@@ -0,0 +1,9 @@
+---
+'@objectstack/plugin-security': patch
+---
+
+`security/explain` answers a transfer of a row the caller cannot read the way the transfer door does: as a record that does not exist.
+
+- **What was wrong.** On the write doors, a row the caller cannot read answers what a nonexistent id answers: the by-id update or delete the caller addresses gets `404 RECORD_NOT_FOUND`. A transfer's door is the `PATCH` that writes `owner_id`, an update, so a transfer of an unreadable row gets that 404 too. explain's matching rewrite (the missing-record shape, `record: { visible: false }` with no `decidedBy`) keyed on the verb as asked, `update` or `delete`, so it never ran for `transfer`. Where the caller's update policy admitted the hidden row, explain answered `visible: true`, decided by `rls`. Where the caller declared no write policy, it answered `visible: false` decided by `rls`, which is the shape of a 403 refusal, not of the door's 404.
+- **What it does now.** The rewrite asks which operation the verb's door is through the same mapping the by-id write path reads (`transfer` and `restore` as update, `purge` as delete). So every write verb whose door is a by-id update or delete is asked the read question, and a transfer of a row the caller cannot read is `{ visible: false }` with no decider, beside the door's 404.
+- **What is unchanged.** `update` and `delete` are answered exactly as before. `restore` and `purge` are still refused at the object gate for every principal, which answers first. A readable row keeps its verdict for every verb. The object-level `allowed` answers the object question and is not touched. No door changes, and no export is added to the package.
@@ -413,6 +413,11 @@ export interface ExplainEngineDeps {
    * `true` only for absence; a read-time policy refusal answers `false`, and a
    * store fault propagates — exactly as the write path asks it, so the
    * explanation cannot drift from the answer the write gets.
+   *
+   * [#22571] Asked for every explained verb whose door is a by-id update or
+   * delete, read through {@link rlsOperationForVerb}: `update`, `delete`, and
+   * the lifecycle verbs that map onto them (`transfer` and `restore` onto
+   * update, `purge` onto delete).
    */
   recordAbsentToCaller?: (object: string, recordId: string, context: any) => Promise<boolean>;
 }
@@ -2250,8 +2255,19 @@ export async function explainAccess(deps: ExplainEngineDeps, input: ExplainInput
     // gates (which answer first, as they do here), for a principal with an
     // identity, on a record that exists. (A system principal reads every row,
     // so the question cannot change its verdict.)
+    //
+    // [#22571] The door asks that question of the by-id `update` and `delete`
+    // the caller addresses (`addressedByIdWriteId` in `security-plugin.ts`),
+    // and a lifecycle verb reaches it as the operation its door is: a transfer
+    // is the PATCH that writes `owner_id`, an update. So the guard reads the
+    // explained verb through the one mapping step 2.7 reads, `rlsOp`
+    // ({@link rlsOperationForVerb}), never the verb as asked: keyed on the raw
+    // verb, a transfer of a row the caller cannot read was reported visible
+    // beside the transfer door's 404. `restore` and `purge` map the same way
+    // and are refused at the object gate first, so the rewrite never reaches
+    // them while their grants are retired.
     if (
-      (operation === 'update' || operation === 'delete') &&
+      (rlsOp === 'update' || rlsOp === 'delete') &&
       deps.recordAbsentToCaller &&
       context?.userId &&
       recordVerdict.decidedBy !== 'required_permissions' &&
 
@@ -0,0 +1,253 @@
+// Copyright (c) 2026 ObjectStack. Licensed under the Apache-2.0 license.
+//
+// `security/explain` answers a by-id write of a row the caller cannot READ
+// with the missing-record shape the door's 404 is, for EVERY write verb, on
+// both axes that reach that answer.
+//
+// ## The door's question, and the verbs it is asked for
+//
+// Ruling A on the write doors (#21771): a row the caller cannot read is a row
+// that does not exist. The by-id write pre-image gate (step 2.7) asks the read
+// door's own question of the by-id `update` and `delete` the caller addresses
+// (`addressedByIdWriteId`), and answers `404 RECORD_NOT_FOUND` for a row that
+// read does not return. A lifecycle verb meets that question as the operation
+// its door is: a transfer is the update that writes `owner_id` (the engine
+// dispatches no `transfer` operation). That relation is the one mapping
+// `rlsOperationForVerb` declares, so the verbs this file iterates are read off
+// it: every explain verb the mapping sends to `update` or `delete`. A verb added
+// to the mapping is iterated here with no new card, and a verb added to
+// explain's vocabulary fails the totality check below until it has a door row.
