@@ -0,0 +1,17 @@
+---
+'@objectstack/spec': minor
+'@objectstack/objectql': minor
+'@objectstack/platform-objects': minor
+'@objectstack/cli': minor
+'@objectstack/plugin-audit': minor
+---
+
+Clause-②: yes (widening) — `PLATFORM_OBJECTS_BY_PACKAGE['platform-objects']` (and so `PLATFORM_PROVIDED_OBJECT_NAMES` / `isPlatformProvidedObjectName`) lists one more real platform object, `sys_lifecycle_state`. Its readers resolve references against the roster and none refuses an author declaration, so a stack that references the object now resolves it instead of drawing the unknown-platform-name advisory; nothing that was accepted is refused.
+Metadata-protocol: added
+Skills-docs: none — `skills/**` and `content/docs/**` enumerate no platform object roster and teach nothing about the lifecycle sweep's schedule; the object is internal clock state with no data API, so there is nothing for an author to write against it.
+
+The lifecycle sweep remembers when it last completed, so a kernel that reboots onto an existing datastore no longer re-sweeps within a minute of every boot.
+
+`LifecycleService` now keeps a watermark in a new engine-owned, tenant-less object, `sys_lifecycle_state` (declared and registered by `@objectstack/platform-objects`, one row per datastore, id `lifecycle`). At the initial delay the scheduler reads that one row: when the last completed sweep is younger than the sweep interval, the first sweep waits for the interval and the read is the only statement issued. An older or missing watermark, a kernel without the object, or a read that fails (logged at `warn`) sweeps at the initial delay as before. Every sweep that completes with no policy error and a finished reference audit advances the row; a failed or partial sweep leaves it alone. A datastore the process created from empty still defers its first sweep one interval, and now seeds the row. A direct `sweep()` call still always sweeps.
+
+The row is internal state, not a setting: no settings key, no environment variable, no audit row per sweep and no data API (`apiEnabled: false`). `@objectstack/plugin-audit` leaves `sys_lifecycle_state` out of `sys_audit_log` and `sys_activity`, so a sweep writes no ledger row for its own clock. `OS_LIFECYCLE_DISABLED=1` still arms nothing. `os migrate organization-ownership` inventories the new table as deployment-level state with no organization column.
@@ -759,6 +759,14 @@ export const ORGANIZATION_OWNERSHIP_INVENTORY: readonly InventoryEntry[] = [
       `${CENSUS_MAIN}: systemFields.tenant: false; ${D7}: the environment's trusted plugin-publisher keys, ` +
       'read by key id under the system context, never by organization',
   },
+  {
+    object: 'sys_lifecycle_state',
+    census: PMAIN,
+    fate: 'column-drop',
+    citation:
+      `${CENSUS_MAIN}: systemFields.tenant: false; ${D7}: the lifecycle sweeper's clock state, one row per ` +
+      'datastore, written by the sweep under the system context, never by organization',
+  },
   { object: 'sys_scim_connection_credential', census: P1, fate: 'attribution', citation: `${D3_ORG_ROWS}; ${D10_SINGLE}`, anchors: [] },
   {
     object: 'sys_flow_credential',
 
@@ -2638,6 +2638,277 @@ describe('LifecycleService timers', () => {
   });
 });
 
+/**
+ * [#29918] The sweep's watermark: one engine-owned row (`sys_lifecycle_state`,
+ * id `lifecycle`) holding when the scheduled sweep last completed, so a kernel
+ * that reboots onto an existing store reads one row at the initial delay
+ * instead of re-sweeping. Every door the sweep can reach is counted, so "only
+ * the read" is a statement count, not an inference.
