@@ -0,0 +1,24 @@
+---
+'@objectstack/spec': minor
+'@objectstack/service-automation': minor
+'@object-ui/app-shell': minor
+---
+
+feat(spec,automation,app-shell): a flow screen field typed `file` collects an upload, and the run resumes with the uploaded file's id
+
+Clause-②: yes (narrowing)
+Metadata-protocol: semantic
+
+<!-- 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. `ScreenFieldConfigSchema.type` stays an open string, so every flow that parsed before still parses, and nothing exported is removed or narrowed. What changes is what a screen field already declared `type: 'file'` means: the console renders the upload widget for it, and the resume door refuses a value that is not a file id. The remedy is a change in what a caller posts to `resume` (the uploaded file's id), never a rewrite of a package source or a stored row, so there is nothing for `objectstack migrate meta` to rewrite. The other categories are closed on facts: the three packages publish (not unpublished); no ADR-0087 id is named or touched (not registered or already-registered); and no runtime interface, type or export is removed or narrowed (not runtime-interface-only, type-surface-only or runtime-export-retired). -->
+
+A wizard can now ask for a file before the record that will own it exists, and write everything after its last screen.
+
+- **`@objectstack/spec`**: `ScreenFieldConfigSchema.type` (and the `ScreenFieldSpec` contract) documents `'file'` as the second value domain beside `'number'`. A `type: 'file'` field renders the platform upload widget. The upload goes through the file service and lands as a `sys_file` that no record owns yet. The resume carries that file's id, which is ADR-0104 D3's stored form, and nothing else. A later `create_record` or `update_record` node writes the id into an object's `file` field, and that write claims the file for the record. Under the default `runAs: 'user'`, the claim first makes the download door's read check as the run's user; a `runAs: 'system'` run's write is not checked, as no system write is.
+- **`@objectstack/service-automation`**: the resume re-checks a `type: 'file'` field as a value domain. A value that is not a file id, judged by the spec's `isFileIdToken` (the same predicate the claim path reads), is refused with `400 INVALID_SCREEN_INPUT` and the field code `invalid_type` ("must be the id of an uploaded file"). That covers a URL, the expanded `{ id, name, url, … }` read form, a list and a number. The value is never reduced to an id. The refusal writes nothing and keeps the pause, so a corrected resume still lands. An empty optional field and a hidden field are not judged. `image`, `avatar`, `video` and `audio` stay open widget hints.
+- **`@object-ui/app-shell`**: the flow screen dialog renders the object form's `FileField` for a `type: 'file'` field and uploads through the console's `UploadProvider`. While an upload is in flight, Submit is disabled and reads "Uploading…". The resume posts each file field as its bare id, and a prefilled expanded value is reduced to its id first.
+
+**BREAKING** (a resume-acceptance narrowing) for a flow whose `screen` node already declares a field `type: 'file'`. None was found in this repository's examples or packages.
+
+- **Before.** `type: 'file'` was an open widget hint the console did not know, so the field rendered a plain text input, and `POST /automation/:name/runs/:runId/resume` accepted any value for it.
+- **Now.** The field renders the upload widget, and the resume refuses any value that is not a file id with `400 INVALID_SCREEN_INPUT` (`invalid_type`). The refusal keeps the pause.
+- **Fix.** A caller that resumes the run itself, without the console, uploads the file through the file service first and posts the minted `sys_file` id for the field: FROM `{ "contract_file": "https://…/nda.pdf" }` TO `{ "contract_file": "FILE_ID" }`. A field that was never meant to collect an upload takes another `type`, such as `text`.
@@ -785,6 +785,39 @@ and `placeholder`, and the console's flow runner overlays it in the active
 locale — see the flows row in
 [Translations](/docs/ui/translations#what-you-can-translate).
