diff --git a/.changeset/24291-cbp-docblock-tense.md b/.changeset/24291-cbp-docblock-tense.md
new file mode 100644
index 00000000000..3b3d818d68f
--- /dev/null
+++ b/.changeset/24291-cbp-docblock-tense.md
@@ -0,0 +1,13 @@
+---
+'@objectstack/spec': patch
+---
+
+Clause-②: no
+
+The `forceCbpMasterDetailRequired` docblock in `src/data/object.zod.ts` no longer says that today only
+the security gate (`assertControlledByParentWrite`) closes the null-master-FK shape of a
+`controlled_by_parent` object. That was true before the builder's force landed, and the sentence is now
+in the past tense. It also names what has refused the declaration at parse since protocol 18:
+`refuseControlledByParentWithoutOneMaster` refuses a `controlled_by_parent` object none of whose
+`master_detail` fields declares `required: true`. No key, schema, export, accepted value or message text
+changes.
diff --git a/packages/spec/src/data/object.zod.ts b/packages/spec/src/data/object.zod.ts
index 60d11818410..5ee9ab17df9 100644
--- a/packages/spec/src/data/object.zod.ts
+++ b/packages/spec/src/data/object.zod.ts
@@ -3480,10 +3480,14 @@ function assertReferenceViaSiblingDeclared(objectName: unknown, fields: unknown)
  * master FK, the row lands with a null FK, the derived read filter
  * `masterFK IN (accessible master ids)` can never match null — the row is
  * invisible to everyone — and every later by-id write answers
- * `422 MISSING_REQUIRED_FIELD`. Today only the security gate
- * (`assertControlledByParentWrite`) closes that shape, and commit 75b7c240a records that
- * the declaration and the enforcement disagree. This makes the unsafe shape
- * impossible to NEWLY declare:
+ * `422 MISSING_REQUIRED_FIELD`. Before commit 75b7c240a only the security
+ * gate (`assertControlledByParentWrite`) closed that shape, by refusing the
+ * insert at runtime, and that commit records that the declaration and the
+ * enforcement disagreed. Since protocol 18 the parse refuses the declaration
+ * itself: {@link refuseControlledByParentWithoutOneMaster} refuses a
+ * `controlled_by_parent` object none of whose `master_detail` fields declares
+ * `required: true`. The builder makes the unsafe shape impossible to NEWLY
+ * declare:
  *
  * - omitted `required` → forced to `true` (the lint rule
  *   `relationship/master-detail-required` already computes exactly this fix);