fix(macos): prevent background timer suspension (#74)

* feat(macos): add objc2 dependencies and implement app nap and webview suspension handling

- Introduced new dependencies for macOS: objc2, objc2-foundation, and objc2-web-kit.
- Added modules for managing app nap and webview suspension specific to macOS.
- Updated the main application logic to disable app nap and webview suspension when running on macOS.

* fix(macos): use NSActivityUserInitiatedAllowingIdleSystemSleep instead of NSActivityBackground

NSActivityBackground (0xFF) does not actually prevent App Nap — it marks
work as discretionary. Switch to NSActivityUserInitiatedAllowingIdleSystemSleep
which reliably prevents App Nap while still allowing system sleep.

Co-authored-by: Cursor <cursoragent@cursor.com>

---------

Co-authored-by: Cursor <cursoragent@cursor.com>

Author: robinebers

src-tauri/Cargo.lock

@@ -37,3 +37,8 @@ tauri-plugin-updater = "2"
 tauri-plugin-process = "2"
 tokio = { version = "1", features = ["rt-multi-thread", "macros"] }
 regex-lite = "0.1.9"
+
+[target.'cfg(target_os = "macos")'.dependencies]
+objc2 = "0.6"
+objc2-foundation = { version = "0.3", features = ["NSProcessInfo", "NSString"] }
+objc2-web-kit = { version = "0.3", features = ["WKPreferences", "WKWebView", "WKWebViewConfiguration"] }

src-tauri/Cargo.toml

@@ -0,0 +1,38 @@
+//! App Nap prevention for macOS.
+//!
+//! macOS App Nap can suspend background processes to save energy.
+//! This module prevents that so timers and background work continue.
+
+use std::sync::Once;
+
+use objc2::msg_send;
+use objc2::rc::Retained;
+use objc2_foundation::{NSObject, NSProcessInfo, NSString};
+
+static INIT: Once = Once::new();
+
+/// Disables App Nap by starting a background activity.
+///
+/// Tells macOS that the app needs periodic background work and should not
+/// be suspended. The activity persists for the app's lifetime.
+pub fn disable_app_nap() {
+    INIT.call_once(|| {
+        unsafe {
+            let process_info = NSProcessInfo::processInfo();
+            // NSActivityUserInitiatedAllowingIdleSystemSleep (0x00EFFFFF)
+            // Prevents App Nap but still allows the system to sleep per user preferences.
+            // NSActivityBackground (0xFF) does NOT prevent App Nap.
+            let options: u64 = 0x00FFFFFF & !(1u64 << 20);
+            let reason = NSString::from_str("Periodic usage data refresh");
+            let token: Retained<NSObject> = msg_send![
+                &process_info,
+                beginActivityWithOptions: options,
+                reason: &*reason
+            ];
+            // Intentionally leak -- the activity token must persist for the app's lifetime.
+            // Dropping it would re-enable App Nap.
+            std::mem::forget(token);
+            log::info!("App Nap disabled via NSProcessInfo background activity");
+        }
+    });
+}

src-tauri/src/app_nap.rs

@@ -1,6 +1,10 @@
+#[cfg(target_os = "macos")]
+mod app_nap;
 mod panel;
 mod plugin_engine;
 mod tray;
+#[cfg(target_os = "macos")]
+mod webkit_config;
 
 use std::collections::{HashMap, HashSet};
 use tauri_plugin_aptabase::EventTracker;
@@ -284,6 +288,12 @@ pub fn run() {
             #[cfg(target_os = "macos")]
             app.set_activation_policy(tauri::ActivationPolicy::Accessory);
 
+            #[cfg(target_os = "macos")]
+            {
+                app_nap::disable_app_nap();
+                webkit_config::disable_webview_suspension(app.handle());
+            }
+
             use tauri::Manager;
 
             let version = app.package_info().version.to_string();

src-tauri/src/lib.rs

@@ -0,0 +1,26 @@
+//! WebKit configuration for disabling background suspension on macOS.
+//!
+//! By default, WebKit suspends JavaScript execution when the webview is not visible.
+//! This module disables that behavior so auto-update timers continue to fire.
+
+use tauri::Manager;
+
+pub fn disable_webview_suspension(app_handle: &tauri::AppHandle) {
+    let Some(window) = app_handle.get_webview_window("main") else {
+        log::warn!("webkit_config: main window not found");
+        return;
+    };
+
+    if let Err(e) = window.with_webview(|webview| {
+        unsafe {
+            use objc2_web_kit::{WKInactiveSchedulingPolicy, WKWebView};
+            let wk_webview: &WKWebView = &*webview.inner().cast();
+            let config = wk_webview.configuration();
+            let prefs = config.preferences();
+            prefs.setInactiveSchedulingPolicy(WKInactiveSchedulingPolicy::None);
+            log::info!("WebKit inactiveSchedulingPolicy set to None");
+        }
+    }) {
+        log::warn!("Failed to configure WebKit scheduling: {e}");
+    }
+}