@@ -0,0 +1,13 @@
+---
+'@objectstack/spec': patch
+---
+
+Clause-②: no
+
+fix(spec): the object-extension refusals for `hooks` and `listViews` say what `defineStack()` does with a hook or view on another package's object
+
+`ObjectExtensionSchema` refuses `hooks` and `listViews` on an `objectExtensions` entry. Both refusals used to tell the author to declare a top-level hook, or a top-level `view`, "bound to the target object instead". For an object the stack does not define, `defineStack()` refuses both at build, an extended object included, so the route the refusal named could not be taken.
+
+- **`hooks`** now reads: a hook follows the ownership of its object, so declare it as a top-level hook in the stack that defines the object; `defineStack()` refuses a top-level hook bound to an object the stack does not define, an extended one included. The refusal is the recorded decision of ADR-0130 §1.5 ("the split must follow hook ownership").
+- **`listViews`** now reads: declare the views as a top-level `view` in the stack that defines the target object; `defineStack()` refuses a top-level `view` whose `list` or `form` data source is an object the stack does not define, an extended one included.
+- **Unchanged.** What `defineStack()` accepts and refuses, every error code, status and issue path. Only the refusal text moves, with its mirror in the object-extensions guide.
@@ -83,8 +83,8 @@ each one by name with the alternative to use instead:
 | Key you might reach for | Declare this instead |
 |:---|:---|
 | `actions` | A top-level action with `objectName: '<target>'` in the same stack — it stays in the stack's top-level `actions`, and the engine's schema registry attaches it to the target object wherever the object is served, whichever package registers first; a target no loaded package registers fails the boot |
-| `hooks` | A top-level hook bound to the target object |
-| `listViews` | A top-level `view` bound to the target object |
+| `hooks` | A top-level hook in the stack that defines the target object — a hook follows the ownership of its object, and `defineStack()` refuses a top-level hook bound to an object the stack does not define, an extended one included |
+| `listViews` | A top-level `view` in the stack that defines the target object — `defineStack()` refuses a top-level `view` whose `list` or `form` data source is an object the stack does not define, an extended one included |
 | `fieldGroups` | Add the fields here and declare the groups on the owning object, or assign a Page for the layout |
 
 The same holds for any other key: the extension schema is strict, so an unknown key
 
@@ -3988,12 +3988,22 @@ export const ObjectExtensionSchema = lazySchema(() => strictObject({
       'top-level `actions`, and the engine\'s schema registry attaches it to the target ' +
       'object wherever the object is served, whichever package registers first. A target no ' +
       'loaded package registers fails the boot.',
+    // `hooks` and `listViews` name only what `defineStack()` measurably does.
+    // Its cross-reference check (`validateCrossReferences` in `stack.zod.ts`)
+    // judges a top-level hook's `object`, and a top-level view's `list` /
+    // `form` data source, against the objects the stack itself defines — an
+    // extended target is not one of them. For hooks that refusal is a recorded
+    // decision, ADR-0130 §1.5: "the split must follow hook ownership".
     hooks:
-      '`hooks` cannot be contributed through an object extension — declare a top-level ' +
-      'hook bound to the target object instead.',
+      '`hooks` cannot be contributed through an object extension — the merge does not carry ' +
+      'them. A hook follows the ownership of its object: declare it as a top-level hook in ' +
+      'the stack that defines the object. `defineStack()` refuses a top-level hook bound to ' +
+      'an object the stack does not define, an extended one included.',
     listViews:
-      '`listViews` cannot be contributed through an object extension — declare a ' +
-      'top-level `view` bound to the target object instead.',
+      '`listViews` cannot be contributed through an object extension — the merge does not ' +
+      'carry them. Declare the views as a top-level `view` in the stack that defines the ' +
+      'target object. `defineStack()` refuses a top-level `view` whose `list` or `form` data ' +
+      'source is an object the stack does not define, an extended one included.',
     fieldGroups:
       '`fieldGroups` cannot be contributed through an object extension — the merge does ' +
       'not carry them. Add the fields here and declare the groups on the owning object, ' +
 