+//
+// explain's rewrite used to key on the RAW verb (`update` or `delete`), so a
+// transfer of an unreadable row was reported `visible: true` (or refused on
+// `rls`) beside the door's 404.
+//
+// ## The two axes
+//
+//   - read-absent: the caller's write-class policies ADMIT the hidden row and
+//     only the read hides it, so readability alone separates the door's 404
+//     from its admission;
+//   - no policy: the caller's sets carry no write-class policy at all, so the
+//     door composes the write scope from the caller's SELECT narrowing (#7665,
+//     "you cannot mutate what you cannot see"): fail closed, not unbounded.
+//
+// Each cell drives both faces through the real `SecurityPlugin` over a real
+// `ObjectQL` and SQL driver, and asserts the door's own answer too, so a cell
+// cannot go green by both faces drifting together. The callers hold no
+// `org_member` position, so the platform's ownership floor is out of play and
+// each axis is exactly what it says. The REST-level twin, on the `cpg` fixture
+// with the floor in play, is `packages/qa/dogfood/test/explain-write-door-parity.dogfood.test.ts`.
+
+import { describe, it, expect, beforeAll, afterAll, vi } from 'vitest';
+import { ObjectQL } from '@objectstack/objectql';
+import { SqlDriver } from '@objectstack/driver-sql';
+import { ExplainOperationSchema, PermissionSetSchema } from '@objectstack/spec/security';
+import type { ExplainDecision, ExplainOperation } from '@objectstack/spec/security';
+import { SecurityPlugin } from './security-plugin.js';
+import { rlsOperationForVerb } from './lifecycle-verb-rls-operation.js';
+import { defaultPermissionSets } from './objects/default-permission-sets.js';
+
+const SYS = { context: { isSystem: true } } as never;
+const MEMBER_DEFAULT = defaultPermissionSets.find((p) => p.name === 'member_default')!;
+const OBJ = 'qa_read_absent_board';
+
+/** Every write grant, so the object gate admits each verb it can and the row gates answer. */
+const ALL_WRITES = { allowRead: true, allowCreate: true, allowEdit: true, allowDelete: true, allowTransfer: true };
+
+/** The read hides the row named `hidden`; the write-class policies admit every row. */
+const READ_ABSENT_SET = PermissionSetSchema.parse({
+  name: 'qa_read_absent_writer',
+  objects: { [OBJ]: ALL_WRITES },
+  rowLevelSecurity: [
+    { name: 'qa_ra_reads_not_hidden', object: OBJ, operation: 'select', using: "name != 'hidden'" },
+    { name: 'qa_ra_updates_any', object: OBJ, operation: 'update', using: "name != 'nothing'" },
+    { name: 'qa_ra_deletes_any', object: OBJ, operation: 'delete', using: "name != 'nothing'" },
+  ],
+});
+
+/** The same read narrowing, and no write-class policy: the door derives the write scope from it. */
+const NO_POLICY_SET = PermissionSetSchema.parse({
+  name: 'qa_policyless_writer',
+  objects: { [OBJ]: ALL_WRITES },
+  rowLevelSecurity: [
+    { name: 'qa_np_reads_not_hidden', object: OBJ, operation: 'select', using: "name != 'hidden'" },
+  ],
+});
+
+const AXES = [
+  { axis: 'read-absent', set: READ_ABSENT_SET.name },
+  { axis: 'no policy', set: NO_POLICY_SET.name },
+] as const;
+
+type Answer = { kind: 'admitted' } | { kind: 'refused'; code?: string; status?: number };
+
+const landed = (p: Promise<unknown>): Promise<Answer> =>
+  p.then(
+    () => ({ kind: 'admitted' as const }),
+    (e: any) => ({ kind: 'refused' as const, code: e?.code == null ? undefined : String(e.code), status: e?.statusCode ?? e?.status }),
+  );
+
+/**
+ * Every operation explain answers, classified against the door. Total by
+ * construction and checked against the spec's vocabulary below.
