@@ -0,0 +1,25 @@
+---
+'@objectstack/objectql': minor
+'@objectstack/core': minor
+'@objectstack/spec': minor
+'@objectstack/plugin-security': patch
+---
+
+feat(objectql,core): the driver's tenant read scope is the organization wall's verdict — one predicate for Layer 0 and every driver (ADR-0131 D8)
+
+Clause-②: yes (widening)
+
+- **What changed.** The engine no longer derives `DriverOptions.tenantId` / `tenantIds` beside the organization wall. `buildDriverOptions` projects the wall's own verdict onto them: the verdict plugin-security records on the operation (`OperationContext.tenantLayer0Verdict`) where its wall ran, and otherwise the same function over the engine's own facts (the posture in force, the context's organization and membership set). The function, `computeTenantLayer0Verdict` with its input type `TenantLayer0Input`, moves to `@objectstack/core` (new export); `@objectstack/plugin-security`'s `tenant-layer.ts` re-exports it and its Layer 0 is byte-identical.
+- **FROM → TO, per posture, for a read, count, aggregate, update or delete on an object with an organization column:**
+
+  | posture / caller | driver scope before | driver scope now |
+  |:--|:--|:--|
+  | `single`, any caller naming an organization | that organization (plus organization-less rows) | **none** |
+  | `isolated`, member | the active organization | unchanged |
+  | `group`, member | the membership set | unchanged |
+  | walled, exempt `PLATFORM_ADMIN` on a posture-permitting object, or the verified platform owner's read | the active organization | **none** — what Layer 0 already admitted |
+  | walled, system context naming an organization | that organization | unchanged |
+
+- **Not changed.** Inserts and upserts keep the active organization as `tenantId` in every posture: the row is stamped with it, its counter scopes by it, and an upsert that would merge into another organization's row is still refused. Both `orWhereNull` compatibility arms in `SqlDriver.applyTenantScope` stay (their retirement is a later stage of ADR-0131 D13).
+- **Who notices.** A `single` deployment that holds more than one organization was kept apart by the driver only by accident; postures now differ only in enforcement (ADR-0131 D11), and `single` enforces no wall. To keep organizations apart, run the `isolated` or `group` posture. Code that relied on a context organization to narrow a read on `single` names the organization in its own `where`.
+- **Migration.** ADR-0087 semantic entry `driver-read-scope-follows-tenant-wall`. A deployment's `platformGlobalObjects` carve-out already reaches the driver through the column plan (ADR-0131 D7): a declared object carries no organization column, so neither wall has anything to scope.
@@ -73,6 +73,14 @@ export {
   type RefusedEntitlementKey,
 } from './deployment-org-scoping-entitlement.js';
 
+// [ADR-0131 D8] The ONE tenant read predicate — the Layer 0 verdict that
+// plugin-security projects onto its `where` wall and the engine projects onto
+// the driver's native scope (`DriverOptions.tenantId` / `tenantIds`).
+export {
+  computeTenantLayer0Verdict,
+  type TenantLayer0Input,
+} from './tenant-layer0-verdict.js';
+
 // `PluginConfigValidator` / `createPluginConfigValidator` were RETIRED here on
 // 2026-08-27 (#11982, ADR-0049 enforce-or-remove; recorded in ADR-0025 §3.7).
 // The kernel never received a plugin's config to validate — factories close
 
@@ -0,0 +1,160 @@
+// Copyright (c) 2026 ObjectStack. Licensed under the Apache-2.0 license.
+
+import {
+  postureEnforcesWall,
+  postureUsesUnionScope,
+  type TenancyPosture,
+  type TenantLayer0Verdict,
+} from '@objectstack/spec/security';
+
+/**
+ * ── The ONE tenant read predicate (ADR-0131 D8 「一道谓词，算一次」) ──────────
+ *
+ * What the organization wall decides for one operation, computed by ONE
+ * function for both of its enforcers:
+ *
+ * - **Layer 0** (`plugin-security`'s `tenant-layer.ts`, ADR-0095 D1) projects
+ *   the verdict onto the `where` predicate it AND-composes first, and records
+ *   it on the operation (`OperationContext.tenantLayer0Verdict`, #15813);
+ * - **the engine** (`@objectstack/objectql`, `buildDriverOptions`) projects the
+ *   same verdict onto `DriverOptions.tenantId` / `tenantIds`, the driver's
+ *   native read scope — the recorded verdict where the wall ran, this function
+ *   over the engine's own facts where it did not (a system context, a by-id
+ *   write, a composition with no security layer).
