@@ -0,0 +1,19 @@
+---
+'@objectstack/service-storage': patch
+---
+
+fix(storage)!: an anonymous write carries no file
+
+Ruling C ("an anonymous submission carries no file") now holds at every anonymous write door of ADR-0138 D2, not only at the public form door. A record write whose caller has no user, such as the guest an `authRequired: false` endpoint executes as under the grants a deployment binds to the guest, may not put a value in a file field (`file`, `image`, `avatar`, `video`, `audio`). It is refused before anything is written, with the form door's envelope: `400 VALIDATION_FAILED`, one `fields[]` entry per refused field carrying the ADR-0114 field code `invalid_value` and the field's label. An empty or absent file field is written as before. Signed-in callers, system writes and context-less programmatic writes are unchanged. No error code is added.
+
+Clause-②: no (narrowing) — an anonymous write that carried a value in a file field is refused. Nothing that was refused becomes accepted.
+
+Metadata-protocol: none (a write path's file rule; nothing a metadata author writes changes)
+
+<!-- adr-0087: not-required (no-migration-prescription) No metadata moves: no spec key, authorable spelling, object definition, stored row or stored shape is added, removed, renamed or re-shaped, and no exported declaration is removed or narrowed, so there is nothing for `objectstack migrate meta` to rewrite. What changes is which record writes the file-reference path accepts (an anonymous caller's write carrying a file value is refused). The remedy is a change of who provides the file (a signed-in caller), never a rewrite of a package source or a stored row. The other categories are closed on facts: the package publishes (not unpublished); no ADR-0087 id is named or touched (not registered or already-registered); and nothing exported is removed or narrowed (not runtime-interface-only, type-surface-only or runtime-export-retired). -->
+
+**BREAKING** for an anonymous write that carried a file value, shipped as `patch` because the metadata protocol does not move.
+
+- **Before.** Only the public form door refused a file value from an anonymous caller.
+- **Now.** Every write whose caller has no user is refused with `400 VALIDATION_FAILED` when a file field carries a value.
+- **Fix.** Leave file fields empty in an anonymous write. A file is provided by a signed-in caller, through the authenticated upload doors.
@@ -125,9 +125,10 @@ describe('sys_file public-scope backfill (#22443 ruling B) — a real ObjectQL o
    * the source row's scope on the copy.
    */
   // The claiming write acts in an organization: `product` is created by this
-  // release, whose tenant column is NOT NULL (ADR-0131 D1).
+  // release, whose tenant column is NOT NULL (ADR-0131 D1). [#25694] Its
+  // caller is signed in: an anonymous write carries no file.
   const copyBySecondReference = (recordId: string, fileId: string) =>
-    engine.insert('product', { id: recordId, title: recordId, image: fileId }, { context: { tenantId: 'org_a' } } as any);
+    engine.insert('product', { id: recordId, title: recordId, image: fileId }, { context: { userId: 'u_writer', tenantId: 'org_a' } } as any);
 
   it('a deployment with no public rows runs clean: it counts zero and writes nothing', async () => {
     await engine.insert('sys_file', { ...legacyPublicRow('f_user'), scope: 'user' }, SYSTEM as any);
 
@@ -9,6 +9,7 @@ import {
   type FileReferenceEngine,
 } from './file-reference-lifecycle.js';
 import { assertEngineFindOnePredicate } from '@objectstack/objectql';
+import { resolveThrownHttpError } from '@objectstack/types';
 
 const silentLogger = () => ({ info: vi.fn(), warn: vi.fn(), debug: vi.fn() });
 
