@@ -0,0 +1,56 @@
+---
+'@objectstack/spec': minor
+---
+
+fix(spec)!: a flattened `view` overlay is judged by the member its `viewKind` names, so a column-less list patch has its list keys judged instead of stripped by the form member (#20186)
+
+**BREAKING** accept-set change on the `view` write door (`PUT /api/v1/meta/view/:name`, the Studio and MCP save), and on every door that parses `ViewMetadataSchema` (the assembled-manifest `viewItems:` union included). It narrows, and it widens two small classes, both declared below. It ships as `minor` under the repo's launch-window convention for breaking changes.
+
+Clause-②: yes (narrowing)
+
+## What was wrong
+
+The two flattened overlay members of `ViewMetadataSchema` shared one `viewKind: 'list' | 'form'` enum. The list member required `columns`, so it refused a column-less `viewKind: 'list'` body. The union then tried the form member, which requires no list key and `.strip()`s every one, and ACCEPTED the body. `diagnoseViewMetadata` named `formOverlay`, the parse output was `type: 'simple'` (a form), and the body's `sort`, `searchableFields` and `timeline` were never judged. Measured through the real `saveMetaItem` on `origin/main` @ `4df101c3`, and again at `ce70876e`: a retired bare-string `sort`, a `timeline.metaFields` and a non-array `searchableFields` each answered `success: true`, and the row held them as sent. The mirror held too: the list member accepted a `viewKind: 'form'` body carrying list `columns`.
+
+That column-less list body is not a malformed one. It is what the console stores on every toolbar save (sort, hidden fields, inline edit, column widths) for a code-defined list view: objectui's `persistViewPatch` stores the patch and nothing else, per the maintainer ruling 「`persistViewPatch` 只存 patch,不存 merged base」.
+
+## What it does now
+
+- **One `viewKind` per member.** The list overlay member admits `viewKind: 'list'` only; the form overlay member admits `viewKind: 'form'` only. A flattened body is judged by the member its `viewKind` names, and `diagnoseViewMetadata` names that member.
+- **The list member judges a column-less patch.** `columns` is optional on the flattened list overlay member only. The authoring `ListViewSchema` keeps it required: an authored list view is a full config, never a patch. The console's patch-only writes keep saving, stored verbatim, and a lean list patch now parses to a list (`type: 'grid'`), not to `type: 'simple'`.
+- **A column-less body that names a `type` is still refused**, now located at `columns`: a body that sets `type` is a full inline config, and a full config lists its columns. The refusal names both ways out.
+- **A field list under a form overlay's `columns` is refused** at `columns`: on a form view `columns` is the body-column count.
+- The served JSON Schema (`/api/v1/meta/types/view`) is still an `anyOf` of four members. The only movements: each overlay member's `viewKind` enum names one value, the list overlay member no longer lists `columns` as required, and in the output direction it no longer lists `type` as required (the `grid` default is still declared and still applied).
+
+## FROM → TO
+
+Each row is refused now and was accepted before, on a flattened overlay:
+
+| you wrote | write instead |
+|:--|:--|
+| `viewKind: 'list'`, no `columns`, `sort: 'name desc'` | `sort: [{ field: 'name', order: 'desc' }]` — the bare string clause was retired in 17.5.0 |
+| `viewKind: 'list'`, no `columns`, `sort: [{ field, direction: 'desc' }]` | `sort: [{ field, order: 'desc' }]` |
+| `viewKind: 'list'`, no `columns`, `timeline: { …, metaFields: [...] }` | delete `metaFields`: the timeline block has no such key |
+| `viewKind: 'list'`, no `columns`, `searchableFields: 'name'` | `searchableFields: ['name']` |
+| `viewKind: 'list'`, no `columns`, `sharing: { enabled: true, publicLink, … }` (the form public-link block) | the list `sharing` block, `sharing: { type: 'personal' \| 'collaborative', lockedBy? }`, or delete `sharing` |
+| any other list key the list view schema refuses, on a column-less list overlay | the value the list view schema accepts — the refusal names the key |
+| `viewKind: 'form'` with `columns: ['name', …]` | a field list means a list view: `viewKind: 'list'`; for a form, `sections: [{ fields: ['name', …] }]` and `columns` as a count (`columns: 2`) |
+
+**The one-line fix:** read the refusal. It is located at the key it refuses and says what that key takes.
