fix(authz): carry derived posture rung on ExecutionContext (#2947) (#2956)

The ADR-0095 D2 posture ladder is derived once by the shared authz resolver
from capability grants, but both entry points that build the ExecutionContext
(rest-server, runtime resolveExecutionContext) dropped it — so any
enforcement-side reader of context.posture always saw undefined (the same drop
that forced the explain layer to re-derive it, #2949).

- spec: ExecutionContextSchema gains an optional `posture` field (reuses
  AuthzPostureSchema; no api-surface change — schema tracked as a const).
- rest + runtime: plumb authz.posture through when present.
- tests: assert PLATFORM_ADMIN / MEMBER are carried and guest stays unset.

Additive and behavior-preserving: no enforcement decision consumes posture yet.


Claude-Session: https://claude.ai/code/session_019QRUvVfpvSycAHMMF2xTxs

Co-authored-by: Claude <noreply@anthropic.com>

Author: os-zhuang

.changeset/authz-2947-posture-plumb.md

@@ -0,0 +1,20 @@
+---
+'@objectstack/spec': minor
+'@objectstack/runtime': patch
+'@objectstack/rest': patch
+---
+
+fix(authz): carry the derived posture rung on ExecutionContext (#2947)
+
+The ADR-0095 D2 posture ladder (`PLATFORM_ADMIN > TENANT_ADMIN > MEMBER >
+EXTERNAL`) is derived once by the shared authz resolver from capability grants,
+but both HTTP/MCP entry points that build the `ExecutionContext` dropped it —
+so any enforcement-side reader of `context.posture` always saw `undefined`
+(the same drop that forced the explain layer to re-derive it, #2949).
+
+`ExecutionContextSchema` now carries an optional `posture` field, and both
+`rest-server` and the runtime `resolveExecutionContext` plumb the resolver's
+value through. Additive and **behavior-preserving**: no enforcement decision
+consumes `posture` yet — whether the hot path evaluates *by* posture remains a
+larger ADR-level decision — this only stops the already-computed value from
+being discarded, so enforcement and explain read the same derived rung.

packages/rest/src/rest-server.ts

@@ -1202,6 +1202,10 @@ export class RestServer {
                 permissions: authz.permissions,
                 systemPermissions: authz.systemPermissions,
                 ...(authz.tabPermissions ? { tabPermissions: authz.tabPermissions } : {}),
+                // [ADR-0095 D2 / #2947] Carry the derived posture rung so the
+                // enforcement side reads the SAME value the resolver computed,
+                // instead of dropping it here (the boundary this issue closes).
+                ...(authz.posture ? { posture: authz.posture } : {}),
                 isSystem: false,
                 org_user_ids: authz.org_user_ids,
                 ...(authGate ? { authGate } : {}),

packages/runtime/src/security/resolve-execution-context.test.ts

@@ -323,6 +323,9 @@ describe('resolveExecutionContext — platform-scoped (null-org) grants (ADR-006
     expect(ctx.tenantId).toBe('orgA');
     expect(ctx.permissions).toContain('admin_full_access');
     expect(ctx.systemPermissions).toContain('manage_platform_settings');
+    // [#2947] the derived posture rung is now CARRIED on the ctx (previously
+    // dropped at this entry). An unscoped admin_full_access grant → PLATFORM_ADMIN.
+    expect(ctx.posture).toBe('PLATFORM_ADMIN');
   });
 
   it('still drops a grant scoped to a DIFFERENT org', async () => {
@@ -334,6 +337,60 @@ describe('resolveExecutionContext — platform-scoped (null-org) grants (ADR-006
   });
 });
 
