@@ -0,0 +1,38 @@
+---
+'@objectstack/spec': minor
+---
+
+feat(spec): a view that declares no page size now shows 50 per page — `PaginationConfigSchema.pageSize` defaults to 50 (was 25)
+
+The platform display page size is 50 (maintainer ruling on objectui#9853,
+「9853 默认页大小改为50」). It is declared in one place, the view contract's
+`PaginationConfigSchema.pageSize`, and the renderer reads that spec default
+rather than keeping a number of its own — so the change lands in the protocol
+first.
+
+**What changes for an author who omits the page size:**
+
+- A view whose `pagination` block does not set `pageSize` now parses to
+  `pageSize: 50` where it parsed to `25`: 50 rows per page on a paged view, and
+  a fetch ceiling of 50 on a view with no pager (kanban, gallery, timeline).
+- A view with no `pagination` block at all parses with none, before and after;
+  its page size comes from the renderer, which takes this spec default (the
+  Console does so once objectui#9853 lands).
+
+**What does not change:** the accept set. `pageSize` is still a positive
+integer; `0`, negatives and fractions are refused exactly as before, and every
+page size an author wrote parses to the number they wrote.
+
+### Migration: FROM → TO
+
+| FROM | TO |
+| :--- | :--- |
+| a view that declares no page size and relied on 25 rows per page | write it: `pagination: { pageSize: 25 }` |
+| a view that declares no page size and should follow the platform default | change nothing — it now shows 50 |
+| reading `PaginationConfigParsed.pageSize` after parsing a `pagination` block without `pageSize` | it yields `50` where it yielded `25`; the type is unchanged |
+| reading the published JSON Schema's `default` for `ui/PaginationConfig` `pageSize` | it is `50` |
+
+The move is declared in `DEFAULT_CHANGES_BY_MAJOR`
+(`packages/spec/scripts/lib/default-changes.ts`, `ui/PaginationConfig:pageSize`
+25 → 50) and carried on the upgrade path as the semantic entry
+`view-pagination-page-size-default-50`.
@@ -927,7 +927,7 @@ View filter rule
 
 | Property | Type | Required | Description |
 | :--- | :--- | :--- | :--- |
-| **pageSize** | `integer` | optional (default: `25`) | Number of records per page. On a view with no pager (kanban, gallery, timeline) it is the fetch ceiling, and the renderer owes two things: bound its fetch at this number, and, when the filtered set is larger than it, show a visible truncation signal saying what is on screen is not the whole set |
+| **pageSize** | `integer` | optional (default: `50`) | Number of records per page. On a view with no pager (kanban, gallery, timeline) it is the fetch ceiling, and the renderer owes two things: bound its fetch at this number, and, when the filtered set is larger than it, show a visible truncation signal saying what is on screen is not the whole set |
 | **pageSizeOptions** | `integer[]` | optional | Available page size options |
 
 ### Nested Shape: `ListView.kanban`
@@ -1326,7 +1326,7 @@ View filter rule
 
 | Property | Type | Required | Description |
 | :--- | :--- | :--- | :--- |
-| **pageSize** | `integer` | optional (default: `25`) | Number of records per page. On a view with no pager (kanban, gallery, timeline) it is the fetch ceiling, and the renderer owes two things: bound its fetch at this number, and, when the filtered set is larger than it, show a visible truncation signal saying what is on screen is not the whole set |
+| **pageSize** | `integer` | optional (default: `50`) | Number of records per page. On a view with no pager (kanban, gallery, timeline) it is the fetch ceiling, and the renderer owes two things: bound its fetch at this number, and, when the filtered set is larger than it, show a visible truncation signal saying what is on screen is not the whole set |
 | **pageSizeOptions** | `integer[]` | optional | Available page size options |
 
 ### Nested Shape: `ObjectListView.kanban`
@@ -1595,7 +1595,7 @@ Quick-filter field configuration
 
 | Property | Type | Required | Description |
 | :--- | :--- | :--- | :--- |
-| **pageSize** | `integer` | optional (default: `25`) | Number of records per page. On a view with no pager (kanban, gallery, timeline) it is the fetch ceiling, and the renderer owes two things: bound its fetch at this number, and, when the filtered set is larger than it, show a visible truncation signal saying what is on screen is not the whole set |
+| **pageSize** | `integer` | optional (default: `50`) | Number of records per page. On a view with no pager (kanban, gallery, timeline) it is the fetch ceiling, and the renderer owes two things: bound its fetch at this number, and, when the filtered set is larger than it, show a visible truncation signal saying what is on screen is not the whole set |
 | **pageSizeOptions** | `integer[]` | optional | Available page size options |
 
 
 
