diff --git a/‎.changeset/18785-one-permission-fold.md‎
Lines changed: 12 additions & 0 deletions b/‎.changeset/18785-one-permission-fold.md‎
Lines changed: 12 additions & 0 deletions
diff --git a/‎packages/lint/src/build-access-matrix.test.ts‎
Lines changed: 120 additions & 0 deletions b/‎packages/lint/src/build-access-matrix.test.ts‎
Lines changed: 120 additions & 0 deletions
diff --git a/‎packages/lint/src/build-access-matrix.ts‎
Lines changed: 22 additions & 5 deletions b/‎packages/lint/src/build-access-matrix.ts‎
Lines changed: 22 additions & 5 deletions
diff --git a/‎packages/plugins/plugin-security/src/permission-evaluator.test.ts‎
Lines changed: 177 additions & 0 deletions b/‎packages/plugins/plugin-security/src/permission-evaluator.test.ts‎
Lines changed: 177 additions & 0 deletions
@@ -0,0 +1,12 @@
+---
+"@objectstack/lint": patch
+"@objectstack/plugin-security": patch
+---
+
+`PermissionEvaluator.checkObjectPermission` and `buildAccessMatrix` now ASK `@objectstack/spec`'s `objectPermissionGrants` instead of restating the super-user fold — one rule, one definition (#18785).
+
+"Does this effective object permission grant this verb?" had three independent implementations: the spec helper published in 17.4, the enforcement door in `@objectstack/plugin-security`, and the access-matrix snapshot in `@objectstack/lint`. A differential over the full input space — every declared object-permission bit (`allowCreate` / `allowRead` / `allowEdit` / `allowDelete` / `allowTransfer` / `allowExport` / `viewAllRecords` / `modifyAllRecords`) in all three authorable states, 6561 entries by 6 verbs — found **zero** disagreements, so this is a structural convergence and **no behaviour changes**.
+
+- **No API change, no bit changes meaning.** The read bypass is still `viewAllRecords || modifyAllRecords`, the write bypass is still `modifyAllRecords` alone, `allowCreate` still has no super-user bypass, and `export` is still `grant ∧ read`.
+- **The export door keeps its cross-set shape.** `checkObjectPermission('export', …)` still asks `(∃ set granting export) ∧ (∃ set granting read)` across the resolved set list — the same answer the `/me/permissions` most-permissive merge hands the client. Folding it per set would have narrowed the door.
+- **Both consumers are pinned to the fold independently of the helper**, so a change to one cell of `objectPermissionGrants` reddens them rather than propagating silently.
@@ -76,3 +76,123 @@ describe('diffAccessMatrix (semantic review lines)', () => {
     expect(lines.some((l) => l.includes('record baseline (OWD): private → public_read_write'))).toBe(true);
   });
 });
+
+/*
+ * [#18785] The CRUD columns are the SPEC's fold, asked — this is the pin that
+ * says so.
+ *
+ * `buildAccessMatrix` used to restate the super-user fold inline. The rule —
+ * "does this effective object permission grant this verb?" — is stated once in
+ * `@objectstack/spec`'s `objectPermissionGrants`, and the enforcement door
+ * (`PermissionEvaluator.checkObjectPermission`) asks the same function, so the
+ * snapshot a human signs off cannot drift away from the 403 the server hands
+ * out.
+ *
+ * ⚠️ The expectation below is written INDEPENDENTLY of the spec helper, from
+ * the rule as the card states it: read bypasses on `viewAllRecords ||
+ * modifyAllRecords`; write bypasses on `modifyAllRecords` alone and NEVER
+ * create. Comparing the matrix against `objectPermissionGrants` instead would
+ * be a tautology — both sides would move together and the pin would survive any
+ * change to the fold. This way an ablation of one spec cell reddens it.
+ *
+ * The enumeration is exhaustive over the declared object-permission bits, in
+ * all three authorable states (`true` / `false` / absent), because every
+ * implementation compares with `=== true` and absence is what an author
+ * produces by omission.
