feat(core,spec): B2+B4 — posture ladder + capability-derived posture (ADR-0095 D2/D3, #2920)

Resolve an explicit monotonic posture rung
(PLATFORM_ADMIN > TENANT_ADMIN > MEMBER > EXTERNAL) once in
resolveAuthzContext and carry it on ResolvedAuthzContext.posture.

D2 — new @objectstack/core/security module posture-ladder.ts reuses the spec
AuthzPosture enum, pins the rung -> injection-rule mapping (one rule per rung),
and locks its two ADR-required invariants as unit tests: strict nesting
(rung n's visible set superset of n-1) and EXTERNAL deny-by-default (explicit
shares only; OWD never widens it). EXTERNAL is defined/test-locked but never
resolved (no external principal type yet); the floor is MEMBER.

D3 — the rung derives from held capability grants, never a better-auth role:
PLATFORM_ADMIN from the unscoped admin_full_access grant (the same
viewAllRecords/modifyAllRecords evidence the superuser bypass trusts),
TENANT_ADMIN from the organization_admin grant. The better-auth role remains a
provisioning source only (auto-org-admin-grant.ts, mapMembershipRole); no
enforcement path adjudicates the raw role, closing the #2836 dual-track class.

Behavior-preserving: enforcement is unchanged (per-object Layer 0 exemption +
per-side superuser bypass still gate access); posture is an additive derived,
explainable field. authz-matrix-gate + dogfood authz-conformance stay green.

- spec: add ORGANIZATION_ADMIN constant; auto-org-admin-grant.ts reuses it.
- resolve-authz-context.test.ts: principal x grants -> posture matrix + nesting.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_019QRUvVfpvSycAHMMF2xTxs

Author: claude

.changeset/adr-0095-d2-d3-posture-ladder.md

@@ -0,0 +1,34 @@
+---
+"@objectstack/core": minor
+"@objectstack/spec": minor
+---
+
+ADR-0095 D2/D3: the authorization kernel now resolves an explicit **posture
+ladder** — a monotonic principal tier `PLATFORM_ADMIN > TENANT_ADMIN > MEMBER >
+EXTERNAL` — once, in `resolveAuthzContext`, and carries it on
+`ResolvedAuthzContext.posture`.
+
+- **D2 — the ladder.** New `@objectstack/core/security` module `posture-ladder.ts`
+  reuses the spec `AuthzPosture` enum and pins the rung → row-visibility
+  injection-rule mapping (exactly one rule per rung) plus its two ADR-required
+  invariants as unit-tested properties: strict nesting (rung *n*'s visible set ⊇
+  rung *n−1*'s) and the `EXTERNAL` deny-by-default semantics (explicitly shared
+  rows only — OWD baselines and sharing rules never widen it). `EXTERNAL` is
+  defined and test-locked now but never resolved: no external principal type
+  exists yet (portal/ADR-0093), so the resolver's floor is `MEMBER`.
+- **D3 — capability-derived, single track.** The rung derives from held
+  **capability grants**, never a better-auth role: `PLATFORM_ADMIN` from the
+  unscoped `admin_full_access` grant (the same `viewAllRecords`/`modifyAllRecords`
+  evidence the superuser bypass trusts), `TENANT_ADMIN` from the
+  `organization_admin` grant. The better-auth `role='admin'` remains only a
+  *provisioning source* of those grants (`auto-org-admin-grant.ts`,
+  `mapMembershipRole`); no enforcement path reads the raw role, closing the
+  #2836 dual-track adjudication class by construction.
+- New spec export `ORGANIZATION_ADMIN` (the org-admin capability-grant name),
+  alongside the existing `ADMIN_FULL_ACCESS`.
+
+**Behavior-preserving.** Enforcement is unchanged — the per-object Layer 0
+exemption and per-side superuser bypass still gate access exactly as before;
+`posture` is an additive, derived, explainable field. The `authz-matrix-gate`
+unit snapshot and the dogfood authz-conformance matrix stay green. No migration
+required.

packages/core/src/security/index.ts

@@ -87,6 +87,19 @@ export {
   type ResolveAuthzInput,
   type ResolveLocalizationInput,
 } from './resolve-authz-context.js';
+
+// ADR-0095 D2/D3 — the monotonic posture ladder: derivation from capability
+// grants + the rung→injection-rule mapping and its tested invariants.
+export {
+  POSTURE_LADDER,
+  POSTURE_RANK,
+  POSTURE_INJECTION_RULE,
+  derivePosture,
+  postureVisibleRows,
+  type PostureEvidence,
+  type LadderRow,
+  type LadderPrincipal,
+} from './posture-ladder.js';
 export { isAuthGateAllowlisted, evaluateAuthGate, type AuthGate } from './auth-gate.js';
 
