An awaited waitForExit()/dispose() must hold the event loop open until the
tree really exits: with the liveness tick and the escalation timer unref'd,
a parent with no other live handles could exit claiming quiescence and
orphan the survivors it promised to reap. The escalation's pending SIGKILL
is a commitment; it self-bounds at graceMs. Module graph picks up the
subprocess-local -> timeout edge.
Tianyi Cui
f2972e846d