diff --git a/.changeset/adr-0069-d3-enforced-mfa.md b/.changeset/adr-0069-d3-enforced-mfa.md
new file mode 100644
index 0000000000..f6d60d5ca3
--- /dev/null
+++ b/.changeset/adr-0069-d3-enforced-mfa.md
@@ -0,0 +1,17 @@
+---
+'@objectstack/platform-objects': minor
+'@objectstack/service-settings': minor
+'@objectstack/plugin-auth': minor
+---
+
+Auth: enforced MFA (ADR-0069 D3, P1)
+
+Completes the session-validation gate: when `mfa_required` (new `auth` setting) is on, an authenticated user without TOTP enrolled is blocked from protected resources with `403 MFA_REQUIRED` once their `mfa_grace_period_days` (default 7) window elapses — while the two-factor enrollment endpoints stay reachable so they can comply. Reuses the `authGate` seam shipped in #2388 (a second posture branch in `computeAuthGate`).
+
+- New `auth` settings `mfa_required` (toggle) + `mfa_grace_period_days`; enabling `mfa_required` also force-enables the `twoFactor` plugin so `/two-factor/*` enrollment exists.
+- New `sys_user.mfa_required_at` column — the grace clock, stamped lazily the first time a user is seen required-but-unenrolled.
+- `isAuthGateActive()` now also trips on `mfa_required` (still zero-overhead when off).
+
+Default-off / additive (no upgrade behavior change); per ADR-0049 the setting ships with its enforcement.
+
+**Needs an objectui follow-up**: the Console should handle a `403 MFA_REQUIRED` by showing the TOTP-enrollment prompt. Per-org `sys_organization.require_mfa` and the dispatcher/MCP gate remain follow-ups (#2375).
diff --git a/packages/platform-objects/src/identity/sys-user.object.ts b/packages/platform-objects/src/identity/sys-user.object.ts
index ce2f715eb5..e60cf51511 100644
--- a/packages/platform-objects/src/identity/sys-user.object.ts
+++ b/packages/platform-objects/src/identity/sys-user.object.ts
@@ -458,6 +458,16 @@ export const SysUser = ObjectSchema.create({
       description: 'Timestamp of the last password change. Backs password_expiry_days; system-managed.',
     }),
 
+    // ADR-0069 D3 — when enforced MFA first applied to this user; starts the
+    // grace clock. Stamped lazily at session validation; system-managed.
+    mfa_required_at: Field.datetime({
+      label: 'MFA Required At',
+      required: false,
+      readonly: true,
+      group: 'Admin',
+      description: 'When enforced MFA first applied to this user (grace-period clock). Backs mfa_required; system-managed.',
+    }),
+
     ai_access: Field.boolean({
       label: 'AI Access',
       defaultValue: false,
diff --git a/packages/plugins/plugin-auth/src/auth-manager.test.ts b/packages/plugins/plugin-auth/src/auth-manager.test.ts
index 35a5e95833..99c00a12f2 100644
--- a/packages/plugins/plugin-auth/src/auth-manager.test.ts
+++ b/packages/plugins/plugin-auth/src/auth-manager.test.ts
@@ -1908,4 +1908,71 @@ describe('AuthManager', () => {
       expect(arg.password_changed_at instanceof Date).toBe(true);
     });
   });
+
+  // ADR-0069 D3: enforced MFA — reuses the auth-gate seam (same computeAuthGate).
