@@ -0,0 +1,16 @@
+---
+'@objectstack/objectql': patch
+---
+
+fix(objectql): a file field reads the same whether or not the projection lists `id`
+
+Clause-②: no
+Metadata-protocol: none
+
+A reader who may not read `sys_file` (every member whose application grants no `sys_file` read) is served a file field by the verdict of the record that owns the file, matched on that record's `id`. A read whose projection left `id` out, such as `GET /api/v1/data/OBJECT?select=FILE_FIELD`, gave that verdict no record key, so a file the reader may read came back as `{ id, metadataRefused: true }`, while `select=id,FILE_FIELD` answered the full `{ id, name, size, mimeType, url }`.
+
+`find` and `findOne` now read `id` for any projection that names a file field and cut it back off the answer, the same way a formula's widened columns are cut. So:
+
+- A permitted reader gets the full file value with or without `id` in `select` / `fields`, on `GET /data/:object`, `POST /data/:object/query` and `GET /data/:object/:id`.
+- The answer still carries exactly the columns the caller named: no `id` is added to a row that did not ask for it.
+- A reader the owning record's verdict refuses is still answered `{ id, metadataRefused: true }`, with or without `id`.
@@ -384,14 +384,35 @@ describe('a refused sys_file read still hydrates a file the record being read ow
     expect(rows.d5.attachment).toEqual(asFileReader.d5.attachment);
   });
 
-  it('a read whose projection leaves out id cannot name its owner record, so every id keeps the marker', async () => {
+  it('[#26672] a read whose projection leaves out id still names its owner record — and answers no id it did not name', async () => {
     const { engine, calls } = await boot();
 
     const rows = await engine.find('doc', { fields: ['attachment'], context: READER_CTX });
+    const withId = byId(await engine.find('doc', { fields: ['id', 'attachment'], context: READER_CTX }));
+
+    // The same verdict as the projection that names `id`: d1 owns OWNED and
+    // hydrates it, d3 holds a copy of it and keeps the marker.
+    expect(rows).toContainEqual({ attachment: hydrated(OWNED, 'owned.pdf') });
+    expect(rows).toContainEqual({ attachment: refused(OWNED) });
+    expect(withId.d1.attachment).toEqual(hydrated(OWNED, 'owned.pdf'));
+    expect(withId.d3.attachment).toEqual(refused(OWNED));
+    for (const row of rows) expect(Object.keys(row)).toEqual(['attachment']);
+    expect(calls[0]?.ownerIds).toContain('d1');
+
+    const one = await engine.findOne('doc', { where: { id: 'd1' }, fields: ['attachment'], context: READER_CTX });
+    expect(one).toEqual({ attachment: hydrated(OWNED, 'owned.pdf') });
+  });
 
-    expect(rows.find((r: any) => r.attachment?.id === OWNED && !r.attachment.metadataRefused)).toBeUndefined();
-    expect(rows.filter((r: any) => r.attachment != null)).toContainEqual({ attachment: refused(OWNED) });
-    expect(calls).toEqual([]);
+  it('[#26672] …and a reader the verdict refuses is still refused when the projection leaves out id', async () => {
+    const { engine } = await boot({ allow: [] });
+
+    const rows = await engine.find('doc', { fields: ['attachment'], context: READER_CTX });
+    expect(rows.filter((r: any) => r.attachment != null)).toEqual(
+      [refused(OWNED), refused(OWNED), refused(TOMBSTONE_OWNED), refused(PENDING_OWNED), refused(OTHER_OBJECT)]
+        .map((attachment) => ({ attachment })),
+    );
+    const one = await engine.findOne('doc', { where: { id: 'd1' }, fields: ['attachment'], context: READER_CTX });
+    expect(one).toEqual({ attachment: refused(OWNED) });
   });
 
   it('the happy path costs no warn; the one debug line counts what the verdict allowed', async () => {
 
