// Record ui.stats().objects, call mountCycle(), then inspect phase.value and
// pending.value.status(). Close the tab: the referenced Block still waits.
// releaseCycle() removes both external references; the next objects query
// should return to the same baseline before the five-minute wait finishes.
holder = ui.state(0)
pending = ui.state(0)
phase = ui.state(0)
class CycleRect: RectBlock {
    peer: Object
    function wait(self: CycleRect): Unit {
        gate = ui.sleep(self,"sleep",300000)
        phase.set(1)
        done = await gate
        phase.set(2)
        self.peer.title = "等待已结束"
    }
    function measure(self: CycleRect, mount: Mount, constraints: Constraints): MeasureResult {
        observed = self.peer.title
        return MeasureResult(180,40)
    }
    function paint(self: CycleRect, mount: Mount, geometry: Bounds): DisplayList {
        observed = self.peer.title
        return RectBlock.paint(self,mount,geometry)
    }
}
function mountCycle(): Unit {
    transient = Page()
    transient.title = "临时引用环"
    rect = CycleRect(180,40,8,"#3868D9",transient)
    transient.render(rect)
    holder.set(transient)
    phase.set(0)
    pending.set(ui.spawn(rect,"workflow",rect.wait))
}
function releaseCycle(): Unit {
    holder.value.close()
    holder.set(0)
    pending.set(0)
}
base = Page()
base.title = "GC 基线"
base.render(TextBlock("关闭临时 Page 后应回收引用环",2))