+ *
+ *  - `by_id_door`: the engine write the verb's door is, addressed by id;
+ *  - `object_gate_refused`: the object gate refuses the verb to every
+ *    principal (its grant is retired until the lifecycle batch returns it) and
+ *    no route dispatches it, so the object-level CRUD layer answers first;
+ *  - `no_by_id_write`: a read, an insert or an export — no row is written by id.
+ */
+type DoorRow =
+  | { kind: 'by_id_door'; door: (rig: Rig, id: string, caller: Caller) => Promise<Answer> }
+  | { kind: 'object_gate_refused' }
+  | { kind: 'no_by_id_write' };
+
+type Caller = { userId: string; positions: string[]; permissions: string[]; posture: string };
+type Rig = { engine: ObjectQL; plugin: SecurityPlugin };
+
+const DOORS: Record<ExplainOperation, DoorRow> = {
+  update: {
+    kind: 'by_id_door',
+    door: (r, id, c) => landed(r.engine.update(OBJ, { title: 'edited' }, { where: { id }, context: c } as never)),
+  },
+  delete: {
+    kind: 'by_id_door',
+    door: (r, id, c) => landed(r.engine.delete(OBJ, { where: { id }, context: c } as never)),
+  },
+  // The transfer door: the update that writes `owner_id`.
+  transfer: {
+    kind: 'by_id_door',
+    door: (r, id, c) => landed(r.engine.update(OBJ, { owner_id: 'usr_successor' }, { where: { id }, context: c } as never)),
+  },
+  restore: { kind: 'object_gate_refused' },
+  purge: { kind: 'object_gate_refused' },
+  create: { kind: 'no_by_id_write' },
+  read: { kind: 'no_by_id_write' },
+  export: { kind: 'no_by_id_write' },
+};
+
+/** The write verbs: every explain verb whose door the mapping names a by-id update or delete. */
+const WRITE_VERBS = ExplainOperationSchema.options.filter((v) => ['update', 'delete'].includes(rlsOperationForVerb(v)));
+
+const callerFor = (set: string): Caller => ({ userId: `usr_${set}`, positions: ['qa_pos'], permissions: [set], posture: 'MEMBER' });
+
+let rig: Rig;
+
+beforeAll(async () => {
+  const engine = new ObjectQL();
+  engine.registerDriver(
+    new SqlDriver({ client: 'better-sqlite3', connection: { filename: ':memory:' }, useNullAsDefault: true }) as never,
+    true,
+  );
+  await engine.init();
+  engine.registerApp({
+    id: 'com.objectstack.qa.explain-read-absent-every-write-verb',
+    name: 'Explain read-absent: every write verb',
+    version: '1.0.0',
+    type: 'plugin',
+    scope: 'system',
+    objects: [
+      {
+        name: OBJ,
+        label: 'Board',
+        sharingModel: 'public_read_write',
+        fields: {
+          id: { name: 'id', type: 'text', primaryKey: true },
+          name: { name: 'name', type: 'text' },
+          title: { name: 'title', type: 'text' },
+          owner_id: { name: 'owner_id', type: 'text' },
+        },
+      },
+    ],
+  } as never);
+  await engine.syncSchemas();
+  // One unreadable and one readable row per (axis, verb), so a delete or a
+  // transfer that lands never changes another cell's row.
+  for (const { set } of AXES) {
+    for (const verb of ExplainOperationSchema.options) {
+      await engine.insert(OBJ, [
+        { id: `${set}_${verb}_hidden`, name: 'hidden', title: 'x', owner_id: 'usr_founder' },
+        { id: `${set}_${verb}_shown`, name: 'shown', title: 'x', owner_id: 'usr_founder' },
+      ], SYS);
+    }
+  }
+  const services: Record<string, unknown> = {
+    manifest: { register: vi.fn() },
+    objectql: engine,
+    metadata: {
+      get: async (_type: string, name: string) => engine.getSchema(name) ?? null,
+      list: async () => [MEMBER_DEFAULT, READ_ABSENT_SET, NO_POLICY_SET],
+    },
+  };
+  const ctx = {
+    logger: { info: vi.fn(), warn: vi.fn(), error: vi.fn(), debug: vi.fn() },
+    registerService: vi.fn(),
+    // The lifecycle hooks are collected and never fired, so no bootstrap read
+    // is left running into the engine teardown.