 // ADR-0091 D1/D2 — grant validity windows, the shared resolution-time predicate.

packages/core/src/security/posture-ladder.test.ts

@@ -0,0 +1,122 @@
+// Copyright (c) 2026 ObjectStack. Licensed under the Apache-2.0 license.
+
+import { describe, it, expect } from 'vitest';
+import type { AuthzPosture } from '@objectstack/spec/security';
+import {
+  POSTURE_LADDER,
+  POSTURE_RANK,
+  POSTURE_INJECTION_RULE,
+  derivePosture,
+  postureVisibleRows,
+  type LadderRow,
+  type LadderPrincipal,
+} from './posture-ladder.js';
+
+/**
+ * ADR-0095 D2/D3 posture-ladder invariants. This file locks the two properties
+ * the ADR requires as TESTED invariants — strict nesting and EXTERNAL
+ * deny-by-default — plus the capability-only derivation (never a role). The
+ * end-to-end row behavior is guarded separately by plugin-security's
+ * `authz-matrix-gate` and the dogfood conformance matrix; here we assert the
+ * ladder's mathematical shape.
+ */
+
+// ── Reference dataset: one principal, escalating posture ─────────────────────
+// p is a member of org-1. The dataset is chosen so each rung STRICTLY adds rows.
+const p: LadderPrincipal = { userId: 'u1', organizationId: 'org-1' };
+const ROWS: LadderRow[] = [
+  { id: 'r1', organization_id: 'org-1', owner_id: 'u1' },                 // owned by p       → MEMBER+
+  { id: 'r2', organization_id: 'org-1', owner_id: 'u2', owdVisible: true }, // OWD baseline   → MEMBER+
+  { id: 'r3', organization_id: 'org-1', owner_id: 'u2', owdVisible: false }, // in-org, hidden → TENANT_ADMIN+
+  { id: 'r4', organization_id: 'org-1', owner_id: 'u2', sharedTo: ['u1'] },  // shared to p    → EXTERNAL+/MEMBER+
+  { id: 'r5', organization_id: 'org-2', owner_id: 'u3' },                    // foreign org    → PLATFORM_ADMIN+
+];
+
+const idsOf = (rows: LadderRow[]) => new Set(rows.map((r) => r.id));
+const isSuperset = (big: Set<string>, small: Set<string>) => [...small].every((x) => big.has(x));
+
+describe('AuthzPosture ladder — ordering (ADR-0095 D2)', () => {
+  it('POSTURE_LADDER is high→low and POSTURE_RANK is strictly monotonic', () => {
+    expect(POSTURE_LADDER).toEqual(['PLATFORM_ADMIN', 'TENANT_ADMIN', 'MEMBER', 'EXTERNAL']);
+    expect(POSTURE_RANK).toEqual({ PLATFORM_ADMIN: 3, TENANT_ADMIN: 2, MEMBER: 1, EXTERNAL: 0 });
+    for (let i = 1; i < POSTURE_LADDER.length; i++) {
+      expect(POSTURE_RANK[POSTURE_LADDER[i - 1]]).toBeGreaterThan(POSTURE_RANK[POSTURE_LADDER[i]]);
+    }
+  });
+
+  it('every rung maps to exactly one injection rule', () => {
+    for (const rung of POSTURE_LADDER) {
+      expect(typeof POSTURE_INJECTION_RULE[rung]).toBe('string');
+      expect(POSTURE_INJECTION_RULE[rung].length).toBeGreaterThan(0);
+    }
+    expect(Object.keys(POSTURE_INJECTION_RULE).sort()).toEqual([...POSTURE_LADDER].sort());
+  });
+});
+
+describe('AuthzPosture ladder — strict nesting invariant (ADR-0095 D2)', () => {
+  it('visible(rung n) ⊇ visible(rung n−1) for every adjacent pair, strictly here', () => {
+    const visible: Record<AuthzPosture, Set<string>> = {
+      EXTERNAL: idsOf(postureVisibleRows('EXTERNAL', ROWS, p)),
+      MEMBER: idsOf(postureVisibleRows('MEMBER', ROWS, p)),
+      TENANT_ADMIN: idsOf(postureVisibleRows('TENANT_ADMIN', ROWS, p)),
