docs: phase 72 - count-flat closure sweeps + alpha 1.4 A/B decision rule

EXPERIMENTS.md

@@ -3620,3 +3620,27 @@ sign-frequency over a many-fleet stress ensemble rather than a
 one-fleet mean; stress validator ready at /tmp/c36/stress_winner.py.
 FINAL: cv.py UNCHANGED (an uncalibrated instrument would mislead);
 selection stays 4c93883 first, 60d65da/71bfff2 second slot only.
+
+## Phase 72 - Final count-flat closure (c28/c37/c38) + alpha 1.4 public A/B ship (user call)
+
+Deadline corrected to 02:00 CEST (midnight UTC) - time for one more
+public A/B. Count-flat space closed with three sweeps (all paired vs
+1541.3, parity exact in each driver):
+- c28 hyperparams (logbag C/bags, gapHGB l2/leaf): 8 arms, ALL lose or
+  wash (+5.6..+34.2). Champion hyperparameters locally optimal.
+- c37 blend-weight jitter (+/-.05 around .50/.30/.20, 6 directions):
+  ALL lose +23..+50 (several ~2sig AGAINST). Sharp optimum.
+- c38 averaging ensembles (leaders' style, order-only: device-bootstrap
+  x3, drop-fifth x5, time-snapshot x3, feature-set x2): best is a 0.3sig
+  wash (devboot -6.2+/-24.9), timebag a 2.2sig LOSS. Averaging destroys
+  the favorable seed-0 configuration (same lesson as wave T seed-bag).
+ALPHA 1.4 SHIP (62e9d91, count-coupled, explicit user call): fresh
+confirm on head config bgkf 1498.3 (-43.0+/-43.0, 1.0sig, 19W/24L,
+swaps 2.27->2.97/fleet = podium operating point 15-18/scen; mean carried
+by death-heavy origins - the public read arbitrates). Static path
+governs held-out fleets (submit.py:836 ALPHA_STATIC), both knobs set.
+Rehearsal: 520->688 swaps (+32.3%), 43/48 scenarios; ship-code counts
+byte-identical to env-override run. Old-ordering alpha 1.5 failure
+(2189) predates ft2 - this is the operating-point hypothesis' first
+test on the current ordering. DECISION RULE: public < 1575.31 -> select
+62e9d91; else select 4c93883. Revert = both alpha defaults 1.0.