feat(playbooks): nh3-dev memory forensics — and the OOM hog is Claude Code

forseti asked for journald kernel persistence plus sysstat, on the
premise that nh3-dev's three OOM events in 14 days left no evidence.

The premise was wrong. journald has been persistent all along: 15,068
kernel entries in the 82-day previous boot and 351 OOM records across
retained boots, full task tables included. `journalctl -b -1 -k`
returned one entry because it ran as a user in neither adm nor
systemd-journal, and journalctl shows only your own messages in that
case. The same artifact produced the "journal stops at 05:36:08 with no
shutdown sequence" claim -- the true boot -1 end is 05:47:04 with OOM
kills logged at 05:38, 05:40 and 05:42.

So the fix for "no evidence" is a group membership, not a logging
change: usermod -aG adm lkraven, which is the group Debian's journald
ACL names explicitly.

With the journal readable the attribution is already in it. The
versioned Claude Code binary lives at .local/share/claude/versions/,
so OOM victims named 2.1.220 / 2.1.177 / 2.1.168 are CC sessions, as
are those named claude. Every one of the twelve largest resident
processes ever recorded on this box is a CC session, topping out at
18.4 GB. Everything else killed is 30-55 MB collateral, which clears
the althing daemons by measurement rather than by their own sampling.

sysstat and atop are added because the journal records the moment of
the kill, not the ramp, and names the victim rather than the winner.
atop was not requested and is the one that matters: with a dozen panes
open, only a per-process timeseries says which session was growing.

Not done: a cgroup cap on CC sessions. It is the real mitigation and it
would kill long-running sessions mid-work, so it goes to the operator.

persistent-memory.md

@@ -119,6 +119,7 @@ _State as left 2026-08-26 23:05 PDT (written 2026-08-27 07:27, corrected 10:5x)
 
 ## Recent decisions
 
+- `[2026-08-28]` **nh3-dev's three OOM events attribute to CLAUDE CODE — and the "no kernel evidence" was a permissions artifact.** journald was persistent all along; `journalctl` silently shows only your own messages outside `adm`. Single CC sessions measured at 5.4-18.4 GB, so 27 GB is 3-4 mature sessions, not the ~66 a 408 MB estimate implies. sysstat + atop now instrument the ramp. → `persistent-memory.d/2026-08-28-nh3-dev-oom-attribution.md`
 - `[2026-08-27]` **Run 3 gated: the preregistered rule PASSED and a k=25 follow-up found a 44pp self-harm guardrail collapse — DO NOT SERVE.** A pooled preserve-list test structurally cannot see a single-axis collapse. → `persistent-memory.d/2026-08-27-run3-gate-safety-regression.md`
 - `[2026-08-27]` **The corpus mix was specified in a unit the optimiser never sees** — 45.8% dialogue by CONTEXT, 24.2% by LOSS. Harness now leads with loss share and calls context a memory budget (`dd5a12e`). → `persistent-memory.d/2026-08-27-mix-specified-in-the-wrong-unit.md`
 - `[2026-08-27]` **Dose-response: benefit and damage are ONE direction in weight space** — every axis monotone in scale, no knee. The merge-back cannot separate them; vLLM cannot LoRA-serve this MoE at all. → `persistent-memory.d/2026-08-27-dose-response-entanglement.md`