+  describe('enforced MFA gate (ADR-0069 D3)', () => {
+    const SECRET = 'test-secret-at-least-32-chars-long';
+    const makeEngine = (user: any) => ({
+      findOne: vi.fn(async (_o: string, q: any) => {
+        const w = q?.where ?? {};
+        if (!user) return null;
+        return Object.entries(w).every(([k, v]) => (user as any)[k] === v) ? user : null;
+      }),
+      update: vi.fn(async () => ({})),
+    });
+    const mgr = (engine: any, extra: any = {}) => {
+      const warn = vi.spyOn(console, 'warn').mockImplementation(() => {});
+      const m = new AuthManager({ secret: SECRET, baseUrl: 'http://localhost:3000', dataEngine: engine, ...extra });
+      warn.mockRestore();
+      return m;
+    };
+
+    it('isAuthGateActive is true when mfaRequired (even with expiry off)', () => {
+      expect(mgr(makeEngine(null), { mfaRequired: true }).isAuthGateActive()).toBe(true);
+      expect(mgr(makeEngine(null), {}).isAuthGateActive()).toBe(false);
+    });
+
+    it('blocks MFA_REQUIRED for an un-enrolled user past the grace window', async () => {
+      const old = new Date(Date.now() - 30 * 86_400_000).toISOString();
+      const m = mgr(makeEngine({ id: 'u1', two_factor_enabled: false, mfa_required_at: old }), {
+        mfaRequired: true, mfaGracePeriodDays: 7,
+      });
+      const g = await (m as any).computeAuthGate('u1', undefined, false);
+      expect(g?.code).toBe('MFA_REQUIRED');
+    });
+
+    it('does NOT block within the grace window', async () => {
+      const recent = new Date(Date.now() - 1 * 86_400_000).toISOString();
+      const m = mgr(makeEngine({ id: 'u1', two_factor_enabled: false, mfa_required_at: recent }), {
+        mfaRequired: true, mfaGracePeriodDays: 7,
+      });
+      await expect((m as any).computeAuthGate('u1', undefined, false)).resolves.toBeUndefined();
+    });
+
+    it('stamps mfa_required_at the first time (null) and does not block yet', async () => {
+      const engine = makeEngine({ id: 'u1', two_factor_enabled: false, mfa_required_at: null });
+      const m = mgr(engine, { mfaRequired: true, mfaGracePeriodDays: 7 });
+      await expect((m as any).computeAuthGate('u1', undefined, false)).resolves.toBeUndefined();
+      const wrote = engine.update.mock.calls.find((c: any[]) => 'mfa_required_at' in (c[1] ?? {}));
+      expect(wrote).toBeTruthy();
+      expect(wrote[1].mfa_required_at instanceof Date).toBe(true);
+    });
+
+    it('does NOT block an enrolled user (two_factor_enabled)', async () => {
+      const old = new Date(Date.now() - 30 * 86_400_000).toISOString();
+      const m = mgr(makeEngine({ id: 'u1', two_factor_enabled: true, mfa_required_at: old }), {
+        mfaRequired: true, mfaGracePeriodDays: 7,
+      });
+      await expect((m as any).computeAuthGate('u1', undefined, false)).resolves.toBeUndefined();
+    });
+
+    it('grace 0 blocks an un-enrolled user immediately (after the clock is set)', async () => {
+      const past = new Date(Date.now() - 1000).toISOString();
+      const m = mgr(makeEngine({ id: 'u1', two_factor_enabled: false, mfa_required_at: past }), {
+        mfaRequired: true, mfaGracePeriodDays: 0,
+      });
+      const g = await (m as any).computeAuthGate('u1', undefined, false);
+      expect(g?.code).toBe('MFA_REQUIRED');
+    });
+  });
 });
diff --git a/packages/plugins/plugin-auth/src/auth-manager.ts b/packages/plugins/plugin-auth/src/auth-manager.ts
index 17c10c7d56..3273b366e4 100644
--- a/packages/plugins/plugin-auth/src/auth-manager.ts
+++ b/packages/plugins/plugin-auth/src/auth-manager.ts
@@ -311,6 +311,17 @@ export interface AuthManagerOptions extends Partial<AuthConfig> {
    */
   passwordExpiryDays?: number;
 
+  /**
+   * ADR-0069 D3 — enforced MFA. When true, an authenticated user without TOTP
+   * enrolled (`sys_user.two_factor_enabled`) is gated out of protected resources
+   * (`MFA_REQUIRED`) once their grace window elapses, until they enroll. Shares
+   * the `customSession` → `user.authGate` seam with password expiry.
+   */
+  mfaRequired?: boolean;
+
+  /** Days a user may defer MFA enrollment before the hard block. Default 7. */
+  mfaGracePeriodDays?: number;
+
   /**
    * ADR-0069 D2 — better-auth-native per-IP rate limiting, passed through to
    * better-auth's core `rateLimit`. The settings bind tightens `customRules`
@@ -2275,7 +2286,10 @@ export class AuthManager {
    * default), keeping the gate zero-overhead until an admin opts in.