@@ -1797,6 +1797,8 @@ function planFormulaProjection(
  * on driver-sql (a projection is exactly the named columns — no `id` unless it
  * is named) and pinned against it in `engine-formula-projection-trim.test.ts`.
  * `id` is cut like any other widened column when the caller did not name it.
+ * [#26672] The `id` {@link withFileOwnerKey} adds for a file field's owner
+ * verdict is cut the same way.
  *
  * ## Where it runs, and why there
  *
@@ -1834,6 +1836,35 @@ function rowsWithoutFormulaWidening<T>(rows: T, widened: ReadonlySet<string> | u
   return rows.map((row) => withoutFormulaWidening(row, widened)) as unknown as T;
 }
 
+/**
+ * [#26672] A projection that names a file field reads the record's `id` too,
+ * and the key is cut back off the answer like the formula widening is.
+ *
+ * File-reference hydration judges a reader refused `sys_file` read by the
+ * record that OWNS each file (#22637, `readParentDerivedFiles`), matched on
+ * that record's `id`. A projection that left `id` out handed it rows with no
+ * key, so a file the reader may read answered `{ id, metadataRefused: true }`
+ * to `select=<file field>` and the full value to `select=id,<file field>`. The
+ * verdict must not depend on whether the caller listed `id`, so the driver is
+ * asked for it here and {@link withoutFormulaWidening} trims it at the
+ * `return`: the caller still gets exactly the columns it named, and a reader
+ * the verdict refuses is still refused.
+ *
+ * Touches only an explicit projection that names a file field and not `id`;
+ * a projection the formula planner widened already carries `id`.
+ */
+function withFileOwnerKey(
+  schema: any,
+  requestedFields: string[] | undefined,
+  planned: { projected?: string[]; widened?: string[] },
+): { projected?: string[]; widened?: string[] } {
+  if (!schema?.fields || !Array.isArray(requestedFields) || requestedFields.length === 0) return planned;
+  const projected = planned.projected ?? requestedFields;
+  if (projected.includes('id')) return planned;
+  if (!requestedFields.some((f) => FILE_REFERENCE_TYPES.has((schema.fields as any)[f]?.type))) return planned;
+  return { projected: [...projected, 'id'], widened: [...(planned.widened ?? []), 'id'] };
+}
+
 /**
  * [#7095] ORDER BY a field whose value is computed on read — refused HERE, on
  * the engine's own public boundary, and no longer only at the REST ingress.
@@ -12951,9 +12982,11 @@ export class ObjectQL implements IObjectQLEngine {
    * Returns, per allowed file id, the owning record's id and its servable row
    * — `null` when the row is owned and allowed but not servable, which the
    * caller reads as the bare id a `sys_file` reader would see. An id absent
-   * from the map keeps the refused marker. Unwired, no record ids (a
-   * projection that left out `id`), or a failure: an empty map — every id
-   * stays refused, the answer before this existed.
+   * from the map keeps the refused marker. Unwired, no record ids, or a
+   * failure: an empty map — every id stays refused, the answer before this
+   * existed. [#26672] `find` / `findOne` read `id` for any projection that
+   * names a file field ({@link withFileOwnerKey}), so a caller's projection
+   * that leaves `id` out does not land here.
    */
   private async readParentDerivedFiles(
     objectName: string,
@@ -13502,10 +13535,12 @@ export class ObjectQL implements IObjectQLEngine {
     // driver, where the #3821 ladder answered it with EVERY field.
     assertProjectionHasNoDottedPaths(object, 'find', _findSchema, ast.fields);
     const _findFormula = planFormulaProjection(_findSchema, ast.fields);
-    if (_findFormula.projected) ast.fields = _findFormula.projected;
+    // [#26672] …and a file field's owner key — see `withFileOwnerKey`.
+    const _findProjection = withFileOwnerKey(_findSchema, ast.fields, _findFormula);
+    if (_findProjection.projected) ast.fields = _findProjection.projected;
     // [#22300] The columns that widening added, cut back off the answer at the
     // `return` — see `withoutFormulaWidening`.
-    const _findWidened = _findFormula.widened ? new Set(_findFormula.widened) : undefined;
+    const _findWidened = _findProjection.widened ? new Set(_findProjection.widened) : undefined;
 
