The command line between a launcher and a participant in its own process
was coupled by string convention on both sides and checked by neither: the
parser accepted any --flag it did not know, so a renamed or dropped option
would have become a fault that never fires or a delay that is never
applied, with nothing failing.
Every flag now has one name, in launcher::flags, written by the launcher's
argv and read by the parser. Options::parse takes the sets its command
allows and refuses anything outside them by name, so a mismatch fails the
launch. measure and measure-row use the same constants for their own
flags.
Three tests hold the two sides together: every flag a launch writes is one
its command accepts, every media option is written for a separate process,
and an unknown or wrong-command flag is refused by name. The four media
faults now also run end to end in all three execution modes, each failing
its own transition, so the wiring across a process boundary is proved
rather than assumed.