@@ -46,7 +46,6 @@
     "jose": "^6.2.12"
   },
   "devDependencies": {
-    "@objectstack/driver-memory": "workspace:*",
     "@objectstack/driver-sql": "workspace:*",
     "@objectstack/formula": "workspace:*",
     "@objectstack/objectql": "workspace:*",
 
@@ -15,16 +15,19 @@
  * let a write take the deployment's last platform administrator — the
  * fail-open this file pins shut.
  *
- * Every case runs a REAL {@link ObjectQL} engine over a real driver
- * (better-sqlite3 `:memory:`, or driver-memory), registers the real guard, and
- * asks the real resolver. Three things are pinned:
+ * Every case runs a REAL {@link ObjectQL} engine over better-sqlite3
+ * `:memory:`, registers the real guard, and asks the real resolver. Three
+ * things are pinned:
  *
  *  1. **Where the row can exist.** Through the engine, an organization-less
  *     grant is derived or refused wherever the organization object is
  *     registered (ADR-0131 D9), and refused by the NOT NULL column a fresh SQL
- *     table carries (D1) where it is not. Two compositions can still hold one:
- *     a lean embedding on driver-memory, and a store built before 18.x.
- *  2. **The negative pin** — in both, with a verified `OS_PLATFORM_OWNER_EMAIL`
+ *     table carries (D1) where it is not. What can still hold one is a column
+ *     that is NOT NULL nowhere: a store built before 18.x, or a driver that
+ *     enforces no NOT NULL (driver-memory, measured on #24883), in a lean
+ *     embedding that registers no organization object or beneath the engine.
+ *     The nullable column stands in for both here.
+ *  2. **The negative pin** — in both shapes, with a verified `OS_PLATFORM_OWNER_EMAIL`
  *     account as the resolver's only platform administrator and an
  *     organization-less grant holder beside it, banning that administrator is
  *     REFUSED.
@@ -36,7 +39,6 @@
 import { describe, it, expect, beforeEach, afterEach } from 'vitest';
 import { ObjectQL } from '@objectstack/objectql';
 import { SqlDriver } from '@objectstack/driver-sql';
-import { InMemoryDriver } from '@objectstack/driver-memory';
 import { resetPlatformAdminEmailMemo, resolveAuthzContext } from '@objectstack/core';
 import { ADMIN_FULL_ACCESS } from '@objectstack/spec/identity';
 
@@ -93,7 +95,6 @@ const sysUserPosition = {
   fields: { id: { ...text('id'), primaryKey: true }, user_id: text('user_id'), position: text('position'), organization_id: text('organization_id') },
 };
 
-type DriverKind = 'sqlite' | 'memory';
 interface Rig {
   engine: ObjectQL;
   /** The driver itself, for the rows only a store built before 18.x holds. */
@@ -122,19 +123,19 @@ afterEach(async () => {
   }
 });
 
-async function boot(kind: DriverKind, opts: { organizationObject: boolean; legacyStore?: boolean }): Promise<Rig> {
+async function boot(opts: { organizationObject: boolean; nullableTenantColumn?: boolean }): Promise<Rig> {
   const engine = new ObjectQL();
   engines.push(engine);
-  const driver = kind === 'sqlite'
-    ? new SqlDriver({ client: 'better-sqlite3', connection: { filename: ':memory:' }, useNullAsDefault: true })
-    : new InMemoryDriver();
-  engine.registerDriver(driver as never, true);
+  const driver = new SqlDriver({ client: 'better-sqlite3', connection: { filename: ':memory:' }, useNullAsDefault: true });
+  engine.registerDriver(driver, true);
   await engine.init();
   const objects = [sysUser, sysMember, sysUserPermissionSet, sysUserPosition, ...(opts.organizationObject ? [sysOrganization] : [])];
   for (const o of objects) engine.registry.registerObject(o as never);
   await engine.syncSchemas();
-  // A store built before 18.x: the tenant column nullable (ADR-0131 D1).
-  if (opts.legacyStore) await relaxEveryRegisteredTenantColumn(engine);
+  // A tenant column that is NOT NULL nowhere: a store built before 18.x has one
+  // (ADR-0131 D1 makes a fresh one NOT NULL), and so does a driver that
+  // enforces no NOT NULL.
+  if (opts.nullableTenantColumn) await relaxEveryRegisteredTenantColumn(engine);
   bindTestSecurityCatalog(engine, { permissions: [{ name: ADMIN_FULL_ACCESS }] });
   registerLastAdminGuard(engine as unknown as LastAdminGuardEngine, { packageId: 'test.last-admin-guard-parity' });
   return { engine, driver: driver as unknown as Rig['driver'] };
@@ -173,22 +174,29 @@ async function refusalOf(write: Promise<unknown>): Promise<{ code?: unknown; sta
 