+      PLATFORM_ADMIN: idsOf(postureVisibleRows('PLATFORM_ADMIN', ROWS, p)),
+    };
+
+    // The concrete visible sets for this dataset (documents the ladder).
+    expect(visible.EXTERNAL).toEqual(new Set(['r4']));
+    expect(visible.MEMBER).toEqual(new Set(['r1', 'r2', 'r4']));
+    expect(visible.TENANT_ADMIN).toEqual(new Set(['r1', 'r2', 'r3', 'r4']));
+    expect(visible.PLATFORM_ADMIN).toEqual(new Set(['r1', 'r2', 'r3', 'r4', 'r5']));
+
+    // Superset chain (⊇) AND strict growth (⊋) up the ladder — from low rank up.
+    const lowToHigh = [...POSTURE_LADDER].reverse(); // EXTERNAL → PLATFORM_ADMIN
+    for (let i = 1; i < lowToHigh.length; i++) {
+      const lower = visible[lowToHigh[i - 1]];
+      const higher = visible[lowToHigh[i]];
+      expect(isSuperset(higher, lower)).toBe(true);           // ⊇ (the invariant)
+      expect(higher.size).toBeGreaterThan(lower.size);        // ⊋ (this dataset)
+    }
+  });
+});
+
+describe('AuthzPosture ladder — EXTERNAL semantics lock (ADR-0095 D2)', () => {
+  it('EXTERNAL sees ONLY explicitly shared rows — OWD never widens it', () => {
+    // A principal with zero shares sees nothing, even though r2 is OWD-visible.
+    const stranger: LadderPrincipal = { userId: 'ext-1', organizationId: 'org-1' };
+    expect(postureVisibleRows('EXTERNAL', ROWS, stranger)).toEqual([]);
+
+    // Make EVERY row OWD-visible: EXTERNAL is still empty for the stranger —
+    // a permissive OWD baseline cannot widen an external principal's visibility.
+    const allPublic = ROWS.map((r) => ({ ...r, owdVisible: true }));
+    expect(postureVisibleRows('EXTERNAL', allPublic, stranger)).toEqual([]);
+
+    // The only source is explicit shares: p sees exactly the row shared to p.
+    const seen = postureVisibleRows('EXTERNAL', allPublic, p);
+    expect(seen.map((r) => r.id)).toEqual(['r4']);
+    expect(seen.every((r) => (r.sharedTo ?? []).includes(p.userId))).toBe(true);
+  });
+
+  it('a misconfiguration can only SHRINK external visibility, never widen it', () => {
+    // Dropping a share removes exactly that row; nothing else appears.
+    const withoutShare = ROWS.map((r) => (r.id === 'r4' ? { ...r, sharedTo: [] } : r));
+    expect(postureVisibleRows('EXTERNAL', withoutShare, p)).toEqual([]);
+  });
+});
+
+describe('AuthzPosture — derivation from capability grants only (ADR-0095 D3)', () => {
+  it('maps held capability grants to a rung; platform wins over tenant', () => {
+    expect(derivePosture({ isPlatformAdmin: true, isTenantAdmin: false })).toBe('PLATFORM_ADMIN');
+    expect(derivePosture({ isPlatformAdmin: true, isTenantAdmin: true })).toBe('PLATFORM_ADMIN');
+    expect(derivePosture({ isPlatformAdmin: false, isTenantAdmin: true })).toBe('TENANT_ADMIN');
+    expect(derivePosture({ isPlatformAdmin: false, isTenantAdmin: false })).toBe('MEMBER');
+  });
+
+  it('never derives EXTERNAL (no external principal type exists yet)', () => {
+    const combos: Array<[boolean, boolean]> = [
+      [true, true], [true, false], [false, true], [false, false],
+    ];
+    for (const [isPlatformAdmin, isTenantAdmin] of combos) {
+      expect(derivePosture({ isPlatformAdmin, isTenantAdmin })).not.toBe('EXTERNAL');
+    }
+  });
+});

