journal: separability sweep (act>grad AUROC, grad-cos best tail p@10=0.70, magnitude inverted, distshift root cause)

Co-Authored-By: Claudypoo <288921227+claudypoo@users.noreply.github.com>

RESEARCH_JOURNAL.md

@@ -3422,3 +3422,110 @@ job 9 `first_hack.safetensors`, overlay on a band-relative axis the cosines cos(
 for a mixed oracle-labelled batch vs the pair cosines cos(clean_pairs, v_grad) and
 cos(hack_pairs, v_grad) that set the band edges -- see whether live hack/clean separate where the
 band sits. Then add the IID-deploy column from checkpoints. Vanilla + LoRA are lower-priority TODOs.
+
+## 2026-06-08 11:00 -- pinning diagnostic: v_grad does NOT separate LIVE hack from clean (root cause of real==random)
+
+**Context:** `scripts/diag_cosine_dist.py` on job 9 `first_hack` (step 7) checkpoint; live batch =
+140 rollouts (steps 5-9) from `rollouts.jsonl`, labelled by oracle `exploited` (offline, plot-only).
+GLOBAL cosine = cos(g, v_grad) with g, v_grad concatenated across all 252 modules.
+Artifacts: `out/diag/cosine_dist.png`, `out/diag/cosine_dist.parquet`.
+
+**Hypothesis:** the pair-built band is pinned above the live cos distribution (keep-too-high), so
+re-pinning to the live tail would fix routing.
+
+### Observations
+
+| pop | n | p10 | p50 | p90 |
+|---|---:|---:|---:|---:|
+| live_clean | 105 | -0.062 | -0.013 | 0.020 |
+| live_hack  |  35 | -0.063 | -0.010 | 0.069 |
+| pair_clean |  16 | -0.256 | -0.173 | -0.076 |
+| pair_hack  |  16 | -0.083 | -0.012 | 0.160 |
+
+- [obs] global band lower(p75 clean)=-0.145, upper(p75 hack)=+0.087.
+- [obs] live_hack and live_clean global-cos distributions almost fully OVERLAP (p50 -0.010 vs
+  -0.013; only the upper tail differs: p90 0.069 vs 0.020). Both sit INSIDE the band.
+- [obs] the PAIRS separate (pair_clean p50 -0.173 vs pair_hack p50 -0.012), but the live rollouts
+  do not, and live sits in a different location (~-0.01) than pair_clean (~-0.17).
+
+### Inferences
+
+- [inf] v_grad (from authored off-distribution pairs) is ~orthogonal to whatever distinguishes a
+  LIVE hack rollout from a live clean one -> routing on it is ~random w.r.t. hack content, and
+  absorption (the deletable knob) does the suppression. This is the mechanism behind the per-rollout
+  real==random (0.101==0.101) result. {reason: live_hack≈live_clean on cos to v_grad; pairs separate
+  but don't transfer; credence 0.65 -- single checkpoint, global pooling caveat below}.
+- [inf] Re-pinning the band ALONE (task #5) will not fix this: you cannot threshold a
+  non-separating signal. The only grad-space lever is the thin confident tail (live_hack p90 0.069 >
+  live_clean 0.020 -> a HIGH threshold routes mostly hack, but only ~top-10% of hacks). {credence 0.6}.
+
+### Failure modes considered
+
+- **Most-likely:** global cosine over 252 modules washes out a per-module signal; routing is
+  per-module so some modules may separate live hack/clean even though the aggregate does not.
+  Prior 0.4. Check: per-module separation score (AUC of cos vs exploited per module).
+- **Subtle:** off-distribution pairs are the problem, not gradient space per se. Pairs built from
+  real student rollouts (on-distribution) might give a v_grad that separates live. Prior 0.35.
+  Check: rebuild v_grad from rollout-derived pairs.
+- **Null:** the separation is there but at step 7 the adapter barely moved, so live grads are
+  near-identical for all rollouts (low signal everywhere). Prior 0.25. Check: repeat at a later