     // Drop any requested PLAIN field that doesn't exist on the schema.
     // Without this, drivers (notably SqlDriver) emit `SELECT unknown_col
@@ -13821,9 +13856,11 @@ export class ObjectQL implements IObjectQLEngine {
     // [#7642] Caller's own projection, before planning rewrites it — see `find`.
     const _findOneRequestedFields = Array.isArray(ast.fields) ? [...ast.fields] : undefined;
     const _findOneFormula = planFormulaProjection(_findOneSchema, ast.fields);
-    if (_findOneFormula.projected) ast.fields = _findOneFormula.projected;
+    // [#26672] Same as `find`: a file field's owner key is read too.
+    const _findOneProjection = withFileOwnerKey(_findOneSchema, ast.fields, _findOneFormula);
+    if (_findOneProjection.projected) ast.fields = _findOneProjection.projected;
     // [#22300] Same as `find`: what the widening added is cut at the `return`.
-    const _findOneWidened = _findOneFormula.widened ? new Set(_findOneFormula.widened) : undefined;
+    const _findOneWidened = _findOneProjection.widened ? new Set(_findOneProjection.widened) : undefined;
 
     // Drop unknown PLAIN fields — see the equivalent block in `find()` for
     // the rationale, and for why this tolerance is plain-columns-only ([#7589]
 