 
+#### A file field
+
+`type: 'file'` asks for a file before the record that will own it exists, so a
+wizard can collect everything first and write once, after its last screen:
+
+```typescript
+{ id: 'ask', type: 'screen', config: { fields: [
+  { name: 'contract_name', label: 'Name', type: 'text', required: true },
+  { name: 'contract_file', label: 'Signed copy', type: 'file', required: true },
+] } },
+{ id: 'write', type: 'create_record', config: { objectName: 'contract',
+  fields: { name: { dialect: 'cel', source: 'contract_name' }, doc: { dialect: 'cel', source: 'contract_file' } } } },
+```
+
+- **The console uploads, the run receives the file's id.** The flow dialog
+  renders the platform upload widget and uploads through the file service. The
+  file lands as a `sys_file` that no record owns yet, and Submit stays disabled
+  until the upload settles. The resume carries the file's **id**, the stored
+  form of a `file` field.
+- **The write after the screen claims the file.** Writing the id into an
+  object's `file` field makes that record the file's one owner. Under the
+  default `runAs: 'user'` the write first checks that the run's user may read
+  the file, as the download door does. A `runAs: 'system'` run's write is not
+  checked, as no system write is.
+- **Anything but an id is refused on resume.** Like `type: 'number'`, `file` is a
+  shape `validateScreenInputs` checks. A URL, the expanded
+  `{ id, name, url, … }` read form, a list or a number is refused with
+  `invalid_type` inside the run's `INVALID_SCREEN_INPUT`, never reduced to an id.
+  The run stays parked, and the corrected submission still lands.
+- **One file per field.** A screen field has no `multiple`, `accept` or `maxSize`.
+  The target `file` field's own `accept` / `maxSize` still apply at the write
+  that claims the file.
+
 **Screen (object form):**
 
 Set `config.objectName`
 
@@ -278,7 +278,7 @@ A value: a CEL value envelope `{ dialect: 'cel', source }` evaluated by the expr
 | :--- | :--- | :--- | :--- |
 | **name** | `string` | ✅ | Field name (the flow variable the value binds to) — a name without a leading `$` (the `$` names are the flow engine's own), read as `{{ name }}` |
 | **label** | `string` | optional | Display label |
-| **type** | `string` | optional | Input type |
+| **type** | `string` | optional | Input type — an open widget hint (text, number, select, …); `file` renders the platform upload widget and the screen resumes with the uploaded file's id, which a later node writes into a `file` field |
 | **required** | `boolean` | optional | Whether a value is required to submit |
 | **options** | `{ value: any; label: string }[]` | optional | Choices for a select-style field; option values must stay distinct when read as text |
 | **defaultValue** | `any` | optional | Prefilled value: a CEL value envelope `{ dialect: 'cel', source }` evaluated when the screen is served (the client receives the value, never the envelope), or a literal written as it is — a `{…}` template token is refused |
@@ -300,7 +300,7 @@ A value: a CEL value envelope `{ dialect: 'cel', source }` evaluated by the expr
 | :--- | :--- | :--- | :--- |
 | **name** | `string` | ✅ | Field name (the flow variable the value binds to) — a name without a leading `$` (the `$` names are the flow engine's own), read as `{{ name }}` |
 | **label** | `string` | optional | Display label |
-| **type** | `string` | optional | Input type |
+| **type** | `string` | optional | Input type — an open widget hint (text, number, select, …); `file` renders the platform upload widget and the screen resumes with the uploaded file's id, which a later node writes into a `file` field |
 | **required** | `boolean` | optional | Whether a value is required to submit |
 | **options** | `{ value: any; label: string }[]` | optional | Choices for a select-style field; option values must stay distinct when read as text |
 | **defaultValue** | `any` | optional | Prefilled value: a CEL value envelope `{ dialect: 'cel', source }` evaluated when the screen is served (the client receives the value, never the envelope), or a literal written as it is — a `{…}` template token is refused |
 
@@ -0,0 +1,111 @@
+// Copyright (c) 2026 ObjectStack. Licensed under the Apache-2.0 license.
+//
+// Flow screen file-intake fixture (#25801).
