fix(native): eliminate explorer hang deadlock and improve taskbar crash recovery

.github/workflows/ci.yml

@@ -0,0 +1,40 @@
+name: CI
+
+on:
+  push:
+    branches: [ main, "fix/**", "feat/**" ]
+  pull_request:
+    branches: [ main ]
+
+permissions:
+  contents: read
+
+jobs:
+  build-and-test:
+    name: Build, Test & Package
+    runs-on: windows-latest
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+
+      - name: Setup Rust toolchain
+        uses: dtolnay/rust-toolchain@stable
+
+      - name: Rust Cache
+        uses: Swatinem/rust-cache@v2
+
+      - name: Check code
+        run: cargo check --all-targets
+
+      - name: Run unit tests
+        run: cargo test --all
+
+      - name: Build release binary
+        run: cargo build --release
+
+      - name: Upload release artifact
+        uses: actions/upload-artifact@v4
+        with:
+          name: claude-code-usage-monitor-release
+          path: target/release/claude-code-usage-monitor.exe
+          if-no-files-found: error

src/native_interop.rs

@@ -7,7 +7,6 @@ use windows::Win32::Graphics::Gdi::{
     EnumDisplayMonitors, GetMonitorInfoW, HDC, HMONITOR, MONITORINFO,
 };
 use windows::Win32::UI::Accessibility::{SetWinEventHook, UnhookWinEvent, HWINEVENTHOOK};
-use windows::Win32::UI::Shell::{SHAppBarMessage, ABM_GETTASKBARPOS, APPBARDATA};
 use windows::Win32::UI::WindowsAndMessaging::*;
 
 // Window style constants
@@ -104,7 +103,7 @@ pub fn find_taskbars() -> Vec<TaskbarWindow> {
         if len > 0 {
             let class_name = String::from_utf16_lossy(&class_name[..len as usize]);
             if class_name == "Shell_TrayWnd" || class_name == "Shell_SecondaryTrayWnd" {
-                if let Some(rect) = get_taskbar_rect(hwnd).or_else(|| get_window_rect_safe(hwnd)) {
+                if let Some(rect) = get_taskbar_rect(hwnd) {
                     taskbars.push(TaskbarWindow { hwnd, rect });
                 }
             }
@@ -143,29 +142,13 @@ pub fn find_child_window(parent: HWND, class_name: &str) -> Option<HWND> {
     }
 }
 
-/// Get taskbar position via SHAppBarMessage
+/// Get taskbar position safely.
+/// We use get_window_rect_safe directly because GetWindowRect is a non-blocking
+/// kernel-mode query that returns immediately even if explorer.exe is hung or unresponsive.
+/// SHAppBarMessage sends a synchronous LPC message to explorer.exe's UI message loop,
+/// which deadlocks the monitor thread if Explorer hangs (Event 1002).
 pub fn get_taskbar_rect(taskbar_hwnd: HWND) -> Option<RECT> {
-    unsafe {
-        let mut class_name = [0u16; 64];
-        let len = GetClassNameW(taskbar_hwnd, &mut class_name);
-        if len > 0 {
-            let class_name = String::from_utf16_lossy(&class_name[..len as usize]);
-            if class_name == "Shell_SecondaryTrayWnd" {
-                return get_window_rect_safe(taskbar_hwnd);
-            }
-        }
-
-        let mut abd = APPBARDATA {
-            cbSize: std::mem::size_of::<APPBARDATA>() as u32,
-            hWnd: taskbar_hwnd,
-            ..Default::default()
-        };
-        let result = SHAppBarMessage(ABM_GETTASKBARPOS, &mut abd);
-        if result == 0 {
-            return None;
-        }
-        Some(abd.rc)
-    }
+    get_window_rect_safe(taskbar_hwnd)
 }
 
 /// Get the bounding rectangle of a window

src/window.rs

@@ -406,7 +406,7 @@ fn relaunch_self() {
 fn spawn_taskbar_watchdog() {
     std::thread::spawn(move || loop {
         std::thread::sleep(Duration::from_secs(TASKBAR_WATCH_INTERVAL_SECS));
-        let (shell_hosted, windows) = {
+        let invalid = {
             let state = lock_state();
             let Some(state) = state.as_ref() else {
                 continue;
@@ -422,20 +422,26 @@ fn spawn_taskbar_watchdog() {
                     )
                 })
             });
-            (
-                shell_hosted,
-                std::iter::once(state.hwnd)
-                    .chain(state.mirror_hwnds.iter().copied())
-                    .chain(state.desktop_hwnds.iter().flatten().copied())
-                    .collect::<Vec<_>>(),
-            )
+            if !shell_hosted {
+                continue;
+            }
+            std::iter::once(state.hwnd)
+                .chain(state.mirror_hwnds.iter().copied())
+                .chain(state.desktop_hwnds.iter().flatten().copied())
+                .any(|window| unsafe {
+                    let hwnd = window.to_hwnd();
+                    if !IsWindow(Some(hwnd)).as_bool() {
+                        return true;
+                    }
+                    // When hosted inside a shell window (like Shell_TrayWnd or Progman),
+                    // Windows does not always destroy cross-process child windows when Explorer restarts.
+                    // If this window has a parent that is now destroyed, flag it as invalid.
+                    match GetParent(hwnd).ok() {
+                        Some(p) if !p.is_invalid() => !IsWindow(Some(p)).as_bool(),
+                        _ => false,
+                    }
+                })
         };
-        if !shell_hosted {
-            continue;
-        }
-        let invalid = windows
-            .iter()
-            .any(|window| unsafe { !IsWindow(Some(window.to_hwnd())).as_bool() });
         if invalid && !native_interop::find_taskbars().is_empty() {
             diagnose::log("watchdog: shell-hosted surface was destroyed -> relaunching");
             relaunch_self();

src/window/host_geometry.rs

@@ -34,7 +34,7 @@ pub(super) fn refresh_theme_host_geometry() {
 }
 
 fn refresh_with(query: impl FnOnce() -> Vec<ThemeHostGeometry>) {
-    // SHAppBarMessage can dispatch another layout notification before returning.
+    // Layout queries can dispatch another layout notification before returning.
     // Reentrant readers keep using the last complete snapshot; never wait here.
     if REFRESHING.swap(true, Ordering::Acquire) {
         return;

src/window/message_loop.rs

@@ -545,6 +545,7 @@ pub(super) unsafe extern "system" fn wnd_proc(
             // and tray-icon-only themes keep their owner HWND, so restore the
             // registrations when the shell broadcasts its return.
             sync_tray_icon(hwnd);
+            render_layered();
             LRESULT(0)
         }
         WM_DESTROY => {