Which screen is next, where a returning person resumes, whether a URL
may be visited, and what the counter says are all one function of the
published ledger and answers, so the page guard, the screens and the
shell cannot disagree. Q6 is in the order only while an area needs a
unit and the account does not already answer it; the first-result task
follows the spec's fixed priority (a connection the browser can finish,
then the first medication for a daily schedule, then one reading for
the first area) and is left out for a record somebody else will run,
because the three tasks write the caller's own record.
Tested before the screens exist; the two rules a screen would most
easily get wrong were broken on purpose and the tests went red.
