Batch codex-04 / PR 18329: isolated Linux systemd scope probe

Environment: Node 24.21.0, systemd 255, Linux x64.
Stand-in parent process spawns one Node child which allocates 4 MiB blocks.
Only the disposable scope is limited: MemoryMax=64M, MemorySwapMax=0.
Both runs retain TimeoutStopSec=10s and use --collect.
This probes the policy applied by AgentScope; it is not a live Codex test.

BEFORE (OOMPolicy=stop):
Foreground launcher exit: 143 (SIGTERM). Parent cannot report child exit.

AFTER (OOMPolicy=continue):
{"parentAlive":true,"childExitCode":null,"childSignal":"SIGKILL"}
low 0
high 0
max 37
oom 1
oom_kill 1
oom_group_kill 0

Foreground launcher exit: 0. Parent survives child OOM kill.

Not verified: real Codex under memory pressure, app-server as OOM victim, systemd-oomd, older systemd, macOS, Windows, Electron desktop, iOS, Android.