+ */
+describe('LifecycleService sweep watermark (#29918)', () => {
+  const INTERVAL = 5_000;
+  const DELAY = 1_000;
+
+  function watermarkEngine(opts: {
+    row?: Record<string, unknown> | null;
+    fresh?: boolean;
+    registered?: boolean;
+    findOneImpl?: () => Promise<Record<string, unknown> | null>;
+    deleteImpl?: (object: string, options: any) => any;
+    auditImpl?: () => Promise<unknown>;
+  } = {}) {
+    const captured = captureEngine(
+      [{ name: 'sys_job_run', lifecycle: { class: 'telemetry', retention: { maxAge: '30d' } } }],
+      { deleteImpl: opts.deleteImpl },
+    );
+    const { engine } = captured;
+    const reads: Array<{ object: string; where: unknown; context: unknown }> = [];
+    const inserts: Array<{ object: string; data: Record<string, unknown>; context: unknown }> = [];
+    const updates: Array<{ object: string; data: Record<string, unknown>; context: unknown }> = [];
+    const audits: unknown[] = [];
+    const settingsReads: string[] = [];
+    let stored: Record<string, unknown> | null = opts.row ?? null;
+    engine.registry.getObject = (name: string) =>
+      name === 'sys_lifecycle_state' && opts.registered !== false ? { name } : undefined;
+    engine.wasDatastoreCreatedFromEmpty = () => opts.fresh === true;
+    engine.findOne = async (object: string, options: any) => {
+      reads.push({ object, where: options?.where, context: options?.context });
+      return opts.findOneImpl ? opts.findOneImpl() : stored;
+    };
+    engine.insert = async (object: string, data: any, options: any) => {
+      inserts.push({ object, data, context: options?.context });
+      stored = { ...data };
+      return data;
+    };
+    engine.update = async (object: string, data: any, options: any) => {
+      updates.push({ object, data, context: options?.context });
+      stored = { ...(stored ?? {}), ...data };
+      return data;
+    };
+    engine.inspectDanglingReferences = async (options: unknown) => {
+      audits.push(options);
+      if (opts.auditImpl) return opts.auditImpl();
+      return { findings: [], scannedObjects: [], unreadableObjects: [] };
+    };
+    const getSettings = () => ({
+      async get(namespace: string, key: string) {
+        settingsReads.push(`${namespace}.${key}`);
+        return { value: undefined };
+      },
+    });
+    /** Every statement the sweep (and the watermark) could issue, by door. */
+    const statements = () =>
+      captured.deletes.length + reads.length + inserts.length + updates.length + audits.length + settingsReads.length;
+    return { ...captured, reads, inserts, updates, audits, settingsReads, getSettings, statements, row: () => stored };
+  }
+
+  const iso = (ms: number) => new Date(ms).toISOString();
+
+  async function bootAndReachInitialDelay(
+    harness: ReturnType<typeof watermarkEngine>,
+    extra: Partial<ConstructorParameters<typeof LifecycleService>[0]> = {},
+  ) {
+    const svc = service(harness.engine, {
+      initialDelayMs: DELAY,
+      sweepIntervalMs: INTERVAL,
+      getSettings: harness.getSettings,
+      ...extra,
+    });
+    svc.start();
+    await vi.advanceTimersByTimeAsync(DELAY);
+    return svc;
+  }
+
+  it('a reboot whose watermark is younger than the interval issues only the watermark read at the initial delay', async () => {
+    vi.useFakeTimers();
+    try {
+      const harness = watermarkEngine({ row: { id: 'lifecycle', last_swept_at: iso(FIXED_NOW - (INTERVAL - 1)) } });
+      const svc = await bootAndReachInitialDelay(harness);
+
+      expect(harness.reads).toEqual([
+        { object: 'sys_lifecycle_state', where: { id: 'lifecycle' }, context: expect.objectContaining({ isSystem: true }) },
+      ]);
+      // Zero statements beyond the read: no reap, no settings, no audit, no write.
+      expect(harness.statements()).toBe(1);
+      expect(harness.deletes).toHaveLength(0);
+
+      // The next sweep is due on the interval, and it advances the watermark.
+      await vi.advanceTimersByTimeAsync(INTERVAL);
+      expect(harness.deletes).toHaveLength(1);
+      expect(harness.audits).toHaveLength(1);
+      expect(harness.updates).toEqual([
+        {
+          object: 'sys_lifecycle_state',
+          data: expect.objectContaining({ id: 'lifecycle', last_swept_at: iso(FIXED_NOW) }),
+          context: expect.objectContaining({ isSystem: true }),
+        },
+      ]);
+      expect(harness.inserts).toHaveLength(0);
+      svc.stop();
+    } finally {
+      vi.useRealTimers();
+    }
+  });
+
+  it('a watermark one interval old or older sweeps at the initial delay and advances it', async () => {
+    vi.useFakeTimers();
+    try {
+      for (const age of [INTERVAL, INTERVAL * 10]) {
+        const harness = watermarkEngine({ row: { id: 'lifecycle', last_swept_at: iso(FIXED_NOW - age) } });
+        const svc = await bootAndReachInitialDelay(harness);
+        expect(harness.deletes).toHaveLength(1);
+        expect(harness.audits).toHaveLength(1);
+        // The boot read said the row exists, so the advance is one update, no second read.
