feat: add Linux inotify real-time kernel watching for instant app install/uninstall detection

quickshell/modules/launcher/AppLauncher.qml

@@ -51,6 +51,7 @@ PanelWindow {
             openProgress = 0.0
             openAnim.restart()
             AppLauncherService.reset()
+            AppLauncherService.reload()
             searchField.text = ""
             root.selectedIndex = 0
             Qt.callLater(() => {

quickshell/services/python/app_launcher_service.py

@@ -231,6 +231,8 @@ def parse_desktop_apps():
 
 def watch_directory_changes():
     import select
+    import ctypes
+
     dirs = [
         '/usr/share/applications',
         '/usr/local/share/applications',
@@ -239,6 +241,27 @@ def watch_directory_changes():
         os.path.expanduser('~/.local/share/flatpak/exports/share/applications')
     ]
 
+    # Initialize Linux kernel inotify for 0ms instant file creation/deletion notifications
+    inotify_fd = -1
+    try:
+        libc = ctypes.CDLL("libc.so.6")
+        inotify_init = libc.inotify_init
+        inotify_add_watch = libc.inotify_add_watch
+        inotify_init.restype = ctypes.c_int
+        inotify_add_watch.argtypes = [ctypes.c_int, ctypes.c_char_p, ctypes.c_uint32]
+        inotify_add_watch.restype = ctypes.c_int
+
+        fd = inotify_init()
+        if fd >= 0:
+            # IN_CREATE | IN_DELETE | IN_MODIFY | IN_MOVED_FROM | IN_MOVED_TO | IN_ATTRIB
+            mask = 0x00000100 | 0x00000200 | 0x00000002 | 0x00000040 | 0x00000080 | 0x00000004
+            for d in dirs:
+                if os.path.exists(d):
+                    inotify_add_watch(fd, d.encode('utf-8'), mask)
+            inotify_fd = fd
+    except Exception:
+        inotify_fd = -1
+
     def get_state_snapshot():
         snapshot = {}
         for d in dirs:
@@ -260,13 +283,25 @@ def watch_directory_changes():
 
     while True:
         try:
-            # Check for non-blocking stdin input (reload requests from QML)
+            read_fds = [sys.stdin]
-            rlist, _, _ = select.select([sys.stdin], [], [], 0.5)
+            if inotify_fd >= 0:
+                read_fds.append(inotify_fd)
+
+            rlist, _, _ = select.select(read_fds, [], [], 0.4)
             if rlist:
+                for fd in rlist:
+                    if fd == sys.stdin:
                         line = sys.stdin.readline()
                         if line:
                             parse_desktop_apps()
                             last_snapshot = get_state_snapshot()
+                    elif fd == inotify_fd:
+                        # Flush inotify events and trigger re-parse
+                        try:
+                            os.read(inotify_fd, 4096)
+                        except Exception: pass
+                        parse_desktop_apps()
+                        last_snapshot = get_state_snapshot()
                 continue
 
             current_snapshot = get_state_snapshot()
@@ -274,7 +309,7 @@ def watch_directory_changes():
                 last_snapshot = current_snapshot
                 parse_desktop_apps()
         except Exception:
-            time.sleep(0.5)
+            time.sleep(0.4)
 
 if __name__ == '__main__':
     watch_directory_changes()