@@ -0,0 +1,14 @@
+---
+'@objectstack/cli': patch
+'@objectstack/runtime': patch
+---
+
+fix(cli, runtime): the 18.0 operator messages say that 18.0 supports fresh `single` installs only
+
+Clause-②: no
+
+- **The v18 boot refusal on a v17-shaped database** now says first that 18.0 does not upgrade a v17 database: keep it on a 17.x release until the 18.x release that carries the upgrade path. Before, it named only `os migrate organization-ownership`, which refuses in 18.0 as well, so the operator reached the answer in two hops.
+- **The fix list for an unrecognized `OS_TENANCY_POSTURE`** (printed by `os serve` and `os doctor`) still lists `group` and `isolated`, and now says beside each that 18.0 refuses it at boot.
+- **`os doctor` reports a walled posture.** Under `group` or `isolated` it prints a `Tenancy posture` warning: 18.0 supports `single` only, so the next `os serve` (and so `os dev` and `os start`) refuses the posture at boot. The row is a warning, so doctor's exit code does not change. Before, doctor printed nothing about a valid posture.
+
+Nothing else changes. The refusals themselves, their codes and their exit codes are as before.
@@ -19,6 +19,11 @@ still apply — widened to the three postures.
 <Callout type="warn" title="18.0: single only">
 18.0 supports fresh `single` installs; upgrades and walled postures arrive in 18.x. In 18.0 `os serve` (and so `os dev` and `os start`) refuses `group` and
 `isolated` at boot with `NOT_IMPLEMENTED`, before it reads a config.
+A database an 18.0 install creates takes the same 18.x upgrade path as a v17 one.
+The refusal covers the `os` boot path only. The one-shot `os migrate`, `os verify`,
+`os secret` and `os storage` boots and embedded hosts (`createStandaloneStack`,
+`@objectstack/adapter-hono`) are not refused, and none of them is a supported
+walled deployment in 18.0.
 </Callout>
 
 <Callout type="info" title="Renamed, not re-configured">
@@ -38,7 +43,7 @@ fallback **input** to posture resolution. See
 | Layer 0 organization wall | none — the layer is inert | `organization_id IN accessible_org_ids` (union / MOAC) | `organization_id = <active organization>` |
 | Read reach | the whole dataset, subject to RBAC | every organization the caller currently holds a membership in | the active organization only |
 | Shape | one logical tenant; sub-units modelled as business units in one tree | organizations are membership / invitation boundaries over one shared dataset | legal-entity / sovereignty isolation — the hard wall |
-| `organization_id` filled in on write | no | yes | yes |
+| `organization_id` filled in on write | yes — the Default Organization | yes | yes |
 | Enterprise `@objectstack/organizations` | not needed | **required** | **required** |
 | Default organization | one bootstrapped "Default Organization" | owned by the enterprise runtime | owned by the enterprise runtime |
 | Org-management UI (create / switch org) | hidden | shown | shown |
@@ -101,6 +106,42 @@ posture it does not list. A runtime that declares nothing entitles both.
 
 ---
 
+## Who owns a row
+
+Ownership is the same under every posture; a posture changes only whether the
+wall is enforced (ADR-0131 D11). Three rules decide where a fact lives
+(ADR-0131 D1–D7):
+
+1. **A managed package's metadata is not in the database.** Its definitions
+   (objects, fields, views, positions, permission sets, capabilities, sharing
+   rules, templates, flows) are sealed code. What a customer changes is
+   environment-level state beside them: an overlay, an on/off switch, a clone
+   or an extension.
+2. **A row in a table with an organization column was written by that
+   organization.** Every such row carries its organization, and refers to a
+   declared item by its machine name. `NULL` is not an owner: no row is
+   "global" or platform-wide because its `organization_id` is empty.
+3. **A table with no organization column is deployment-level or code-level.**
+   Permissions protect it, not the wall.
+
+Under `single` a write into a table with an organization column takes the
+Default Organization, the only one there is. A system write that names no
+organization is stamped with it, or refused loudly when the deployment holds
+zero organizations or two or more. Nothing writes an organization-less row
+there.
+
+<Callout type="info" title="Platform tables with no organization">
+A platform table (logs, job runs, messaging, configuration) has one of the two
+shapes above, never a third. With no organization column, it is deployment-level
+by design, and its rows carry no organization on any posture. With one, every
+row belongs to an organization. A v17 install could leave organization-less rows
+in such a table. Those rows are what the 18.x upgrade ceremony resolves, table
+by table, before an 18.x server will serve that database (ADR-0131 D10). Until
+that release, keep the database on 17.x.
+</Callout>
+
+---
+
 ## How the posture resolves
 
