No item with that ID on the active page (the message names Whiteboard_SwitchPage).
The item exists but is not an HTML widget.
No board is on screen to run the command (pure engine / surface not bound).
A widget tool was sent through the synchronous entry point; use the async one.
The widget never reported ready within the deadline.
The widget was ready but still handling an earlier command until the deadline; retry.
The widget accepted the command but did not answer within the deadline.
The widget's document reloaded while the command was in flight.
The widget was unmounted while the command was in flight.
A ref from an earlier inspect no longer points at an element.
A label matched several elements; the error lists the candidate refs.
Nothing matched the target.
The target element is disabled.
The widget or the element opted out of agent operation, or the field is protected.
The widget has no action by that name; the error lists the registered names.
The widget's action handler threw; the error carries its message.
The host's widget-access policy does not allow this command.
The host vetoed this specific command; the error carries its reason.
The tool arguments are missing or malformed.
Machine-readable failure codes for widget commands and the widget agent tools. They travel to the model as
errorCodeon the tool result, so each one names a situation the model can act on.