+
+A column-less list overlay that names a `type` (`{ viewKind: 'list', type: 'kanban', … }` without `columns`) was refused before and is refused now; only its location moved, to `columns`. Add `columns`, or drop `type` to save the body as a patch.
+
+## Declared widening (why `Clause-②: yes`)
+
+Two classes of column-less, type-less `viewKind: 'list'` bodies go from refused to accepted:
+
+- **W2** — a list-legal value under a key both members declare with different schemas: `aria` (the form member carries a retirement tombstone there), an i18n `description` (the form member takes a plain string only), the list `sharing` block (the form member's is the public-link block), and a valid legacy `options` bag (the form member pins `options` absent). Measured: `{ name, object, viewKind: 'list', aria: { ariaLabel: 'Leads' } }` was refused, and is accepted. This is the change working: a list body is judged by list rules.
+- **W1** — an invalid value under one of the 19 form-only keys (`layout`, `sections`, `title`, …). Measured: `{ name, object, viewKind: 'list', isPinned: true, layout: 'diagonal' }` was refused (the form member judged `layout`), and is accepted with `layout` dropped unread. That is the list member's existing handling of a key it does not declare: a list overlay WITH `columns` and `layout: 'diagonal'` was already accepted the same way. It is a named residual, not a contract.
+
+## Census
+
+- **objectstack** @ `4df101c3` (examples, packages): no source writes a flattened `viewKind: 'list'` body without `columns` as a literal; every literal hit is a test fixture, a changelog line or a comment. `examples/**` authors views as containers (15 files with `listViews`) and carries no `viewKind` at all.
+- **objectui**, at the `.objectui-sha` pin `f8a9d0fb0` and at `main` `25c7d584e`, and **cloud** `main` `48d7066`: no source literal either. The one real producer is dynamic: objectui's `buildPersistedViewBody` returns `{ ...patch, viewKind }` for an overlay and `updateViewConfig` stamps `object`, `name` and the overlay marker. Those bodies keep saving, now judged by the list member.
+- **Production `sys_metadata` rows: NOT MEASURED.** No deployment's store is reachable from the repository. A stored row that fails keeps being read and served exactly as stored. It is refused only on its next save, and the refusal names the key.
+
+<!-- adr-0087: registered view-overlay-judged-by-viewkind-arm -->
@@ -410,3 +410,100 @@ describe('[#20051] the save door judges a flat list overlay\'s `options` bag', (
         expect((ViewMetadataSchema as any).safeParse(body).success).toBe(true);
     });
 });
+
+/**
+ * #20186 — a flattened overlay is judged by the member its `viewKind` names,
+ * pinned at the WRITE DOOR (the spec-side pins: `view-overlay-viewkind-arm.test.ts`).
+ *
+ * Before: a column-less `viewKind: 'list'` body was refused by the list member
+ * (no `columns`) and ACCEPTED by the form member, which strips every list key —
+ * so a retired `sort` string answered `success: true` and the row held it as
+ * sent. Now the list member judges the column-less PATCH (the ruled storage
+ * shape of every console toolbar save, maintainer ruling on #7494), and its
+ * invalid list keys are refused, located, with nothing stored. Same double as
+ * the blocks above, so the save runs the real repository path.
