systemd's default OOMPolicy=stop tears the whole unit down the moment the
kernel kills any process in its cgroup, so a single over-large subagent
takes the daemon and every sibling session with it — measured on a live
agent, both units show OOMPolicy=stop today, which is exactly the "every
live subagent session was cut mid-turn" symptom.
That blast radius is also what would make the preceding commit a bad
trade: deliberately putting this unit first in the OOM queue is only an
improvement if losing one subagent isn't losing all of them. OOMPolicy=
continue scopes the loss to the process the kernel actually chose, and
leaves the daemon alive to report the kill instead of vanishing and being
restarted with an empty session map.
Refs #4316
33aa2bdbc8