+ *
+ * Before this module the engine derived the driver's scope on its own, from
+ * the active organization alone: a scope under `single`, where the wall is
+ * inert, and a scope for the exempt platform admin, whom the wall lets
+ * through — two walls, two answers. Here, so `@objectstack/objectql` and
+ * `@objectstack/plugin-security` (both already depend on this package) read
+ * one decision rather than two copies of it.
+ */
+
+/** Inputs the Layer 0 decision needs — all cheap, already-loaded facts. */
+export interface TenantLayer0Input {
+  /**
+   * [ADR-0105 D1] The tenancy posture actually IN FORCE (`tenancy.posture`) —
+   * the single fact that decides what this layer enforces:
+   *
+   * - `single`   → inert (no wall)
+   * - `group`    → `organization_id IN accessibleOrgIds` (union / MOAC)
+   * - `isolated` → `organization_id = organizationId` (the hard wall)
+   *
+   * A degraded deployment (a wall requested but not enforceable) already
+   * resolves to `single` at the service, so this layer never sees a posture it
+   * cannot honour.
+   */
+  tenancyPosture: TenancyPosture;
+  /** The resolved authz context's active organization id (`ExecutionContext.tenantId`). */
+  organizationId?: string;
+  /**
+   * [ADR-0105 D2] The caller's org access set
+   * (`ExecutionContext.accessible_org_ids`) — every organization they hold a
+   * currently-valid membership in. Read ONLY under the `group` posture, where
+   * it is the wall. An empty/absent set there denies (fail closed): a principal
+   * with no membership has no group data reach.
+   */
+  accessibleOrgIds?: readonly string[];
+  /**
+   * Whether the object carries an `organization_id` column. `undefined` = the
+   * schema/field-set could not be resolved yet (boot); treated as "assume tenant
+   * object" so a not-yet-registered object still fails safe toward isolation
+   * (parity with the pre-extraction path, which kept the wildcard tenant policy
+   * when the field set was unavailable).
+   */
+  objectHasOrgIdField?: boolean;
+  /**
+   * Whether the object opted out of tenancy (`tenancy.enabled === false` or
+   * `systemFields.tenant === false`) — a platform-global object. Such objects
+   * are NOT tenant objects; Layer 0 contributes nothing.
+   */
+  tenancyDisabled: boolean;
+  /**
+   * Whether the object's POSTURE permits a platform admin to cross the tenant
+   * wall — `private`, platform-global (`tenancy.enabled:false`), or
+   * better-auth-managed (exactly the ADR-0066 ① gate). Business (public) tenant
+   * objects do NOT permit it, so a platform admin stays org-scoped on them.
+   */
+  posturePermitsCrossTenant: boolean;
+  /**
+   * TRUE-platform-admin evidence (ADR-0095 D3 `PLATFORM_ADMIN` rung) for THIS
+   * operation side. This is the ONLY gate that lets a caller cross the tenant
+   * wall, so it MUST distinguish a PLATFORM operator from a TENANT `org_admin`.
+   *
+   * It is NOT merely the superuser bit (`viewAllRecords`/`modifyAllRecords`):
+   * `organization_admin` holds that bit via its `'*'` wildcard grant
+   * (`default-permission-sets.ts`), so gating the exemption on the superuser bit
+   * alone let an org admin cross the wall on a `private` (or platform-global /
+   * better-auth) TENANT object — the D1 "B2 posture stand-in" gap this field's
+   * former semantics carried. The caller now requires the superuser bit AND a
+   * platform-EXCLUSIVE capability (`manage_metadata`/`manage_platform_settings`/
+   * `studio.access`/`manage_users` — the caps `admin_full_access` carries and
+   * `organization_admin` deliberately withholds), i.e. the `PLATFORM_ADMIN`
+   * posture. It is NEVER the better-auth role. A caller holding no permission
+   * sets (the engine, over its own facts) passes `false`.