@@ -1357,3 +1358,191 @@ describe('a write references only a file its caller may read', () => {
     });
   });
 });
+
+describe('an anonymous write carries no file (#25694, ruling C at every anonymous write door)', () => {
+  /** The guest principal an `authRequired: false` endpoint's write executes as (ADR-0138 D9). */
+  const GUEST = { principalKind: 'guest', positions: ['guest'], isSystem: false, tenantId: 'org_1' };
+  const guestSession = { organizationId: 'org_1', positions: ['guest'] };
+  const SIGNED_IN = { userId: 'u_writer', tenantId: 'org_1' };
+
+  const LABELLED: Record<string, any> = {
+    sys_file: REGISTRY.sys_file,
+    product: {
+      name: 'product',
+      fields: {
+        id: { type: 'text' },
+        name: { type: 'text' },
+        image: { type: 'image', label: 'Photo' },
+        gallery: { type: 'image', multiple: true },
+        manual: { type: 'file' },
+      },
+    },
+  };
+
+  function installAdmitting(engine: Engine, storage: any = fakeStorage()) {
+    // A verdict that admits every file: the refusal must not lean on it.
+    const authorizeRead = vi.fn(async () => true);
+    installFileReferenceHooks(engine, () => storage, silentLogger(), authorizeRead);
+    return { storage, authorizeRead };
+  }
+
+  async function write(
+    engine: Engine,
+    phase: 'insert' | 'update',
+    data: Record<string, unknown>,
+    id: string,
+    caller: { session?: any; context?: any },
+  ) {
+    const ctx: any = {
+      object: 'product',
+      event: phase === 'insert' ? 'beforeInsert' : 'beforeUpdate',
+      input: { ...(phase === 'update' ? { id } : {}), data, options: caller.context ? { context: caller.context } : {} },
+      session: caller.session,
+      dispatch: recordDispatch(),
+    };
+    await engine.trigger(ctx.event, ctx);
+    let row: Record<string, unknown> & { id: string };
+    if (phase === 'insert') {
+      row = { ...(ctx.input.data as Record<string, unknown>), id };
+      (engine.tables.product ??= []).push(row);
+    } else {
+      row = (engine.tables.product ?? []).find((r) => String(r.id) === id) as any;
+      Object.assign(row, ctx.input.data);
+    }
+    ctx.event = phase === 'insert' ? 'afterInsert' : 'afterUpdate';
+    ctx.result = row;
+    await engine.trigger(ctx.event, ctx);
+    return row;
+  }
+
+  const asGuest = { session: guestSession, context: GUEST };
+  const refusedBy = (p: Promise<unknown>) => p.then(() => null, (e) => e);
+  const sysFileWrites = (engine: Engine) =>
+    engine.calls.filter((c) => (c.op === 'update' || c.op === 'insert') && c.object === 'sys_file');
+
+  describe('a value in a file field is refused before anything is written', () => {
+    const VALUES: Array<[string, unknown]> = [
+      ['an unclaimed file id', 'file_a'],
+      ['a file id another record owns', 'file_b'],
+      ['an external URL', 'https://example.test/x.png'],
+      ['an inline file value', { url: 'https://example.test/y.png', name: 'y.png' }],
+    ];
+    for (const [what, value] of VALUES) {
+      it(`on insert: ${what}`, async () => {
+        const engine = fakeEngine({
+          registry: LABELLED,
+          files: [file(), file({ id: 'file_b', key: 'user/file_b.png', ref_object: 'product', ref_id: 'p0', ref_field: 'image' })],
+          records: { product: [{ id: 'p0', image: 'file_b' }] },
+        });
+        const { storage, authorizeRead } = installAdmitting(engine);
+
+        const err = await refusedBy(write(engine, 'insert', { name: 'n', image: value }, 'p1', asGuest));
+
+        const answered = resolveThrownHttpError(err);
+        expect({ status: answered.status, code: answered.code }).toEqual({ status: 400, code: 'VALIDATION_FAILED' });
+        expect(err?.fields).toEqual([expect.objectContaining({ field: 'image', code: 'invalid_value', label: 'Photo' })]);
+        expect(err?.fields[0].message).toContain('Photo');
+        // Nothing was written: no row, no claim, no copy, and no file was looked up for it.
+        expect((engine.tables.product ?? []).map((r) => r.id)).toEqual(['p0']);
+        expect(sysFileWrites(engine)).toEqual([]);
+        expect(storage.download).not.toHaveBeenCalled();
+        expect(authorizeRead).not.toHaveBeenCalled();
+      });
+    }
+
+    it('on update', async () => {
+      const engine = fakeEngine({ registry: LABELLED, files: [file()], records: { product: [{ id: 'p1', image: null }] } });
