feat(macos): follow the system theme for the Dock icon

Author: findleyl

src-tauri/Cargo.lock

@@ -99,6 +99,11 @@ tracing-appender = "0.2"
 thiserror = "2"
 anyhow = "1"
 
+[target.'cfg(target_os = "macos")'.dependencies]
+objc2 = "0.6"
+objc2-app-kit = { version = "0.3", features = ["NSApplication", "NSImage", "NSResponder"] }
+objc2-foundation = { version = "0.3", features = ["NSData"] }
+
 [target.'cfg(windows)'.dependencies]
 winreg = "0.52"
 

src-tauri/Cargo.toml

@@ -0,0 +1,44 @@
+//
+// Aster Communications Inc.
+//
+// Copyright (c) 2026 Aster Communications Inc.
+//
+// This file is part of this project.
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program. If not, see <https://www.gnu.org/licenses/>.
+//
+use objc2::{AnyThread, MainThreadMarker};
+use objc2_app_kit::{NSApplication, NSImage};
+use objc2_foundation::NSData;
+use tauri::Theme;
+
+const LIGHT_ICON: &[u8] = include_bytes!("../icons/icon_macos.png");
+const DARK_ICON: &[u8] = include_bytes!("../icons/icon_macos_dark.png");
+
+pub fn apply(theme: Theme) {
+    let Some(main_thread) = MainThreadMarker::new() else {
+        return;
+    };
+    let bytes = match theme {
+        Theme::Dark => DARK_ICON,
+        _ => LIGHT_ICON,
+    };
+    let data = NSData::with_bytes(bytes);
+    let Some(image) = NSImage::initWithData(NSImage::alloc(), &data) else {
+        return;
+    };
+    unsafe {
+        NSApplication::sharedApplication(main_thread).setApplicationIconImage(Some(&image));
+    }
+}

src-tauri/icons/icon_macos_dark.png

@@ -29,6 +29,8 @@ mod crypto;
 mod dav;
 mod db;
 mod diagnostics;
+#[cfg(target_os = "macos")]
+mod dock_icon;
 mod error;
 mod imap;
 mod jmap;
@@ -1805,6 +1807,13 @@ fn main() {
         .setup(move |app| {
             sync::poller::set_global_app_handle(Some(app.handle().clone()));
 
+            #[cfg(target_os = "macos")]
+            dock_icon::apply(
+                app.get_webview_window("main")
+                    .and_then(|w| w.theme().ok())
+                    .unwrap_or(tauri::Theme::Light),
+            );
+
             let icon_bytes = include_bytes!("../icons/128x128.png");
 
             let icon =
@@ -2335,6 +2344,10 @@ fn main() {
                 api.prevent_close();
                 let _ = window.hide();
             }
+            #[cfg(target_os = "macos")]
+            if let WindowEvent::ThemeChanged(theme) = event {
+                dock_icon::apply(*theme);
+            }
         })
         .build(tauri::generate_context!())
         .expect("failed to start aster bridge desktop")