docs: checklist — S5 closed with no gate owed; record the register-corruption find

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

docs/plans/2026-08-07-morning-gate-checklist.md

@@ -28,11 +28,14 @@ now part of every capture.
   sorting-sphere half is real vs retail's registration set but PROVEN unable
   to change any collision outcome (flood and test geometry are the same
   spheres). Fix deferred to the next bake-schema revision.
-- **AD-55 (S5 evidence)** — byte-decoded: retail's Sledding flatness
-  threshold is cos(10°) computed by a live FCOS on π/18; our 0.99999536f is
-  the radian constant misread as degrees. The one-line fix + conformance
-  test lands overnight if a build slot frees; its FEEL check folds into the
-  slope row below.
+- **AD-55 (S5) — closed, and the fix turned out to be a WEEK OLD.** The
+  cos(10°) constant has been live in production since 2026-07-30
+  (`252e8068`); you've been playing on it. Tonight's byte-decode is an
+  independent confirmation. The register row claiming otherwise was a
+  ZOMBIE: an unrelated revert (`a8a7d64b`) resurrected the retired row —
+  and, found by auditing that same revert, had also silently DELETED the
+  then-active AD-56 row. Both corruptions fixed; the class is now a memory
+  rule. No feel gate owed for S5.
 
 ## 2. The sitting