@@ -177,3 +177,40 @@ describe('PackageOwdOverviewPanel — deep-link highlight', () => {
     expect(row.className).toMatch(/bg-primary/);
   });
 });
+
+describe('PackageOwdOverviewPanel — onDirtyChange contract (objectui#2600)', () => {
+  it('reports dirty transitions and resets to clean on unmount', async () => {
+    const onDirtyChange = vi.fn();
+    const { unmount } = renderPanel(freshServer(), { onDirtyChange });
+    await screen.findByTestId('owd-row-crm_contact');
+    expect(onDirtyChange).toHaveBeenLastCalledWith(false);
+
+    fireEvent.change(screen.getByTestId('owd-internal-crm_contact'), { target: { value: 'public_read' } });
+    expect(onDirtyChange).toHaveBeenLastCalledWith(true);
+
+    // Reverting the edit back to the baseline reports clean again.
+    fireEvent.change(screen.getByTestId('owd-internal-crm_contact'), { target: { value: 'private' } });
+    expect(onDirtyChange).toHaveBeenLastCalledWith(false);
+
+    // Dirty again, then unmount — a deliberately-discarded panel must clear
+    // the host's guard by itself (same contract as PermissionMatrixEditPage).
+    fireEvent.change(screen.getByTestId('owd-internal-crm_contact'), { target: { value: 'public_read' } });
+    expect(onDirtyChange).toHaveBeenLastCalledWith(true);
+    unmount();
+    expect(onDirtyChange).toHaveBeenLastCalledWith(false);
+  });
+
+  it('reports clean after a successful save (edits become the new baseline)', async () => {
+    const onDirtyChange = vi.fn();
+    const server = freshServer();
+    renderPanel(server, { onDirtyChange });
+    await screen.findByTestId('owd-row-crm_contact');
+
+    fireEvent.change(screen.getByTestId('owd-internal-crm_contact'), { target: { value: 'public_read' } });
+    expect(onDirtyChange).toHaveBeenLastCalledWith(true);
+
+    fireEvent.click(screen.getByTestId('owd-save'));
+    await waitFor(() => expect(server.saved.length).toBe(1));
+    await waitFor(() => expect(onDirtyChange).toHaveBeenLastCalledWith(false));
+  });
+});
@@ -90,6 +90,11 @@ export interface PackageOwdOverviewPanelProps {
   locale: SupportedLocale;
   /** Object to scroll to / highlight (deep-link from the permission matrix badge). */
   highlightObject?: string | null;
+  /** objectui#2600 — mirrors the unsaved-row state up to the host pillar, whose
+   * rail/header navigation unmounts this panel (SPA nav, so no beforeunload).
+   * Reports `false` on unmount so a confirmed discard clears the host's guard —
+   * same contract as PermissionMatrixEditPage's own onDirtyChange. */
+  onDirtyChange?: (dirty: boolean) => void;
 }
 
 export function PackageOwdOverviewPanel({
@@ -100,6 +105,7 @@ export function PackageOwdOverviewPanel({
   readOnly = false,
   locale,
   highlightObject,
+  onDirtyChange,
 }: PackageOwdOverviewPanelProps): React.ReactElement {
   const [rows, setRows] = React.useState<OwdRow[]>([]);
   const [edits, setEdits] = React.useState<Record<string, OwdEdit>>({});
@@ -203,6 +209,25 @@ export function PackageOwdOverviewPanel({
   const dirtyCount = rowState.filter((s) => s.dirty).length;
   const hasInvalid = rowState.some((s) => s.invalid);
 
+  // Report dirty transitions to the host (see onDirtyChange). Ref-stabilized
+  // so a non-memoized callback prop doesn't refire the effect; the unmount
+  // cleanup reports `false` so a deliberately-discarded panel clears the
+  // host's guard state.
+  const isDirty = dirtyCount > 0;
+  const onDirtyChangeRef = React.useRef(onDirtyChange);
+  React.useEffect(() => {
+    onDirtyChangeRef.current = onDirtyChange;
+  });
+  React.useEffect(() => {
+    onDirtyChangeRef.current?.(isDirty);
+  }, [isDirty]);
+  React.useEffect(
+    () => () => {
+      onDirtyChangeRef.current?.(false);
+    },
+    [],
+  );
+
   const doSave = React.useCallback(async () => {
     const changed = rowState.filter((s) => s.dirty && !s.invalid);
     if (changed.length === 0) return;
 