@@ -0,0 +1,223 @@
+// Copyright (c) 2026 ObjectStack. Licensed under the Apache-2.0 license.
+
+/**
+ * [#26672] A file field's read verdict does not depend on whether the caller's
+ * projection lists `id`.
+ *
+ * ## The defect
+ *
+ * A reader refused `sys_file` read (every member whose application grants no
+ * `sys_file` read) is served a file field by the parent-derived verdict of
+ * #22637: a file whose `ref_object` / `ref_id` name the record being read
+ * hydrates when the download door's field-owned verdict allows this reader.
+ * That verdict is judged per RECORD, by the record's `id`. A projection that
+ * left `id` out (`GET /data/:object?select=attachment`) handed the hydration
+ * rows with no `id`, so no file could be matched to its owner and every one
+ * answered `{ id, metadataRefused: true }` — while `select=id,attachment`
+ * answered the full `{ id, name, size, mimeType, url }` to the same reader.
+ *
+ * ## What is pinned, on the composed REST harness
+ *
+ * `RestServer` → `ObjectStackProtocolImplementation` → `ObjectQL` → a real
+ * `SqlDriver` on better-sqlite3, through the three read doors that reach the
+ * hydration: `GET /data/:object` (`select`), `POST /data/:object/query`
+ * (`fields`) and `GET /data/:object/:id` (`select`, the `findOne` door).
+ *
+ *   - The permitted reader gets the full value with or without `id`, and no
+ *     `id` key the caller did not name.
+ *   - CONTROL the same projection with `id` answers as it did.
+ *   - CONTROL a reader the field-owned verdict refuses is still refused, with
+ *     or without `id`: nothing an unauthorised caller sees is widened.
+ *
+ * ## The stand-ins, and only these
+ *
+ *   - The security layer's `sys_file` refusal: an engine middleware that
+ *     throws `PERMISSION_DENIED` for every non-system `sys_file` read, the
+ *     shape plugin-security's `file-field-hydration-refused.test.ts` measures
+ *     on the real `SecurityPlugin`.
+ *   - The field-owned verdict the storage plugin hands the engine: one that
+ *     allows the reader and nobody else. The real verdict's agreement with the
+ *     download door is pinned in service-storage's
+ *     `field-owned-file-hydration-door-agreement.test.ts`.
+ *
+ * `@objectstack/objectql` resolves through its `exports` to `dist/` here, so
+ * an ablation of the engine is observed only after a rebuild of that package.
+ */
+
+import { describe, it, expect, beforeAll, afterAll } from 'vitest';
+import { ObjectQL } from '@objectstack/objectql';
+import { SqlDriver } from '@objectstack/driver-sql';
+import { ObjectStackProtocolImplementation } from '@objectstack/metadata-protocol';
+import { RestServer } from './rest-server';
+import { installDefaultOrganization } from './default-organization.testkit.js';
+
+const OBJECT = 'rq_filed_doc';
+const SYS = { isSystem: true };
+const READER = 'u_reader';
+const STRANGER = 'u_stranger';
+const FILE_ID = 'f_26672_owned';
+
+const hydrated = {
+  id: FILE_ID, name: 'contract.pdf', size: 2048, mimeType: 'application/pdf', url: `/api/v1/storage/files/${FILE_ID}`,
+};
+const refused = { id: FILE_ID, metadataRefused: true };
+
+function createMockServer() {
+  const noop = () => {};
+  return { get: noop, post: noop, put: noop, delete: noop, patch: noop, use: noop, listen: async () => {}, close: async () => {} };
+}
+
+function makeRes() {
+  const res: any = {
+    write: () => true, end: () => {},
+    header: () => res,
+    status: (code: number) => { res._status = code; return res; },
+    json: (body: any) => { res._json = body; return res; },
+  };
+  return res;
+}
+
+const refusal = () =>
+  Object.assign(new Error('You do not have permission to perform this action.'), {
+    name: 'PermissionDeniedError', code: 'PERMISSION_DENIED', status: 403, statusCode: 403,
+  });
+
+const rowsOf = (res: any): Array<Record<string, unknown>> => res._json?.records ?? res._json?.data ?? res._json;
+const recordOf = (res: any): Record<string, unknown> => res._json?.record ?? res._json;
+
+describe('[#26672] a file field reads the same with or without `id` in the projection', () => {
+  let engine: ObjectQL;
+  let caller = READER;
+  let list: (query: Record<string, unknown>) => Promise<any>;
+  let query: (body: Record<string, unknown>) => Promise<any>;
+  let getById: (id: string, query: Record<string, unknown>) => Promise<any>;
+
+  beforeAll(async () => {
+    engine = new ObjectQL();
+    engine.registerDriver(
+      new SqlDriver({ client: 'better-sqlite3', connection: { filename: ':memory:' }, useNullAsDefault: true }) as any,
+      true,
+    );
+    await engine.init();
+    engine.registry.registerObject({
+      name: OBJECT,
+      label: 'Filed doc',
+      fields: {
+        title: { name: 'title', type: 'text' },
+        attachment: { name: 'attachment', type: 'file' },
+      },
+    } as any);
+    // The storage service's `sys_file`, as far as the hydration reads it.
+    engine.registry.registerObject({
+      name: 'sys_file',
+      label: 'System File',
+      fields: {
+        key: { name: 'key', type: 'text' },
+        name: { name: 'name', type: 'text' },
