diff --git a/ui/packages/app-shell/src/views/RecordDetailView.authoredChildWriteRefreshesParent-26890.test.tsx b/ui/packages/app-shell/src/views/RecordDetailView.authoredChildWriteRefreshesParent-26890.test.tsx
new file mode 100644
index 00000000000..d3d70218e31
--- /dev/null
+++ b/ui/packages/app-shell/src/views/RecordDetailView.authoredChildWriteRefreshesParent-26890.test.tsx
@@ -0,0 +1,351 @@
+/**
+ * ObjectUI
+ * Copyright (c) 2024-present ObjectStack Inc.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+/**
+ * objectstack#26890 — a child write through a related list the record page's
+ * AUTHOR declared refreshes the parent record's header, in place.
+ *
+ * The reported reach (HotCRM on 18.2.0, quote QTE-0007 → Related → Quote Line
+ * Items → New → Create): the line-item hook rolled the total onto the quote,
+ * the server held the new total, and the header kept the old one until a
+ * reload.
+ *
+ * objectui#12244 already re-reads the parent on a child write, but only for the
+ * children the record page DERIVES from the relationship graph
+ * (`deriveRelatedLists`). An authored record page declares its own related
+ * lists — `record:related_list` blocks and `record:reference_rail` entries —
+ * and a child it lists there need not be one the graph derives: its FK may opt
+ * out of the derived lists (`relatedList: false`), the page then being the only
+ * place that child is shown. A write to such a child reached the bus under the
+ * child's name and matched nothing, so the parent row stayed as first loaded.
+ *
+ * What this file pins, through the real page and the real MutationEvent bridge:
+ *
+ *   1. A create, an update and a delete of a child the authored page lists in a
+ *      `record:related_list` block each re-read the parent once, and the
+ *      header shows the server's recomputed total.
+ *   2. The same for a child listed only in a `record:reference_rail` entry.
+ *   3. Scope stays tight: a write to an object the page does not list and the
+ *      graph does not derive does not re-read the parent.
+ *
+ * The fake backend recomputes the rollup itself, as the server's hook does, so
+ * the figure the header shows can only have come from a fresh read of the
+ * parent.
+ */
+
+import * as React from 'react';
+import { describe, it, expect, vi, beforeAll, beforeEach, afterEach } from 'vitest';
+import { render, screen, waitFor, cleanup, act } from '@testing-library/react';
+import { MemoryRouter, Route, Routes } from 'react-router-dom';
+import { MetadataCtx, useMutationInvalidationBridge } from '@object-ui/react';
+import { RelatedCountStore } from '@object-ui/components';
+import type { DataSourceMutationEvent } from '@object-ui/types';
+
+vi.mock('@object-ui/auth', async (importOriginal) => ({
+  ...(await importOriginal<Record<string, unknown>>()),
+  useAuth: () => ({ user: { id: 'u1', name: 'Ada', image: null }, activeOrganization: null }),
+  createAuthenticatedFetch: () => vi.fn(),
+}));
+
+vi.mock('@object-ui/collaboration', async (importOriginal) => ({
+  ...(await importOriginal<Record<string, unknown>>()),
+  useRecordPresence: () => [],
+  PresenceAvatars: () => null,
+}));
+
+vi.mock('sonner', () => ({
+  toast: Object.assign(vi.fn(), {
+    success: vi.fn(),
+    error: vi.fn(),
+    info: vi.fn(),
+    warning: vi.fn(),
+    loading: vi.fn(),
+    dismiss: vi.fn(),
+  }),
+}));
+
+// Orthogonal chrome — same posture as RecordDetailView.childWriteRefreshesParent-12244.