@@ -82,7 +82,7 @@
     "ui/PageTabsProps:position = \"top\"",
     "ui/PageTabsProps:tabStyle = \"line\"",
     "ui/PageVariable:type = \"string\"",
-    "ui/PaginationConfig:pageSize = 25",
+    "ui/PaginationConfig:pageSize = 50",
     "ui/RecordActivityProps:enableMentions = true",
     "ui/RecordActivityProps:enableReactions = false",
     "ui/RecordActivityProps:enableThreading = false",
 
@@ -533,5 +533,26 @@ export const DEFAULT_CHANGES_BY_MAJOR: Readonly<Record<number, readonly Declared
         + '`required` that lists defaulted keys is this repo\'s existing output-mode convention, not '
         + 'a new one.',
     },
+    {
+      key: 'ui/PaginationConfig:pageSize',
+      from: '25',
+      to: '50',
+      reason:
+        'A RULED behaviour change, not a correction: the platform display page size is 50 '
+        + '(maintainer ruling on objectui#9853, verbatim 「9853 默认页大小改为50」), and the spec '
+        + 'declaration is where that number lives — the renderer is ruled to read the spec default '
+        + 'rather than keep a page size of its own (objectui#9853 ruling C′ item 1), so the change '
+        + 'lands here first. '
+        + 'What moves: a view whose `pagination` block omits `pageSize` now parses to `pageSize: 50` '
+        + 'where it parsed to `25` — 50 rows per page on a paged view, and a fetch ceiling of 50 on a '
+        + 'view with no pager (kanban, gallery, timeline). A view with NO `pagination` block parses '
+        + 'with none on either side, so the parse materialises nothing there; the number reaches it '
+        + 'only through a renderer that takes the spec default. The accept set does not move: '
+        + '`pageSize` is still a positive integer, and `0`, negatives and fractions are refused '
+        + 'exactly as before. A `pageSize` written into a document — by its author, or by a tool '
+        + 'that serialised an earlier parse — is an authored value and keeps its number. '
+        + 'To keep 25 rows per page, write it: `pagination: { pageSize: 25 }`. To take the platform '
+        + 'default, change nothing.',
+    },
   ],
 };
@@ -0,0 +1,37 @@
+// Copyright (c) 2026 ObjectStack. Licensed under the Apache-2.0 license.
+
+import type { SemanticMigration } from '../../types.js';
+
+// The display page size a view gets when it declares none moved from 25 to 50
+// (maintainer ruling on objectui#9853). A default move reaches every silent
+// document with no parse error and nothing in the author's diff, so the
+// upgrade path carries it as a TODO: only the deployment can say whether a
+// view that never declared a page size was relying on 25.
+export const entry: SemanticMigration = {
+  id: 'view-pagination-page-size-default-50',
+  // No backticks in `surface` — build-upgrade-guide.ts renders it inside a code
+  // span AND a table cell.
+  surface: 'ui.PaginationConfig.pageSize — an OMITTED page size on a view',
+  replacement: 'nothing, to take the platform display page size of 50. To keep the old 25 rows '
+    + 'per page on a view, write it: `pagination: { pageSize: 25 }`',
+  reason:
+    'A RULED behaviour change on a default, so there is nothing to rewrite and nothing to '
+    + 'refuse: the maintainer set the platform display page size to 50 (「9853 默认页大小改为50」, '
+    + 'objectui#9853), and the declared default of `PaginationConfigSchema.pageSize` moved '
+    + 'from 25 to 50. A `pagination` block that omits `pageSize` now parses to 50 — 50 rows '
+    + 'per page on a paged view, and a fetch ceiling of 50 on a view with no pager (kanban, '
+    + 'gallery, timeline). A view with no `pagination` block at all parses with none on either '
+    + 'side; its page size reaches it through the renderer, which is ruled to read the spec '
+    + 'default rather than keep its own number (objectui#9853 ruling C′ item 1). Not losslessly '
+    + 'convertible because the question is intent, not text: a mechanical pass that wrote '
+    + '`pageSize: 25` into every silent view would preserve the old number and defeat the '
+    + 'ruling, and one that wrote 50 would add nothing the default does not already do. Only '
+    + 'the deployment knows which silent views were relying on 25. The accept set is unchanged '
+    + '— a positive integer — and every authored `pageSize` parses exactly as before.',
+  acceptanceCriteria:
+    'An empty pagination configuration parses to a page size of 50, and a list view carrying '
+    + '`pagination: {}` parses to `pagination.pageSize` 50; an authored '
+    + '`pagination: { pageSize: 25 }` still parses to 25; `pageSize: 0`, a negative and a '
+    + 'fraction are still refused. A view that must keep 25 rows per page declares '
+    + '`pagination: { pageSize: 25 }` and shows 25 rows on its first page.',
+};
@@ -14207,6 +14207,39 @@ const step18: MigrationStep = {
         + 'equals, and operator: "in" with value: ["won"] — select the same rows, so the result '
         + 'set cannot tell you which the metadata meant, and only the author knows.',
     },
+    // The display page size a view gets when it declares none moved from 25 to 50
+    // (maintainer ruling on objectui#9853). A default move reaches every silent
+    // document with no parse error and nothing in the author's diff, so the
+    // upgrade path carries it as a TODO: only the deployment can say whether a
+    // view that never declared a page size was relying on 25.
+    {
+      id: 'view-pagination-page-size-default-50',
+      // No backticks in `surface` — build-upgrade-guide.ts renders it inside a code
+      // span AND a table cell.
+      surface: 'ui.PaginationConfig.pageSize — an OMITTED page size on a view',
+      replacement: 'nothing, to take the platform display page size of 50. To keep the old 25 rows '
+        + 'per page on a view, write it: `pagination: { pageSize: 25 }`',
+      reason:
+        'A RULED behaviour change on a default, so there is nothing to rewrite and nothing to '
+        + 'refuse: the maintainer set the platform display page size to 50 (「9853 默认页大小改为50」, '
+        + 'objectui#9853), and the declared default of `PaginationConfigSchema.pageSize` moved '
+        + 'from 25 to 50. A `pagination` block that omits `pageSize` now parses to 50 — 50 rows '
+        + 'per page on a paged view, and a fetch ceiling of 50 on a view with no pager (kanban, '
+        + 'gallery, timeline). A view with no `pagination` block at all parses with none on either '
+        + 'side; its page size reaches it through the renderer, which is ruled to read the spec '
+        + 'default rather than keep its own number (objectui#9853 ruling C′ item 1). Not losslessly '
+        + 'convertible because the question is intent, not text: a mechanical pass that wrote '
+        + '`pageSize: 25` into every silent view would preserve the old number and defeat the '
+        + 'ruling, and one that wrote 50 would add nothing the default does not already do. Only '
+        + 'the deployment knows which silent views were relying on 25. The accept set is unchanged '
+        + '— a positive integer — and every authored `pageSize` parses exactly as before.',
+      acceptanceCriteria:
+        'An empty pagination configuration parses to a page size of 50, and a list view carrying '
+        + '`pagination: {}` parses to `pagination.pageSize` 50; an authored '
+        + '`pagination: { pageSize: 25 }` still parses to 25; `pageSize: 0`, a negative and a '
+        + 'fraction are still refused. A view that must keep 25 rows per page declares '
+        + '`pagination: { pageSize: 25 }` and shows 25 rows on its first page.',
+    },
     {
       id: 'wait-node-event-config-required',
       surface:
 