+      installAdmitting(engine);
+
+      const err = await refusedBy(write(engine, 'update', { image: 'file_a' }, 'p1', asGuest));
+
+      expect(err?.code).toBe('VALIDATION_FAILED');
+      expect(err?.fields).toEqual([expect.objectContaining({ field: 'image', code: 'invalid_value' })]);
+      expect(engine.tables.product[0].image).toBeNull();
+      expect(engine.tables.sys_file[0].ref_id ?? null).toBeNull();
+    });
+
+    it('every file field carrying a value is named in one envelope, by its label or else its name', async () => {
+      const engine = fakeEngine({ registry: LABELLED, files: [file()] });
+      installAdmitting(engine);
+
+      const err = await refusedBy(
+        write(engine, 'insert', { image: 'file_a', gallery: ['file_a'], manual: 'https://example.test/m.pdf' }, 'p1', asGuest),
+      );
+
+      expect(err?.code).toBe('VALIDATION_FAILED');
+      expect(err?.fields.map((f: any) => [f.field, f.code, f.label])).toEqual([
+        ['image', 'invalid_value', 'Photo'],
+        ['gallery', 'invalid_value', 'gallery'],
+        ['manual', 'invalid_value', 'manual'],
+      ]);
+    });
+  });
+
+  describe('CONTROL — what the rule leaves as it was', () => {
+    it('an anonymous write with every file field empty or absent is written', async () => {
+      const engine = fakeEngine({ registry: LABELLED, files: [file()] });
+      installAdmitting(engine);
+
+      for (const [id, data] of [
+        ['p1', { name: 'absent' }],
+        ['p2', { name: 'null', image: null }],
+        ['p3', { name: 'blank', image: '' }],
+        ['p4', { name: 'empty set', gallery: [] }],
+      ] as const) {
+        await write(engine, 'insert', { ...data }, id, asGuest);
+      }
+
+      expect(engine.tables.product.map((r) => r.id)).toEqual(['p1', 'p2', 'p3', 'p4']);
+      expect(engine.tables.sys_file[0].ref_id ?? null).toBeNull();
+    });
+
+    it('an anonymous update that clears a file field, or leaves it out, is written', async () => {
+      const engine = fakeEngine({ registry: LABELLED, records: { product: [{ id: 'p1', name: 'a', image: null }] } });
+      installAdmitting(engine);
+
+      await write(engine, 'update', { name: 'b' }, 'p1', asGuest);
+      await write(engine, 'update', { image: null }, 'p1', asGuest);
+
+      expect(engine.tables.product[0]).toMatchObject({ name: 'b', image: null });
+    });
+
+    it('a signed-in caller\'s write still claims the file', async () => {
+      const engine = fakeEngine({ registry: LABELLED, files: [file()] });
+      installAdmitting(engine);
+
+      await write(engine, 'insert', { image: 'file_a' }, 'p1', {
+        session: { userId: SIGNED_IN.userId, organizationId: 'org_1' },
+        context: SIGNED_IN,
+      });
+
+      expect(engine.tables.sys_file[0]).toMatchObject({ ref_object: 'product', ref_id: 'p1', ref_field: 'image' });
+    });
+
+    it('a system write and a context-less write still claim the file', async () => {
+      const engine = fakeEngine({ registry: LABELLED, files: [file(), file({ id: 'file_c', key: 'user/file_c.png' })] });
+      installAdmitting(engine);
+
+      await write(engine, 'insert', { image: 'file_a' }, 'p1', { session: { isSystem: true }, context: { isSystem: true } });
+      await write(engine, 'insert', { image: 'file_c' }, 'p2', {});
+
+      expect(engine.tables.sys_file.map((f) => [f.id, f.ref_id ?? null])).toEqual([
+        ['file_a', 'p1'],
+        ['file_c', 'p2'],
+      ]);
+    });
+
+    it('an object with no file field is not judged', async () => {
+      const engine = fakeEngine({ files: [file()] });
+      installAdmitting(engine);
+      const ctx: any = {
+        object: 'tag', event: 'beforeInsert', input: { data: { label: 'file_a' }, options: { context: GUEST } },
+        session: guestSession, dispatch: recordDispatch(),
+      };
+
+      await engine.trigger('beforeInsert', ctx);
+
+      expect(engine.calls).toEqual([]);
+    });
+  });
+});
@@ -4,6 +4,8 @@ import { randomUUID } from 'node:crypto';
 import { FILE_REFERENCE_TYPES, isFileIdToken, RAW_FILE_VALUES_CONTEXT_KEY } from '@objectstack/spec/data';
 import type { IStorageService } from '@objectstack/spec/contracts';
 import type { ExecutionContext } from '@objectstack/spec/kernel';
+import { isEmptyForRequired } from '@objectstack/core';
+import { validationFailure } from '@objectstack/types';
 import { callerContext } from './attachment-access-hooks.js';
 