+vi.mock('./ActionConfirmDialog', () => ({ ActionConfirmDialog: () => null }));
+vi.mock('./ActionParamDialog', () => ({ ActionParamDialog: () => null }));
+vi.mock('./ActionResultDialog', () => ({ ActionResultDialog: () => null }));
+vi.mock('./FlowRunner', () => ({ FlowRunner: () => null }));
+vi.mock('./MetadataInspector', () => ({
+  MetadataPanel: () => null,
+  useMetadataInspector: () => ({ showDebug: false, toggle: () => {} }),
+}));
+
+import { RecordDetailView } from './RecordDetailView';
+
+beforeAll(() => {
+  Object.defineProperty(window, 'innerWidth', { configurable: true, value: 1280 });
+});
+
+const APP = 'crm';
+const PARENT = 'os_26890_quote';
+/** Listed in a `record:related_list` block; its FK opts out of the derived lists. */
+const LINE = 'os_26890_quote_line';
+/** Listed only in the rail; its FK opts out of the derived lists too. */
+const NOTE = 'os_26890_quote_note';
+/** Points at the parent with `relatedList: false` and appears nowhere on the page. */
+const AUDIT = 'os_26890_quote_audit';
+const RECORD_ID = 'q-7';
+
+const parentObject = {
+  name: PARENT,
+  label: 'Quote',
+  fields: {
+    id: { type: 'text', label: 'Id' },
+    name: { type: 'text', label: 'Name' },
+    total_price: { type: 'number', label: 'Total' },
+  },
+};
+
+const childOf = (name: string, label: string) => ({
+  name,
+  label,
+  fields: {
+    id: { type: 'text', label: 'Id' },
+    name: { type: 'text', label: 'Name' },
+    quantity: { type: 'number', label: 'Quantity' },
+    unit_price: { type: 'number', label: 'Unit Price' },
+    quote: { type: 'master_detail', reference: PARENT, label: 'Quote', relatedList: false },
+  },
+});
+
+const OBJECTS = [parentObject, childOf(LINE, 'Quote Line'), childOf(NOTE, 'Quote Note'), childOf(AUDIT, 'Quote Audit')];
+
+/** The quote's authored record page, reduced to the blocks this card is about. */
+const RECORD_PAGE = {
+  name: 'os_26890_quote_detail',
+  label: 'Quote',
+  type: 'record',
+  object: PARENT,
+  kind: 'full',
+  template: 'default',
+  isDefault: true,
+  regions: [
+    {
+      name: 'main',
+      width: 'large',
+      components: [
+        { type: 'page:header', properties: { title: '{name}' } },
+        { type: 'record:details', properties: { sections: [{ name: 'o', label: 'Overview', fields: ['total_price'] }] } },
+        {
+          type: 'record:related_list',
+          id: 'quote_lines',
+          properties: { objectName: LINE, relationshipField: 'quote', columns: ['name', 'quantity'], limit: 10 },
+        },
+      ],
+    },
+    {
+      name: 'aside',
+      width: 'small',
+      components: [
+        {
+          type: 'record:reference_rail',
+          id: 'quote_rail',
+          properties: { entries: [{ objectName: NOTE, relationshipField: 'quote', limit: 3 }] },
+        },
+      ],
+    },
+  ],
+};
+
+/**
+ * A backend that owns the rollup: every write to a line recomputes the
+ * parent's `total_price` server-side; the client only learns the new figure by
+ * reading the parent again. Writes are announced through `onMutation`, the
+ * event the console's MutationEvent bridge fans out onto the bus — the create
+ * the record-form overlay makes included.
+ */
+function makeBackend() {
+  const lines = [
+    { id: 'l-1', name: 'Seat licence', quantity: 3, unit_price: 2000, quote: RECORD_ID },
+    { id: 'l-2', name: 'Onboarding', quantity: 1, unit_price: 3000, quote: RECORD_ID },
+  ];
+  const rollup = () => lines.reduce((sum, l) => sum + l.quantity * l.unit_price, 0);
+  const listeners = new Set<(e: DataSourceMutationEvent) => void>();
+  const emit = (e: DataSourceMutationEvent) => {
+    for (const l of Array.from(listeners)) l(e);
+  };
+  const ds = {
+    find: vi.fn(async (objectName: string) => {
+      if (objectName !== LINE) return { data: [], total: 0 };
+      return { data: lines.map((l) => ({ ...l })), total: lines.length };
+    }),
+    findOne: vi.fn(async (objectName: string, id: string) => {
+      if (objectName !== PARENT || id !== RECORD_ID) return null;
+      return { id: RECORD_ID, name: 'QTE-0007', total_price: rollup() };
+    }),
+    create: vi.fn(async (objectName: string, row: { name: string; quantity: number; unit_price: number }) => {
+      const created = { id: `l-${lines.length + 1}`, quote: RECORD_ID, ...row };
+      if (objectName === LINE) lines.push(created);
+      // The adapter's create event names the resource, not the id.
