fix(computer_use): correct type_text MCP tool name and implement drag action

Bug 3: The cua_backend type_text() method called MCP tool 'type_text_chars'
which does not exist in current cua-driver. Changed to 'type_text' which is
the correct MCP tool name.

Bug 4: The drag() method returned a hardcoded 'not supported' error even
though cua-driver exposes a 'drag' MCP tool. Implemented proper drag
dispatching with coordinate-based and element-based targeting.

Added dispatch-level validation for drag to ensure from/to coordinates
or elements are provided before calling any backend.

Fixes #24170 (bugs 3 and 4)

tools/computer_use/cua_backend.py

@@ -497,9 +497,25 @@ class CuaDriverBackend(ComputerUseBackend):
         button: str = "left",
         modifiers: Optional[List[str]] = None,
     ) -> ActionResult:
-        # cua-driver does not expose a drag tool.
-        return ActionResult(ok=False, action="drag",
-                            message="drag is not supported by the cua-driver backend.")
+        pid = self._active_pid
+        if pid is None:
+            return ActionResult(ok=False, action="drag",
+                                message="No active window — call capture() first.")
+        args: Dict[str, Any] = {"pid": pid}
+        if from_element is not None and to_element is not None:
+            if self._active_window_id is None:
+                return ActionResult(ok=False, action="drag",
+                                    message="No active window_id for element-based drag.")
+            args["from_element"] = from_element
+            args["to_element"] = to_element
+            args["window_id"] = self._active_window_id
+        elif from_xy is not None and to_xy is not None:
+            args["from_x"], args["from_y"] = int(from_xy[0]), int(from_xy[1])
+            args["to_x"], args["to_y"] = int(to_xy[0]), int(to_xy[1])
+        else:
+            return ActionResult(ok=False, action="drag",
+                                message="drag requires from_element/to_element or from_coordinate/to_coordinate.")
+        return self._action("drag", args)
 
     def scroll(
         self,
@@ -534,10 +550,7 @@ class CuaDriverBackend(ComputerUseBackend):
         if pid is None:
             return ActionResult(ok=False, action="type_text",
                                 message="No active window — call capture() first.")
-        # Safari WebKit AXTextField does not accept AX attribute writes (type_text),
-        # so use type_text_chars which synthesises individual key events instead.
-        # This works universally across all macOS apps in background mode.
-        return self._action("type_text_chars", {"pid": pid, "text": text})
+        return self._action("type_text", {"pid": pid, "text": text})
 
     def key(self, keys: str) -> ActionResult:
         pid = self._active_pid

tools/computer_use/tool.py

@@ -357,6 +357,12 @@ def _dispatch(backend: ComputerUseBackend, action: str, args: Dict[str, Any]) ->
         return _maybe_follow_capture(backend, res, capture_after)
 
     if action == "drag":
+        has_elements = args.get("from_element") is not None and args.get("to_element") is not None
+        has_coords = args.get("from_coordinate") and args.get("to_coordinate")
+        if not has_elements and not has_coords:
+            return json.dumps({
+                "error": "drag requires from_coordinate/to_coordinate or from_element/to_element",
+            })
         res = backend.drag(
             from_element=args.get("from_element"),
             to_element=args.get("to_element"),