Cross-platform discovery and identity for desktop applications.

appcatalog exposes two deliberately separate concepts:

• applications registered with the operating system;
• the application that owns the foreground window right now.

It preserves native identity namespaces instead of matching localized names: macOS bundle identifiers, Windows executable paths, X11 WM_CLASS, and Wayland application IDs.

let applications = appcatalog::applications()?;
if let Some(foreground) = appcatalog::foreground_application()? {
    if let Some(application) = applications
        .iter()
        .find(|application| application.matches(&foreground))
    {
        println!("{} is in front", application.name);
    }
}
# Ok::<(), appcatalog::Error>(())

Catalog discovery means applications registered with the desktop environment. Portable executables, AppImages, or unregistered bundles may not appear.

Icon metadata is returned lazily as a file, theme name, or platform resource. application_icon renders an identity's icon at a requested pixel size into straight-alpha RGBA8 pixels, ready for a GPU texture or an image encoder (macOS today; the Linux and Windows backends report no icon yet). The library has no GUI or async-runtime dependency.

• macOS discovery scans the standard system, network, and per-user application directories. Bundles registered from custom locations or external volumes may not appear.
• Native Wayland foreground observation requires the wlr-foreign-toplevel-management protocol (sway, Hyprland, river, and other wlroots compositors). GNOME and KDE expose no stable, general-purpose API for the active native window; XWayland windows still use the X11 fallback.
• Windows discovery currently covers classic per-user and common Start Menu shortcuts. Packaged/UWP AppsFolder registrations are not yet enumerated.

Licensed under either of Apache License, Version 2.0 or MIT license at your option.