+ */
+describe('#20186 the save door judges a flattened overlay by the member its viewKind names', () => {
+    const ID = { name: 'crm_lead.all', object: 'crm_lead' } as const;
+    const LIST = { ...ID, viewKind: 'list' } as const;
+    const FORM = { ...ID, viewKind: 'form' } as const;
+
+    /** The refusal, with its envelope asserted and NO row written. */
+    async function refused(item: Record<string, unknown>): Promise<Array<{ path: string; code?: string; message: string }>> {
+        const { protocol, rows } = makeProtocol();
+        let err: any;
+        try {
+            await (protocol as any).saveMetaItem({ type: 'view', name: item.name as string, item });
+        } catch (e) { err = e; }
+        expect(err?.code).toBe('INVALID_METADATA');
+        expect(err?.status).toBe(422);
+        expect(Array.from(rows.values()).filter((r) => r.type === 'view')).toHaveLength(0);
+        return err.issues;
+    }
+    const at = (issues: Array<{ path: string; code?: string; message: string }>, path: string) => {
+        const hit = issues.find((i) => i.path === path);
+        expect(hit, `no issue at \`${path}\` in ${JSON.stringify(issues)}`).toBeDefined();
+        return hit!;
+    };
+
+    it('the headline `{ name, object, viewKind: list, sort }` saves, and the row is the body as sent', async () => {
+        const body = { ...LIST, sort: [{ field: 'name', order: 'asc' }] };
+        expect(await storedViewBody(body.name, body)).toEqual(body);
+    });
+
+    it('the objectui sort toggle (`{ ...patch, viewKind }` + object / name / _isOverride) saves verbatim', async () => {
+        const body = { sort: [{ field: 'name', order: 'desc' }], viewKind: 'list', ...ID, _isOverride: true };
+        expect(await storedViewBody(body.name, body)).toEqual(body);
+    });
+
+    it('a retired bare-string `sort`: 422 at `sort`, with the 17.5.0 retirement prescription', async () => {
+        const issue = at(await refused({ ...LIST, sort: 'name desc' }), 'sort');
+        expect(issue.code).toBe('invalid_type');
+        expect(issue.message).toContain('The bare string `sort` clause was removed from `view.sort` in @objectstack/spec 17.5.0');
+    });
+
+    it('the `timeline.metaFields` twin: 422 at `timeline`, naming the key', async () => {
+        const issue = at(await refused({ ...LIST, timeline: { startDateField: 'created', titleField: 'name', metaFields: ['region'] } }), 'timeline');
+        expect(issue.code).toBe('unrecognized_keys');
+        expect(issue.message).toContain('Unrecognized key(s) on this timeline configuration: `metaFields`.');
+    });
+
+    it('a non-array `searchableFields`: 422 at `searchableFields`', async () => {
+        expect(at(await refused({ ...LIST, searchableFields: 'name' }), 'searchableFields').code).toBe('invalid_type');
+    });
+
+    it('a form-style `sharing` on a list body: 422 at `sharing`', async () => {
+        expect(at(await refused({ ...LIST, sharing: { enabled: true } }), 'sharing').code).toBe('unrecognized_keys');
+    });
+
+    it('a column-less list overlay that names a `type`: 422 at `columns`, with the prescription', async () => {
+        const issue = at(await refused({ ...LIST, type: 'kanban', groupByField: 'stage' }), 'columns');
+        expect(issue.code).toBe('custom');
+        expect(issue.message).toMatch(/^This list view overlay sets `type` but lists no `columns`\./);
+    });
+
+    it('the mirror — list `columns` on a `viewKind: form` body: 422 at `columns`, with the count prescription', async () => {
+        const issue = at(await refused({ ...FORM, columns: ['name'] }), 'columns');
+        expect(issue.code).toBe('invalid_type');
+        expect(issue.message).toMatch(/^On a form view `columns` is the NUMBER of body columns/);
+    });
+
+    // W2 — declared widening (`Clause-②: yes (narrowing)`): a list-legal value
+    // under a key both members declare with different schemas, refused before
+    // because the FORM member judged it.
+    it.each([
+        ['aria', { aria: { ariaLabel: 'Leads' } }],
+        ['an i18n description', { description: { en: 'All leads' } }],
+        ['list-style sharing', { sharing: { type: 'personal' } }],
+    ])('W2: %s now saves verbatim', async (_label, extra) => {
+        const body = { ...LIST, ...extra };
+        expect(await storedViewBody(body.name, body)).toEqual(body);
+    });
+
+    it('controls: a real form overlay and a list overlay with `columns` save verbatim', async () => {
+        const form = { ...FORM, type: 'simple', sections: [{ label: 'Main', fields: ['name'] }] };
+        expect(await storedViewBody(form.name, form)).toEqual(form);
+        const list = { ...LIST, columns: ['name'], sort: [{ field: 'name', order: 'asc' }] };
+        expect(await storedViewBody(list.name, list)).toEqual(list);
+    });
+});
@@ -0,0 +1,46 @@
+// Copyright (c) 2026 ObjectStack. Licensed under the Apache-2.0 license.