+    hook: () => undefined,
+    getService: (name: string) => {
+      if (!(name in services)) throw new Error(`service not registered: ${name}`);
+      return services[name];
+    },
+  };
+  const plugin = new SecurityPlugin({ fallbackPermissionSet: 'member_default' });
+  await plugin.init(ctx as never);
+  await plugin.start(ctx as never);
+  rig = { engine, plugin };
+});
+
+afterAll(async () => {
+  try { await rig?.engine.destroy(); } catch { /* noop */ }
+});
+
+const explain = (operation: ExplainOperation, recordId: string, caller: Caller): Promise<ExplainDecision> =>
+  rig.plugin.explainAccessForCaller({ object: OBJ, operation, recordId }, caller);
+
+describe('explain answers a write of a row the caller cannot read as the door does, for every write verb', () => {
+  it('the classification is total: every operation explain answers has a door row', () => {
+    expect([...ExplainOperationSchema.options].sort()).toEqual(Object.keys(DOORS).sort());
+  });
+
+  it("the write verbs are the mapping's: each has a by-id door or is refused at the object gate, and nothing else does", () => {
+    const writeRows = (Object.keys(DOORS) as ExplainOperation[]).filter((v) => DOORS[v].kind !== 'no_by_id_write').sort();
+    expect(writeRows).toEqual([...WRITE_VERBS].sort());
+  });
+
+  for (const { axis, set } of AXES) {
+    describe(axis, () => {
+      for (const verb of WRITE_VERBS) {
+        const row = DOORS[verb];
+        if (row.kind === 'by_id_door') {
+          it(`${verb}: a row the caller cannot read is explained missing, beside the door's 404`, async () => {
+            const caller = callerFor(set);
+            const id = `${set}_${verb}_hidden`;
+            const explained = await explain(verb, id, caller);
+            const door = await row.door(rig, id, caller);
+            expect(door, `${verb} door on the unreadable row`).toEqual({ kind: 'refused', code: 'RECORD_NOT_FOUND', status: 404 });
+            // The missing-record shape: no decider, exactly what an id no row
+            // carries is explained as.
+            expect(explained.record, `explain ${verb}`).toStrictEqual({ recordId: id, visible: false });
+          });
+
+          it(`${verb}: control, a readable row keeps its verdict, beside the door's admission`, async () => {
+            const caller = callerFor(set);
+            const id = `${set}_${verb}_shown`;
+            const explained = await explain(verb, id, caller);
+            const door = await row.door(rig, id, caller);
+            expect(door, `${verb} door on the readable row`).toEqual({ kind: 'admitted' });
+            expect(explained.record, `explain ${verb}`).toMatchObject({ recordId: id, visible: true });
+            expect(explained.record?.decidedBy, `explain ${verb}: a decider names the admission`).toBeDefined();
+          });
+        } else {
+          it(`${verb}: refused at the object gate, for the unreadable and the readable row alike`, async () => {
+            const caller = callerFor(set);
+            for (const id of [`${set}_${verb}_hidden`, `${set}_${verb}_shown`]) {
+              const explained = await explain(verb, id, caller);
+              expect(explained.record, `explain ${verb} ${id}`).toStrictEqual({ recordId: id, visible: false, decidedBy: 'object_crud' });
+            }
+          });
+        }
+      }
+    });
+  }
+});
@@ -27,7 +27,11 @@
  *    floor hand-over (`masterGateCoversOperation`) key on the mapped verb;
  *  - `security/explain` (`explain-engine.ts`), the object-level `rls` layer and
  *    the record-level row story alike, so a `transfer` is explained against the
- *    update-class policies the door judges it by.
+ *    update-class policies the door judges it by;
+ *  - [#22571] `security/explain`'s read-absent rewrite (#21771 ruling A), whose
+ *    guard asks this mapping which operation the explained verb's door is, so a
+ *    `transfer` of a row the caller cannot read gets the missing-record shape
+ *    the transfer door's 404 is.
  *
  * The middleware's AST step (step 3) passes its verb RAW, by design: the
  * engine's middleware vocabulary carries no lifecycle verb, an invariant