r/opencodeCLI Case: Generating an Ubuntu Desktop in the Browser with One Prompt (Complete Prompt + Reproducible Output)

One-sentence takeaway

This is a fully reproducible “one prompt → playable output” case: give the prompt below to LongCat-2.0 through OpenCode, and it generates an interactive Ubuntu desktop simulation that runs in a browser (including a file manager, terminal, settings, lock screen, shutdown animation, and more). Both the prompt and output are public and accessible.

Use cases

• Suitable tasks: Test LongCat-2.0's ability to follow long instructions and generate a large front-end project in one shot; reuse it as a baseline prompt for “large one-shot front-end generation”; use the oneshot-websites skill to produce a website in one click from OpenCode

• Unsuitable tasks: Projects requiring a multi-file project structure, a backend, or persistence (this case is a single-HTML output); low-spec environments sensitive to output size

• Applicable model version: LongCat-2.0 (the author used the meituan/longcat-2.0 model in OpenCode through OpenRouter)

• Applicable client, agent, or API: OpenCode CLI (see the model configuration in prompt directory 06); similar prompts can also be tried in Claude Code / Hermes

• Recommended reasoning level and parameters: Not disclosed; the prompt asks for “no token budget limit,” so a long-output tier is more suitable

Ready-to-use content

Original prompt (full PROMPT.md, English original)

Create a fully interactive web-based emulation of the Ubuntu desktop that feels like a living operating system rather than a static mockup. Recreate the modern Ubuntu experience — the GNOME-based desktop with Ubuntu's Yaru design language: the top bar with its clock, calendar popover, and system status menu; the left-hand Ubuntu Dock with pinned and running applications; the Activities overview with window spread, search, and workspace switching; the app grid of installed applications; and draggable, resizable, minimizable, maximizable windows with believable focus, layering, and edge-snapping behavior.

Let visitors actually use the machine. They should be able to launch apps from the dock and the app grid, search for apps and files in the Activities overview, move and resize windows, tile them to screen halves, maximize and restore them, minimize to the dock, switch between workspaces, and quit applications. Include a working Files app with a navigable folder hierarchy, breadcrumbs, list/grid views, and file open/preview behavior; a Text Editor that can open, edit, and save documents; a Terminal with a believable shell session that responds to common commands (ls, cd, pwd, cat, echo, uname, neofetch-style system info, apt simulations, and graceful "command not found" handling); a Settings app with real panels — appearance/accent color, wallpaper, displays, Wi-Fi/network, sound, notifications, users, and About — whose changes visibly take effect on the desktop; a Calculator; a web browser shell with start page and tabs; and a Software store front, plus whatever smaller utilities (clock, image viewer, system monitor) make the system feel inhabited. Changing the wallpaper or accent color in Settings should restyle the desktop and windows; the top-bar clock should tick and its calendar should highlight today; notifications should arrive, stack in the notification list, and dismiss; the system status menu should offer volume, network, battery, settings, lock, suspend, restart, and power-off flows — with confirmation dialogs, a lock screen showing the time and wallpaper, and a believable shutdown/boot sequence that returns to the session.

Recreate the whole look and feel with close fidelity: the Yaru palette with its aubergine and warm orange accents, Ubuntu typography and icon styling, window chrome with the circular close/minimize/maximize buttons, rounded corners and layered shadows, the dock's running-dot indicators, urgency and hover behavior, app grid folders and pagination, context menus, tooltips, modal dialogs, toast notifications, focus and selection states, loading and error states, and the characteristic motion of the desktop — window open/close animations, overview and workspace transitions, dock reveal, and snapping previews. Preserve the interface's visual proportions, interaction texture, feedback, personality, and tiny behaviors while making the recreation responsive and enjoyable in a browser, and include the secondary and edge states — empty folders, missing files, unsaved-changes prompts, disconnected Wi-Fi, low battery — that make an operating system feel inhabited, not just the most recognizable screen.

Do not take shortcuts, substitute a cookie-cutter desktop template, or stop at a superficial approximation. This skill imposes no token budget limit, so pursue the recreation down to the smallest meaningful interactions, states, transitions, and edge cases, and keep refining the look, feel, behavior, and atmosphere until the system feels complete, cohesive, and convincingly Ubuntu.

Generated result verification (collected 2026-08-18)

• Visiting https://ubuntu.longcat.demos.sulat.com/: The page title is “Ubuntu Desktop.” It includes the Activities overview, a real-time clock, and the Files, Text Editor, Web, Terminal, Settings, Calculator, and System Monitor apps, along with a “Welcome to Ubuntu” prompt—the output is genuinely runnable, not a static screenshot.

• The author's comparison reference in the original post: the Kimi K3 output for the same task at https://ubuntu.k3.demos.sulat.com/ (prompt at https://ubuntu.k3.demos.sulat.com/PROMPT.md), which can be used for cross-model comparison.

• The post's comments confirm that Owl Alpha is the released version of LongCat-2.0 (“Yes this is the release version of owl alpha”); the author recommends pairing it with the oneshot-websites skill to deploy the output to Cloudflare Drop / Vercel Drop.

Raw data and verification notes

• The full prompt is transcribed verbatim from PROMPT.md (collected 2026-08-18, 3,565 characters).

• The demo site was still online and interactive (the page returned a normal DOM and app list during collection).

• A Kimi K3 reference output for the same task exists, supporting cross-model comparison; however, both are single-author self-tests rather than controlled experiments.

Applicability boundaries

• The prompt is very long (about 3.5K characters) and asks for “no token budget limit.” Under ordinary quotas it may hit the output limit (it generally fits within an API limit of 128K tokens, but takes longer to run).

• The output is a single-file web simulation, with gaps from the interaction details and behavior of a real Ubuntu system; the author describes it as a demo, not a production-grade system.

• Reproduction quality depends on the model's reasoning level and client; this case was completed through OpenCode + OpenRouter, while behavior through the official API was not individually verified.