+   */
+  isPlatformAdmin: boolean;
+}
+
+/** The two verdicts that carry no organization — shared, frozen, safe to hand out. */
+const LAYER0_NONE: TenantLayer0Verdict = Object.freeze({ kind: 'none' as const });
+const LAYER0_DENY: TenantLayer0Verdict = Object.freeze({ kind: 'deny' as const });
+
+/**
+ * [#15813 / ADR-0131 D8] Compute the Layer 0 VERDICT — what the wall decides
+ * for this operation, as a value another package can read without re-deriving
+ * it (`TenantLayer0VerdictSchema`, `@objectstack/spec/security`).
+ * `computeTenantLayer0Filter` (plugin-security) is this verdict PROJECTED onto
+ * a `where` predicate; the engine's driver scope is the same verdict projected
+ * onto `DriverOptions`. Neither can disagree with the other, because both are
+ * derived from this verdict, never computed beside it.
+ *
+ * The decision ladder is the wall's own, in the wall's own order: every exit
+ * that answers `null` as a filter answers `none` here, every fail-closed exit
+ * answers `deny`, and the two walled shapes answer the organization(s) they
+ * name. The `group` set is DEDUPLICATED here (`accessible_org_ids` is a
+ * membership list; a repeated membership names one organization once), so a
+ * reader may test `organizationIds.length === 1` and read no further.
+ *
+ * - `none` → the wall contributes nothing (`single` posture; non-tenant object;
+ *   or an exempt platform admin).
+ * - `organization` → the `isolated` wall, `organization_id = <id>`.
+ * - `organizations` → the `group` union wall, `organization_id IN <set>`
+ *   (ADR-0105 D2).
+ * - `deny` → a walled posture on a tenant object, but the context carries no
+ *   organization scope to enforce with (no active org under `isolated`, empty
+ *   access set under `group`) → fail closed (zero rows / write denied).
+ */
+export function computeTenantLayer0Verdict(input: TenantLayer0Input): TenantLayer0Verdict {
+  // `single` posture (incl. a degraded deployment, which resolves to `single`)
+  // → parity with today's policy stripping.
+  if (!postureEnforcesWall(input.tenancyPosture)) return LAYER0_NONE;
+
+  // Not a tenant object: platform-global (tenancy disabled) or simply carries no
+  // `organization_id` column (e.g. better-auth identity tables like `sys_user`).
+  // Layer 0 contributes nothing — the object's own business RLS (Layer 1, e.g.
+  // `_self` carve-outs) is its only scoping.
+  if (input.tenancyDisabled) return LAYER0_NONE;
+  if (input.objectHasOrgIdField === false) return LAYER0_NONE;
+
+  // Exemption is a Layer 0 rule (W2 fix): only a TRUE PLATFORM_ADMIN caller on an
+  // object whose posture permits it crosses the wall — NOT a tenant `org_admin`
+  // that merely holds the superuser bit (Finding 2 / #2937). Layer 1's superuser
+  // bypass no longer implies Layer 0's.
+  if (input.isPlatformAdmin && input.posturePermitsCrossTenant) return LAYER0_NONE;
+
+  // [ADR-0105 D2] `group`: union access over the caller's memberships (MOAC).
+  // The ACTIVE organization no longer bounds reads here — membership does — so
+  // a group-HQ analyst sees every plant they belong to on one screen without
+  // context switching, and a plant admin still sees only their own plants.
+  // An empty access set is the fail-closed case: no membership, no reach.