packages/core/src/security/posture-ladder.ts

@@ -0,0 +1,192 @@
+// Copyright (c) 2026 ObjectStack. Licensed under the Apache-2.0 license.
+
+/**
+ * ── The monotonic posture ladder (ADR-0095 D2/D3) ───────────────────────────
+ *
+ * The principal-tiering enum resolved ONCE in `resolveAuthzContext`
+ * (`PLATFORM_ADMIN > TENANT_ADMIN > MEMBER > EXTERNAL`). This module owns two
+ * things and deliberately nothing more:
+ *
+ *  1. **Derivation (D3).** {@link derivePosture} maps held *capability grants*
+ *     — never a better-auth role — to a rung. `PLATFORM_ADMIN` derives from the
+ *     unscoped `admin_full_access` grant (the `viewAllRecords`/`modifyAllRecords`
+ *     evidence the superuser bypass already trusts); `TENANT_ADMIN` from the
+ *     `organization_admin` grant. The better-auth `role='admin'` is upstream a
+ *     *provisioning source* of those grants (`auto-org-admin-grant.ts`), so it
+ *     never re-enters adjudication here — the #2836 dual-track class is closed
+ *     by construction.
+ *
+ *  2. **The rung → injection-rule mapping + its tested invariants (D2).** Each
+ *     rung maps to EXACTLY ONE row-visibility injection rule
+ *     ({@link POSTURE_INJECTION_RULE}). {@link postureVisibleRows} is the
+ *     REFERENCE MODEL of those rules over a synthetic row-set — it locks the two
+ *     properties the ADR requires as invariants: strict nesting (rung n's
+ *     visible set ⊇ rung n−1's) and the EXTERNAL deny-by-default semantics
+ *     (explicit shares only, OWD never widens it).
+ *
+ * This module is NOT the enforcement path. The effective read/write filter is
+ * `Layer0(tenant) AND Layer1(business RLS)`, computed in `@objectstack/plugin-
+ * security` (`tenant-layer.ts` + `security-plugin.ts`), and the real behavior
+ * guard is the `authz-matrix-gate` unit snapshot + the dogfood conformance
+ * matrix. The reference model here exists so the ladder's *mathematical*
+ * properties can be asserted at the unit layer without an enforcement boot, and
+ * so the EXTERNAL rung — which has no enforcement path yet — cannot be
+ * reinvented differently when portal/external membership arrives.
+ */
+
+import type { AuthzPosture } from '@objectstack/spec/security';
+
+/**
+ * The rung ordering, high privilege → low, matching the spec enum's numeric
+ * values (`PLATFORM_ADMIN=3 … EXTERNAL=0`). Visibility grows monotonically UP
+ * this ladder (see {@link postureVisibleRows}).
+ */
+export const POSTURE_LADDER = [
+  'PLATFORM_ADMIN',
+  'TENANT_ADMIN',
+  'MEMBER',
+  'EXTERNAL',
+] as const satisfies readonly AuthzPosture[];
+
+/** Numeric rank per rung (mirrors the spec `AuthzPosture` enum values). */
+export const POSTURE_RANK: Record<AuthzPosture, number> = {
+  PLATFORM_ADMIN: 3,
+  TENANT_ADMIN: 2,
+  MEMBER: 1,
+  EXTERNAL: 0,
+};
+
+/**
+ * The ONE row-visibility injection rule each rung maps to (ADR-0095 D2). Prose,
+ * because the machine artifacts live in enforcement (Layer 0 + the per-rung
+ * Layer 1 rule); this is the enumerable contract the explain track reports and
+ * {@link postureVisibleRows} models.
+ */
+export const POSTURE_INJECTION_RULE: Record<AuthzPosture, string> = {
+  PLATFORM_ADMIN:
+    'Layer 0 exemption where the object posture permits (private / platform-global / better-auth-managed) — crosses the tenant wall; org-scoped like TENANT_ADMIN on ordinary tenant business objects.',
+  TENANT_ADMIN:
+    'All rows within the active organization (organization_id == ctx.tenantId); no ownership / depth / sharing narrowing.',
+  MEMBER:
+    'Business RLS within the organization — ownership (owner / unit depth), the OWD baseline, and explicit sharing.',
+  EXTERNAL:
+    'Explicitly shared rows ONLY — OWD baselines and sharing rules never apply; a misconfiguration can only shrink visibility, never widen it.',
+};
+
+/** Capability-grant evidence the posture derivation consumes (ADR-0095 D3). */
+export interface PostureEvidence {
+  /**
+   * Holds the UNSCOPED platform-admin capability grant (`admin_full_access` →
+   * `viewAllRecords`/`modifyAllRecords`) — the same evidence the superuser
+   * bypass trusts. NOT a better-auth role.
+   */
+  isPlatformAdmin: boolean;
+  /**
+   * Holds the org-admin capability grant (`organization_admin`, tenant-scoped
