Function sioul_dnd_heard 

#[unsafe(no_mangle)]
pub unsafe extern "C" fn sioul_dnd_heard(
    json: *const c_char,
) -> *mut c_char

A change of this phone’s own do-not-disturb, heard as it happened (DndReceiver, in Sioul’s own process): {on}, the system’s state. A press of the switch when it disagrees with what holds (everywhere::heard_from_system).

Safety

json is null or a zero-terminated text valid for the call.