+ */
+const FOLD_BITS = [
+  'allowCreate', 'allowDelete', 'allowEdit', 'allowExport',
+  'allowRead', 'allowTransfer', 'modifyAllRecords', 'viewAllRecords',
+] as const;
+const BIT_STATES: Array<boolean | undefined> = [true, false, undefined];
+
+/** The fold, restated from the rule — deliberately NOT the spec helper. */
+function referenceFold(p: Record<string, unknown>, verb: 'create' | 'read' | 'edit' | 'delete'): boolean {
+  const modifyAll = p.modifyAllRecords === true;
+  switch (verb) {
+    case 'create': return p.allowCreate === true;
+    case 'read': return p.allowRead === true || p.viewAllRecords === true || modifyAll;
+    case 'edit': return p.allowEdit === true || modifyAll;
+    case 'delete': return p.allowDelete === true || modifyAll;
+  }
+}
+
+function enumerateEntries(): Array<Record<string, unknown>> {
+  const out: Array<Record<string, unknown>> = [];
+  const total = BIT_STATES.length ** FOLD_BITS.length;
+  for (let i = 0; i < total; i++) {
+    const entry: Record<string, unknown> = {};
+    let n = i;
+    for (const bit of FOLD_BITS) {
+      const s = BIT_STATES[n % BIT_STATES.length];
+      n = Math.floor(n / BIT_STATES.length);
+      if (s !== undefined) entry[bit] = s;
+    }
+    out.push(entry);
+  }
+  return out;
+}
+
+describe('buildAccessMatrix CRUD columns — the spec fold, asked (#18785)', () => {
+  it('named cells: the fold as the rule states it', () => {
+    const m = buildAccessMatrix({
+      objects: [{ name: 'o' }],
+      permissions: [
+        { name: 'vad', objects: { o: { viewAllRecords: true } } },
+        { name: 'mad', objects: { o: { modifyAllRecords: true } } },
+        { name: 'none', objects: { o: {} } },
+      ],
+    });
+    const row = (ps: string) => m.entries.find((e) => e.permissionSet === ps)!;
+    // READ bypasses on either super-user bit.
+    expect(row('vad').read).toBe(true);
+    expect(row('mad').read).toBe(true);
+    // WRITE bypasses on Modify All Data ALONE — View All Data is a read power.
+    expect(row('mad').edit).toBe(true);
+    expect(row('mad').delete).toBe(true);
+    expect(row('vad').edit).toBe(false);
+    expect(row('vad').delete).toBe(false);
+    // CREATE is never manufactured by a super-user bit.
+    expect(row('mad').create).toBe(false);
+    expect(row('vad').create).toBe(false);
+    // An entry with no bits grants nothing.
+    expect(row('none')).toMatchObject({ create: false, read: false, edit: false, delete: false });
+  });
+
+  it('exhaustively matches the fold over every declared bit combination', () => {
+    const entries = enumerateEntries();
+    expect(entries.length).toBe(3 ** 8);
+    const m = buildAccessMatrix({
+      objects: [{ name: 'o' }],
+      permissions: entries.map((e, i) => ({ name: `ps_${String(i).padStart(4, '0')}`, objects: { o: e } })),
+    });
+    expect(m.entries.length).toBe(entries.length);
+    const mismatches: string[] = [];
+    let cells = 0;
+    for (let i = 0; i < entries.length; i++) {
+      const row = m.entries.find((e) => e.permissionSet === `ps_${String(i).padStart(4, '0')}`)!;
+      for (const verb of ['create', 'read', 'edit', 'delete'] as const) {
+        cells++;
+        if (row[verb] !== referenceFold(entries[i], verb)) {
+          mismatches.push(`${JSON.stringify(entries[i])} × ${verb}: matrix=${row[verb]} rule=${referenceFold(entries[i], verb)}`);
+        }
+      }
+    }
+    expect(cells).toBe(3 ** 8 * 4);
+    expect(mismatches).toEqual([]);
+  });
+
+  it('the super-user columns stay RAW BITS, not folds', () => {
+    const m = buildAccessMatrix({
+      objects: [{ name: 'o' }],
+      permissions: [{ name: 'mad', objects: { o: { modifyAllRecords: true } } }],
+    });
+    const row = m.entries[0];
+    // Modify All Data implies the read POWER, but it is not a declaration of
+    // View All Data — the reviewer reads the CRUD columns against what the set
+    // actually declares.
