@@ -0,0 +1,13 @@
+---
+'@objectstack/spec': patch
+---
+
+docs(spec): the semantic migration entry `cbp-optional-master-admitted` and `controlledByParentMasterOf` name how a raw parse reads an omitted `required` on the optional master
+
+Clause-②: no
+Metadata-protocol: none
+
+- **Migration entry `cbp-optional-master-admitted`.** Its `replacement` and `acceptanceCriteria` said an omitted `required` on the only `master_detail` of a `controlled_by_parent` object keeps meaning required through `ObjectSchema.create()` and on stored rows, and stopped there. They now also name the raw-parse door, as the maintainer ruled on the optional master: through `ObjectSchema.safeParse`, an object written directly in `defineStack`, or a save door, `required` defaults to `false` before the object is judged, so the omission is admitted as the optional master. `os lint` still reports the omission at `error`. The entry's `id`, `surface` and `reason` are unchanged, and so is its paragraph's meaning in the protocol upgrade guide apart from that added clause.
+- **`controlledByParentMasterOf` (JSDoc).** "One whose `required` is not written names no master" holds on a body read as written. On a parsed field map the omission has already defaulted to `false`, so there the field is the optional master.
+
+Text only: no schema, type, export or runtime answer changes. A test now pins the three doors side by side on one omitted `required`: `ObjectSchema.create()` gives the required master, `ObjectSchema.safeParse` and `defineStack` give the optional master.
@@ -12,6 +12,7 @@ import {
   type ControlledByParentMasterShape,
 } from './index';
 import { ObjectSchema } from './object.zod';
+import { defineStack } from '../stack.zod';
 
 /**
  * [#23272 · ADR-0055 §1] The exported exactly-one-master predicate and
@@ -136,6 +137,33 @@ describe('controlledByParentMasterRefusal — the export and ObjectSchema agree
     expect(controlledByParentMasterOf(built.fields)).toEqual({ field: 'order', optional: false });
   });
 
+  // [#30905 ruling A, record 6687830530 · #31470] The three doors, side by
+  // side, on one omitted `required`. The answers differ BY RULING: the builder
+  // sees the omission and forces the required master; the raw parse and
+  // `defineStack` over a plain object literal read the parsed `false`, the
+  // optional master. Refusing the omission at every door was the option the
+  // ruling did not take; `os lint` reports it at `error` instead.
+  it('the three doors on an omitted required: create() → required master; safeParse and defineStack → optional master', () => {
+    const line = { name: 'cbpd3_line', label: 'Line', sharingModel: 'controlled_by_parent' as const, fields: { order: md('cbpd3_header') } };
+
+    const built = ObjectSchema.create(line as Parameters<typeof ObjectSchema.create>[0]);
+    expect(built.fields.order!.required).toBe(true);
+    expect(controlledByParentMasterOf(built.fields)).toEqual({ field: 'order', optional: false });
+
+    const parsed = ObjectSchema.safeParse(line);
+    expect(parsed.success).toBe(true);
+    expect(parsed.data!.fields.order!.required).toBe(false);
+    expect(controlledByParentMasterOf(parsed.data!.fields)).toEqual({ field: 'order', optional: true });
+
+    const stack = defineStack({
+      manifest: { id: 'com.example.cbp-three-doors', namespace: 'cbpd3', version: '0.0.1', type: 'app', name: 'CBP' },
+      objects: [{ name: 'cbpd3_header', label: 'Header', fields: { name: { type: 'text', label: 'Name' } } }, line],
+    } as never) as unknown as { objects: Array<{ name: string; fields: Record<string, { required?: boolean }> }> };
+    const staged = stack.objects.find((o) => o.name === 'cbpd3_line')!;
+    expect(staged.fields.order!.required).toBe(false);
+    expect(controlledByParentMasterOf(staged.fields)).toEqual({ field: 'order', optional: true });
+  });
+
   it('answers undefined for any other sharing model, as the parse accepts it', () => {
     for (const sharingModel of ['private', 'public_read', 'public_read_write']) {
       const obj = { name: 'pair', label: 'Pair', sharingModel, fields: { a: md('x', { required: true }), b: md('y', { required: true }) } };
 
