btx-e001 T3-a: matched mask arity moves arith:nm only 0.107->0.127 (still < 0.161 majority-digit baseline) — crater is content entropy, not protocol; 1x1 rows reproduce T-2 exactly

t3a_arity_ledger.json

@@ -0,0 +1,35 @@
+{
+ "_env": {
+  "transformers": "5.13.0",
+  "torch": "2.11.0+cu128"
+ },
+ "_prereg": "arith:nm folded <= 0.161 under matched arity => content entropy, not protocol",
+ "arith:1x1": {
+  "n": 395,
+  "gold_1mask": 0.4329,
+  "gold_kmask": 0.4329,
+  "gold_1mask_folded": 0.5266,
+  "gold_kmask_folded": 0.5266
+ },
+ "arith:nm": {
+  "n": 205,
+  "gold_1mask": 0.1073,
+  "gold_kmask": 0.1268,
+  "gold_1mask_folded": 0.1073,
+  "gold_kmask_folded": 0.1268
+ },
+ "story:1x1": {
+  "n": 493,
+  "gold_1mask": 0.5274,
+  "gold_kmask": 0.5274,
+  "gold_1mask_folded": 0.6085,
+  "gold_kmask_folded": 0.6085
+ },
+ "story:nm": {
+  "n": 107,
+  "gold_1mask": 0.1402,
+  "gold_kmask": 0.1402,
+  "gold_1mask_folded": 0.5047,
+  "gold_kmask_folded": 0.5047
+ }
+}