@@ -0,0 +1,100 @@
+// Copyright (c) 2026 ObjectStack. Licensed under the Apache-2.0 license.
+
+/**
+ * `ObjectExtensionSchema` refuses `hooks` and `listViews` on an extension and
+ * says what to do instead. Each sentence makes a claim about `defineStack()`,
+ * and this file holds each claim at `defineStack()` itself:
+ *
+ * - a top-level hook bound to an object the stack does not define is refused at
+ *   build, even when the stack extends that object through `objectExtensions`.
+ *   ADR-0130 §1.5 records that refusal as deliberate: "the split must follow
+ *   hook ownership". A hook on an object the stack defines is accepted;
+ * - a top-level view whose `list` or `form` data source is an object the stack
+ *   does not define is refused the same way, extended or not. A view on an
+ *   object the stack defines is accepted.
+ *
+ * Both refusals come from `validateCrossReferences` in `stack.zod.ts`, which
+ * keeps exactly what it accepts and refuses; only the guidance text names it.
+ */
+
+import { describe, it, expect } from 'vitest';
+import { defineStack } from './stack.zod';
+import { ObjectExtensionSchema } from './data/object.zod';
+
+const manifest = { id: 'com.test.extender', name: 'extender', version: '1.0.0', type: 'app' as const };
+const OWN = { name: 'extender_note', label: 'Note', fields: { title: { type: 'text' as const, label: 'Title' } } };
+const FOREIGN = 'sys_organization';
+const extendsForeign = [{ extend: FOREIGN, fields: { tier: { type: 'text' as const, label: 'Tier' } } }];
+
+const hook = (object: string) => ({ name: 'probe_hook', object, events: ['beforeInsert'], handler: 'noop' });
+const listView = (object: string) => ({
+  list: { type: 'grid', data: { provider: 'object', object }, columns: ['name'] },
+});
+const formView = (object: string) => ({
+  form: { type: 'simple', data: { provider: 'object', object }, sections: [{ label: 'Main', fields: [{ field: 'name' }] }] },
+});
+
+const refusalOf = (config: unknown): any => {
+  try {
+    defineStack(config as any);
+    return undefined;
+  } catch (error) {
+    return error;
+  }
+};
+
+describe('defineStack and a top-level hook bound to an object outside the stack', () => {
+  it('refuses a hook on an object the stack only extends', () => {
+    const err = refusalOf({ manifest, objects: [OWN], objectExtensions: extendsForeign, hooks: [hook(FOREIGN)] });
+    expect(err).toMatchObject({ code: 'STACK_CROSS_REFERENCE_INVALID', status: 422 });
+    expect(err.message).toContain(`Hook 'probe_hook' references object '${FOREIGN}'`);
+  });
+
+  it('accepts a hook on an object the stack defines (the control)', () => {
+    const stack = defineStack({
+      manifest, objects: [OWN], objectExtensions: extendsForeign, hooks: [hook(OWN.name)],
+    } as any);
+    expect(stack.hooks?.map((h) => h.object)).toEqual([OWN.name]);
+  });
+});
+
+describe('defineStack and a top-level view whose data source is an object outside the stack', () => {
+  it('refuses a view whose `list` reads an object the stack only extends', () => {
+    const err = refusalOf({ manifest, objects: [OWN], objectExtensions: extendsForeign, views: [listView(FOREIGN)] });
+    expect(err).toMatchObject({ code: 'STACK_CROSS_REFERENCE_INVALID', status: 422 });
+    expect(err.message).toContain(`View[0].list references object '${FOREIGN}'`);
+  });
+
+  it('refuses a view whose `form` reads an object the stack only extends', () => {
+    const err = refusalOf({ manifest, objects: [OWN], objectExtensions: extendsForeign, views: [formView(FOREIGN)] });
+    expect(err).toMatchObject({ code: 'STACK_CROSS_REFERENCE_INVALID', status: 422 });
+    expect(err.message).toContain(`View[0].form references object '${FOREIGN}'`);
+  });
+
+  it('accepts a view on an object the stack defines (the control)', () => {
+    const stack = defineStack({
+      manifest, objects: [OWN], objectExtensions: extendsForeign, views: [listView(OWN.name)],
+    } as any);
+    expect(stack.views).toHaveLength(1);
+  });
+});
+
+describe('the extension refusal says what defineStack does', () => {
+  const guidanceFor = (key: 'hooks' | 'listViews') => {
+    const parsed = ObjectExtensionSchema.safeParse({ extend: FOREIGN, [key]: key === 'hooks' ? [] : {} });
+    expect(parsed.success).toBe(false);
+    return JSON.stringify(parsed.error?.issues);
+  };
+
+  it('`hooks` names the owning stack and the refusal of an extended target', () => {
+    const text = guidanceFor('hooks');
+    expect(text).toContain('declare it as a top-level hook in the stack that defines the object');
+    expect(text).toContain('refuses a top-level hook bound to an object the stack does not define, an extended one included');
+  });
+
+  it('`listViews` names the owning stack and the refusal of an extended target', () => {
+    const text = guidanceFor('listViews');
+    expect(text).toContain('top-level `view` in the stack that defines the target object');
+    expect(text).toContain('data source is an object the stack does not define, an extended one included');
+  });
+});