@@ -6,14 +6,17 @@
  * The permission matrix in the main panel is keyed by the selected set
  * (`key={current}`) and unmounts entirely when the OWD overview swaps in, so
  * before this guard existed a rail click silently REMOUNTED the matrix and
- * discarded any unsaved cell edits. The pillar now holds the editor's
- * reported dirty state (`onDirtyChange`) and gates every swap on a native
- * confirm:
+ * discarded any unsaved cell edits. The OWD overview batch-editor holds
+ * unsaved rows the same way and unmounts when a set swaps back in
+ * (objectui#2600). The pillar now holds both editors' reported dirty state
+ * (`onDirtyChange`) and gates every swap on a native confirm:
  *
  *   • dirty + switch to another set → confirm; cancel keeps the edits,
  *   • dirty + swap to the OWD overview → same confirm,
+ *   • dirty OWD rows + swap to a set / create flow → same confirm,
  *   • clean switches never prompt,
- *   • re-clicking the already-open set never prompts (nothing remounts),
+ *   • re-clicking the already-open set / overview never prompts (nothing
+ *     remounts),
  *   • a confirmed discard clears the guard (the editor resets on unmount).
  */
 
@@ -38,9 +41,7 @@ vi.mock('../metadata-admin/useMetadata', async (importOriginal) => {
 });
 
 // Rail siblings that are irrelevant to the guard — keep the render light.
-vi.mock('./PackageOwdOverviewPanel', () => ({
-  PackageOwdOverviewPanel: () => <div data-testid="owd-overview" />,
-}));
+// (The OWD overview is NOT mocked: its dirty report is under test.)
 vi.mock('../../components/SuggestedBindingsPanel', () => ({
   SuggestedBindingsPanel: () => null,
 }));
@@ -112,8 +113,10 @@ function makeClient(server: Server) {
     getDraft: async () => null,
     get: async (type: string) =>
       type === 'object' ? { fields: [{ name: 'name', label: 'Name' }] } : null,
-    save: async (_t: string, _n: string, payload: Record<string, unknown>) => {
+    save: async (_t: string, name: string, payload: Record<string, unknown>) => {
       server.saved.push(payload);
+      // Register the set so the post-create reload can list and open it.
+      server.byName[name] = payload;
       return payload;
     },
   } as any;
@@ -211,3 +214,77 @@ describe('AccessPillar — unsaved matrix edits guard', () => {
     expect(within(row).getByRole('checkbox', { name: 'a_account Read' })).not.toBeChecked();
   });
 });
+
+/** Swap the main panel to the (real) OWD overview and edit a row so the panel
+ * reports dirty. Assumes the open matrix is clean, so the swap never prompts. */
+async function openAndDirtyTheOwd() {
+  fireEvent.click(screen.getByRole('button', { name: 'Record sharing (OWD)' }));
+  await screen.findByTestId('owd-internal-a_account');
+  fireEvent.change(screen.getByTestId('owd-internal-a_account'), { target: { value: 'private' } });
+  await screen.findByTestId('owd-dirty-a_account');
+}
+
+const owdInternalValue = () =>
+  (screen.getByTestId('owd-internal-a_account') as HTMLSelectElement).value;
+
+describe('AccessPillar — unsaved OWD overview edits guard (#2600)', () => {
+  it('asks before swapping a dirty overview for a set; cancel keeps the edits', async () => {
+    await renderPillarOnSetA();
+    await openAndDirtyTheOwd();
+
+    confirmSpy.mockReturnValueOnce(false);
+    fireEvent.click(screen.getByRole('button', { name: 'Set A' }));
+    expect(confirmSpy).toHaveBeenCalledTimes(1);
+    // Still on the overview, edit intact.
+    expect(owdInternalValue()).toBe('private');
+
+    // Confirming the same swap discards and mounts the set A matrix.
+    confirmSpy.mockReturnValueOnce(true);
+    fireEvent.click(screen.getByRole('button', { name: 'Set A' }));
+    expect(confirmSpy).toHaveBeenCalledTimes(2);
+    await screen.findByDisplayValue('set_a');
+
+    // The discarded panel reset the guard on unmount — swapping back to the
+    // overview must NOT prompt, and it reloads the untouched baseline.
+    fireEvent.click(screen.getByRole('button', { name: 'Record sharing (OWD)' }));
+    expect(confirmSpy).toHaveBeenCalledTimes(2);
+    await screen.findByTestId('owd-internal-a_account');
+    expect(owdInternalValue()).toBe('');
+  });
+
+  it('never prompts when re-clicking the OWD rail entry (nothing remounts)', async () => {
+    await renderPillarOnSetA();
+    await openAndDirtyTheOwd();
+
+    fireEvent.click(screen.getByRole('button', { name: 'Record sharing (OWD)' }));
+
+    expect(confirmSpy).not.toHaveBeenCalled();
+    // Not remounted — the unsaved edit is still visible.
+    expect(owdInternalValue()).toBe('private');
+  });
+
+  it('gates the create-set flow, and creating lands on the new set matrix', async () => {
+    await renderPillarOnSetA();
+    await openAndDirtyTheOwd();
+
+    // Cancel keeps the overview (and its edits) — no dialog.
+    confirmSpy.mockReturnValueOnce(false);
+    fireEvent.click(screen.getByRole('button', { name: 'New permission set' }));
+    expect(confirmSpy).toHaveBeenCalledTimes(1);
+    expect(screen.queryByRole('dialog')).toBeNull();
+    expect(owdInternalValue()).toBe('private');
+
+    // Confirm opens the creator; submitting swaps the overview out for the
+    // new set's matrix (the discard the gate warned about).
+    confirmSpy.mockReturnValueOnce(true);
+    fireEvent.click(screen.getByRole('button', { name: 'New permission set' }));
+    const dialog = await screen.findByRole('dialog');
+    fireEvent.change(within(dialog).getByPlaceholderText('Display name (e.g. Sales permissions)'), {
+      target: { value: 'Set C' },
+    });
+    fireEvent.click(within(dialog).getByRole('button', { name: 'Create' }));
+
+    await screen.findByDisplayValue('set_c');
+    expect(screen.queryByTestId('owd-overview')).not.toBeInTheDocument();
+  });
+});
@@ -13,6 +13,8 @@
  *   • dirty + pillar switch → confirm; cancel keeps the pillar and its edits,
  *   • dirty + Home → same confirm; cancel stays, confirm leaves,
  *   • dirty + package switch → same confirm,
+ *   • dirty OWD overview rows + pillar switch → same confirm (the pillar
+ *     folds the overview's report into the same bit, objectui#2600 follow-up),
  *   • clean navigation never prompts,
  *   • re-clicking the open pillar never prompts (nothing unmounts),
  *   • a confirmed discard clears the guard (the pillar resets on unmount).
@@ -55,10 +57,8 @@ vi.mock('./packages-io', async (importOriginal) => {
   };
 });
 