+        mime_type: { name: 'mime_type', type: 'text' },
+        size: { name: 'size', type: 'number' },
+        status: { name: 'status', type: 'text' },
+        ref_object: { name: 'ref_object', type: 'text' },
+        ref_id: { name: 'ref_id', type: 'text' },
+        ref_field: { name: 'ref_field', type: 'text' },
+      },
+    } as any);
+    await engine.syncSchemas();
+    await installDefaultOrganization(engine);
+
+    await engine.insert('sys_file', {
+      id: FILE_ID, key: `files/${FILE_ID}.pdf`, name: 'contract.pdf', mime_type: 'application/pdf', size: 2048,
+      status: 'committed', ref_object: OBJECT, ref_id: 'd1', ref_field: 'attachment',
+    } as any, { context: SYS } as any);
+    await engine.insert(OBJECT, { id: 'd1', title: 'Signed', attachment: FILE_ID } as any, { context: SYS } as any);
+
+    engine.registerMiddleware(async (opCtx: any, next: () => Promise<void>) => {
+      if (!opCtx.context?.isSystem) throw refusal();
+      return next();
+    }, { object: 'sys_file' });
+    engine.registerFieldOwnedFileReadAuthorizer(async (_object, ownerIds, context) =>
+      new Set(context?.userId === READER ? ownerIds : []));
+
+    const protocol = new ObjectStackProtocolImplementation(engine as any);
+    const rest = new RestServer(createMockServer() as any, protocol as any, { api: { requireAuth: false } } as any);
+    (rest as any).resolveExecCtx = async () => ({ userId: caller });
+    rest.registerRoutes();
+    const routes = rest.getRoutes();
+    const route = (method: string, path: string) => {
+      const found = routes.find((r: any) => r.method === method && r.path === path);
+      expect(found).toBeDefined();
+      return found!;
+    };
+    const listRoute = route('GET', '/api/v1/data/:object');
+    const queryRoute = route('POST', '/api/v1/data/:object/query');
+    const getRoute = route('GET', '/api/v1/data/:object/:id');
+    list = async (q) => {
+      const res = makeRes();
+      await listRoute.handler({ params: { object: OBJECT }, query: q } as any, res);
+      return res;
+    };
+    query = async (body) => {
+      const res = makeRes();
+      await queryRoute.handler({ params: { object: OBJECT }, body } as any, res);
+      return res;
+    };
+    getById = async (id, q) => {
+      const res = makeRes();
+      await getRoute.handler({ params: { object: OBJECT, id }, query: q } as any, res);
+      return res;
+    };
+  });
+
+  afterAll(async () => {
+    try { await engine?.destroy(); } catch { /* noop */ }
+  });
+
+  const as = (user: string) => { caller = user; };
+
+  it('the refusal it starts from: the reader may not read sys_file directly', async () => {
+    const direct = await engine.find('sys_file', { context: { userId: READER } }).then(() => null, (e: any) => e);
+    expect({ code: direct?.code, status: direct?.statusCode ?? direct?.status }).toEqual({ code: 'PERMISSION_DENIED', status: 403 });
+  });
+
+  it('GET /data/:object?select=<file field>: a permitted reader gets the full value, and no `id` it did not name', async () => {
+    as(READER);
+    const res = await list({ select: 'attachment' });
+    expect(res._status ?? 200).toBe(200);
+    expect(rowsOf(res)).toEqual([{ attachment: hydrated }]);
+  });
+
+  it('POST /data/:object/query with fields: [<file field>]: the same', async () => {
+    as(READER);
+    const res = await query({ fields: ['attachment'] });
+    expect(res._status ?? 200).toBe(200);
+    expect(rowsOf(res)).toEqual([{ attachment: hydrated }]);
+  });
+
+  it('GET /data/:object/:id?select=<file field> (the findOne door): the same', async () => {
+    as(READER);
+    const res = await getById('d1', { select: 'attachment' });
+    expect(res._status ?? 200).toBe(200);
+    const record = recordOf(res);
+    expect(record.attachment).toEqual(hydrated);
+    expect(record).not.toHaveProperty('id');
+  });
+
+  it('CONTROL select=id,<file field> answers as it did', async () => {
+    as(READER);
+    expect(rowsOf(await list({ select: 'id,attachment' }))).toEqual([{ id: 'd1', attachment: hydrated }]);
+    expect(rowsOf(await query({ fields: ['id', 'attachment'] }))).toEqual([{ id: 'd1', attachment: hydrated }]);
+    expect(recordOf(await getById('d1', { select: 'id,attachment' }))).toMatchObject({ id: 'd1', attachment: hydrated });
+  });
+
+  it('CONTROL a reader the field-owned verdict refuses is still refused, with or without `id`', async () => {
+    as(STRANGER);
+    expect(rowsOf(await list({ select: 'attachment' }))).toEqual([{ attachment: refused }]);
+    expect(rowsOf(await list({ select: 'id,attachment' }))).toEqual([{ id: 'd1', attachment: refused }]);
+    expect(rowsOf(await query({ fields: ['attachment'] }))).toEqual([{ attachment: refused }]);
+    expect(rowsOf(await query({ fields: ['id', 'attachment'] }))).toEqual([{ id: 'd1', attachment: refused }]);
+    const byId = recordOf(await getById('d1', { select: 'attachment' }));
+    expect(byId.attachment).toEqual(refused);
+    expect(byId).not.toHaveProperty('id');
+    expect(recordOf(await getById('d1', { select: 'id,attachment' })).attachment).toEqual(refused);
+  });
+});