A click made as a tab closes still reaches its page

Every open tab has its own connection hub in the portal, and each page it shows has a small queue of its own. A click joins that queue and leaves it for the node that owns the button. When the page queue was busy — applying a large update, say — and the tab closed or dropped its connection at that moment, the tab's hub stopped routing for its pages in the same step in which it asked them to shut down. The click was still in the queue, so it was turned away at the tab's own door and the action never ran.

The tab's hub now keeps carrying what its pages had already accepted until those pages have finished shutting down, and only then stops routing. Nothing waits longer than the page takes to hand its queue on, and a click made after the page began closing is still refused rather than sent to a page that is gone.

The measurement and the other teardown route that was already safe are in Refusing a Lost User Action.