 `OS_TENANCY_POSTURE` is the authoritative knob; `OS_MULTI_ORG_ENABLED` is a
 
@@ -41,7 +41,7 @@ segregation-of-duties case the axis exists for. The built-in
 The bypass is **posture-gated for row-level security** (ADR-0066 D2 ①): RLS
 policies are short-circuited only on objects whose posture permits it —
 `access: { default: 'private' }`, `tenancy.enabled: false`
-(platform-global), or better-auth-managed. On an ordinary tenant business
+(deployment-level: no organization column), or better-auth-managed. On an ordinary tenant business
 object, authored and baseline RLS still applies (e.g. `member_default`'s
 owner-scoped write policies keep `org_member` holders owner-scoped on
 `update`/`delete` even when another set grants `modifyAllRecords`), and the
 
@@ -81,7 +81,7 @@ derivation off for that class: an authored `update` predicate then decides
 the `update` *filter* alone, widening past the platform's owner-scoped write
 floor exactly as written. Nothing is derived for `insert`
 (there is no pre-existing row to be visible), and a caller holding the
-read-side superuser bypass (`viewAllRecords` on a private or platform-global
+read-side superuser bypass (`viewAllRecords` on a private or deployment-level
 object) is not narrowed, because their readable set is already unbounded.
 
 **A write widener never reaches a row the caller cannot read.** "You may not
 
@@ -61,7 +61,7 @@ Two things the bits do **not** override, regardless of the OWD:
   `org_member`), so rank-and-file members stay owner-scoped on writes even
   under `public_read_write`. The super-user bits short-circuit RLS **only
   where the object's access posture permits it** — `access: { default:
-  'private' }`, `tenancy.enabled: false` (platform-global), or better-auth
+  'private' }`, `tenancy.enabled: false` (deployment-level: no organization column), or better-auth
   managed objects (ADR-0066 D2 ①). On an ordinary tenant business object,
   `modifyAllRecords` does *not* lift those policies
   (`plugin-security/src/security-plugin.ts` `computeLayeredRlsFilter`).
@@ -195,7 +195,7 @@ unaffected.
 **…and an organization to be scoped by.** `manage_sharing` is declared
 `scope: 'org'`, so the capability alone is not enough: the caller's session
 must also resolve an **active organization**, which is what scopes every rule
-read to "this organization ∪ the platform-global rows". A session that carries
+read to the rule rows that organization wrote. A session that carries
 none — a user who has not selected an organization, or whose active
 organization was cleared — is refused with the same `403 PERMISSION_DENIED`,
 naming the missing organization rather than answering with an empty list.
 
