diff --git a/.changeset/10530-timeline-lookup-display.md b/.changeset/10530-timeline-lookup-display.md
new file mode 100644
index 0000000000..efb36e5be4
--- /dev/null
+++ b/.changeset/10530-timeline-lookup-display.md
@@ -0,0 +1,28 @@
+---
+'@object-ui/plugin-timeline': patch
+---
+
+A timeline no longer crashes when its `titleField` or `descriptionField` names a lookup.
+
+`ObjectTimeline` copied the raw `titleField` and `descriptionField` values onto each
+item, and the renderer puts both in JSX. A lookup is a field like any other, and
+`ObjectTimeline`'s own object fetch expands every declared relation, so a
+lookup-typed title or description arrived as `{ id, name }`. React then threw
+`Objects are not valid as a React child` as soon as the rows landed, and the whole
+timeline failed to render.
+
+The item mapping now derives the title and the description once, as display
+strings, through `@object-ui/core`'s `recordDisplayValueAt`, the resolver
+`ObjectMap` uses for the same two slots:
+
+- an expanded lookup shows its display name;
+- a plain string, a number or a bare id shows as before;
+- a boolean shows as its string, where the old truthiness gate dropped `false` and
+  drew an empty line for `true`;
+- a `0` shows inside its title or description line, where it used to be painted as
+  a bare character beside it;
+- an empty or whitespace-only value, or an expanded record with no display name,
+  shows no line, and surrounding whitespace is trimmed.
+
+No schema or spec key changes. `ObjectTimeline.lookupDisplay-10530.test.tsx` pins
+each case above.
diff --git a/packages/plugin-timeline/src/ObjectTimeline.lookupDisplay-10530.test.tsx b/packages/plugin-timeline/src/ObjectTimeline.lookupDisplay-10530.test.tsx
new file mode 100644
index 0000000000..a46e0f02d3
--- /dev/null
+++ b/packages/plugin-timeline/src/ObjectTimeline.lookupDisplay-10530.test.tsx
@@ -0,0 +1,256 @@
+/**
+ * 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.
+ */
+
+/**
+ * objectui#10530 — a timeline item's `titleField` and `descriptionField`
+ * values reach the rail as display STRINGS.
+ *
+ * Either key names any field, and a lookup is a field like any other.
+ * `ObjectTimeline`'s own object fetch expands every declared relation
+ * (`buildExpandFields(objectDef?.fields)`), so a lookup-typed title or
+ * description arrives as `{ id, name }`. The item mapping used to copy that raw
+ * value onto the item, and the renderer puts both in JSX as React children, so
+ * the whole rail threw `Objects are not valid as a React child` as soon as the
+ * rows landed.
+ *
+ * The mapping now derives both once, through `@object-ui/core`'s
+ * `recordDisplayValueAt`: the resolver `ObjectMap` uses for the same two slots
+ * (objectui#10456, `ObjectMap.descriptionDisplay-10456.test.tsx`, whose shape
+ * this file mirrors). An expanded lookup reads as its display name, a bare id
+ * as itself, a number or a boolean as its string, and an empty value as no
+ * line at all.
+ *
+ * The plain-string, number and bare-id arms are the controls. Each rendered as
+ * text before the fix, so each must stay green when the fix is removed, while
+ * the expanded arms go red.
+ *
+ * `./renderer` is deliberately NOT mocked: the text is read off the real
+ * `TimelineRenderer` output, the surface a user sees. Harness as in
+ * `ObjectTimeline.metaFieldsRetired-10222.test.tsx`, plus an error boundary so
+ * the unfixed crash reads as the React error itself rather than a timeout.
