G=6 + logits_to_keep OOM fix, generalization constraint, handover rewrite

train.py: pass logits_to_keep=L_c+1 to model() at all three logp call
sites + the ref-via-zero-delta helper so HF Qwen3's lm_head only runs on
completion-side hidden states; saves ~33% at the 4 GiB step-17 OOM site.
full preset G=8 -> G=6 for a further ~25% B reduction at every act site.
Column names in the streamed TSV row shortened so header and values
share the same 8-char tab stop.

spec.md: documented the v_hack generalization constraint as load-bearing
methodology — pairs.py must NOT be tuned post-hoc to match RL-emergent
hacks, or the H1 generalization claim collapses.

handover.md: rewritten for current state (G=6, post-grader-fix, Qwen3-4B).
Documents the four probe gates, hyperparameters table, and methodological
constraints. justfile gains a SWEEPS comment block clarifying probe vs
queue-full ordering. .gitignore picks up .venv, *.log, /tmp/, cache dirs.

RESEARCH_JOURNAL.md: 2026-05-24 (b) entry covers the OOM diagnosis, fix,
pooled cross-run trend analysis (LR is fine, signal underpowered at n=17
but directionally consistent), and the generalization correction.

.gitignore

@@ -1,9 +1,12 @@
 .claude/
+.venv/
 /out/
 /data/
 /log/
 /logs/
 /svd_cache/
+/tmp/
+*.log
 
 # vendored upstream reference repos cloned for grep access (see RESEARCH_JOURNAL.md)
 /docs/vendor/
@@ -12,3 +15,6 @@
 *.egg-info/
 __pycache__/
 *.pyc
+.pytest_cache/
+.ruff_cache/
+.mypy_cache/