What Even Is an OS Now? Thomas Ptacek on AI, Apps, and a New Phone

In a personal essay published on September 25, the engineer Thomas Ptacek says he is leaving Fly.io to work with Kurt on a new project: a phone. AI, he writes, is dissolving the boundary between programmers and users, and most software will soon be conjured by the people who use it rather than shipped to them as fixed-function apps.

The line between programmers and users

His Mac menu bar and task switcher are cluttered with programs he built for himself, with English as his programming language, and he argues that what he does on his computer, any power user will soon do on theirs.

Software with an audience of one

He asks what computing looks like when many, perhaps most, applications have an audience of one or two people, how such software is distributed and what it runs on. He predicts the next casualty of the industry's history of distribution, from boxed products to CD-ROMs to downloads: the prefabricated, fixed-function application.

Strangers, he writes, will stop shipping finished apps and supply building blocks instead. Big browsers and word processors will survive, but thousands of times more small programs will be assembled from parts. His examples are deliberately mundane: a weather forecast for a Chicago neighborhood the nearest stations miss.

Do operating systems still make sense?

Much of the essay is about what operating systems are for. Their core purpose, Ptacek writes, is not access to hardware but partitioning applications from one another and controlling how they communicate. That makes sense when all your software comes from strangers; much less when most software on a device shares one provenance; and almost none when applications are malleable.

Mainstream phones, he notes, were planned in 2023, when computers still ran applications written by professional programmers. He says the soul of those phones is "stuck in the 1970s," and that today's flagships do the job of a DEC PDP-11: running prefab applications. The phone he and Kurt are building is not for showing off AAA mobile games: it builds apps on the device, on demand.

Why it matters

Ptacek is upfront that he is "talking his book," and he acknowledges the history of grand predictions attached to new-startup announcements. Still, the essay registers as a statement of where experienced systems people think the ground is moving, and how fast. He describes the past year as a hundred years happening at once, and the industry as destabilized in a way not seen since the personal computer arrived. As children, he writes, we believed computers could do anything if we could get our hands on them; we became professional developers to learn how much they fall short, and now we have to think like kids again.