@@ -129,7 +129,7 @@ that silently does not happen.
 | 23 | **Referential-integrity check skipped** | objectql | Get: writes proceed against unreachable/unresolvable targets. Lose: an `isSystem` caller can write a **dangling reference** | `packages/objectql/src/engine.ts#assertReferencesResolve` |
 | 23b | **Position-catalog check skipped** — a `sys_user_position` write whose `position` names no position in the security catalog is not refused | plugin-security | Get: a system writer can store an assignment naming no position — the seed loader writes `stack.data` from `AppPlugin.start()` under a system context, as invitation acceptance and the platform's own bootstraps do. Lose: such a row grants nothing and nothing says so. A non-system insert, or a non-system update that changes `position`, is refused `400 VALIDATION_FAILED` / `reference_not_found` instead when the security catalog holds no position of that name: the environment registry (ADR-0131 D3), one per deployment, which takes no organization, so a name only a `sys_position` row carries — any organization's — is refused like one nobody carries. It is the same stand-down as the engine's referential-integrity check for a lookup column | `packages/plugins/plugin-security/src/position-catalog-refusal.ts#assertPositionNamesCatalogRow` |
 | 23c | **Grant-name catalog check skipped** — a `sys_user_permission_set` write whose `permission_set` names no permission set in the security catalog is not refused | plugin-security | Get: a system writer can store a grant naming a set not yet registered — seed replay and boot provisioning may write the grant before the definition it names is registered. Lose: such a row grants nothing and nothing says so. A non-system insert, or a non-system update that changes `permission_set`, is refused `400 VALIDATION_FAILED` / `reference_not_found` instead when the security catalog holds no set by that name; a grant that names no set at all is refused `required` for every caller. The grant names its set by name alone, and nothing derives the name from `permission_set_id` (ADR-0131 D4, D10) | `packages/plugins/plugin-security/src/grant-permission-set-name.ts#onInsert`, `#onUpdate` |
-| 23d | **Grant-holder membership check skipped** — a `sys_user_position` or `sys_user_permission_set` write naming a user with no `sys_member` row in the row's organization is not refused | plugin-security | Get: a system writer can store such a grant — invitation acceptance writes the membership and its placement together, and seed replay, the organization-admin reconcile and the platform bootstraps write grants as the system. Lose: such a row takes effect once its user is admitted to the organization. A non-system insert, or a non-system update that moves `user_id` or `organization_id`, is refused `400 VALIDATION_FAILED` / `reference_not_found` at `user_id` instead, for every caller, a platform administrator included; the membership is read as `{ isSystem: true, tenantId }` with `tenantId` the row's own organization, never another one. A row stored with no organization is a global grant and is not judged | `packages/plugins/plugin-security/src/grant-holder-membership-refusal.ts#onInsert`, `#onUpdate` |
+| 23d | **Grant-holder membership check skipped** — a `sys_user_position` or `sys_user_permission_set` write naming a user with no `sys_member` row in the row's organization is not refused | plugin-security | Get: a system writer can store such a grant — invitation acceptance writes the membership and its placement together, and seed replay, the organization-admin reconcile and the platform bootstraps write grants as the system. Lose: such a row takes effect once its user is admitted to the organization. A non-system insert, or a non-system update that moves `user_id` or `organization_id`, is refused `400 VALIDATION_FAILED` / `reference_not_found` at `user_id` instead, for every caller, a platform administrator included; the membership is read as `{ isSystem: true, tenantId }` with `tenantId` the row's own organization, never another one. A row stored with no organization is not judged. Under `single`, 18.0 stamps a new grant with the Default Organization, so such a row is one an earlier release wrote | `packages/plugins/plugin-security/src/grant-holder-membership-refusal.ts#onInsert`, `#onUpdate` |
 | 24 | Tenant-audit warning silenced; `bypassTenantAudit` threaded to the driver | objectql | Get: unscoped system writes stop warning. Lose: the signal that would flag a genuine user-path scoping bug | `packages/objectql/src/engine.ts#buildDriverOptions` |
 | 25 | Engine-owned / append-only write guard bypassed | plugin-security | Get: generic writes to `managedBy` engine-owned objects | `packages/plugins/plugin-security/src/system-write-guard.ts#isUserContextWrite`, `#assertEngineOwnedWriteAllowed` |
 | 26 | Identity write guard bypassed (ADR-0092) | plugin-auth | Get: direct writes to identity tables through the generic data path | `packages/plugins/plugin-auth/src/identity-write-guard.ts#isUserContextWrite` |
 
@@ -455,7 +455,9 @@ describe('os doctor, end to end, against a posture that only exists in .env', ()
 
   it('names the file, refuses to call the environment functional, and exits 1', async () => {
     // ── Control: the same .env, a posture that parses ─────────────────────
-    fs.writeFileSync(path.join(tmp, '.env'), 'OS_TENANCY_POSTURE=isolated\n');
+    // `single`, not `isolated`: 18.0 refuses a walled posture at `os serve`, so
+    // doctor reports one, and a walled control would carry a posture row.
+    fs.writeFileSync(path.join(tmp, '.env'), 'OS_TENANCY_POSTURE=single\n');
     const healthy = await runDoctor();
 
     expect(healthy.exitCode).toBeUndefined();
 
