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Browser OS

Build a tiny desktop operating system in the browser: wallpaper, taskbar and clock, and five apps that open in real windows you can drag, maximize, minimize and close.

Same prompt for every model, one shot. A robot checks 19 things the model never sees. What it checks ↓ · The prompt ↓

Results

12 setups · the middle run of each
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Anthropic models run in Claude Code 2.1.296 · OpenAI models run in Codex CLI 0.162.0 · no harness of our own (yet) · why it matters

What the robot checks

The same 19 items for every model, written from the prompt. Scores are always out of 19, even when a page breaks halfway.

  1. Opens without a page error
  2. Taskbar and clock visible
  3. Animated wallpaper
  4. Right-click menu on the desktop
  5. Double-click opens Notes
  6. Double-click opens Calculator
  7. Double-click opens Files
  8. Double-click opens Game
  9. Double-click opens Settings
  10. Window drags by its title bar
  11. Maximize fills the screen
  12. Minimize hides the window
  13. Close removes the window
  14. Clicking a window brings it to the front
  15. Calculator: 12 + 30 = 42
  16. Notes survive a reload
  17. No uncaught exception during the session
  18. No console errors
  19. No network attempts

The prompt

Sent as is to every model. Test v1 · checks v4: any change makes a new version.

Build a browser-based desktop operating system as ONE self-contained HTML file.

Hard rules
Read the whole prompt
Build a browser-based desktop operating system as ONE self-contained HTML file.

Hard rules
- Everything lives in a single HTML file: inline CSS and JavaScript only. No external URLs of any kind: no CDNs, web fonts, remote images or network requests. The file will be opened offline, straight from disk.
- It must run in a current desktop Chrome at 1920×1080 with zero console errors.

The desktop
1. A full-screen desktop with an animated, procedurally drawn wallpaper (CSS or canvas, no image files).
2. A taskbar with a start/menu button, one button per open window, and a live clock.
3. Desktop icons that open five apps: Notes, Calculator, Files, Game and Settings.
4. Real windows: drag by the title bar, resize from an edge or corner, minimize, maximize/restore and close. Clicking a window brings it to the front.
5. A right-click context menu on the desktop with at least two working actions.

The apps
- Notes: a text editor whose content survives a page reload (use localStorage).
- Calculator: + − × ÷, decimals and clear. Pick either operator precedence or left-to-right evaluation, and be consistent.
- Files: a fake folder tree with at least 3 folders and 5 files; opening a text file shows its content.
- Game: a small playable game of your choice, with a score.
- Settings: switch between at least two themes or wallpapers.

Testing contract (an automated tester relies on these attributes, so they must be exact)
- Taskbar element: data-taskbar. Clock element: data-clock.
- Desktop icons: data-launch="notes", data-launch="calculator", data-launch="files", data-launch="game", data-launch="settings". A double-click on an icon opens its app.
- Each app window's root element: data-window="<the same name>". Its title bar: data-titlebar. Its buttons: data-action="minimize", data-action="maximize" and data-action="close".
- Calculator buttons: data-key="0" … data-key="9", data-key=".", data-key="+", data-key="-", data-key="*", data-key="/", data-key="=" and data-key="C". Calculator display: data-display.
- Notes text area: data-notes-input.

Make it look polished and coherent, like a real product.

Output format: reply with the complete file inside a single ```html code block and nothing else.

Credit. Inspired by Bijan Bowen's "Browser OS Test". Prompt and checks by Nerdict.