Phone view: the last canvas stopping, and a slow phone catching up

When the only canvas stopped while the phone view was open, the page went blank until it was reloaded. It now goes to the start page, which says that no canvas is running and offers to try again. A phone on a slow network that falls behind now gets the newest state of every canvas once it has caught up. Before, updates held back for it could get lost, and a canvas stayed out of date on the phone until it next changed.