@@ -157,7 +157,13 @@ export interface ControlledByParentMaster {
  *   declared `required: false`, that field is the optional master;
  * - anything else (two required masters, two `master_detail` fields none of
  *   them required, one whose `required` is not written, a required `lookup`
- *   only, nothing) names no master: `undefined`.
+ *   only, nothing) names no master: `undefined`. "Not written" holds only on
+ *   a map read as written (an authored or stored body no parse has touched).
+ *   On a PARSED map the omission has already defaulted to `false`, so through
+ *   a raw parse (`ObjectSchema.safeParse`, an object written directly in
+ *   `defineStack`, a save door) that field IS the optional master, as
+ *   maintainer ruling A on #30905 (record 6687830530) reads it; the builder
+ *   (`ObjectSchema.create()`) forces it to `true` first, the required master.
  *
  * Judges the master only. Whether the one master is writable (`readonly` /
  * `system`) is {@link controlledByParentMasterRefusal}'s question, and the
 
@@ -11,8 +11,12 @@ import type { SemanticMigration } from '../../types.js';
 // no master is read by its owner and by View All on the detail; a row that
 // names one is read through its master, as before. An OMITTED `required` keeps
 // its meaning where the spec sees the omission (the builder force and the D2
-// conversion cbp-master-detail-required-defaulted, both unchanged). No D2
-// conversion: nothing is rewritten.
+// conversion cbp-master-detail-required-defaulted, both unchanged). A raw
+// parse cannot see it: the field default writes `false` first, so an object
+// written directly in `defineStack`, or saved through a save door, reads an
+// omitted `required` as the optional master. That divergence is ruled, not a
+// gap: maintainer ruling A on #30905 (ruling record 6687830530) chose it over
+// refusing the omission at every door. No D2 conversion: nothing is rewritten.
 //
 // The write side followed under ADR-0055 §3 as amended (same ruling A, PR
 // #31082), and the `replacement` below records it beside the read side: a
@@ -37,8 +41,11 @@ export const entry: SemanticMigration = {
     + 'master is unchanged: a row whose stored required master reference is empty is still refused with '
     + '`422 MISSING_REQUIRED_FIELD`. Declare `required: true` when every row must name its master; an '
     + 'omitted `required` keeps meaning '
-    + 'required through `ObjectSchema.create()` and on stored rows, and `os lint` reports it at `error` so the '
-    + 'author writes one of the two.',
+    + 'required through `ObjectSchema.create()` and on stored rows. Through a raw parse (an object written '
+    + 'directly in `defineStack`, or saved through a save door) it does not: `required` defaults to `false` '
+    + 'before the object is judged, so an omitted `required` there is read as the optional master, as the '
+    + 'maintainer ruled rather than refusing the omission at every door. `os lint` reports the omission at '
+    + '`error` so the author writes one of the two.',
   reason:
     'The rule "a rep sees the contacts of the accounts they own; a contact need not have an account" had no '
     + 'declarative form: `controlled_by_parent` refused a `master_detail` that is not required at the builder '
@@ -60,5 +67,7 @@ export const entry: SemanticMigration = {
     + '"resolves no master relation" line), a member who can read a master reads that master\'s rows, the '
     + 'owner of a row with an empty master reads that row, a holder of View All on the object reads every '
     + 'row with an empty master, and nobody else reads one. An object whose `master_detail` omits `required` '
-    + 'is still forced to `required: true` by the builder and converted to it on stored rows.',
+    + 'is still forced to `required: true` by the builder and converted to it on stored rows; through a raw '
+    + 'parse (`ObjectSchema.safeParse`, an object written directly in `defineStack`, a save door) the same '
+    + 'omission is admitted as the optional master, its field parsed as `required: false`.',
 };