Leaked materials from 2024 have revealed that Microsoft has built a working prototype Copilot OS that is platform agnostic, derived from the Microsoft Edge web browser and runs on top of Windows or Android, focused on the web and agentic experiences.
This project is codenamed Aion, and while its status is currently unknown, the leaked materials confirm that such a project was in active development and reached a stage in which the code was functional. With all the material leaked, we have a pretty good idea about how this OS experience looked and functioned.
According to the leaked materials, Aion is a UI shell built entirely with web tech, using a modified version of the Edge web browser. The interface is Edge, but altered to include desktop-like interfaces and functionality such as a Start menu, Taskbar, and cascading windows.
The documents confirm that Aion was capable of running on top of Windows 11 as a desktop shell replacement, or on AOSP Android. There’s also a third compatible OS mentioned called Win3, which sources say was a special modified version of the Windows codebase with less legacy cruft, resulting in a lighter OS experience with faster boot times, longer battery life, and better security at the expense of legacy app support.
Aion seemingly wasn’t compatible with legacy Windows apps, with the leaked video mentioning it only running web apps and websites, with tight Windows 365 integration for when users need access to a legacy Windows experience.
The Aion interface was built around Copilot and agentic AI experiences. It features a familiar looking Taskbar along the bottom of the interface, where the system tray and running apps appear. It also features a Start menu, except this time it’s powered by Copilot and features a Copilot icon instead of a Windows one.
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The Copilot Start menu is where users go to begin tasks, browse the web, or open web apps. The entire interface is built around Copilot, with users interacting with the OS via a multi-modal omnibox that can jumpstart tasks or workflows, find files, browse the web, initiate AI chat, and open web apps.
The new Start menu provides quick access to recent websites and files, and also groups recent activites into Spaces that let you launch multiple activities at once via a single click, curated by Copilot. Web apps will run in their own floating windows like real apps do on Windows, letting users cascade, minimize, and snap them.
The Spaces that Copilot curates also appear in the Taskbar when open. These appear as buckets, highlighted in a different color to let you know that these items are all being grouped together by the AI for picking up where you left off at a later point.
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Because Aion only runs web apps, it’s capable of understanding the context of everything you have open using Copilot. That means Copilot as an agent is capable of completing tasks on your behalf if asked by the user, and can answer any questions about the things that are open or were recently viewed at any time.
Aion also includes a feature that lets users complete tasks while staying in the flow of chat. For example, if the user wanted to send a summary of a web page to a friend or colleague via email, users could simply ask Copilot to do that, and the agent would pull in an email draft and let the user check it over and send it without ever leaving the Copilot chat interface.
It’s unclear if Project Aion is ever intended to ship, or if it’ll remain an internal experiment never to see the light of day. So far, we’ve not seen any official confirmation that a Copilot OS is going ahead. Microsoft recently announced Project Solara, an agentic OS that runs on Windows and Android codebases that utilizes a just-in-time UI approach to generate experiences on the fly.
While not the same, perhaps Microsoft has opted to go in a different direction for its agentic OS vision.
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