+  if (postureUsesUnionScope(input.tenancyPosture)) {
+    const orgIds = input.accessibleOrgIds;
+    if (!orgIds || orgIds.length === 0) return LAYER0_DENY;
+    return { kind: 'organizations', organizationIds: [...new Set(orgIds)] };
+  }
+
+  // `isolated`: the hard wall. Missing active org → fail closed.
+  if (!input.organizationId) return LAYER0_DENY;
+  return { kind: 'organization', organizationId: input.organizationId };
+}
@@ -46,21 +46,25 @@
  *
  * Seams 1 and 2 read the two STATIC signals: the deployment posture and the
  * object's own metadata. The engine's decision to scope is neither. It is
- * `Engine.buildDriverOptions`:
- *
- * ```ts
- * const hasTenant =
- *   execCtx?.tenantId !== undefined && !isTenancyDisabled(objectSchema) && !isFederated;
- * ```
- *
- * — the engine scopes unless the object opts OUT, while seam 2 refuses only an
- * explicit opt-IN. An object that OMITS the `tenancy` block falls between them:
- * the engine scopes it, seam 2 never sees it, and seam 1 passes because the
- * posture really is `single`. A `single` posture constrains the WALL, not the
- * number of organizations, so rows still carry whichever `organization_id` they
- * were written with — and this driver used to discard the scope and answer with
- * EVERY organization's rows. That is the silent non-isolation this whole guard
- * exists to remove, reappearing on the DEFAULT case.
+ * `Engine.buildDriverOptions`, and it is made per CALL: a read, update or
+ * delete is scoped by the organization wall's verdict (ADR-0131 D8 — none
+ * under `single`), and an insert or upsert carries the caller's active
+ * organization as its write target in EVERY posture, unless the object opts
+ * OUT of tenancy.
+ *
+ * Seam 2 refuses only an explicit opt-IN. An object that OMITS the `tenancy`
+ * block falls between them: the engine hands it the write target, seam 2 never
+ * sees it, and seam 1 passes because the posture really is `single`. A `single`
+ * posture constrains the WALL, not the number of organizations, so rows still
+ * carry whichever `organization_id` they were written with — and this driver
+ * used to discard the scope it was handed and answer as if it had applied it.
+ * That is the silent non-isolation this whole guard exists to remove,
+ * reappearing on the DEFAULT case.
+ *
+ * (Before ADR-0131 D8 the engine also derived a READ scope under `single` from
+ * the context's organization alone; it no longer does, because the wall it would
+ * mirror is inert there. The seam still judges whatever scope arrives, so it is
+ * unchanged by that: what no longer arrives is no longer refused.)
  *
  * Why the gap cannot be closed at seam 1 or 2 — measured, not assumed:
  * `execCtx?.tenantId !== undefined` is a property of the REQUEST, and at
@@ -183,8 +187,9 @@ export interface TenancyAwareSchema {
  * (twelve seeded by the app, one minted by the platform for the admin), with
  * rows carrying whichever `organization_id` they were written with. And the
  * omission it describes is not the absence of a tenant signal but its default
- * PRESENCE — `Engine.buildDriverOptions` scopes an object unless it opts out,
- * so "omits the block" is precisely the SCOPED case, not the exempt one.
+ * PRESENCE — `Engine.buildDriverOptions` hands an object a write target (and,
+ * under a wall, a read scope) unless it opts out, so "omits the block" is
+ * precisely the SCOPED case, not the exempt one.
  *
  * The sentence is recorded rather than deleted because it is what justified
  * this predicate being an opt-IN test, and anyone re-reading that decision needs
 
@@ -145,6 +145,10 @@ const TIERS: readonly Tier[] = ['native', 'in-memory'];
 async function makeEngine(tier: Tier) {
     const { driver, reads } = makeDriver(tier === 'native');
     const engine = new ObjectQL();
+    // [ADR-0131 D8] The `context` proof is that the caller's organization
+    // reaches the driver as its read scope — which it does only under a wall;
+    // under `single` (the env default) the scope is none.
+    engine.setTenancyPostureProvider(() => 'isolated');
     engine.registerDriver(driver, true);
     await engine.init();
     (engine.registry as any).registerObject(account);