+      emit({ type: 'create', resource: objectName, record: created });
+      return created;
+    }),
+    update: vi.fn(async (objectName: string, id: string, patch: { quantity?: number }) => {
+      if (objectName === LINE) {
+        const line = lines.find((l) => l.id === id);
+        if (line) Object.assign(line, patch);
+      }
+      emit({ type: 'update', resource: objectName, id });
+      return { id, ...patch };
+    }),
+    delete: vi.fn(async (objectName: string, id: string) => {
+      if (objectName === LINE) {
+        const at = lines.findIndex((l) => l.id === id);
+        if (at >= 0) lines.splice(at, 1);
+      }
+      emit({ type: 'delete', resource: objectName, id });
+      return true;
+    }),
+    onMutation: (cb: (e: DataSourceMutationEvent) => void) => {
+      listeners.add(cb);
+      return () => listeners.delete(cb);
+    },
+  };
+  return { ds, rollup };
+}
+
+type FakeDataSource = ReturnType<typeof makeBackend>['ds'];
+
+/** The console mounts the MutationEvent bridge once, in `AppContent`. */
+function ConsoleHost({ dataSource, children }: { dataSource: unknown; children: React.ReactNode }) {
+  useMutationInvalidationBridge(dataSource);
+  return <>{children}</>;
+}
+
+function renderPage(ds: FakeDataSource) {
+  const metadata = {
+    objects: OBJECTS,
+    pages: [RECORD_PAGE],
+    loading: false,
+    error: null,
+    refresh: async () => {},
+    invalidate: () => {},
+    ensureType: async () => [],
+    getItem: async () => null,
+    getItemsByType: () => [],
+  } as unknown as React.ContextType<typeof MetadataCtx>;
+  return render(
+    <MemoryRouter initialEntries={[`/apps/${APP}/${PARENT}/record/${RECORD_ID}`]}>
+      <MetadataCtx.Provider value={metadata}>
+        <ConsoleHost dataSource={ds}>
+          <Routes>
+            <Route
+              path="/apps/:appName/:objectName/record/:recordId"
+              element={<RecordDetailView dataSource={ds} objects={OBJECTS} onEdit={() => {}} />}
+            />
+          </Routes>
+        </ConsoleHost>
+      </MetadataCtx.Provider>
+    </MemoryRouter>,
+  );
+}
+
+/** Reads of the PARENT record — the read every header block draws from. */
+const parentReads = (ds: FakeDataSource) =>
+  ds.findOne.mock.calls.filter(([objectName, id]) => objectName === PARENT && id === RECORD_ID).length;
+
+/** Is `figure` (e.g. 9000) on screen, in any grouping the number formatter picks? */
+const figureShown = (figure: number) => {
+  const text = document.body.textContent ?? '';
+  return text.includes(String(figure)) || text.includes(figure.toLocaleString('en-US'));
+};
+
+/** Let any refetch a change could have scheduled land before reading. */
+const settle = () => act(async () => {
+  await new Promise((r) => setTimeout(r, 50));
+});
+
+async function settledPage() {
+  const backend = makeBackend();
+  renderPage(backend.ds);
+  await waitFor(() => expect(parentReads(backend.ds)).toBe(1));
+  await screen.findByText('Seat licence');
+  await waitFor(() => expect(figureShown(backend.rollup())).toBe(true));
+  return backend;
+}
+
+beforeEach(() => {
+  cleanup();
+  RelatedCountStore._reset();
+  vi.stubGlobal(
+    'fetch',
+    vi.fn(async () =>
+      new Response(JSON.stringify({ data: [] }), {
+        status: 200,
+        headers: { 'content-type': 'application/json' },
+      }),
+    ),
+  );
+});
+
+afterEach(() => {
+  vi.unstubAllGlobals();
+  vi.restoreAllMocks();
+});
+
+describe('RecordDetailView — a child write through an AUTHORED related list refreshes the parent (objectstack#26890)', () => {
+  it('a create of a line the authored related list shows re-reads the parent once and shows the recomputed total', async () => {
+    const { ds, rollup } = await settledPage();
+    expect(rollup()).toBe(9000);
+    const headerBefore = document.querySelector('header');
+
+    await act(async () => {
+      await ds.create(LINE, { name: 'Training', quantity: 2, unit_price: 2700 });
+    });
+
+    expect(rollup()).toBe(14400);
+    await waitFor(() => expect(parentReads(ds)).toBe(2));
+    await waitFor(() => expect(figureShown(14400)).toBe(true));
+    expect(figureShown(9000)).toBe(false);
+    await settle();
+    expect(parentReads(ds)).toBe(2);
+    // In place: the same header node.