-// Rail siblings / docks that are irrelevant to the guard — keep the render light.
-vi.mock('./PackageOwdOverviewPanel', () => ({
-  PackageOwdOverviewPanel: () => <div data-testid="owd-overview" />,
-}));
+// Rail siblings / docks that are irrelevant to the guard — keep the render
+// light. (The OWD overview is NOT mocked: its dirty report is under test.)
 vi.mock('../../components/SuggestedBindingsPanel', () => ({
   SuggestedBindingsPanel: () => null,
 }));
@@ -217,6 +217,32 @@ describe('Studio header — unsaved pillar edits guard (#2600)', () => {
     await screen.findByDisplayValue('set_a');
   });
 
+  it('gates a pillar switch on dirty OWD overview rows (#2600 follow-up)', async () => {
+    await renderSurfaceOnAccess();
+    // Swap the main panel to the (real) OWD overview and edit a row so the
+    // panel's dirty report crosses AccessPillar into the surface guard.
+    fireEvent.click(screen.getByRole('button', { name: 'Record sharing (OWD)' }));
+    await screen.findByTestId('owd-internal-a_account');
+    fireEvent.change(screen.getByTestId('owd-internal-a_account'), { target: { value: 'private' } });
+
+    confirmSpy.mockReturnValueOnce(false);
+    fireEvent.click(screen.getByRole('link', { name: 'Interfaces' }));
+    expect(confirmSpy).toHaveBeenCalledTimes(1);
+    // Still on the overview, edit intact.
+    expect((screen.getByTestId('owd-internal-a_account') as HTMLSelectElement).value).toBe('private');
+
+    // Confirming discards and leaves; the unmounting pillar resets the guard,
+    // so walking back to Access must NOT prompt again.
+    confirmSpy.mockReturnValueOnce(true);
+    fireEvent.click(screen.getByRole('link', { name: 'Interfaces' }));
+    expect(confirmSpy).toHaveBeenCalledTimes(2);
+    await screen.findByText('This package has no app yet');
+
+    fireEvent.click(screen.getByRole('link', { name: 'Access' }));
+    expect(confirmSpy).toHaveBeenCalledTimes(2);
+    await screen.findByDisplayValue('set_a');
+  });
+
   it('switches pillars without prompting when clean', async () => {
     await renderSurfaceOnAccess();