1.1 Overview
Atrium is the Peios web UI. A browser pointed at a Peios machine gets a login page; a successful logon gets a desktop — windows, apps, a terminal — served by that machine and running on it. Atrium is not a management panel over the system; the browser tab is the user's session.
Four decisions shape everything else in this manual:
- The browser is a renderer. All session state — which windows exist, which is focused, the chord table — lives on the machine, in the user's session host. Every connected browser tab holds a mirror of that state and asks for changes; no tab owns anything. Two tabs, or a laptop and a phone, are two views of one desktop.
- The shell is thin; applications are the product. The shell owns login, windows, focus, keybinds and the launcher, and nothing else. Everything a user opens is an application: a directory of web files with a manifest, drawn in an iframe, talking through one SDK (chapter 5).
- Privilege is split across three processes. The one privileged process holds no network socket and parses no HTTP; the process that faces the network runs with every privilege deleted; the process that does the user's work is the user (chapter 2).
- Atrium does not create user processes. Session hosts are submitted to peinit as jobs, with the logon token as the job identity — peinit is their parent, supervisor and record-keeper (§3.2).
Atrium listens on port 8080, unencrypted, and every browser-facing door is one HTTP origin. Transport security and per-application origins are not provided in this version.