@@ -0,0 +1,25 @@
+---
+'@objectstack/cli': minor
+---
+
+feat(cli): `os migrate organization-ownership --apply` — the v18 organization-ownership ceremony's apply step and post-check (ADR-0131 D10, ceremony items 2 to 4)
+
+Clause-②: yes (widening)
+
+The command that planned the ceremony now performs it. Without `--apply` nothing changes: the read-only plan, written to a file. With `--apply`:
+
+- **The backup comes first.** It is the operator's act: pass `--backup-taken`, or answer yes at the prompt. A non-interactive run without the flag is refused before the database is opened.
+- **The fates run in order**, each step stopping the run where it meets a blocker:
+  1. **Attribution** — every NULL `organization_id` row the plan derives an owner for takes it (a parent, subject or holder anchor; under `single`, the Default Organization). A row with no derivable owner is never assigned one: it stays NULL and is listed by id.
+  2. **Authored catalog rows** — permission sets and positions an organization authored in Setup become environment metadata through the metadata door (under `single`; under a wall they are reported), with each position's binding rows carried into its `permissionSets`.
+  3. **The verified id→name rewrite** — every `sys_user_permission_set` grant names its set in `permission_set`, then every grant is verified to name a set the security catalog resolves. `permission_set_id` stays.
+  4. **Mirror deletion** — only after that verification, read again just before the first delete: the seeded catalog copies (per organization and NULL residue), the binding rows, seeded capabilities and seeded templates. Authored, customized and organization-stamped rows stay.
+  5. **Column drops** — `organization_id` leaves the deployment-level objects through the schema-drift ceremony (`os migrate apply`'s machinery), never a hand `ALTER`. A table whose rows still need another step keeps its column, and the run says why.
+- **Idempotent and resumable.** Every write is conditioned on the state it changes, and each finished step is checkpointed in `sys_migration` (row `adr-0131-organization-ownership`); a run interrupted mid-step resumes at that step and never re-derives an owner already written.
+- **The post-check** re-reads the plan and reports, per table, what remains. The ledger row records `applied_at` once every step has finished and `verified_at` when the post-check also reads zero discrepancies. Exit code 1 while the ceremony is unfinished or the post-check finds a discrepancy.
+- A JSON report is written beside the plan (`organization-ownership-apply-TIMESTAMP.json`, or `--out`); an existing file is never overwritten.
+
+```bash
+os migrate organization-ownership --out plan.json            # read the plan first
+os migrate organization-ownership --apply --backup-taken     # then perform it
+```
@@ -0,0 +1,68 @@
+// Copyright (c) 2026 ObjectStack. Licensed under the Apache-2.0 license.
+
+/**
+ * `os migrate organization-ownership --apply` asks about the backup before it
+ * opens the database (ADR-0131 D10 ceremony item 2): without `--backup-taken`
+ * a non-interactive run is refused, and the boot never happens. The flag means
+ * nothing without `--apply`, and is refused there too.
+ */
+
+import { afterEach, describe, expect, it, vi } from 'vitest';
+import { fileURLToPath } from 'node:url';
+
+const boot = vi.hoisted(() => vi.fn(async () => {
+  throw new Error('the database was opened');
+}));
+vi.mock('../../utils/schema-migrate.js', () => ({ bootSchemaStack: boot }));
+
+const { default: MigrateOrganizationOwnership } = await import('./organization-ownership.js');
+
+const CLI_ROOT = fileURLToPath(new URL('../../..', import.meta.url));
+
+async function runJson(argv: string[]): Promise<{ payload: Record<string, unknown>; exitCode: unknown }> {
+  const chunks: string[] = [];
+  const savedExit = process.exitCode;
+  vi.spyOn(process.stdout, 'write').mockImplementation(((chunk: unknown, ...rest: unknown[]) => {
+    chunks.push(String(chunk));
+    const cb = rest.find((a) => typeof a === 'function') as (() => void) | undefined;
+    if (cb) cb();
+    return true;
+  }) as typeof process.stdout.write);
+  vi.spyOn(process.stderr, 'write').mockImplementation((() => true) as typeof process.stderr.write);
+  try {
+    await MigrateOrganizationOwnership.run(argv, { root: CLI_ROOT });
+  } catch (error) {
+    if ((error as { oclif?: unknown }).oclif === undefined) throw error;
+  }
+  const exitCode = process.exitCode;
+  process.exitCode = savedExit;
+  vi.restoreAllMocks();
+  return { payload: JSON.parse(chunks.join('').trim()) as Record<string, unknown>, exitCode };
+}
+
+afterEach(() => {
+  boot.mockClear();
+});
+
+describe('os migrate organization-ownership --apply — the backup precondition', () => {
+  it('refuses a non-interactive --apply without --backup-taken, before the boot', async () => {
+    const { payload, exitCode } = await runJson(['--apply', '--json']);
+    expect(payload).toMatchObject({ error: 'apply_refused', reason: 'backup-unacknowledged' });
+    expect(exitCode).toBe(1);
+    expect(boot).not.toHaveBeenCalled();
+  });
+
+  it('refuses --backup-taken without --apply, before the boot', async () => {
+    const { payload, exitCode } = await runJson(['--backup-taken', '--json']);
+    expect(payload).toMatchObject({ error: 'plan_refused', reason: 'flag-without-apply' });
+    expect(exitCode).toBe(1);
+    expect(boot).not.toHaveBeenCalled();
+  });
+
+  it('with --backup-taken, goes on to the boot', async () => {
+    const { payload } = await runJson(['--apply', '--backup-taken', '--json']);
+    expect(payload).toMatchObject({ error: 'boot_failed', reason: 'boot-failed' });
+    expect(boot).toHaveBeenCalledTimes(1);
+    expect(boot.mock.calls[0]).toEqual([expect.objectContaining({ deferSchemaDdl: true, composeHostStack: true })]);
+  });
+});