What a launch from a checkpoint shows, read from the checkpoint's screen (the
Top its type carries): a pre-session screen is a process without a session,
so the launch opens the login home; any other screen is a signed-in process,
whose launch starts on the launch's first screen; a wide ScreenId — a
checkpoint that crossed JSON storage, where the screen is known only at run
time — may be either, so its result is the union. This mirrors what the
launch does at run time: it reads the stored session, not the screen.
What a launch from a checkpoint shows, read from the checkpoint's screen (the
Topits type carries): a pre-session screen is a process without a session, so the launch opens the login home; any other screen is a signed-in process, whose launch starts on the launch's first screen; a wideScreenId— a checkpoint that crossed JSON storage, where the screen is known only at run time — may be either, so its result is the union. This mirrors what the launch does at run time: it reads the stored session, not the screen.