 /**
@@ -51,6 +53,18 @@ import { callerContext } from './attachment-access-hooks.js';
  * the read check. System writes and context-less programmatic calls carry no
  * caller to ask, and reference files as before.
  *
+ * ### An anonymous write carries no file
+ *
+ * [#25694] Ruling C (record 6384525042), held at every anonymous write door
+ * rather than at the public form door alone: a write whose caller has no user
+ * (ADR-0138 D2's anonymous write doors: the guest envelope of an
+ * `authRequired: false` endpoint, under whatever grants a deployment binds to
+ * the guest) may not put a value in a file field. It is refused before the driver runs, naming each
+ * field, with the form door's envelope ({@link assertAnonymousWriteCarriesNoFile}).
+ * The read verdict above would admit a `public_read` file to such a caller,
+ * and keep any other id as written; neither is a file the anonymous caller
+ * may provide. An empty or absent file field is written as before.
+ *
  * ### The one write that cannot honour it, and is refused
  *
  * [#7102] A predicate (`multi: true`) update has ONE payload for N matched
@@ -277,6 +291,50 @@ async function findReferenceableFile(
   return (await authorizeRead(row, caller)) ? row : null;
 }
 
+/**
+ * [#25694] Ruling C at every anonymous write door: an anonymous write carries
+ * no file. A file is provided by a signed-in caller, through the authenticated
+ * upload doors; a caller with no user has none to provide, so a value in a
+ * file field of its write is refused, whether it names a platform file (one it
+ * may download or not) or anything else. Judged before the driver runs and
+ * before any file is looked up, so a refused write leaves nothing behind.
+ *
+ * The form door's own judgement (`form-routes.ts`, #25572), held at the
+ * engine: the same emptiness rule (`isEmptyForRequired`), and the same
+ * envelope — one `400 VALIDATION_FAILED` naming every refused field by its
+ * label with the closed ADR-0114 field code `invalid_value`. The form door
+ * keeps its own judgement, which answers before anything reaches the engine.
+ *
+ * `caller` is {@link referencingCallerOf}'s answer, the caller the read
+ * verdict is asked about: a system write and a context-less programmatic
+ * write have none, and are not judged; a caller with no user is anonymous.
+ */
+function assertAnonymousWriteCarriesNoFile(
+  engine: FileReferenceEngine,
+  object: string,
+  data: Record<string, unknown>,
+  fileFields: string[],
+  caller: ExecutionContext | null,
+): void {
+  if (!caller || caller.userId) return;
+  const refused: Array<{ field: string; code: 'invalid_value'; message: string; label: string }> = [];
+  for (const field of fileFields) {
+    if (!Object.prototype.hasOwnProperty.call(data, field)) continue;
+    const def = fieldDefOf(engine, object, field);
+    if (isEmptyForRequired(def, data[field])) continue;
+    const declared = typeof def?.label === 'string' ? def.label.trim() : '';
+    const label = declared.length > 0 ? declared : field;
+    refused.push({
+      field,
+      code: 'invalid_value',
+      message: `${label} cannot take a file here: an anonymous write carries no file. `
+        + 'Leave it empty, or sign in and provide the file from your account.',
+      label,
+    });
+  }
+  if (refused.length > 0) throw validationFailure(refused.map((f) => f.message).join('; '), refused);
+}
+
 /** Bound on owned files released per record delete. */
 const RELEASE_BATCH_LIMIT = 1_000;
 
@@ -869,9 +927,11 @@ export function installFileReferenceHooks(
       if (!object || !data || typeof data !== 'object') return;
       const fileFields = activeFileFields(engine, object);
       if (fileFields.length === 0) return;
+      const caller = referencingCallerOf(ctx);
+      assertAnonymousWriteCarriesNoFile(engine, object, data, fileFields, caller);
       await applyCopyOnClaim(
         engine, getStorage, logger, object, null, data, fileFields,
-        actingOrganizationOf(ctx), referencingCallerOf(ctx), authorizeRead, mintedCopiesFor(ctx),
+        actingOrganizationOf(ctx), caller, authorizeRead, mintedCopiesFor(ctx),
       );
     },
     { packageId: PACKAGE_ID },
@@ -885,6 +945,10 @@ export function installFileReferenceHooks(
       if (!object || !data || typeof data !== 'object') return;
       const fileFields = activeFileFields(engine, object);
       if (fileFields.length === 0) return;
+      // [#25694] Before the predicate refusal below: an anonymous write is
+      // refused for what it carries, whichever shape the write takes.
+      const caller = referencingCallerOf(ctx);
+      assertAnonymousWriteCarriesNoFile(engine, object, data, fileFields, caller);
       // [#6966] "Is this a multi-update?" is the engine's marker, not the shape
       // of `input.id`. A per-row context names ITS row, so the old
       // `ids.length === 1` test answered "single update" on every row of a
@@ -928,7 +992,7 @@ export function installFileReferenceHooks(
       // analysis a later edit has to re-derive.
       await applyCopyOnClaim(
         engine, getStorage, logger, object, recordId, data, fileFields,
-        actingOrganizationOf(ctx), referencingCallerOf(ctx), authorizeRead, mintedCopiesFor(ctx),
+        actingOrganizationOf(ctx), caller, authorizeRead, mintedCopiesFor(ctx),
       );
     },
     { packageId: PACKAGE_ID },