+ */
+import React from 'react';
+import { render, screen, waitFor, cleanup } from '@testing-library/react';
+import { describe, it, expect, vi, afterEach } from 'vitest';
+import { ObjectTimeline } from './ObjectTimeline';
+
+vi.mock('@object-ui/react', async (importOriginal) => {
+  const actual = await (importOriginal() as Promise<Record<string, unknown>>);
+  return {
+    ...actual,
+    useDataScope: () => undefined,
+    useNavigationOverlay: () => ({
+      isOverlay: false,
+      handleClick: vi.fn(),
+      selectedRecord: null,
+      isOpen: false,
+      close: vi.fn(),
+      setIsOpen: vi.fn(),
+      mode: 'overlay',
+      view: undefined,
+    }),
+  };
+});
+
+afterEach(() => cleanup());
+
+/** Catches a render error so an arm can assert on it by name. */
+class RenderErrorBoundary extends React.Component<
+  { children: React.ReactNode },
+  { message: string | null }
+> {
+  state: { message: string | null } = { message: null };
+  static getDerivedStateFromError(error: Error) {
+    return { message: error.message };
+  }
+  render() {
+    return this.state.message !== null
+      ? <div data-testid="render-error">{this.state.message}</div>
+      : this.props.children;
+  }
+}
+
+const OBJECT = 'task';
+
+/** `account` is the lookup under test; `subject` is an ordinary text field. */
+const FIELDS = {
+  subject: { type: 'text' },
+  starts_at: { type: 'datetime' },
+  account: { type: 'lookup', reference_to: 'account' },
+};
+
+/** An expanded lookup, as a server `$expand` returns the related record. */
+const ACME = { id: 'a1', name: 'Acme' };
+
+/** One start date per row, ascending, so the rail's order is the rows' order. */
+const DATES = ['2026-01-01T09:00:00Z', '2026-01-02T09:00:00Z', '2026-01-03T09:00:00Z'];
+
+type Row = { subject?: unknown; account?: unknown };
+
+function rows(values: Row[]) {
+  return values.map((v, i) => ({ id: `t${i + 1}`, starts_at: DATES[i], ...v }));
+}
+
+/**
+ * A server double that expands `account` only when the query asks for it, and
+ * otherwise answers the bare foreign key. So the display name can reach the
+ * rail only through the component's own `$expand`.
+ */
+function makeDataSource(values: Row[]) {
+  return {
+    find: vi.fn(async (_object: string, params?: { $expand?: string[] }) => {
+      const expand = params?.$expand ?? [];
+      return {
+        data: rows(values).map((r) => {
+          const account = r.account as { id?: unknown } | undefined;
+          return expand.includes('account') || account == null || typeof account !== 'object'
+            ? r
+            : { ...r, account: account.id };
+        }),
+      };
+    }),
+    findOne: vi.fn(),
+    create: vi.fn(),
+    update: vi.fn(),
+    delete: vi.fn(),
+    getObjectSchema: vi.fn(async (name: string) => ({ name, fields: FIELDS })),
+  };
+}
+
+function mount(props: Record<string, unknown>) {
+  render(
+    <RenderErrorBoundary>
+      <ObjectTimeline {...(props as unknown as React.ComponentProps<typeof ObjectTimeline>)} />
+    </RenderErrorBoundary>,
+  );
+}
+
+/** Wait until every row drew its date, or the rail threw. */
+async function settled(count: number) {
+  await waitFor(() => {
+    if (screen.queryByTestId('render-error')) return;
+    expect(document.querySelectorAll('[data-testid="timeline-canvas"] time')).toHaveLength(count);
+  });
+}
+
+function renderError(): string | null {
+  return screen.queryByTestId('render-error')?.textContent ?? null;
+}
+
+/** The title lines (`TimelineTitle` is an `h3`), in rail order. */
+function titles(): Array<string | null> {
+  return Array.from(document.querySelectorAll('[data-testid="timeline-canvas"] h3')).map((el) => el.textContent);
+}
+
+/** The description lines (`TimelineDescription` is a `p`), in rail order. */
+function descriptions(): Array<string | null> {
+  return Array.from(document.querySelectorAll('[data-testid="timeline-canvas"] p')).map((el) => el.textContent);
+}
+
