detach method
void
detach()
Unbinds from the current planner, removing the re-emit listener so nothing
leaks past the planner's lifetime. Called by Planner from its dispose
and on a controller swap — not part of the consumer API. Safe to call
when already detached.
Implementation
void detach() {
_inner?.triggerUpdate.removeListener(notifyListeners);
_inner = null;
}