COSMIC Desktop Environment

COSMIC is a modern, configurable, and lightweight Wayland desktop environment developed by System76. It is designed to be fast, efficient and user-friendly while maintaining a professional appearance. As of April 2025, COSMIC’s latest release is Alpha 7, with a beta release planned in the coming months.

Enabling COSMIC in Ghaf

COSMIC is the default desktop environment in Ghaf. If you wish to explicitly configure or customize the desktop environment, you can still set it manually in your graphics configuration:

profiles.graphics.compositor = "cosmic";

This configuration sets COSMIC as the active desktop environment for Ghaf.

Note

Starting from April 2025, COSMIC DE is fully integrated into NixOS options, and its tools are included in nixpkgs. Prior to this, COSMIC had to be added to Ghaf from the external flake nixos-cosmic.

Configuration Components

COSMIC’s configuration in Ghaf consists of several key components:

1. Core COSMIC DE Configuration

COSMIC handles its configuration via simple Rust Object Notation (RON) files located in the user’s home directory under .config/cosmic.

In the Ghaf Nix configuration, however, we have introduced a conversion mechanism where the entire directory tree is represented by a single YAML file (cosmic.config.yaml). This YAML file acts as the system default COSMIC configuration and is applied to all fresh installations of Ghaf.

If the user makes manual changes to the configuration while using Ghaf, those changes will take precedence over the system defaults.

2. Ghaf COSMIC Nix Configuration

The cosmic.nix module in Ghaf customizes COSMIC to better align with the system’s requirements. Below are the key modifications and adjustments made:

Disabled COSMIC Settings pages

• User Management: The page-users feature in COSMIC settings is disabled.
• Power Settings: The page-power feature is removed, as power management is handled by swayidle and ghaf-powercontrol.
• Sound Settings: The page-sound feature is disabled, with audio control managed by a custom service.

Replacements and Overrides

• Icon Theme: The default COSMIC icon theme is changed to Papirus icon theme.
• GTK Settings: Some default GTK settings are applied to ensure a consistent look and feel.
• Session Management: COSMIC’s session management integrates with ghaf-session.target for better control of Ghaf services.
• Power Management: swayidle replaces cosmic-idle as the default idle and power manager, including configuration for automatic suspend and brightness adjustments.
• Audio Control: A custom Ghaf audio control service works alongside the COSMIC audio applet to provide Ghaf-specific audio control features.

Additional Changes

• DBUS Proxy Integration: Custom DBUS proxy sockets are added for audio, network, and Bluetooth applets.
• Configuration Format: COSMIC’s configuration is centralized into a single YAML file (cosmic.config.yaml) for easier management and deployment. This configuration is installed as an explicit package ghaf-cosmic-config, the derivation of which can be found in cosmic.nix.
• Disabled Services: Several default services, such as geoclue2, pipewire, and gnome-keyring, are explicitly disabled.

These changes ensure that COSMIC in Ghaf is tailored to the system’s specific needs.

Configuration Files

The main configuration files are located in the modules/desktop/graphics/ directory:

• modules/dektop/graphics - cosmic-config - cosmic-config-to-yaml.sh Helper script to convert .config/cosmic to a YAML config - cosmic.config.yaml Main COSMIC desktop configuration which expands into .config/cosmic - cosmic.nix Main COSMIC Nix configuration

Known Limitations

• COSMIC does not allow forcing Server-Side Decorations for apps running under COSMIC
• COSMIC does not yet support all common Wayland protocols (e.g. zwlr_virtual_pointer_manager_v1, etc.)
• COSMIC is still in relatively early development, with a Beta release planned some time in 2025

For more detailed information about COSMIC’s architecture and features, visit the COSMIC Epoch repository and the System76 COSMIC Epoch homepage.