+// ---------------------------------------------------------------------------
+// [#2947 / ADR-0095 D2] The derived posture rung must be CARRIED down the HTTP /
+// MCP entry, not dropped. The rung itself is derived from CAPABILITY grants by
+// the shared authz resolver (asserted exhaustively in the posture-ladder tests);
+// here we only prove the value survives the ExecutionContext construction — i.e.
+// the enforcement side reads the SAME value the resolver computed.
+// ---------------------------------------------------------------------------
+describe('resolveExecutionContext — posture plumbing (#2947)', () => {
+  const RAW = 'osk_posture';
+  function makeQlFor(permissionSets: any[], userPermSets: any[]) {
+    const tables: Record<string, any[]> = {
+      sys_api_key: [{ id: 'k1', key: hashApiKey(RAW), revoked: false, user_id: 'u1', organization_id: 'orgA', expires_at: FUTURE }],
+      sys_member: [{ user_id: 'u1', organization_id: 'orgA', role: 'member' }],
+      sys_user_permission_set: userPermSets,
+      sys_permission_set: permissionSets,
+      sys_position: [], sys_position_permission_set: [], sys_user_position: [],
+    };
+    return {
+      async find(object: string, opts: any) {
+        const rows = tables[object] ?? [];
+        const where = opts?.where ?? {};
+        return rows.filter((row) => {
+          for (const [k, v] of Object.entries(where)) {
+            if (v !== null && typeof v === 'object') {
+              if (Array.isArray((v as any).$in) && !(v as any).$in.includes(row[k])) return false;
+              continue;
+            }
+            if ((v ?? null) !== (row[k] ?? null)) return false;
+          }
+          return true;
+        });
+      },
+    };
+  }
+  const opts = (ql: any) => ({ getService: async () => undefined, getQl: async () => ql, request: { headers: { 'x-api-key': RAW } } });
+
+  it('carries MEMBER for an ordinary principal (no admin / org-admin capability)', async () => {
+    const ql = makeQlFor(
+      [{ id: 'ps_basic', name: 'sales_rep', system_permissions: '[]', object_permissions: '{}' }],
+      [{ id: 'ups1', user_id: 'u1', permission_set_id: 'ps_basic', organization_id: null }],
+    );
+    const ctx = await resolveExecutionContext(opts(ql));
+    expect(ctx.userId).toBe('u1');
+    expect(ctx.permissions).not.toContain('admin_full_access');
+    expect(ctx.posture).toBe('MEMBER');
+  });
+
+  it('leaves posture UNSET for an anonymous (guest) request — no principal, no rung', async () => {
+    const ctx = await resolveExecutionContext(makeOpts([], {}));
+    expect(ctx.userId).toBeUndefined();
+    expect(ctx.posture).toBeUndefined();
+  });
+});
+
 describe('principal taxonomy at the HTTP entry (ADR-0090 D9/D10)', () => {
   it('a sessionless request resolves as a guest principal holding only the guest position', async () => {
     const ctx = await resolveExecutionContext(makeOpts([], {}));

packages/runtime/src/security/resolve-execution-context.ts

@@ -203,6 +203,10 @@ export async function resolveExecutionContext(opts: ResolveOptions): Promise<Exe
   if (authz.email) ctx.email = authz.email;
   if (authz.accessToken) ctx.accessToken = authz.accessToken;
   if (authz.tabPermissions) ctx.tabPermissions = authz.tabPermissions;
+  // [ADR-0095 D2 / #2947] Carry the derived posture rung down the runtime /
+  // MCP entry too, so this path and the REST path present enforcement the same
+  // value. Present only for an authenticated principal (guest → absent).
+  if (authz.posture) ctx.posture = authz.posture;
   (ctx as any).org_user_ids = authz.org_user_ids;
 
   // OAuth provenance: surface the token's granted scopes so the MCP

packages/spec/src/kernel/execution-context.zod.ts

@@ -18,6 +18,7 @@ import { z } from 'zod';
  *   engine.find('account', { context: { userId: '...', tenantId: '...' } })
  */
 import { lazySchema } from '../shared/lazy-schema';
+import { AuthzPostureSchema } from '../security/explain.zod';
 export const ExecutionContextSchema = lazySchema(() => z.object({
   /** Current user ID (resolved from session) */
   userId: z.string().optional(),
@@ -92,6 +93,19 @@ export const ExecutionContextSchema = lazySchema(() => z.object({
    */
   audience: z.enum(['internal', 'external']).optional(),
 
+  /**
+   * [ADR-0095 D2/B2 — posture ladder] The monotonic authorization rung the
+   * principal evaluated at (`PLATFORM_ADMIN > TENANT_ADMIN > MEMBER > EXTERNAL`),
+   * derived once by the shared authz resolver from capability grants — never a
+   * better-auth role. Carried here so enforcement/explain read the SAME derived
+   * value instead of each re-deriving it (the divergence #2949 patched at the
+   * explain boundary; #2947 closes the enforcement-boundary drop). Additive and
+   * behavior-preserving: no enforcement decision consumes it yet — whether the
+   * hot path evaluates BY posture is a larger ADR-level decision. Absent for
+   * contexts resolved before the ladder existed or where no principal resolved.
+   */
+  posture: AuthzPostureSchema.optional(),
+
   /**
    * [ADR-0090 D10 — P1 shape] Delegation link for agent/service principals
    * acting on behalf of a user. Agent effective permission = the agent's own