 describe('[ADR-0131 D1/D9] where an organization-less admin_full_access grant can still be written', () => {
   type Expect = 'derived' | 'refused-d9' | 'refused-not-null' | 'stored-null';
-  const cases: Array<{ kind: DriverKind; organizations: number | 'no-object'; posture: 'single' | 'isolated'; expected: Expect }> = [
-    { kind: 'sqlite', organizations: 'no-object', posture: 'single', expected: 'refused-not-null' },
-    { kind: 'sqlite', organizations: 0, posture: 'single', expected: 'refused-d9' },
-    { kind: 'sqlite', organizations: 1, posture: 'single', expected: 'derived' },
-    { kind: 'sqlite', organizations: 2, posture: 'single', expected: 'refused-d9' },
-    { kind: 'sqlite', organizations: 0, posture: 'isolated', expected: 'refused-d9' },
-    { kind: 'sqlite', organizations: 1, posture: 'isolated', expected: 'refused-d9' },
-    { kind: 'sqlite', organizations: 2, posture: 'isolated', expected: 'refused-d9' },
-    { kind: 'memory', organizations: 'no-object', posture: 'single', expected: 'stored-null' },
-    { kind: 'memory', organizations: 0, posture: 'single', expected: 'refused-d9' },
+  type Column = 'fresh' | 'nullable';
+  const cases: Array<{ column: Column; organizations: number | 'no-object'; posture: 'single' | 'isolated'; expected: Expect }> = [
+    { column: 'fresh', organizations: 'no-object', posture: 'single', expected: 'refused-not-null' },
+    { column: 'fresh', organizations: 0, posture: 'single', expected: 'refused-d9' },
+    { column: 'fresh', organizations: 1, posture: 'single', expected: 'derived' },
+    { column: 'fresh', organizations: 2, posture: 'single', expected: 'refused-d9' },
+    { column: 'fresh', organizations: 0, posture: 'isolated', expected: 'refused-d9' },
+    { column: 'fresh', organizations: 1, posture: 'isolated', expected: 'refused-d9' },
+    { column: 'fresh', organizations: 2, posture: 'isolated', expected: 'refused-d9' },
+    // The engine's no-organization-object exit (ADR-0131 D9) leaves the row
+    // organization-less; only the column could refuse it.
+    { column: 'nullable', organizations: 'no-object', posture: 'single', expected: 'stored-null' },
+    { column: 'nullable', organizations: 1, posture: 'single', expected: 'derived' },
+    { column: 'nullable', organizations: 1, posture: 'isolated', expected: 'refused-d9' },
   ];
 
   for (const c of cases) {
-    it(`${c.kind}, ${c.organizations === 'no-object' ? 'no organization object' : `${c.organizations} organization(s)`}, ${c.posture}: ${c.expected} — and the guard agrees with the resolver about its holder`, async () => {
+    it(`${c.column} tenant column, ${c.organizations === 'no-object' ? 'no organization object' : `${c.organizations} organization(s)`}, ${c.posture}: ${c.expected} — and the guard agrees with the resolver about its holder`, async () => {
       process.env.OS_TENANCY_POSTURE = c.posture;
-      const { engine, driver } = await boot(c.kind, { organizationObject: c.organizations !== 'no-object' });
+      const { engine, driver } = await boot({
+        organizationObject: c.organizations !== 'no-object',
+        nullableTenantColumn: c.column === 'nullable',
+      });
       const organizations = typeof c.organizations === 'number' ? c.organizations : 0;
       // Written beneath the engine, before anything has asked it about
       // organizations: its probe reads the table at the grant insert below.
@@ -221,11 +229,6 @@ describe('[ADR-0131 D1/D9] where an organization-less admin_full_access grant ca
       expect(banRefusal?.code).toBe(isAdmin ? 'PERMISSION_DENIED' : undefined);
     });
   }
-
-  it('driver-memory refuses a walled posture outright — no walled composition holds the row there', async () => {
-    process.env.OS_TENANCY_POSTURE = 'isolated';
-    await expect(boot('memory', { organizationObject: true })).rejects.toMatchObject({ code: 'MEMORY_MULTI_TENANT_UNSUPPORTED' });
-  });
 });
 
 describe('[ADR-0131 D5] the negative pin: an organization-less holder is no survivor', () => {
@@ -244,9 +247,9 @@ describe('[ADR-0131 D5] the negative pin: an organization-less holder is no surv
     expect(await resolverStanding(rig.engine, 'usr_legacy'), 'the holder is no administrator to the resolver').toBe(false);
   }
 
-  it('⭐ a lean embedding on driver-memory (no sys_organization): banning the only platform administrator is REFUSED', async () => {
+  it('⭐ a lean embedding (no sys_organization) whose tenant column is NOT NULL nowhere: banning the only platform administrator is REFUSED', async () => {
     process.env.OS_TENANCY_POSTURE = 'single';
-    const rig = await boot('memory', { organizationObject: false });
+    const rig = await boot({ organizationObject: false, nullableTenantColumn: true });
     await seedTwoCandidates(rig, false);
 
     await expect(ban(rig.engine, 'usr_owner')).rejects.toMatchObject({ code: 'PERMISSION_DENIED', status: 403 });
@@ -256,7 +259,7 @@ describe('[ADR-0131 D5] the negative pin: an organization-less holder is no surv
 
   it('⭐ a store built before 18.x (sys_organization registered, the row beneath the engine): the same ban is REFUSED', async () => {
     process.env.OS_TENANCY_POSTURE = 'single';
-    const rig = await boot('sqlite', { organizationObject: true, legacyStore: true });
+    const rig = await boot({ organizationObject: true, nullableTenantColumn: true });
     await rig.driver.create('sys_organization', { id: DEFAULT_ORG, name: 'Default', slug: 'default' });
     await seedTwoCandidates(rig, true);
 
@@ -271,7 +274,7 @@ describe('[ADR-0131 D5] the positive control: the Default Organization\'s grant
     process.env.OS_TENANCY_POSTURE = 'single';
     process.env.OS_PLATFORM_OWNER_EMAIL = OWNER;
     resetPlatformAdminEmailMemo();
-    const { engine } = await boot('sqlite', { organizationObject: true });
+    const { engine } = await boot({ organizationObject: true });
     await engine.insert('sys_organization', { id: DEFAULT_ORG, name: 'Default Organization', slug: 'default' }, SYSTEM);
     await seedUser(engine, 'usr_promoted', 'promoted@corp.example');
     await engine.insert(