+        expect(harness.reads).toHaveLength(1);
+        expect(harness.inserts).toHaveLength(0);
+        expect(harness.updates).toHaveLength(1);
+        expect(harness.row()).toMatchObject({ id: 'lifecycle', last_swept_at: iso(FIXED_NOW) });
+        svc.stop();
+      }
+    } finally {
+      vi.useRealTimers();
+    }
+  });
+
+  it('no watermark row on an existing store sweeps at the initial delay and writes it', async () => {
+    vi.useFakeTimers();
+    try {
+      const harness = watermarkEngine({ row: null });
+      const svc = await bootAndReachInitialDelay(harness);
+      expect(harness.deletes).toHaveLength(1);
+      expect(harness.audits).toHaveLength(1);
+      expect(harness.reads).toHaveLength(1);
+      expect(harness.updates).toHaveLength(0);
+      expect(harness.inserts).toEqual([
+        {
+          object: 'sys_lifecycle_state',
+          data: expect.objectContaining({ id: 'lifecycle', last_swept_at: iso(FIXED_NOW) }),
+          context: expect.objectContaining({ isSystem: true }),
+        },
+      ]);
+      svc.stop();
+    } finally {
+      vi.useRealTimers();
+    }
+  });
+
+  it('a store this boot created still defers the first sweep, seeds the watermark without reading it, and sweeps one interval later', async () => {
+    vi.useFakeTimers();
+    try {
+      const harness = watermarkEngine({ fresh: true });
+      const svc = await bootAndReachInitialDelay(harness);
+      expect(harness.deletes).toHaveLength(0);
+      expect(harness.audits).toHaveLength(0);
+      expect(harness.settingsReads).toEqual([]);
+      expect(harness.reads).toHaveLength(0);
+      expect(harness.inserts).toEqual([
+        {
+          object: 'sys_lifecycle_state',
+          data: expect.objectContaining({ id: 'lifecycle', last_swept_at: iso(FIXED_NOW) }),
+          context: expect.objectContaining({ isSystem: true }),
+        },
+      ]);
+
+      await vi.advanceTimersByTimeAsync(INTERVAL);
+      expect(harness.deletes).toHaveLength(1);
+      expect(harness.updates).toHaveLength(1);
+      svc.stop();
+    } finally {
+      vi.useRealTimers();
+    }
+  });
+
+  it('a sweep that fails a policy, or whose audit throws, leaves the watermark unchanged', async () => {
+    const before = { id: 'lifecycle', last_swept_at: iso(FIXED_NOW - INTERVAL * 10) };
+    const reapFails = watermarkEngine({
+      row: { ...before },
+      deleteImpl: () => {
+        throw new Error('driver refused the delete');
+      },
+    });
+    const failed = await service(reapFails.engine, { sweepIntervalMs: INTERVAL }).sweep();
+    expect(failed.errors.length).toBeGreaterThan(0);
+    expect(reapFails.inserts).toHaveLength(0);
+    expect(reapFails.updates).toHaveLength(0);
+    expect(reapFails.row()).toEqual(before);
+
+    const auditFails = watermarkEngine({
+      row: { ...before },
+      auditImpl: async () => {
+        throw new Error('audit could not read');
+      },
+    });
+    const partial = await service(auditFails.engine, { sweepIntervalMs: INTERVAL }).sweep();
+    expect(partial.errors).toEqual([]);
+    expect(auditFails.deletes).toHaveLength(1);
+    expect(auditFails.inserts).toHaveLength(0);
+    expect(auditFails.updates).toHaveLength(0);
+    expect(auditFails.row()).toEqual(before);
+  });
+
+  it('a watermark read that fails sweeps at the initial delay and says so at warn', async () => {
+    vi.useFakeTimers();
+    try {
+      const warns: string[] = [];
+      const harness = watermarkEngine({
+        findOneImpl: async () => {
+          throw new Error('connection refused');
+        },
+      });
+      const svc = await bootAndReachInitialDelay(harness, {
+        logger: { info: () => {}, warn: (m: string) => warns.push(m), debug: () => {} },
+      });
+      expect(harness.deletes).toHaveLength(1);
+      expect(harness.audits).toHaveLength(1);
+      expect(warns.filter((m) => m.includes('watermark could not be read'))).toHaveLength(1);
+      svc.stop();
+    } finally {
+      vi.useRealTimers();
+    }
+  });
+
+  it('an engine that does not register sys_lifecycle_state is never asked for it, and sweeps at the initial delay', async () => {
+    vi.useFakeTimers();
+    try {
+      const harness = watermarkEngine({ registered: false, row: { id: 'lifecycle', last_swept_at: iso(FIXED_NOW) } });
+      const svc = await bootAndReachInitialDelay(harness);
+      expect(harness.deletes).toHaveLength(1);
+      expect(harness.reads).toHaveLength(0);
+      expect(harness.inserts).toHaveLength(0);
+      expect(harness.updates).toHaveLength(0);
+      svc.stop();
+    } finally {
+      vi.useRealTimers();
+    }
+  });
+
+  it('a direct sweep() sweeps whatever the watermark says, and advances it', async () => {
+    const harness = watermarkEngine({ row: { id: 'lifecycle', last_swept_at: iso(FIXED_NOW) } });
+    await service(harness.engine, { sweepIntervalMs: INTERVAL }).sweep();
+    expect(harness.deletes).toHaveLength(1);
+    expect(harness.audits).toHaveLength(1);
+    // Unknown presence on a direct call: one read to decide, then the update.
+    expect(harness.reads).toHaveLength(1);
+    expect(harness.updates).toHaveLength(1);
+  });
+
+  it('OS_LIFECYCLE_DISABLED still arms nothing: no watermark read, no write', async () => {
+    vi.useFakeTimers();
+    process.env.OS_LIFECYCLE_DISABLED = '1';
+    try {
+      const harness = watermarkEngine({ row: null });
+      const svc = service(harness.engine, { initialDelayMs: DELAY, sweepIntervalMs: INTERVAL });
+      svc.start();
+      await vi.advanceTimersByTimeAsync(INTERVAL * 4);
+      expect(harness.statements()).toBe(0);
+      svc.stop();
+    } finally {
+      delete process.env.OS_LIFECYCLE_DISABLED;
+      vi.useRealTimers();
+    }
+  });
+});
+
 /**
  * [#4551] The read-only referential-integrity audit rides this sweep's clock.
  *