+    expect(row.modifyAllRecords).toBe(true);
+    expect(row.viewAllRecords).toBe(false);
+    expect(row.read).toBe(true);
+  });
+});
@@ -15,7 +15,12 @@
  * AI may draft grants freely; it cannot silently change who can do what.
  */
 
-import type { AccessMatrixParsed, AccessMatrixEntry } from '@objectstack/spec/security';
+import type {
+  AccessMatrixParsed,
+  AccessMatrixEntry,
+  EffectiveObjectPermission,
+} from '@objectstack/spec/security';
+import { objectPermissionGrants } from '@objectstack/spec/security';
 import { recordsOf } from './object-graph.js';
 
 type AnyRec = Record<string, unknown>;
@@ -39,13 +44,25 @@ export function buildAccessMatrix(stack: AnyRec): AccessMatrixParsed {
     const objects = (ps.objects && typeof ps.objects === 'object' ? ps.objects : {}) as AnyRec;
     for (const [objName, rawPerm] of Object.entries(objects)) {
       const p = (rawPerm ?? {}) as AnyRec;
+      // [#18785] The CRUD bits are the SPEC's fold, asked — never restated.
+      // `objectPermissionGrants` is the one definition of "does this effective
+      // object permission grant this verb?", and the enforcement door
+      // (`PermissionEvaluator.checkObjectPermission`) asks the same function.
+      // A matrix restating the fold inline is a second implementation of a
+      // security rule whose whole job is to be reviewable: it would keep
+      // answering the old way for a full release after the door changed, and
+      // the snapshot diff — the artefact a human signs off — would say nothing.
+      // The two super-user columns below are RAW BITS, not folds: they report
+      // what the set declares, which is the context the reviewer reads the CRUD
+      // columns against.
+      const effective = p as EffectiveObjectPermission;
       const entry: AccessMatrixEntry = {
         permissionSet: psName,
         object: objName,
-        create: p.allowCreate === true,
-        read: p.allowRead === true || p.viewAllRecords === true || p.modifyAllRecords === true,
-        edit: p.allowEdit === true || p.modifyAllRecords === true,
-        delete: p.allowDelete === true || p.modifyAllRecords === true,
+        create: objectPermissionGrants(effective, 'allowCreate'),
+        read: objectPermissionGrants(effective, 'allowRead'),
+        edit: objectPermissionGrants(effective, 'allowEdit'),
+        delete: objectPermissionGrants(effective, 'allowDelete'),
         viewAllRecords: p.viewAllRecords === true,
         modifyAllRecords: p.modifyAllRecords === true,
       };
 
@@ -0,0 +1,177 @@
+// Copyright (c) 2026 ObjectStack. Licensed under the Apache-2.0 license.
+
+/**
+ * [#18785] The enforcement door asks ONE fold.
+ *
+ * "Does this effective object permission grant this verb?" is stated once, in
+ * `@objectstack/spec`'s `objectPermissionGrants`.
+ * `PermissionEvaluator.checkObjectPermission` — the fold the server actually
+ * applies — asks that function instead of restating it, and so does
+ * `@objectstack/lint`'s `buildAccessMatrix`. Before this card the rule had
+ * three implementations that happened to agree; agreeing today is not a
+ * property a security rule can be left resting on.
+ *
+ * ⚠️ The expectation here is written INDEPENDENTLY of the spec helper, from the
+ * rule itself: read bypasses on `viewAllRecords || modifyAllRecords`; write
+ * bypasses on `modifyAllRecords` ALONE and never create; export is
+ * `grant ∧ read`. Asserting `checkObjectPermission === objectPermissionGrants`
+ * would be a tautology — both sides move together, and the pin would survive
+ * any change to the fold, including a wrong one. Stated this way, changing one
+ * cell of the spec helper reddens this file, which is the only evidence that
+ * the door is really asking it.
+ *
+ * The enumeration is exhaustive over the declared object-permission bits in all
+ * three authorable states (`true` / `false` / absent): every implementation
+ * compares with `=== true`, and absence is the state an author reaches by
+ * omission.