+    expect(document.querySelector('header')).toBe(headerBefore);
+  });
+
+  it('an update and a delete of such a line each re-read the parent', async () => {
+    const { ds } = await settledPage();
+
+    await act(async () => {
+      await ds.update(LINE, 'l-2', { quantity: 2 });
+    });
+    await waitFor(() => expect(parentReads(ds)).toBe(2));
+    await waitFor(() => expect(figureShown(12000)).toBe(true));
+
+    await act(async () => {
+      await ds.delete(LINE, 'l-1');
+    });
+    await waitFor(() => expect(parentReads(ds)).toBe(3));
+    await waitFor(() => expect(figureShown(6000)).toBe(true));
+  });
+
+  it('a write to a child the page lists only in its reference rail re-reads the parent', async () => {
+    const { ds } = await settledPage();
+
+    await act(async () => {
+      await ds.create(NOTE, { name: 'Discount approved', quantity: 0, unit_price: 0 });
+    });
+
+    await waitFor(() => expect(parentReads(ds)).toBe(2));
+  });
+
+  it('a write to a child the page does not list and the graph does not derive does not re-read the parent', async () => {
+    const { ds } = await settledPage();
+
+    await act(async () => {
+      await ds.create(AUDIT, { name: 'Viewed', quantity: 0, unit_price: 0 });
+    });
+    await settle();
+
+    expect(parentReads(ds)).toBe(1);
+  });
+});
diff --git a/ui/packages/app-shell/src/views/RecordDetailView.tsx b/ui/packages/app-shell/src/views/RecordDetailView.tsx
index 2db4cf58cd1..5ae368d9288 100644
--- a/ui/packages/app-shell/src/views/RecordDetailView.tsx
+++ b/ui/packages/app-shell/src/views/RecordDetailView.tsx
@@ -25,6 +25,7 @@ import { SkeletonDetail } from '../skeletons/index.js';
 import { ManagedByBadge, useManagedByNote } from '../components/ManagedByBadge.js';
 import { isSetupAppSegment } from '../console/setupApp.js';
 import { deriveRelatedLists } from '../utils/deriveRelatedLists.js';
+import { recordPageChildObjects } from './recordPageChildObjects.js';
 import { stripDiscussionNodes, hasExplicitAttachments, hasExplicitApprovals } from '../utils/pageSchemaIntrospect.js';
 import { ActionConfirmDialog, type ConfirmDialogState } from './ActionConfirmDialog.js';
 import { ActionParamDialog, type ParamDialogState } from './ActionParamDialog.js';
@@ -1850,13 +1851,19 @@ export function RecordDetailView({ dataSource, objects, onEdit, objectNameOverri
   // knows what it depends on. That covers every child-write path at one seam,
   // and costs one parent read per change, however many lists are mounted.
   //
-  // The children are the page's derived related lists, keyed by CONTENT
-  // (AGENTS.md #10 — `childRelations` is a memo). A change both subscriptions
+  // The children are the page's derived related lists, plus the ones its
+  // author lists on it (objectstack#26890): an authored page's
+  // `record:related_list` blocks and `record:reference_rail` entries may name a
+  // child the graph does not derive — its FK opted out with `relatedList:
+  // false`, the page being the only place it is shown — and a create through
+  // that list left the header's total stale. Keyed by CONTENT (AGENTS.md #10 —
+  // `childRelations` and the page are memos). A change both subscriptions
   // match — a `'*'`, or this record when the object references itself — bumps
   // both nonces from one dispatch; React batches the two updates into one
   // render, so the row is still read once.
+  const authoredChildObjects = useMemo(() => recordPageChildObjects(effectivePage), [effectivePage]);
   const relatedChildObjectsKey = JSON.stringify(
-    Array.from(new Set(childRelations.map((r) => r.childObject))).sort(),
+    Array.from(new Set([...childRelations.map((r) => r.childObject), ...authoredChildObjects])).sort(),
   );
   useEffect(() => {
     const childObjects = JSON.parse(relatedChildObjectsKey) as string[];
diff --git a/ui/packages/app-shell/src/views/recordPageChildObjects.test.ts b/ui/packages/app-shell/src/views/recordPageChildObjects.test.ts
new file mode 100644
index 00000000000..8b8c406863e
--- /dev/null
+++ b/ui/packages/app-shell/src/views/recordPageChildObjects.test.ts
@@ -0,0 +1,85 @@
+/**
+ * ObjectUI
+ * Copyright (c) 2024-present ObjectStack Inc.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+/**
+ * objectstack#26890 — which child objects an authored record page lists. The
+ * page-level behaviour (a write to one re-reads the parent) is pinned in
+ * `RecordDetailView.authoredChildWriteRefreshesParent-26890.test.tsx`; this
+ * file pins the arms the walk reads and the ones it must not.
