Function check_new_tab 

pub(crate) fn check_new_tab(
    state: &AppState,
    meta: &HashMap<String, Value>,
) -> Result<(), String>

Check the identity a client gives a new browser tab (pane.open): an Incognito one that is well formed, within the cap unless it shares a jar already open. Anything else fails the open rather than quietly browsing in the shared jar.