscape and the strategies they employ to maintain their positions.