@@ -148,11 +148,12 @@ describe('R2 outside controlled_by_parent — the verdict is unchanged', () => {
   });
 });
 
-// What actually reaches the rule from the authoring builder. Under
+// What reaches the rule from the authoring builder. Under
 // `controlled_by_parent`, `ObjectSchema.create()` forces an omitted `required`
-// to `true` and refuses an explicit `false`, but never inspects `readonly` or
-// `system` — so the two flagged shapes leave the builder intact, and this rule
-// is the authoring-time refusal they meet.
+// to `true` and refuses an explicit `false`; the parse it ends in refuses a one
+// master marked `readonly` or `system` (spec shape `master-not-writable`), so
+// the two flagged shapes no longer leave the builder, and this rule reports
+// them on a stack that never went through it.
 describe('R2 over objects built by ObjectSchema.create()', () => {
   const build = (field: ReturnType<typeof Field.masterDetail>) =>
     ObjectSchema.create({
 
@@ -33,7 +33,9 @@ export const entry: SemanticMigration = {
     + 'still reaches it from any object not authored through the builder. The security gate keeps '
     + 'refusing these inserts. (The later step-18 entry `cbp-master-relation-tiers-retired` goes '
     + 'further for the first shape: a `master_detail` without `required: true` is refused at parse, '
-    + 'and the runtime no longer resolves a master from it.)',
+    + 'and the runtime no longer resolves a master from it. The same entry now refuses the other two '
+    + 'at parse on the object\'s one required master, so `ObjectSchema.create` no longer lets them '
+    + 'through either.)',
   acceptanceCriteria:
     '`os lint` reports no `relationship/master-detail-required` finding at `error`: on every '
     + 'object declaring `sharingModel: \'controlled_by_parent\'`, each `master_detail` reference '