feat(computer_use): add switch_desktop with overlay-safe restart

Stop the overlay subprocess before switching virtual desktops,
then restart it on the new desktop — avoids the tkinter display
context teardown that kills the overlay during SendInput-based
Ctrl+Win+Left/Right.

- _switch_desktop_via_keybd(): stop overlay → two-phase SendInput
  → restart overlay
- switch_desktop() method on WindowsUIABackend
- Schema and dispatch updated with 'switch_desktop' action and
  'direction' parameter

Co-authored-by: lEWFkRAD

tools/computer_use/schema.py

@@ -59,6 +59,7 @@ COMPUTER_USE_SCHEMA: Dict[str, Any] = {
                     "wait",
                     "list_apps",
                     "focus_app",
+                    "switch_desktop",
                 ],
                 "description": (
                     "Which action to perform. `capture` is free (no side "
@@ -208,6 +209,16 @@ COMPUTER_USE_SCHEMA: Dict[str, Any] = {
                     "matching the background co-work model."
                 ),
             },
+            # ── switch_desktop ──────────────────────────────────────
+            "direction": {
+                "type": "string",
+                "enum": ["left", "right"],
+                "description": (
+                    "Only for action='switch_desktop'. Switches to the "
+                    "adjacent virtual desktop. Requires Windows 10+ with "
+                    "multiple virtual desktops."
+                ),
+            },
             # ── return shape ───────────────────────────────────────
             "capture_after": {
                 "type": "boolean",

tools/computer_use/tool.py

@@ -426,6 +426,13 @@ def _dispatch(backend: ComputerUseBackend, action: str, args: Dict[str, Any]) ->
         res = backend.set_value(value=str(value), element=args.get("element"))
         return _maybe_follow_capture(backend, res, capture_after)
 
+    if action == "switch_desktop":
+        direction = args.get("direction", "")
+        if not hasattr(backend, "switch_desktop"):
+            return json.dumps({"error": "switch_desktop not supported by current backend"})
+        res = backend.switch_desktop(str(direction))
+        return json.dumps({"ok": res.ok, "message": res.message})
+
     return json.dumps({"error": f"unknown action {action!r}"})
 
 

tools/computer_use/windows_backend.py

@@ -295,6 +295,50 @@ def _press_combo(vks: List[int]) -> None:
     _send_inputs(seq)
 
 
+def _switch_desktop_via_keybd(direction: str, overlay_client) -> bool:
+    """Switch virtual desktop, keeping the overlay alive across the transition.
+
+    Any SendInput-based virtual-desktop switch kills the full-screen tkinter
+    overlay subprocess because the display-context change tears down its X11
+    connection.  Workaround: stop the overlay → switch → restart it on the
+    new desktop.
+    """
+    VK_CONTROL = 0x11
+    VK_LWIN = 0x5B
+    VK_LEFT = 0x25
+    VK_RIGHT = 0x27
+
+    vk_dir = VK_LEFT if direction == "left" else VK_RIGHT
+
+    press = [_key_event(VK_CONTROL, True),
+             _key_event(VK_LWIN, True),
+             _key_event(vk_dir, True)]
+    release = [_key_event(vk_dir, False),
+               _key_event(VK_LWIN, False),
+               _key_event(VK_CONTROL, False)]
+
+    try:
+        # 1. Gracefully stop the overlay before switching
+        overlay_client.stop()
+
+        # 2. Switch virtual desktop
+        _send_inputs(press)
+        time.sleep(0.08)
+        _send_inputs(release)
+
+        # 3. Restart overlay on the new desktop
+        overlay_client._dead = False  # we killed it on purpose, not a crash
+        overlay_client.start()
+        return True
+    except Exception:
+        try:
+            overlay_client._dead = False
+            overlay_client.start()
+        except Exception:
+            pass
+        return False
+
+
 def _type_unicode(text: str) -> None:
     """Type text via KEYEVENTF_UNICODE; newlines become Return taps."""
     batch: List[_INPUT] = []
@@ -990,6 +1034,23 @@ class WindowsUIABackend(ComputerUseBackend):
         except Exception as e:
             return ActionResult(ok=False, action="key", message=f"key failed: {e}")
 
+    def switch_desktop(self, direction: str) -> ActionResult:
+        """Switch to adjacent virtual desktop.
+
+        Temporarily stops the overlay subprocess before switching and
+        restarts it on the new desktop, because any SendInput-based
+        virtual-desktop transition kills the full-screen tkinter window.
+        """
+        if direction not in ("left", "right"):
+            return ActionResult(ok=False, action="switch_desktop",
+                                message=f"unknown direction {direction!r}")
+        self._overlay.send({"cmd": "flash", "text": f"switch desktop · {direction}", "ttl": 1.0})
+        ok = _switch_desktop_via_keybd(direction, self._overlay)
+        return ActionResult(
+            ok=ok, action="switch_desktop",
+            message=(f"switched to {direction} virtual desktop"
+                     if ok else "virtual desktop switch failed"))
+
     # ── Native-value mutation ───────────────────────────────────────
     def set_value(self, value: str, element: Optional[int] = None) -> ActionResult:
         if element is None: