@@ -0,0 +1,10 @@
+---
+'@objectstack/plugin-sharing': patch
+---
+
+fix(plugin-sharing): a refused write on a federated object whose mapped owner column the driver did not serve is logged again
+
+Clause-②: no
+Metadata-protocol: none
+
+A federated object that maps a remote column onto `owner_id` through `external.columnMap`, served by a plugin driver that does not apply the map, returns rows with no `owner_id`, so every member edit or delete is refused. The refusal is unchanged. Since the mapped class stopped counting as a phantom owner anchor, the one-line server warning that tells the operator why had stopped firing. It fires again, at most once per object, as the new `UNSERVED_OWNER_WRITE_DENY_NOTICE`, which names the driver returning no value for the mapped or declared owner column. A driver that serves the column, including a row whose owner is NULL, stays silent.
@@ -57,7 +57,11 @@ import {
   type EngineUpdateDispatchInput,
 } from '@objectstack/metadata-core';
 import { ERROR_CODE_LEDGER } from '@objectstack/spec/api';
-import { SharingService, PHANTOM_ANCHOR_WRITE_DENY_NOTICE } from './sharing-service.js';
+import {
+  SharingService,
+  PHANTOM_ANCHOR_WRITE_DENY_NOTICE,
+  UNSERVED_OWNER_WRITE_DENY_NOTICE,
+} from './sharing-service.js';
 
 /** The caller: an ordinary member whose read/write DEPTH is narrower than `org`. */
 const MEMBER = 'usr_member_1';
@@ -821,3 +825,112 @@ describe('[#8418] the phantom-anchor write refusal is diagnosed, not changed', (
     });
   });
 });
+
+/**
+ * [#27662] The mapped owner column the driver never served is diagnosed too.
+ *
+ * #27425 counted an `external.columnMap` entry onto `owner_id` as the author
+ * declaring the owner column, which took the object out of
+ * `hasPhantomOwnerAnchor` — and so out of the #8418 line above. A plugin driver
+ * that does not apply the map answers with the remote column's own name, the
+ * pre-image carries no `owner_id`, and every member write is refused in
+ * silence again. The refusal is right and stays; the silence is what goes.
+ *
+ * The discrimination is the KEY, not the value: a driver that applies the map
+ * and serves a NULL owner is an ordinary owner-less row (silent, like
+ * `LOCAL_OWNERLESS` above), while a row with no `owner_id` key at all is the
+ * driver dropping the column.
+ */
+describe('[#27662] a mapped owner column the driver did not serve is diagnosed, not changed', () => {
+  const OTHER = 'usr_other';
+  const mapped = (name: string) =>
+    federatedSchema({ name, external: { remoteName: 'rows', columnMap: { assignee: 'owner_id' } } });
+
+  let svc: SharingService;
+  let warn: ReturnType<typeof vi.fn>;
+
+  beforeEach(() => {
+    warn = vi.fn();
+    svc = new SharingService({
+      engine: makeEngine(
+        {
+          // A plugin driver that ignores the map: rows carry `assignee`, never `owner_id`.
+          ext_plugin_mapped: mapped('ext_plugin_mapped'),
+          ext_plugin_mapped_2: mapped('ext_plugin_mapped_2'),
+          // The SQL driver applies the map, so `owner_id` is served (possibly NULL).
+          ext_sql_mapped: mapped('ext_sql_mapped'),
+          ext_with_real_owner: DECLARED_REAL_OWNER,
+          sys_record_share: { name: 'sys_record_share' },
+        },
+        {
+          ext_plugin_mapped: [{ id: 'p1', assignee: MEMBER, name: 'Mine, unmapped' }],
+          ext_plugin_mapped_2: [{ id: 'q1', assignee: MEMBER, name: 'Also unmapped' }],
+          ext_sql_mapped: [
+            { id: 's_mine', owner_id: MEMBER, name: 'Mine' },
+            { id: 's_theirs', owner_id: OTHER, name: 'Theirs' },
+            { id: 's_nobody', owner_id: null, name: 'Owner-less' },
+          ],
+          ext_with_real_owner: [
+            { id: 'a1', owner_id: MEMBER, name: 'Acme' },
+            { id: 'a2', owner_id: OTHER, name: 'Globex' },
+          ],
+        },
+      ),
+      logger: { info: vi.fn(), warn, error: vi.fn() } as never,
+    });
+  });
+
+  const ctx = (scope = 'own') => ({ userId: MEMBER, __writeScope: scope }) as never;
+  const notices = () => warn.mock.calls.filter((c) => c[0] === UNSERVED_OWNER_WRITE_DENY_NOTICE);
+  const phantomNotices = () => warn.mock.calls.filter((c) => c[0] === PHANTOM_ANCHOR_WRITE_DENY_NOTICE);
+
+  it('a map-ignoring plugin driver: still DENIES, and says why once', async () => {
+    // The caller's id IS in the row — under `assignee`, where the gate cannot
+    // see it. So the refusal is the driver's doing, not the caller's.
+    expect(await svc.checkEdit('ext_plugin_mapped', 'p1', ctx())).toBe('deny');
+    expect(await svc.checkDelete('ext_plugin_mapped', 'p1', ctx())).toBe('deny');
+    expect(await svc.checkEdit('ext_plugin_mapped', 'p1', ctx('org'))).toBe('deny');
+
+    expect(notices()).toHaveLength(1);
+    expect(notices()[0][1]).toMatchObject({ object: 'ext_plugin_mapped', ownerField: 'owner_id', userId: MEMBER });
+    // …and not the phantom wording, which would send the operator to the metadata.
+    expect(phantomNotices()).toHaveLength(0);
+  });
+
+  it('the wording names the driver and the mapped owner column', async () => {
+    await svc.checkEdit('ext_plugin_mapped', 'p1', ctx());
+    const [message] = notices()[0];
+    expect(message).toContain('the driver returned no value for the owner column');
+    expect(message).toContain('external.columnMap');
+  });
+
+  it('a SECOND map-ignoring object gets its own line; a different caller does not re-arm one', async () => {
+    await svc.checkEdit('ext_plugin_mapped', 'p1', ctx());
+    await svc.checkEdit('ext_plugin_mapped', 'p1', { userId: OTHER, __writeScope: 'own' } as never);
+    await svc.checkEdit('ext_plugin_mapped_2', 'q1', ctx());
+    expect(notices().map((c) => (c[1] as { object: string }).object)).toEqual([
+      'ext_plugin_mapped',
+      'ext_plugin_mapped_2',
+    ]);
+  });
+
+  it('a map-applying driver is silent: own row allows, another owner and a NULL owner deny', async () => {
+    expect(await svc.checkEdit('ext_sql_mapped', 's_mine', ctx())).toBe('allow');
+    expect(await svc.checkEdit('ext_sql_mapped', 's_theirs', ctx())).toBe('deny');
+    // The served-NULL row reaches the same `owner == null` arm as the plugin
+    // driver's row. The key is present, so it is an ordinary owner-less row.
+    expect(await svc.checkEdit('ext_sql_mapped', 's_nobody', ctx())).toBe('deny');
+    expect(warn).not.toHaveBeenCalled();
+  });
+
+  it('a declared-owner control is silent, allow and deny alike', async () => {
+    expect(await svc.checkEdit('ext_with_real_owner', 'a1', ctx())).toBe('allow');
+    expect(await svc.checkEdit('ext_with_real_owner', 'a2', ctx())).toBe('deny');
+    expect(warn).not.toHaveBeenCalled();
+  });
+
+  it('a record that does not exist says nothing about the driver', async () => {
+    expect(await svc.checkEdit('ext_plugin_mapped', 'missing', ctx())).toBe('deny');
+    expect(warn).not.toHaveBeenCalled();
+  });
+});
@@ -22,6 +22,7 @@ export {
   SharingService,
   effectiveSharingModel,
   PHANTOM_ANCHOR_WRITE_DENY_NOTICE,
+  UNSERVED_OWNER_WRITE_DENY_NOTICE,
   type SharingEngine,
   type SharingServiceOptions,
   type OrphanShareSweepOptions,
 
@@ -36,7 +36,7 @@ import { resolveTenantFieldName } from '@objectstack/objectql';
 import { owdForAudience } from '@objectstack/core';
 import { MEMBERSHIP_ROLE_EXTERNAL } from '@objectstack/spec/identity';
 import { WRITE_ACCESS_LEVELS, normalizeAccessLevel } from './access-level.js';
-import { hasPhantomOwnerAnchor } from './federated-phantom-anchors.js';
+import { hasPhantomOwnerAnchor, isFederatedObject } from './federated-phantom-anchors.js';
 import {
   deleteRowsForDeletedRecords,
   sweepOrphanedRowsByRecordExistence,
@@ -403,6 +403,28 @@ export const PHANTOM_ANCHOR_WRITE_DENY_NOTICE =
   'injected anchor, not a remote column, so ownership can never match; ' +
   'declare the real remote owner column or change the sharing model';
 
+/**
+ * [#27662] The second silent cause of the same refusal: a federated object
+ * whose owner column is NOT the phantom anchor — the author mapped a remote
+ * column onto `owner_id` through `external.columnMap`, or declared `owner_id`
+ * outright — served by a driver that returns rows with no `owner_id` key at
+ * all. A plugin driver that does not apply `columnMap` is the measured case: it
+ * answers with the remote column's own name, so the pre-image has no owner, and
+ * every member write is refused exactly as on a phantom anchor (fail closed,
+ * correct). Since #27425 took the mapped class out of
+ * {@link hasPhantomOwnerAnchor}, {@link PHANTOM_ANCHOR_WRITE_DENY_NOTICE} no
+ * longer fires for it, and its wording ("injected anchor") would be wrong if it
+ * did — the metadata is right here, the driver is what drops the column.
+ *
+ * Keyed on the row, not on which of the two declarations the author used: an
+ * absent key is the one fact both share, and a present `null` (an ordinary
+ * owner-less row over a driver that DOES serve the column) stays silent.
+ */
+export const UNSERVED_OWNER_WRITE_DENY_NOTICE =
+  '[sharing] write refused: the driver returned no value for the owner column this ' +
+  'federated object maps (external.columnMap) or declares, so ownership can never match; ' +
+  'use a driver that serves the mapped owner column or change the sharing model';
+
 /**
  * [ADR-0111 D2] The narrow slice of `ISecurityService` the management gate
  * needs — kept structural so unit tests can pass a stub and so a deployment
@@ -946,7 +968,8 @@ export class SharingService implements ISharingService {
       limit: 1,
       context: SYSTEM_CTX,
     });
-    const owner = Array.isArray(own) && own[0] ? (own[0] as any)[OWNER_FIELD] : undefined;
+    const row = Array.isArray(own) ? (own[0] as Record<string, unknown> | undefined) : undefined;
+    const owner = row ? row[OWNER_FIELD] : undefined;
     if (owner == null) {
       // [#8418] The refusal is unchanged — `return false` below is the same
       // `false` this line has always returned, and the diagnostic is emitted
@@ -955,8 +978,10 @@ export class SharingService implements ISharingService {
       // actually defeats the fast path, not the mere fact that the object is
       // federated: an author-declared remote `owner_id` that happens to be NULL
       // on this row reaches here too, and `hasPhantomOwnerAnchor` is what tells
-      // the two apart (provenance, never an `external` test).
-      this.notePhantomAnchorWriteDeny(object, context);
+      // the two apart (provenance, never an `external` test). [#27662] The row
+      // goes along so a mapped or declared owner column the driver did not
+      // serve is told apart from one it served as NULL.
+      this.notePhantomAnchorWriteDeny(object, context, row);
       return false;
     }
     // Middleware-stamped, not a field of the envelope — see buildReadFilter().
@@ -984,14 +1009,28 @@ export class SharingService implements ISharingService {
    * that can misreport the thing it exists to explain is worse than silence.
    * The latch is claimed BEFORE the log so a throwing logger cannot turn one
    * suppressed line into one throw per row (#6783's ordering, same reason).
+   *
+   * [#27662] A federated object whose owner column is real by declaration (a
+   * `columnMap` entry onto `owner_id`, or a declared field) gets
+   * {@link UNSERVED_OWNER_WRITE_DENY_NOTICE} instead, under the same latch,
+   * when the pre-image `row` came back with no `owner_id` key. No row at all
+   * (the record does not exist) says nothing about the driver and stays silent.
    */
-  private notePhantomAnchorWriteDeny(object: string, context: ExecutionContext): void {
+  private notePhantomAnchorWriteDeny(
+    object: string,
+    context: ExecutionContext,
+    row: Record<string, unknown> | undefined,
+  ): void {
     if (this.phantomAnchorNotified.has(object)) return;
     try {
       const schema = this.engine.getSchema?.(object);
-      if (!hasPhantomOwnerAnchor(schema)) return;
+      let notice: string;
+      if (hasPhantomOwnerAnchor(schema)) notice = PHANTOM_ANCHOR_WRITE_DENY_NOTICE;
+      else if (isFederatedObject(schema) && row !== undefined && row[OWNER_FIELD] === undefined) {
+        notice = UNSERVED_OWNER_WRITE_DENY_NOTICE;
+      } else return;
       this.phantomAnchorNotified.add(object);
-      this.logger?.warn?.(PHANTOM_ANCHOR_WRITE_DENY_NOTICE, {
+      this.logger?.warn?.(notice, {
         object,
         ownerField: OWNER_FIELD,
         userId: context?.userId ?? 'unknown',