    */
   public isAuthGateActive(): boolean {
-    return (Math.floor(Number(this.config.passwordExpiryDays) || 0) > 0);
+    return (
+      Math.floor(Number(this.config.passwordExpiryDays) || 0) > 0 ||
+      this.config.mfaRequired === true
+    );
   }
 
   /**
@@ -2288,28 +2302,56 @@ export class AuthManager {
   private async computeAuthGate(
     userId: string,
     _activeOrgId: string | undefined,
-    _twoFactorEnabled: boolean,
+    _twoFactorEnabledHint: boolean,
   ): Promise<{ code: string; message: string } | undefined> {
     const expiryDays = Math.floor(Number(this.config.passwordExpiryDays) || 0);
-    if (expiryDays <= 0) return undefined; // no gate feature active
+    const mfaRequired = this.config.mfaRequired === true;
+    if (expiryDays <= 0 && !mfaRequired) return undefined; // no gate feature active
     const engine = this.getDataEngine();
     if (!engine || !userId) return undefined;
     try {
       const SYSTEM_CTX = { isSystem: true, roles: [], permissions: [] };
       const u = await engine.findOne('sys_user', {
-        where: { id: userId }, fields: ['password_changed_at'], context: SYSTEM_CTX,
+        where: { id: userId },
+        fields: ['password_changed_at', 'two_factor_enabled', 'mfa_required_at'],
+        context: SYSTEM_CTX,
       } as any);
-      const changed = u?.password_changed_at;
-      // Null = never expires (existing accounts on upgrade) until the next change.
-      if (changed) {
-        const ageMs = Date.now() - new Date(changed).getTime();
-        if (ageMs > expiryDays * 86_400_000) {
+
+      // ── Password expiry ───────────────────────────────────────────────
+      if (expiryDays > 0) {
+        const changed = u?.password_changed_at;
+        // Null = never expires (existing accounts on upgrade) until next change.
+        if (changed && Date.now() - new Date(changed).getTime() > expiryDays * 86_400_000) {
           return {
             code: 'PASSWORD_EXPIRED',
             message: 'Your password has expired. Please change it to continue.',
           };
         }
       }
+
+      // ── Enforced MFA ──────────────────────────────────────────────────
+      // A user without TOTP enrolled is blocked once their grace window
+      // elapses. The clock (`mfa_required_at`) starts the first time we see
+      // them required-but-unenrolled (stamped lazily, best-effort).
+      if (mfaRequired && !(u?.two_factor_enabled === true || u?.two_factor_enabled === 1)) {
+        const graceDays = Math.max(0, Math.floor(Number(this.config.mfaGracePeriodDays ?? 7)));
+        let requiredAt = u?.mfa_required_at;
+        if (!requiredAt) {
+          requiredAt = new Date();
+          // Best-effort: start the grace clock; never block on the write.
+          engine
+            .update('sys_user', { id: userId, mfa_required_at: requiredAt }, { context: SYSTEM_CTX } as any)
+            .catch(() => undefined);
+        }
+        const elapsedMs = Date.now() - new Date(requiredAt).getTime();
+        if (elapsedMs > graceDays * 86_400_000) {
+          return {
+            code: 'MFA_REQUIRED',
+            message:
+              'Multi-factor authentication is required. Please set up an authenticator app to continue.',
+          };
+        }
+      }
     } catch {
       return undefined; // fail-open
     }
diff --git a/packages/plugins/plugin-auth/src/auth-plugin.test.ts b/packages/plugins/plugin-auth/src/auth-plugin.test.ts
index 028c31cf6c..d6acd46a9b 100644
--- a/packages/plugins/plugin-auth/src/auth-plugin.test.ts
+++ b/packages/plugins/plugin-auth/src/auth-plugin.test.ts
@@ -694,6 +694,24 @@ describe('AuthPlugin', () => {
       expect((manager as any).isAuthGateActive()).toBe(true);
     });
 
+    it('binds mfa_required and force-enables the twoFactor plugin (ADR-0069 D3)', async () => {
+      const { manager } = await bootWithAuthSettings({ mfa_required: { value: true, source: 'global' } });
+      const cfg = (manager as any).config;
+      expect(cfg.mfaRequired).toBe(true);
+      expect(cfg.plugins?.twoFactor).toBe(true);
+      expect((manager as any).isAuthGateActive()).toBe(true);
+    });
+
+    it('binds mfa_grace_period_days', async () => {
+      const { manager } = await bootWithAuthSettings({ mfa_grace_period_days: { value: 14, source: 'global' } });
+      expect((manager as any).config.mfaGracePeriodDays).toBe(14);
+    });
+
+    it('clamps mfa_grace_period_days to a max of 90', async () => {
+      const { manager } = await bootWithAuthSettings({ mfa_grace_period_days: { value: 999, source: 'global' } });
+      expect((manager as any).config.mfaGracePeriodDays).toBe(90);
+    });
+
     it('binds account-lockout settings (ADR-0069 D2)', async () => {
       const { manager } = await bootWithAuthSettings({
         lockout_threshold: { value: 5, source: 'global' },
diff --git a/packages/plugins/plugin-auth/src/auth-plugin.ts b/packages/plugins/plugin-auth/src/auth-plugin.ts
index b2d8cfcef2..97eeb658be 100644
--- a/packages/plugins/plugin-auth/src/auth-plugin.ts
+++ b/packages/plugins/plugin-auth/src/auth-plugin.ts
@@ -518,6 +518,24 @@ export class AuthPlugin implements Plugin {
           if (Number.isFinite(n) && n >= 0) patch.passwordExpiryDays = Math.min(3650, n);
         }
 
+        // Enforced MFA (ADR-0069 D3). Enabling it also turns the twoFactor
+        // plugin on so the /two-factor/* enrollment endpoints exist — otherwise
+        // gated users would have no way to comply.