+ */
+
+import { describe, it, expect } from 'vitest';
+import type { PermissionSet } from '@objectstack/spec/security';
+import { PermissionEvaluator, MODIFY_ALL_WRITE_KEYS } from './permission-evaluator';
+
+const evaluator = new PermissionEvaluator();
+const OBJ = 'deal';
+
+const set = (name: string, objects: Record<string, unknown>): PermissionSet =>
+  ({ name, objects } as unknown as PermissionSet);
+
+/** The ObjectQL operation that asks each `allow*` bit at the door. */
+const OPERATION_FOR: Record<Verb, string> = {
+  allowRead: 'find',
+  allowCreate: 'insert',
+  allowEdit: 'update',
+  allowDelete: 'delete',
+  allowTransfer: 'transfer',
+  allowExport: 'export',
+};
+
+type Verb = 'allowRead' | 'allowCreate' | 'allowEdit' | 'allowDelete' | 'allowTransfer' | 'allowExport';
+const VERBS: Verb[] = ['allowRead', 'allowCreate', 'allowEdit', 'allowDelete', 'allowTransfer', 'allowExport'];
+
+const FOLD_BITS = [
+  'allowCreate', 'allowDelete', 'allowEdit', 'allowExport',
+  'allowRead', 'allowTransfer', 'modifyAllRecords', 'viewAllRecords',
+] as const;
+const BIT_STATES: Array<boolean | undefined> = [true, false, undefined];
+
+/** The fold, restated from the rule — deliberately NOT the spec helper. */
+function referenceFold(p: Record<string, unknown>, verb: Verb): boolean {
+  const modifyAll = p.modifyAllRecords === true;
+  const read = p.allowRead === true || p.viewAllRecords === true || modifyAll;
+  switch (verb) {
+    case 'allowRead': return read;
+    case 'allowCreate': return p.allowCreate === true;
+    case 'allowEdit': return p.allowEdit === true || modifyAll;
+    case 'allowDelete': return p.allowDelete === true || modifyAll;
+    case 'allowTransfer': return p.allowTransfer === true || modifyAll;
+    case 'allowExport': return p.allowExport === true && read;
+  }
+}
+
+function enumerateEntries(): Array<Record<string, unknown>> {
+  const out: Array<Record<string, unknown>> = [];
+  const total = BIT_STATES.length ** FOLD_BITS.length;
+  for (let i = 0; i < total; i++) {
+    const entry: Record<string, unknown> = {};
+    let n = i;
+    for (const bit of FOLD_BITS) {
+      const s = BIT_STATES[n % BIT_STATES.length];
+      n = Math.floor(n / BIT_STATES.length);
+      if (s !== undefined) entry[bit] = s;
+    }
+    out.push(entry);
+  }
+  return out;
+}
+
+describe('checkObjectPermission — the one fold, asked (#18785)', () => {
+  it('named cells: the fold as the rule states it', () => {
+    const ask = (entry: Record<string, unknown>, verb: Verb) =>
+      evaluator.checkObjectPermission(OPERATION_FOR[verb], OBJ, [set('ps', { [OBJ]: entry })]);
+
+    // READ bypasses on EITHER super-user bit (Modify All implies View All).
+    expect(ask({ viewAllRecords: true }, 'allowRead')).toBe(true);
+    expect(ask({ modifyAllRecords: true }, 'allowRead')).toBe(true);
+
+    // WRITE bypasses on Modify All Data ALONE — View All Data is a read power
+    // and must never widen a write.
+    expect(ask({ modifyAllRecords: true }, 'allowEdit')).toBe(true);
+    expect(ask({ modifyAllRecords: true }, 'allowDelete')).toBe(true);
+    expect(ask({ modifyAllRecords: true }, 'allowTransfer')).toBe(true);
+    expect(ask({ viewAllRecords: true }, 'allowEdit')).toBe(false);
+    expect(ask({ viewAllRecords: true }, 'allowDelete')).toBe(false);
+    expect(ask({ viewAllRecords: true }, 'allowTransfer')).toBe(false);
+
+    // CREATE is never manufactured by a super-user bit.
+    expect(ask({ modifyAllRecords: true }, 'allowCreate')).toBe(false);
+    expect(ask({ viewAllRecords: true }, 'allowCreate')).toBe(false);
+    expect(ask({ allowCreate: true }, 'allowCreate')).toBe(true);
+
+    // EXPORT is a CONJUNCTION: the grant alone grants nothing, and the
+    // super-user bits satisfy the read half without implying export.
