fix(theme/windows): switch to dark-light based theme detection

src-tauri/src/utils/resolve/mod.rs

@@ -22,6 +22,8 @@ use clash_verge_signal;
 
 pub mod dns;
 pub mod scheme;
+#[cfg(target_os = "windows")]
+pub mod theme;
 pub mod ui;
 pub mod window;
 pub mod window_script;
@@ -64,6 +66,8 @@ pub fn resolve_setup_async() {
         init_verge_config().await;
         Config::verify_config_initialization().await;
         init_window().await;
+        #[cfg(target_os = "windows")]
+        theme::start_windows_app_theme_watcher();
 
         let core_init = AsyncHandler::spawn(|| async {
             init_service_manager().await;

src-tauri/src/utils/resolve/theme.rs

@@ -0,0 +1,55 @@
+//! Windows app theme watcher.
+//!
+//! NOTE:
+//! Tauri's theme API is unreliable on Windows and may miss or delay
+//! system theme change events. As a workaround, we poll the system
+//! theme via the `dark-light` crate and emit a custom
+//! `verge://app-theme-changed` event to keep the frontend in sync.
+//!
+//! Windows-only, best-effort.
+
+use std::time::Duration;
+
+use dark_light::{Mode as SystemTheme, detect as detect_system_theme};
+use tauri::Emitter as _;
+
+use crate::{core::handle, process::AsyncHandler};
+
+const APP_THEME_EVENT: &str = "verge://app-theme-changed";
+
+fn resolve_apps_theme_mode() -> Option<&'static str> {
+    match detect_system_theme().ok()? {
+        SystemTheme::Dark => Some("dark"),
+        SystemTheme::Light => Some("light"),
+        SystemTheme::Unspecified => None,
+    }
+}
+
+pub fn start_windows_app_theme_watcher() {
+    AsyncHandler::spawn(|| async move {
+        let app_handle = handle::Handle::app_handle().clone();
+        let mut last_theme = resolve_apps_theme_mode();
+
+        if let Some(theme) = last_theme {
+            let _ = app_handle.emit(APP_THEME_EVENT, theme);
+        }
+
+        loop {
+            if handle::Handle::global().is_exiting() {
+                break;
+            }
+
+            tokio::time::sleep(Duration::from_millis(500)).await;
+            let Some(theme) = resolve_apps_theme_mode() else {
+                continue;
+            };
+
+            if last_theme.as_ref() == Some(&theme) {
+                continue;
+            }
+
+            last_theme = Some(theme);
+            let _ = app_handle.emit(APP_THEME_EVENT, theme);
+        }
+    });
+}