+
+import type { SemanticMigration } from '../../types.js';
+
+// #20186, route C-prime (seat answers 5855433719 / 5855548706). A write-time
+// re-routing of the flattened view overlays: each member judges only the
+// `viewKind` it names. The stored rows it newly refuses are read and served
+// exactly as before and fail only on their next save, which is why this is a
+// semantic entry and not a conversion — which value a refused key meant is a
+// fact only its author holds.
+export const entry: SemanticMigration = {
+  id: 'view-overlay-judged-by-viewkind-arm',
+  surface:
+    'A flattened `view` overlay saved through the metadata write door (`PUT /api/v1/meta/view/:name`, the '
+    + 'Studio / MCP save) whose `viewKind` names one family while the body was judged by the other: a '
+    + 'column-less `viewKind: "list"` body, which only the form overlay member used to accept (its list keys '
+    + '`sort`, `searchableFields`, `timeline`, `sharing` and the rest stripped unread), and a `viewKind: "form"` '
+    + 'body carrying list `columns`, which only the list overlay member used to accept.',
+  replacement:
+    'Each overlay is judged by the member its `viewKind` names. A column-less list overlay is a patch on the '
+    + 'view it shadows and carries list keys the list view schema accepts: a `sort` array of `{ field, order }` '
+    + '(the bare string clause was retired in 17.5.0), no `timeline.metaFields` (the timeline block has no such '
+    + 'key), an array `searchableFields`, and the list `sharing` block (`{ type, lockedBy }`), not the form '
+    + 'public-link block. A column-less list overlay names no `type`; one that does is a full inline config and '
+    + 'lists its `columns`. A form overlay\'s `columns` is its body-column count (an integer); a field list '
+    + 'means the body is a list view (`viewKind: "list"`) or belongs in `sections: [{ fields }]`.',
+  reason:
+    'Both overlay members shared one `viewKind: list | form` enum. The list member required `columns`, so it '
+    + 'refused the column-less list patch the console writes on every toolbar save (the ruled patch-only '
+    + 'storage shape, maintainer ruling: 「`persistViewPatch` 只存 patch,不存 merged base」); the '
+    + 'union then tried the form member, which requires no list key and strips every one, and accepted it — '
+    + 'so a retired `sort` string or a `timeline.metaFields` the list schema refuses by name was saved with '
+    + '`success: true` and stored as sent. Measured on `origin/main` @ `4df101c3` and again at `ce70876e` '
+    + '(after the `options`-bag door landed) through the real save. Ruled route C-prime: each member admits one `viewKind`, the list '
+    + 'member judges a column-less patch (`columns` optional there only; the authoring list view keeps it '
+    + 'required), and a column-less body that names a `type` stays refused at `columns`. Not convertible: '
+    + 'whether a refused value was a typo or a stale capability is the author\'s call.',
+  acceptanceCriteria:
+    'Every stored flattened `view` overlay saves again unchanged. A row that does not is refused '
+    + '`422 INVALID_METADATA` on its next save, with the issue located at the refused key (`sort`, `timeline`, '
+    + '`searchableFields`, `sharing`, `columns`) and carrying that key\'s own message — for a column-less list '
+    + 'overlay naming a `type`, the prescription at `columns`; for a field list on a form overlay, the '
+    + 'body-column-count prescription at `columns`. Nothing is rewritten on read and nothing is refused on '
+    + 'read: a row that fails is served exactly as stored until it is saved. Verify by re-saving each stored '
+    + 'flattened overlay (a GET then a PUT of the same body) and reading a `200`.',
+};