Fix X11 key injection modifier release handling

src/desktop_x11.py

@@ -437,11 +437,17 @@ class X11Adapter:
             if keycode == 0:
                 continue
             keycodes.append(keycode)
-        for code in keycodes:
+        pressed: list[int] = []
-            xtest.fake_input(dpy, X.KeyPress, code)
+        try:
-        for code in reversed(keycodes):
+            for code in keycodes:
-            xtest.fake_input(dpy, X.KeyRelease, code)
+                xtest.fake_input(dpy, X.KeyPress, code)
-        dpy.flush()
+                pressed.append(code)
+        finally:
+            for code in reversed(pressed):
+                xtest.fake_input(dpy, X.KeyRelease, code)
+            # Ensure all synthetic key events are processed before the display
+            # may be closed by callers.
+            dpy.sync()
 
     def _keysym_for_char(self, ch: str) -> tuple[int | None, bool]:
         if ch.isupper():

tests/test_desktop_x11.py

@@ -65,6 +65,49 @@ class DesktopX11Tests(unittest.TestCase):
 
         display_obj.close.assert_called_once_with()
 
+    @patch("desktop_x11.xtest.fake_input")
+    def test_send_combo_releases_keys_and_syncs(self, fake_input):
+        adapter = self._adapter()
+        dpy = MagicMock()
+        dpy.keysym_to_keycode.side_effect = [10, 20, 30]
+
+        adapter._send_combo(dpy, ["Control_L", "Shift_L", "v"])
+
+        expected_calls = [
+            ((dpy, 2, 10),),
+            ((dpy, 2, 20),),
+            ((dpy, 2, 30),),
+            ((dpy, 3, 30),),
+            ((dpy, 3, 20),),
+            ((dpy, 3, 10),),
+        ]
+        self.assertEqual(fake_input.call_args_list, expected_calls)
+        dpy.sync.assert_called_once_with()
+
+    @patch("desktop_x11.xtest.fake_input")
+    def test_send_combo_releases_pressed_keys_when_press_fails(self, fake_input):
+        adapter = self._adapter()
+        dpy = MagicMock()
+        dpy.keysym_to_keycode.side_effect = [10, 20]
+
+        def _fake_input(_dpy, event_type, code):
+            if event_type == 2 and code == 20:
+                raise RuntimeError("press failed")
+            return None
+
+        fake_input.side_effect = _fake_input
+
+        with self.assertRaisesRegex(RuntimeError, "press failed"):
+            adapter._send_combo(dpy, ["Control_L", "v"])
+
+        expected_calls = [
+            ((dpy, 2, 10),),
+            ((dpy, 2, 20),),
+            ((dpy, 3, 10),),
+        ]
+        self.assertEqual(fake_input.call_args_list, expected_calls)
+        dpy.sync.assert_called_once_with()
+
 
 if __name__ == "__main__":
     unittest.main()