recover() kept a survivor only when a bwrap outer pid outlived SIGKILL, so
the Q2 refusal (BUILD.md:177-179, t1-sessions.md:109) had no test. A leftover
whose runner still ran after its outer pid was gone was ended and dropped.
Now recover() waits on the outer pid and the runner, keeps any leftover where
either still runs, and logs that it still runs. check() reads only the
survivors that still run.
session-launch.test.mjs adds a test where a sessionless leftover's runner is
a sleep child and its outer pid is gone. It asserts the legacy-run-live
refusal with no launch and no session workspace, then one launch once the
child exits. BUILD.md adds mutants M10-M12 and replaces the "no test" note.
jason.woltje
42fd3edd45