+        if (isExplicit('mfa_required')) {
+          const on = asBoolean(values.mfa_required, false);
+          patch.mfaRequired = on;
+          if (on) {
+            patch.plugins = {
+              ...(patch.plugins ?? {}),
+              twoFactor: true,
+            } as AuthManagerOptions['plugins'];
+          }
+        }
+        if (isExplicit('mfa_grace_period_days')) {
+          const n = Math.floor(Number(values.mfa_grace_period_days));
+          if (Number.isFinite(n) && n >= 0) patch.mfaGracePeriodDays = Math.min(90, n);
+        }
+
         // Session lifetime — days → seconds for better-auth's `session`
         // (`expiresIn` = absolute lifetime; `updateAge` = refresh threshold).
         const session: { expiresIn?: number; updateAge?: number } = {};
diff --git a/packages/services/service-settings/src/manifests/auth.manifest.test.ts b/packages/services/service-settings/src/manifests/auth.manifest.test.ts
index f202e584f3..f1f2be9e55 100644
--- a/packages/services/service-settings/src/manifests/auth.manifest.test.ts
+++ b/packages/services/service-settings/src/manifests/auth.manifest.test.ts
@@ -25,6 +25,7 @@ describe('authSettingsManifest', () => {
     expect(keys).toEqual([
       'email_password_enabled',
       'google_enabled',
+      'mfa_required',
       'password_reject_breached',
       'password_require_complexity',
       'require_email_verification',
@@ -66,6 +67,7 @@ describe('authSettingsManifest', () => {
     expect(byKey('rate_limit_window_seconds').default).toBe(60);
     expect(byKey('password_history_count').default).toBe(0);
     expect(byKey('password_expiry_days').default).toBe(0);
+    expect(byKey('mfa_grace_period_days').default).toBe(7);
   });
 
   it('exposes encrypted Google OAuth credential fields', () => {
diff --git a/packages/services/service-settings/src/manifests/auth.manifest.ts b/packages/services/service-settings/src/manifests/auth.manifest.ts
index a369f4b9e8..04ec2ce9ce 100644
--- a/packages/services/service-settings/src/manifests/auth.manifest.ts
+++ b/packages/services/service-settings/src/manifests/auth.manifest.ts
@@ -180,6 +180,34 @@ const manifest = {
       max: 3600,
       description: 'Sliding window over which the request cap above is counted.',
     },
+    {
+      type: 'group',
+      id: 'multi_factor',
+      label: 'Multi-factor',
+      required: false,
+      description: 'Require members to protect their account with an authenticator app (TOTP).',
+    },
+    {
+      type: 'toggle',
+      key: 'mfa_required',
+      label: 'Require multi-factor authentication',
+      required: false,
+      default: false,
+      description:
+        'Users without an authenticator enrolled are blocked from data once their grace period ends. Enabling this also turns on the two-factor feature so users can enroll.',
+      visible: "${data.email_password_enabled !== false}",
+    },
+    {
+      type: 'number',
+      key: 'mfa_grace_period_days',
+      label: 'MFA grace period (days)',
+      required: false,
+      default: 7,
+      min: 0,
+      max: 90,
+      description: 'How long users may defer enrollment before the hard block. 0 blocks immediately.',
+      visible: "${data.mfa_required === true}",
+    },
     {
       type: 'group',
       id: 'sessions',