+   * `viewAllRecords`/`modifyAllRecords`). Provisioned from the better-auth
+   * owner/admin role upstream, consumed here only as a held capability.
+   */
+  isTenantAdmin: boolean;
+}
+
+/**
+ * Resolve the principal's posture rung from held capability grants (ADR-0095 D3).
+ *
+ * Returns `PLATFORM_ADMIN` | `TENANT_ADMIN` | `MEMBER`. It NEVER returns
+ * `EXTERNAL`: no external principal type exists yet (the sharing chain has no
+ * portal/guest-share concept — ADR-0095 W4). The `EXTERNAL` rung, its injection
+ * rule, and its semantics are defined and test-locked ({@link postureVisibleRows},
+ * {@link POSTURE_INJECTION_RULE}) so that when portal/external membership lands
+ * (ADR-0093) the derivation gains an EXTERNAL branch HERE without the rung being
+ * reinvented. `MEMBER` is the authenticated-principal floor.
+ */
+export function derivePosture(evidence: PostureEvidence): AuthzPosture {
+  if (evidence.isPlatformAdmin) return 'PLATFORM_ADMIN';
+  if (evidence.isTenantAdmin) return 'TENANT_ADMIN';
+  return 'MEMBER';
+}
+
+// ── Reference visibility model (invariant lock, NOT enforcement) ─────────────
+
+/** A synthetic record for the ladder reference model. */
+export interface LadderRow {
+  id: string;
+  /** The row's tenant. `undefined` = a non-tenant (platform-global) row. */
+  organization_id?: string;
+  /** The row's owner (drives the MEMBER ownership disjunct). */
+  owner_id?: string;
+  /**
+   * Whether an OWD-derived source would admit this row for a member (public
+   * baseline / criteria sharing). EXTERNAL deliberately ignores this field.
+   */
+  owdVisible?: boolean;
+  /** User ids this row is EXPLICITLY shared to (the only EXTERNAL source). */
+  sharedTo?: readonly string[];
+}
+
+/** The principal the reference model evaluates a rung for. */
+export interface LadderPrincipal {
+  userId: string;
+  /** The principal's active organization (undefined for an unscoped principal). */
+  organizationId?: string;
+}
+
+function isSharedTo(row: LadderRow, userId: string): boolean {
+  return (row.sharedTo ?? []).includes(userId);
+}
+
+/** EXTERNAL rung: explicitly shared rows ONLY — never OWD, never org-wide. */
+function externalVisible(rows: readonly LadderRow[], p: LadderPrincipal): LadderRow[] {
+  return rows.filter((r) => isSharedTo(r, p.userId));
+}
+
+/**
+ * MEMBER rung: business RLS within the org — ownership OR OWD baseline OR
+ * explicit sharing. Composed as `EXTERNAL ∪ (in-org ownership/OWD)` so the
+ * EXTERNAL ⊆ MEMBER leg of the nesting invariant holds by construction.
+ */
+function memberVisible(rows: readonly LadderRow[], p: LadderPrincipal): LadderRow[] {
+  const shared = new Set(externalVisible(rows, p));
+  return rows.filter(
+    (r) =>
+      shared.has(r) ||
+      (r.organization_id === p.organizationId && (r.owner_id === p.userId || r.owdVisible === true)),
+  );
+}
+
+/**
+ * TENANT_ADMIN rung: all rows in the active organization. Composed as
+ * `MEMBER ∪ (all in-org)` so MEMBER ⊆ TENANT_ADMIN holds by construction.
+ */
+function tenantAdminVisible(rows: readonly LadderRow[], p: LadderPrincipal): LadderRow[] {
+  const member = new Set(memberVisible(rows, p));
+  return rows.filter((r) => member.has(r) || r.organization_id === p.organizationId);
+}
+
+/** PLATFORM_ADMIN rung: crosses the tenant wall — every row (⊇ TENANT_ADMIN trivially). */
+function platformAdminVisible(rows: readonly LadderRow[]): LadderRow[] {
+  return [...rows];
+}
+
+/**
+ * Reference model of the per-rung injection rule: the visible-row set a rung
+ * would resolve to over `rows` for `principal`. Used to lock the ADR-0095 D2
+ * invariants (strict nesting + EXTERNAL deny-by-default). NOT an enforcement
+ * path — see the module header.
+ */
+export function postureVisibleRows(
+  posture: AuthzPosture,
+  rows: readonly LadderRow[],
+  principal: LadderPrincipal,
+): LadderRow[] {
+  switch (posture) {
+    case 'PLATFORM_ADMIN':
+      return platformAdminVisible(rows);
+    case 'TENANT_ADMIN':
+      return tenantAdminVisible(rows, principal);
+    case 'MEMBER':
+      return memberVisible(rows, principal);
+    case 'EXTERNAL':
+      return externalVisible(rows, principal);
+  }
+}