+    expect(ask({ allowExport: true }, 'allowExport')).toBe(false);
+    expect(ask({ allowExport: true, allowRead: true }, 'allowExport')).toBe(true);
+    expect(ask({ allowExport: true, viewAllRecords: true }, 'allowExport')).toBe(true);
+    expect(ask({ modifyAllRecords: true }, 'allowExport')).toBe(false);
+
+    // An entry with no bits grants nothing at all.
+    for (const verb of VERBS) expect(ask({}, verb)).toBe(false);
+  });
+
+  it('exhaustively matches the fold over every declared bit combination', () => {
+    const entries = enumerateEntries();
+    expect(entries.length).toBe(3 ** 8);
+    const mismatches: string[] = [];
+    let cells = 0;
+    for (const entry of entries) {
+      const sets = [set('ps', { [OBJ]: entry })];
+      for (const verb of VERBS) {
+        cells++;
+        const got = evaluator.checkObjectPermission(OPERATION_FOR[verb], OBJ, sets);
+        const want = referenceFold(entry, verb);
+        if (got !== want) mismatches.push(`${JSON.stringify(entry)} × ${verb}: door=${got} rule=${want}`);
+      }
+    }
+    expect(cells).toBe(3 ** 8 * VERBS.length);
+    expect(mismatches).toEqual([]);
+  });
+
+  it('the Modify-All write-bypass CLASS is exactly what this file derives from its own dispatch map', () => {
+    // MODIFY_ALL_WRITE_KEYS no longer decides anything — it states, on this
+    // side, which bits the class contains, derived from OPERATION_TO_PERMISSION
+    // and DESTRUCTIVE_OPERATIONS. Holding the fold to it is what makes a future
+    // destructive operation added to the map go red in the spec instead of
+    // silently losing its bypass (#1883).
+    expect([...MODIFY_ALL_WRITE_KEYS].sort()).toEqual(['allowDelete', 'allowEdit', 'allowTransfer']);
+    const mad = { modifyAllRecords: true };
+    for (const key of MODIFY_ALL_WRITE_KEYS) {
+      expect(evaluator.checkObjectPermission(OPERATION_FOR[key as Verb], OBJ, [set('ps', { [OBJ]: mad })])).toBe(true);
+    }
+    for (const verb of VERBS.filter((v) => !MODIFY_ALL_WRITE_KEYS.has(v as never) && v !== 'allowRead')) {
+      expect(evaluator.checkObjectPermission(OPERATION_FOR[verb], OBJ, [set('ps', { [OBJ]: mad })])).toBe(false);
+    }
+  });
+
+  it('export stays a CROSS-SET conjunction — the two halves may arrive from different sets', () => {
+    // The spec cell is `grant ∧ read` over ONE effective entry; this door asks
+    // it over the whole resolved set list, which is what the `/me/permissions`
+    // most-permissive per-object merge hands the client. Collapsing it per set
+    // would deny this caller.
+    const reader = set('reader', { [OBJ]: { allowRead: true } });
+    const exporter = set('exporter', { [OBJ]: { allowExport: true } });
+    expect(evaluator.checkObjectPermission('export', OBJ, [reader, exporter])).toBe(true);
+    expect(evaluator.checkObjectPermission('export', OBJ, [exporter, reader])).toBe(true);
+    expect(evaluator.checkObjectPermission('export', OBJ, [exporter])).toBe(false);
+    expect(evaluator.checkObjectPermission('export', OBJ, [reader])).toBe(false);
+  });
+
+  it('the unmapped-operation posture is untouched by the convergence', () => {
+    const grant = set('ps', { [OBJ]: { allowRead: true, allowEdit: true, modifyAllRecords: true } });
+    // Destructive but unmapped ⇒ denied unconditionally, bypass never consulted.
+    expect(evaluator.checkObjectPermission('restore', OBJ, [grant])).toBe(false);
+    expect(evaluator.checkObjectPermission('purge', OBJ, [grant])).toBe(false);
+    // Non-destructive unknown ⇒ default-allow, as before.
+    expect(evaluator.checkObjectPermission('customReadSideOp', OBJ, [grant])).toBe(true);
+  });
+});