item 21: GSM carry-cot 57.4% (5x prior best); control isolates whiteboard to drop-bucket; E2-N/A2 planned

results-loop/PROTOCOL_UNIFIED.md

@@ -494,3 +494,28 @@ no fixed k solves but some k does.
     Honest note: arm outputs are VISIBLE tokens (~40) — this is the
     budget-CoT-with-loop hybrid, a scope change from latent planning,
     run at Nils's explicit direction ("do gsm8k and such").
+
+--- Outcome, item 21 (scored 2026-07-16 ~06:30). Harvest: 427 verified
+terse CoTs (292 hard, 135 easy; 73.5% yield, ~3 min). Grid (n=256,
+base 10.9/93.1/0.8/0.0 overall/easy/hard/drop):
+  arm A carry  2:2  53.9  (82.8 / 60.6 / 37.0)
+  arm A carry  2:6  57.4  (72.4 / 63.8 / 45.0)
+  control FF   2:2  49.6  (79.3 / 59.8 / 28.0)
+  control FF   2:6  54.7  (82.8 / 66.9 / 31.0)
+(a) CONFIRMED, dramatically: best cell 57.4% vs the previous best GSM
+arm's 12.1% — a 5x jump to full-CoT territory (~53%) at ~1/4 the
+visible tokens. Dense verified supervision was indeed the binding
+constraint; the supervision-density theory of the GSM failure is now
+POSITIVELY confirmed, not just by absence. (b) MIXED: A-vs-B delta
++4.3 at p=2 (clears the >=3 bar), +2.7 at p=6 (misses); hard/easy
+shuffle within noise between arms, BUT the whiteboard shows a
+consistent, specific signature: DROP items (unreachable by the base
+model even with full CoT at labeling) — A beats B by +9 and +14 points
+there in the two cells. Interpretation: scratchpad supervision carries
+the bulk; the carry chain specifically extends reach into previously
+unreachable problems. McNemar p-values pending (mcnemar_carrycot.py
+ready; classifier-blocked at scoring time). (c) CONFIRMED: easy damage
+much reduced vs answer-only carry (83->72-83 vs 83->45). Ladder gate:
+technically met at p=2; decision on stage B/A2/E2-N deferred to the
+morning review with the p-values in hand — the drop-bucket signature,
+if it survives pairing, is the strongest argument for continuing.