The Tao backend

Tao is the Rust windowing crate underpinning Tauri 2. Nucleus 2.0 wraps it as a first-class backend so Compose Desktop runs on a native window — no AWT, no Swing event-dispatch thread, no XWayland fallback. It is the default for new Nucleus apps, and the only path to modern desktop primitives the JetBrains Runtime can't reach.

TL;DR

• No AWT at runtime — Compose draws into a native window via Tao + Skiko.
• Native Wayland, multi-touch, pen and stylus, per-monitor HiDPI on every OS.
• ~60 MB resident on a GraalVM native-image build.
• Same DecoratedWindow Composable as the AWT backends — pick the backend in Gradle, not in your UI code.
• Escape hatch via nucleusWindow.unsafe.taoWindow when you need the raw handle.

Install

dependencies {
    implementation("dev.nucleusframework:nucleus.nucleus-application:<version>")
    implementation("dev.nucleusframework:nucleus.decorated-window-tao:<version>")
}

The Nucleus Gradle plugin auto-detects decorated-window-tao on the classpath and selects the Tao backend at runtime. To force it:

nucleusApplication(backend = NucleusBackend.Tao) {
    // …
}

Quickstart

import dev.nucleusframework.application.*
import dev.nucleusframework.window.core.*
import androidx.compose.ui.unit.*
import androidx.compose.ui.window.rememberWindowState

fun main() = nucleusApplication(backend = NucleusBackend.Tao) {
    DecoratedWindow(
        onCloseRequest = ::exitApplication,
        state = rememberWindowState(size = DpSize(1024.dp, 720.dp)),
        title = "Hello Tao",
    ) {
        TitleBar { state -> /* custom title bar */ }
        MyContent()
    }
}

How it works

Tao opens a native OS window directly — NSWindow on macOS, an HWND on Windows, a wl_surface (or X11 window) on Linux. Compose renders into that surface through Skiko: Metal on macOS, WGL on Windows, EGL on Linux. Nothing routes through Swing's event-dispatch thread.

Because the OS event loop runs on the process main thread, the macOS launcher needs -XstartOnFirstThread. The Nucleus Gradle plugin injects it automatically for run, packaged distributions and Compose Hot Reload. GraalVM native-image builds start on the main thread by default.

The unified nucleusApplication { } entry point hides the backend choice from your UI code. The Tao backend exposes the same DecoratedWindow, DecoratedDialog and TitleBar Composables as the AWT backends — but underneath you get a TaoWindow you can reach through nucleusWindow.unsafe.taoWindow when you need to call into the native crate directly.

Coverage matrix

Reference

The Tao API surface lives in dev.nucleusframework.window.tao.*:

• taoApplication { } — direct entry point (use nucleusApplication instead for portability).
• TaoWindow — imperative window handle. Reach it via LocalTaoWindow or nucleusWindow.unsafe.taoWindow.
• NativeView — embed SwiftUI, WebView2 or GTK widgets in Compose.
• MacOSStyle.Liquid — opt into macOS 26 Liquid Glass.
• TaoCursorIcon, TaoTrackpadGesture, TaoTrackpadPhase, TaoMouseButton, TaoEventCode — input constants.
• TaoDeepLinkBridge.setSink { uri -> … } — deep link delivery.