+ */
+
+import { describe, it, expect } from 'vitest';
+import { recordPageChildObjects } from './recordPageChildObjects';
+
+describe('recordPageChildObjects (objectstack#26890)', () => {
+  it('names every related list and rail entry at any depth, sorted and once', () => {
+    const page = {
+      type: 'record',
+      object: 'quote',
+      regions: [
+        {
+          name: 'main',
+          components: [
+            {
+              type: 'page:tabs',
+              properties: {
+                items: [
+                  {
+                    value: 'related',
+                    children: [
+                      { type: 'record:related_list', properties: { objectName: 'quote_line', relationshipField: 'quote' } },
+                      // The element data-source binding the block's gate maps onto `objectName`.
+                      { type: 'record:related_list', dataSource: { object: 'quote_term' }, properties: { relationshipField: 'quote' } },
+                    ],
+                  },
+                ],
+              },
+            },
+          ],
+        },
+        {
+          name: 'aside',
+          components: [
+            {
+              type: 'record:reference_rail',
+              properties: {
+                entries: [
+                  { objectName: 'quote_note', relationshipField: 'quote' },
+                  { objectName: 'quote_line', relationshipField: 'quote' },
+                ],
+              },
+            },
+          ],
+        },
+      ],
+    };
+
+    expect(recordPageChildObjects(page)).toEqual(['quote_line', 'quote_note', 'quote_term']);
+  });
+
+  it('does not name the objects other blocks bind, or a non-string value', () => {
+    const page = {
+      type: 'record',
+      object: 'quote',
+      regions: [
+        {
+          name: 'main',
+          components: [
+            { type: 'element:chart', dataSource: { object: 'opportunity' } },
+            { type: 'record:line_items', properties: { childObject: 'quote_line', parentObject: 'quote' } },
+            { type: 'record:related_list', properties: { objectName: { $expr: 'child' } } },
+            { type: 'record:reference_rail', properties: { entries: [{ objectName: 7 }] } },
+          ],
+        },
+      ],
+    };
+
+    expect(recordPageChildObjects(page)).toEqual([]);
+    expect(recordPageChildObjects(null)).toEqual([]);
+  });
+});
diff --git a/ui/packages/app-shell/src/views/recordPageChildObjects.ts b/ui/packages/app-shell/src/views/recordPageChildObjects.ts
new file mode 100644
index 00000000000..1aa8d64263c
--- /dev/null
+++ b/ui/packages/app-shell/src/views/recordPageChildObjects.ts
@@ -0,0 +1,54 @@
+/**
+ * ObjectUI
+ * Copyright (c) 2024-present ObjectStack Inc.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+/**
+ * The child objects a record page's AUTHOR lists on it (objectstack#26890).
+ *
+ * `RecordDetailView` re-reads its record when one of its related children is
+ * written (objectui#12244), so a rollup the server recomputes from the children
+ * reaches the header. The children it watched were only the ones the
+ * relationship graph derives (`deriveRelatedLists`). An authored page declares
+ * its own lists, and a child it lists need not be derived: its FK may opt out
+ * of the derived lists (`relatedList: false`), the page then being the only
+ * place that child is shown. This names those children, from the page itself:
+ *
+ *  - every `record:related_list` block's object — `properties.objectName`, or
+ *    the node's own `dataSource.object` binding, which the block's element
+ *    data-source gate maps onto `objectName`;
+ *  - every `record:reference_rail` entry's `objectName`.
+ *
+ * At any depth of the page's regions, tabs and containers. Only a string names
+ * an object. Sorted and deduplicated, so the caller can key on the content.
+ */
+export function recordPageChildObjects(page: unknown): string[] {
+  const out = new Set<string>();
+  const add = (value: unknown) => {
+    if (typeof value === 'string' && value) out.add(value);
+  };
+  const walk = (node: unknown) => {
+    if (Array.isArray(node)) {
+      for (const item of node) walk(item);
+      return;
+    }
+    if (!isRecord(node)) return;
+    const props = isRecord(node.properties) ? node.properties : undefined;
+    if (node.type === 'record:related_list') {
+      add(props?.objectName);
+      if (isRecord(node.dataSource)) add(node.dataSource.object);
+    } else if (node.type === 'record:reference_rail' && Array.isArray(props?.entries)) {
+      for (const entry of props.entries) if (isRecord(entry)) add(entry.objectName);
+    }
+    for (const child of Object.values(node)) walk(child);
+  };
+  walk(page);
+  return [...out].sort();
+}
+
+function isRecord(value: unknown): value is Record<string, unknown> {
+  return !!value && typeof value === 'object' && !Array.isArray(value);
+}