The stop-URL contract passed with the two ids swapped and read the backend
from the working directory; nothing called a real beacon's onSettled or its
library pass-through; the kept-point rule was held by its constants only.
- The client's resume thresholds equal the server's (read from both sources).
- The session stop's URL matches the route the server serves it on.
- The player stops its server session by its item and its own id on an unload and on close,
and keeps it when the page only goes into the back/forward cache.
peter