@@ -168,7 +168,7 @@ describe('doctor — the posture description an operator reads names the declara
   it('leg (i) — the `isolated` fix-list bullet names it, with the spacing intact', () => {
     expect(renderIsolatedBullet()).toBe(
       `        • OS_TENANCY_POSTURE=isolated — organization wall + the ${PKG} runtime `
-      + "(the legacy spelling 'multi' is accepted and normalizes to this)",
+      + "(the legacy spelling 'multi' is accepted and normalizes to this); refused at boot in 18.0, which supports single only",
     );
   });
 
@@ -242,14 +242,14 @@ describe('#12464 CONTROL — these pins can say no', () => {
     // decorative. Anchored on the exact regression interpolation invites.
     const expected =
       `        • OS_TENANCY_POSTURE=isolated — organization wall + the ${PKG} runtime `
-      + "(the legacy spelling 'multi' is accepted and normalizes to this)";
+      + "(the legacy spelling 'multi' is accepted and normalizes to this); refused at boot in 18.0, which supports single only";
     expect(
       `        • OS_TENANCY_POSTURE=isolated — organization wall + the ${PKG} runtime`
-      + "(the legacy spelling 'multi' is accepted and normalizes to this)",
+      + "(the legacy spelling 'multi' is accepted and normalizes to this); refused at boot in 18.0, which supports single only",
     ).not.toBe(expected);
     expect(
       `      • OS_TENANCY_POSTURE=isolated — organization wall + the ${PKG} runtime `
-      + "(the legacy spelling 'multi' is accepted and normalizes to this)",
+      + "(the legacy spelling 'multi' is accepted and normalizes to this); refused at boot in 18.0, which supports single only",
     ).not.toBe(expected);
     // …and says yes to the real thing, so the two `not.toBe`s above are a
     // reading rather than a pair of vacuous truths.
 
@@ -61,6 +61,7 @@ import { TENANCY_POSTURES } from '@objectstack/spec/security';
 
 import Doctor, {
   resolveTenancyPostureOrFinding,
+  walledPostureFinding,
   readDotenvFiles,
   type DotenvReading,
 } from './doctor.js';
@@ -290,7 +291,9 @@ describe('os doctor reports an unrecognized posture and exits non-zero', () => {
 
   it('names OS_TENANCY_POSTURE, refuses to call the environment functional, and exits 1', async () => {
     // ── Control: the same environment with a posture that parses ──────────
-    process.env.OS_TENANCY_POSTURE = 'isolated';
+    // `single`, not `isolated`: 18.0 refuses a walled posture at `os serve`, so
+    // doctor reports one (`walledPostureFinding`, below) and it is no control.
+    process.env.OS_TENANCY_POSTURE = 'single';
     const healthy = await runDoctor();
 
     // Doctor completes normally. This is the sentence #5382 quoted, and here it
@@ -343,4 +346,33 @@ describe('os doctor reports an unrecognized posture and exits non-zero', () => {
     // `}, 60_000)` cases in this package (`utils/sqlite-occupancy.test.ts`,
     // `utils/schema-migrate.deferred-ddl.integration.test.ts`).
   }, 60_000);
+
+  it('18.0 — a walled posture is reported as a warning naming the `os serve` refusal, and exits 0', async () => {
+    process.env.OS_TENANCY_POSTURE = 'group';
+    const walled = await runDoctor();
+    expect(walled.out).toContain('Tenancy posture');
+    expect(walled.out).toContain("the tenancy posture is 'group'");
+    expect(walled.out).toContain('`os serve`');
+    expect(walled.out).toContain('Environment is functional but has some warnings');
+    expect(walled.exitCode).toBeUndefined();
+  }, 60_000);
+});
+
+describe('walledPostureFinding — 18.0 supports `single` only', () => {
+  it('answers null for `single`, a warning row for each walled posture', () => {
+    for (const posture of TENANCY_POSTURES) {
+      const row = walledPostureFinding(posture);
+      if (posture === 'single') {
+        expect(row).toBeNull();
+        continue;
+      }
+      expect(row?.name).toBe('Tenancy posture');
+      expect(row?.status).toBe('warning');
+      expect(row?.message).toContain(`'${posture}'`);
+      expect(row?.message).toContain('18.0');
+      expect(row?.fix).toContain('OS_TENANCY_POSTURE=single');
+    }
+    expect(TENANCY_POSTURES).toContain('group');
+    expect(TENANCY_POSTURES).toContain('isolated');
+  });
 });