@@ -1434,20 +1434,23 @@ describe('SelectionConfigSchema', () => {
 });
 
 describe('PaginationConfigSchema', () => {
-  it('should default pageSize to 25', () => {
+  it('should default pageSize to 50', () => {
     const pagination = {};
 
     const result = PaginationConfigSchema.parse(pagination);
-    expect(result.pageSize).toBe(25);
+    expect(result.pageSize).toBe(50);
   });
 
   it('should accept custom page size', () => {
+    // 25 — the pre-#20050 default, which an author who wants it back now
+    // writes explicitly. A value OTHER than the default, so this pin still
+    // discriminates "the authored value survives" from "the default applied".
     const pagination = {
-      pageSize: 50,
+      pageSize: 25,
     };
 
     const result = PaginationConfigSchema.parse(pagination);
-    expect(result.pageSize).toBe(50);
+    expect(result.pageSize).toBe(25);
   });
 
   it('should accept page size options', () => {
 
@@ -1096,12 +1096,17 @@ export const SelectionConfigSchema = lazySchema(() => strictObject({
 
 /**
  * List View Pagination Configuration
+ *
+ * `pageSize` defaults to 50 — the platform's display page size, set by the
+ * maintainer's ruling on objectui#9853 (「9853 默认页大小改为50」). This
+ * declaration is the one place that number lives: a renderer reads the spec
+ * default, it never keeps a page size of its own.
  */
 export const PaginationConfigSchema = lazySchema(() => strictObject({
   surface: 'this pagination configuration',
   history: VIEW_HISTORY,
 }, {
-  pageSize: z.number().int().positive().default(25).describe(
+  pageSize: z.number().int().positive().default(50).describe(
     'Number of records per page. On a view with no pager (kanban, gallery, timeline) it is the fetch '
     + 'ceiling, and the renderer owes two things: bound its fetch at this number, and, when the filtered '
     + 'set is larger than it, show a visible truncation signal saying what is on screen is not the whole set',