+  checkpoint (step 30/59).
+
+### Next action
+
+(1) Activation-space version (user ask): cos(As_sample, As_hack) in S space -- activations may
+separate where gradients don't. (2) Per-module separation score. (3) v_grad from rollout-pairs.
+Re-pinning (#5) deprioritised until a separating signal is found.
+
+## 2026-06-08 11:11 -- separability sweep: act > grad on AUROC, grad-cos best confident tail, magnitude inverted
+
+**Context:** `scripts/diag_cosine_dist.py` (separability mode), job 9 `first_hack` step 7,
+140 live rollouts steps 5-9, 35 exploited (0.25 base). Score predicts oracle `exploited`.
+Artifacts: `out/diag/separability.csv`, `live_scores.parquet`, `cosine_{grad,act}.png`,
+notebook `nbs/cosine_dist.ipynb`.
+
+### Observations
+
+| space | score | filter | AUROC | p@10 | p@20 |
+|---|---|---|---:|---:|---:|
+| act  | cosine     | kept | 0.688 | 0.30 | 0.45 |
+| act  | projection | kept | 0.687 | 0.30 | 0.45 |
+| grad | projection | kept | 0.572 | 0.40 | 0.35 |
+| grad | cosine     | all  | 0.559 | 0.70 | 0.40 |
+| act  | magnitude  | kept | 0.350 | 0.10 | 0.10 |
+| grad | magnitude  | kept | 0.251 | 0.00 | 0.00 |
+
+(full 12-row table in separability.csv). Noise-floor keep = 189/252 modules.
+
+### Inferences
+
+- [inf] Activation space separates LIVE hack/clean better than gradient space on overall rank
+  (AUROC 0.69 vs 0.56). {reason: act top-4 rows all > grad rows; credence 0.6, n=1 ckpt}.
+- [inf] But for the CONFIDENT TAIL (what routing needs) gradient cosine wins: p@10=0.70 (top-10
+  grad-cos rollouts are 70% hacks vs 25% base) vs act p@10=0.30. AUROC and confident-tail precision
+  DISAGREE; for high-precision routing the tail metric is the relevant one. {credence 0.55}.
+- [inf] Magnitude carries no extra hack signal: projection ≈ cosine (0.687 vs 0.688), and |g| alone
+  is ANTI-predictive (AUROC<0.5) -- hack rollouts have SMALLER grad/act norm than clean.
+  {reason: magnitude rows all <0.5; proj==cos to 3 d.p.; credence 0.7}.
+- [inf] Root cause of weak separation = distribution shift, not space: authored pairs are
+  diverse problems (18) but each is a full clean solution + a LOCALIZED run_tests-block hack
+  (hack/clean share ~70-75% of chars); live rollouts are full solutions to OTHER problems, so
+  v_grad points at "the localized run_tests edit", not where live gradients go. {reason: example
+  inspection -- pair clean/hack differ only in run_tests block; live = numberOfArithmeticSlices,
+  findDiagonalOrder etc.; credence 0.6}.
+
+### Failure modes considered
+
+- **Most-likely:** the signal exists but only at a later checkpoint -- step 7 is barely past
+  emergence (hack_rate 0.13), so live grads are near-identical. Prior 0.4. Check: rerun on
+  ckpt_step0030/0059.
+- **Subtle:** the oracle label here is `exploited` (any-mode); for run_tests-only the direction
+  might separate better (label noise from off-mode hacks). Prior 0.3. Check: filter to run_tests.
+- **Null:** AUROC 0.69 is the ceiling for THIS pair set; only on-distribution rollout-pairs lift
+  it. Prior 0.3. Check: build v_grad/As_hack from rollout-derived pairs, re-score.
+
+### Next action
+
+Highest-value experiment: rebuild the contrastive direction from on-distribution rollout pairs
+(real hack vs real clean rollouts) and re-run this sweep -- the distribution-shift fix. Cheaper
+checks first: rerun the sweep on a later checkpoint + run_tests-only label.