The seed's revert (mesh-catalog #526) was refused on 'would stop running node',
while a self-composing node would have refused its placement's absence, kept
what runs and marked every have failed until a restart. endWhenUnplaced ends the
agent's run when the key goes, so it begins again on the controller's
compositions, as at a start without a key; the composer refuses nothing while
unplaced; the node's have says whose compositions it applies (Composes); the
shadow answers a deleted placement Returns, verdict same.