Satya Nadella has once again referred to Copilot as a “new OS for work”, a characterization that has sparked discussions among industry observers. This statement emerged during a leadership update, shortly after Microsoft introduced its latest iteration of Copilot. Initially, Nadella made this claim on social media, and it has since become a recurring theme in his messaging about the product.
Currently, the “new” Copilot app is available for users, although features like Home, Code, and Autopilot are still in the pipeline. This app serves as a replacement for the previously named Microsoft 365 Copilot, and users can access it by updating through the Microsoft Store.
Upon examining the installation folder of build 154.0.4258.37, it becomes evident that what Nadella refers to as an OS is, in fact, a standard Windows app. The underlying architecture reveals that copilotapp.exe functions as a rebranded Microsoft Edge launcher, built on a Chromium framework. Thus, while Microsoft touts a new operating system for work, it is essentially an app operating within the Windows 11 environment, presenting a rather layered and complex narrative.
Satya Nadella is calling Copilot an OS again, and Microsoft has a reason
In a recent post dated October 1, announcing LinkedIn CEO Ryan Roslansky‘s departure from Microsoft at the end of 2026, Nadella reiterated his vision for Copilot. He stated, “With Copilot, we are executing rapidly against our vision to build a new OS for work that spans every model, every form factor, and every task, with Office fully embedded in Copilot and vice versa!”
This perspective aligns with Microsoft’s strategy to consolidate various work functions into a single platform. By merging its Copilot identities and simplifying the app’s name to just “Copilot,” the company aims to create a unified workspace experience.
Microsoft wants Copilot to become the layer above your apps
According to an announcement made on September 25, the new Copilot integrates features such as Home, which includes Chat and Cowork, alongside Office applications like Word, Excel, and PowerPoint. The upcoming Code feature will allow users to create apps and workflows using plain language, while Autopilot—formerly known as Scout—will act as a persistent assistant, functioning even when not actively prompted.
Additionally, a proactive command center named Today is set to manage emails, calendars, Teams threads, meetings, and tasks. Apps developed through the Code feature will operate within the Copilot Managed Runtime, all within the Microsoft 365 ecosystem.
Traditionally, an operating system serves as the foundational layer through which users access applications, files, and services. Microsoft envisions Copilot fulfilling this role for work-related tasks. While this strategy may resonate with the company’s objectives, it remains to be seen whether users will embrace this characterization.
Most of the big Copilot features aren’t in the app yet
As of now, features like Home and Code are expected to roll out through the Frontier program in the coming weeks. Autopilot has just entered private preview, and the Today feature will follow suit shortly. Currently, the Copilot app available to users is primarily a chat interface, featuring Search, Library, Agents, and Notebooks. Future updates will enhance this app rather than starting anew with a different framework.
The Copilot app looks like Windows software, but Chromium does most of the work
Microsoft markets Copilot as a desktop application, alongside its web and mobile versions. From a user’s perspective, it appears to function as a traditional app. However, a closer inspection reveals that copilotapp.exe is a lightweight 4.99MB launcher that relies on the DLLs associated with the Edge browser process.
In the installation folder, a complete Edge 154 build, approximately 520MB in size, is present, including a substantial msedge.dll file that encompasses the entire browser along with necessary components. The Copilot app also inherits various Edge features, such as the IE mode adapter and Widevine DRM.
When initiated, Copilot loads specific URLs for personal and work accounts, utilizing Chromium’s rendering processes. This architecture results in significant RAM consumption, even when the app is idle.
The new Copilot isn’t the WebView2 wrapper Microsoft shipped before
Microsoft has iterated on Copilot’s architecture multiple times. Initially, a more native WinUI version was released, but the company shifted towards a web-based wrapper earlier this year. The current build has moved away from embedding web content within a native shell, opting instead to make a Chromium browser the core of the application.
Microsoft built a native WinUI host with the Chromium core
While it may be tempting to dismiss Copilot as merely a website, it is supported by a secondary component, copilotapphost.exe. This WinUI 3 application, crafted in C# on .NET 10, enables functionalities such as voice activation and screen sharing. However, the native UI is minimal, primarily activating for specific Windows features.
Communication between the two components occurs through a Windows named-pipe bridge, facilitating interactions for various tasks. Interestingly, the host’s manifest aligns precisely with that of the Microsoft 365 Copilot app, indicating a shared infrastructure for both consumer and work versions of Copilot.
But Microsoft is finally making WinUI better while Copilot goes the other way
In a somewhat ironic twist, Microsoft has recently released Windows App SDK 2.5 Experimental, which includes enhancements for WinUI. Despite the company’s focus on native Windows development, one of its flagship applications is built on Chromium, highlighting a divergence in priorities.
The Copilot “OS” philosophy isn’t new
Internal documents regarding Project Aion, a prototype labeled CopilotOS, reveal a vision that replaces traditional desktop elements with a Copilot web shell. While the current Copilot app is not identical to Aion, the similarities in their design philosophies are noteworthy.
Nadella’s characterization of Copilot as an OS reflects Microsoft’s ambition to create a cohesive workspace integrating chat, Office applications, coding, and agent functionalities. However, the distinction between serving as a work layer and functioning as an operating system remains a critical point of discussion.