+/** The `$expand` the settled query actually asked the server for. */
+function lastExpand(dataSource: ReturnType<typeof makeDataSource>): string[] {
+  const calls = dataSource.find.mock.calls;
+  return calls[calls.length - 1]?.[1]?.$expand ?? [];
+}
+
+/** Mount over the component's own object fetch. */
+async function mountFetched(schema: Record<string, unknown>, values: Row[]) {
+  const dataSource = makeDataSource(values);
+  mount({ schema: { type: 'object-timeline', objectName: OBJECT, ...schema }, dataSource });
+  await waitFor(() => expect(dataSource.find).toHaveBeenCalled());
+  await settled(values.length);
+  return dataSource;
+}
+
+/** Mount over inline rows, which never fetch. */
+async function mountInline(schema: Record<string, unknown>, values: Row[]) {
+  mount({ schema: { type: 'object-timeline', ...schema }, data: rows(values) });
+  await settled(values.length);
+}
+
+/** The spec block: `startDateField` and `titleField` are required there. */
+const TITLE_IS_SUBJECT = { timeline: { startDateField: 'starts_at', titleField: 'subject' } };
+const DESCRIPTION_IS_ACCOUNT = { ...TITLE_IS_SUBJECT, descriptionField: 'account' };
+const TITLE_IS_ACCOUNT = { timeline: { startDateField: 'starts_at', titleField: 'account' } };
+
+describe('timeline titles and descriptions render as a display string (objectui#10530)', () => {
+  // ── THE CARD'S DEFECT, ON ITS REACH PATH ──────────────────────────────────
+  // No host rows, only `ObjectTimeline`'s own object fetch. The `$expand`
+  // assertion proves the lookup really is requested expanded on this path, and
+  // the double answers the bare id otherwise, so `Acme` can only arrive that way.
+  it("the reach path: the timeline's own fetch expands a lookup-typed description, and the rail shows its name", async () => {
+    const dataSource = await mountFetched(DESCRIPTION_IS_ACCOUNT, [{ subject: 'Ship it', account: ACME }]);
+
+    expect(lastExpand(dataSource)).toContain('account');
+    expect(renderError(), 'the rail must render, not throw').toBeNull();
+    expect(titles()).toEqual(['Ship it']);
+    expect(descriptions()).toEqual(['Acme']);
+  });
+
+  it("the reach path: the timeline's own fetch expands a lookup-typed title, and the rail shows its name", async () => {
+    const dataSource = await mountFetched(TITLE_IS_ACCOUNT, [{ account: ACME }]);
+
+    expect(lastExpand(dataSource)).toContain('account');
+    expect(renderError(), 'the rail must render, not throw').toBeNull();
+    expect(titles()).toEqual(['Acme']);
+  });
+
+  // ── THE CONTROLS ──────────────────────────────────────────────────────────
+  // A plain string, a number and an unexpanded lookup (its id, a plain string)
+  // each rendered as text before the fix and must render the same after it.
+  it('a plain string, a number and a bare id render as text in the description', async () => {
+    await mountInline(DESCRIPTION_IS_ACCOUNT, [
+      { subject: 'One', account: 'Call back Tuesday' },
+      { subject: 'Two', account: 42 },
+      { subject: 'Three', account: 'a1' },
+    ]);
+
+    expect(renderError()).toBeNull();
+    expect(titles()).toEqual(['One', 'Two', 'Three']);
+    expect(descriptions()).toEqual(['Call back Tuesday', '42', 'a1']);
+  });
+
+  it('a plain string, a number and a bare id render as text in the title', async () => {
+    await mountInline(TITLE_IS_ACCOUNT, [{ account: 'Ship it' }, { account: 42 }, { account: 'a1' }]);
+
+    expect(renderError()).toBeNull();
+    expect(titles()).toEqual(['Ship it', '42', 'a1']);
+  });
+
+  // ── THE RESOLVER'S DEFINITIONS ────────────────────────────────────────────
+  // "No value": an expanded record none of whose keys is a display name (a bare
+  // `{ id }` payload is not a name), and a whitespace-only string. Each renders
+  // no line, and neither throws; the row itself still renders by its date. The
+  // same trim is why a padded string renders without its surrounding spaces.