+//
+// The shape the card asks for: a wizard that collects everything first —
+// including a file — and writes at the end. The record that will own the file
+// does not exist while the screen is open, so the upload lands as a `sys_file`
+// no record owns yet (ADR-0104 D3), the run resumes with that file's id, and
+// the `create_record` after the screen writes the id into the record's `file`
+// field — the write that claims the file for the record.
+//
+// The flow runs as the user (`runAs: 'user'`), so the claiming write is the
+// caller's own and the claim is read-judged as #25692 asks; a member, not the
+// seeded admin, drives it, so that judgement is a real one.
+
+import { defineStack } from '@objectstack/spec';
+import { ObjectSchema, Field } from '@objectstack/spec/data';
+import { PermissionSetSchema, type PermissionSet } from '@objectstack/spec/security';
+import type { Flow } from '@objectstack/spec/automation';
+import { SecurityPlugin, securityDefaultPermissionSets } from '@objectstack/plugin-security';
+
+/** The record the end of the wizard writes, owning the file the screen collected. */
+export const SfiContract = ObjectSchema.create({
+  name: 'sfi_contract',
+  // [ADR-0090 D1] grandfather stamp: the gate under test is the screen's file
+  // intake and the claim, not owner-sharing.
+  sharingModel: 'public_read_write',
+  label: 'Contract',
+  pluralLabel: 'Contracts',
+  fields: {
+    name: Field.text({ label: 'Name', required: true }),
+    doc: Field.file({ label: 'Signed copy' }),
+  },
+});
+
+/**
+ * `sfi_contract_intake` — start → screen (name, file) → create_record → end.
+ *
+ * Nothing is written before the screen is answered: the record and the claim
+ * both come from the one write after it.
+ */
+export const flowScreenFileIntake: Flow = {
+  name: 'sfi_contract_intake',
+  label: 'Contract intake',
+  type: 'screen',
+  status: 'active',
+  runAs: 'user',
+  nodes: [
+    { id: 'start', type: 'start', label: 'Start' },
+    {
+      id: 'ask',
+      type: 'screen',
+      label: 'New contract',
+      config: {
+        title: 'New contract',
+        fields: [
+          { name: 'contract_name', label: 'Name', type: 'text', required: true },
+          { name: 'contract_file', label: 'Signed copy', type: 'file', required: true },
+        ],
+      },
+    },
+    {
+      id: 'write',
+      type: 'create_record',
+      label: 'Create contract',
+      config: {
+        objectName: 'sfi_contract',
+        fields: {
+          name: { dialect: 'cel', source: 'contract_name' },
+          doc: { dialect: 'cel', source: 'contract_file' },
+        },
+      },
+    },
+    { id: 'end', type: 'end', label: 'End' },
+  ],
+  edges: [
+    { id: 'e1', source: 'start', target: 'ask' },
+    { id: 'e2', source: 'ask', target: 'write' },
+    { id: 'e3', source: 'write', target: 'end' },
+  ],
+};
+
+/** What a fresh, grant-less member resolves to: create and read on the contract. */
+export const sfiMemberSet: PermissionSet = PermissionSetSchema.parse({
+  name: 'sfi_fixture_member',
+  label: 'Screen file intake fixture member',
+  objects: {
+    sfi_contract: { allowRead: true, allowCreate: true, allowEdit: true, allowDelete: false },
+  },
+});
+
+/** The platform defaults (the seeded admin keeps full access) plus the member fallback above. */
+export function screenFileFixtureSecurity(): SecurityPlugin {
+  return new SecurityPlugin({
+    defaultPermissionSets: [...securityDefaultPermissionSets, sfiMemberSet],
+    fallbackPermissionSet: sfiMemberSet.name,
+  });
+}
+
+export const screenFileStack = defineStack({
+  manifest: {
+    id: 'com.dogfood.flow-screen-file',
+    namespace: 'sfi',
+    version: '0.0.0',
+    type: 'app',
+    name: 'Flow Screen File Intake Fixture',
+    description: 'A screen flow that collects a file before the record that owns it exists, then writes and claims it.',
+  },
+  objects: [SfiContract],
+  flows: [flowScreenFileIntake],
+});