+  it('an expanded record with no display name, and a blank value, render no line', async () => {
+    await mountInline(DESCRIPTION_IS_ACCOUNT, [
+      { subject: 'One', account: { id: 'a1' } },
+      { subject: 'Two', account: '   ' },
+      { subject: 'Three', account: '  Padded  ' },
+    ]);
+
+    expect(renderError()).toBeNull();
+    expect(titles()).toEqual(['One', 'Two', 'Three']);
+    expect(descriptions()).toEqual(['Padded']);
+  });
+
+  // A zero and a boolean are values, not blanks, so each renders as its string
+  // inside its own line. The renderer's `description && …` gate used to paint a
+  // bare `0` beside the description element, drop `false`, and draw an empty
+  // line for `true`.
+  it('a zero or a boolean renders as its string, inside its line', async () => {
+    await mountInline(DESCRIPTION_IS_ACCOUNT, [
+      { subject: 'One', account: 0 },
+      { subject: 'Two', account: false },
+      { subject: 'Three', account: true },
+    ]);
+
+    expect(renderError()).toBeNull();
+    expect(descriptions()).toEqual(['0', 'false', 'true']);
+  });
+});
diff --git a/packages/plugin-timeline/src/ObjectTimeline.tsx b/packages/plugin-timeline/src/ObjectTimeline.tsx
index 6b21ccaf96..936c83c343 100644
--- a/packages/plugin-timeline/src/ObjectTimeline.tsx
+++ b/packages/plugin-timeline/src/ObjectTimeline.tsx
@@ -10,7 +10,7 @@ import React, { useEffect, useState, useCallback, useMemo } from 'react';
 import type { DataSource, TimelineSchema, ListViewTimelineConfig } from '@object-ui/types';
 import { useDataScope, useNavigationOverlay, useSafeFieldLabel, useSettledSchema } from '@object-ui/react';
 import { NavigationOverlay } from '@object-ui/components';
-import { extractRecords, buildExpandFields, convertSortToQueryParams, createFieldColorResolver } from '@object-ui/core';
+import { extractRecords, buildExpandFields, convertSortToQueryParams, createFieldColorResolver, recordDisplayValueAt } from '@object-ui/core';
 import { usePermissions } from '@object-ui/permissions';
 import { usePullToRefresh } from '@object-ui/mobile';
 import { z } from 'zod';
@@ -573,12 +573,23 @@ export const ObjectTimeline: React.FC<ObjectTimelineProps> = ({
         }
       }
 
+      // The title and the description are derived as display STRINGS, once,
+      // here (objectui#10530). The renderer puts both in JSX as children, and
+      // the raw field value is not text whenever `titleField` or
+      // `descriptionField` names a lookup: the object fetch above expands
+      // every declared relation, so the row carries `{ id, name }`, and React
+      // throws `Objects are not valid as a React child` for the whole rail.
+      //
+      // `recordDisplayValueAt` is the resolver `ObjectMap` uses for the same
+      // two slots (objectui#10456), so one rule answers both: an expanded
+      // lookup reads as its display name, a bare id as itself, a number or a
+      // boolean as its string, and an empty value as no line at all.
       return {
-        title: item[titleField],
+        title: recordDisplayValueAt(item, titleField),
         time: startRaw,
         startDate: startRaw,
         endDate: endRaw,
-        description: item[descField],
+        description: recordDisplayValueAt(item, descField),
         variant: item[variantField] || 'default',
         color: resolveColor(colorRaw),
         group: groupRaw,