feat: update minPageSize default from 100 to 50

README.md

@@ -389,8 +389,8 @@ getPageQuery: ({limit, start, dir, settled}) => ({
 
 The `limit` passed to `getPageQuery` comes from the page size: about three
 viewports' worth of rows at `estimateSize`, but never below the `minPageSize`
-floor (default 100). The floor is sized for short rows; for tall rows (cards,
-comments) 100 rows is many viewports of content, so the floor dominates the
+floor (default 50). The floor is sized for short rows; for tall rows (cards,
+comments) 50 rows is many viewports of content, so the floor dominates the
 formula and each page load renders far more DOM than needed — showing up as
 long tasks when a page lands mid-scroll. Lower it so page size tracks the
 viewport again:

demo/react/e2e/seed-test.ts

@@ -24,7 +24,7 @@ export type TestItem = {
 //   created  ASC            → Test Item 011  (created  = BASE−190H, lowest)
 //
 // The 200 items also give the virtualizer enough rows to exercise paging
-// (the min page size in the demo is 100).
+// (the min page size in the demo is 50).
 const NAMED: TestItem[] = [
   {
     id: 'tstitem001',

demo/react/e2e/tests/app.spec.ts

@@ -14,7 +14,7 @@ test.describe('App', () => {
 
   test('shows the correct item count', async ({page}) => {
     // The virtualizer lazy-loads pages, so the initial count may be an
-    // estimate of the first page only (e.g. "(~100)"). Just verify that
+    // estimate of the first page only (e.g. "(~50)"). Just verify that
     // some item count is displayed in the heading.
     await expect(page.getByText(/\(~?\d+\)/)).toBeVisible({timeout: 15_000});
   });

demo/react/e2e/tests/scroll.spec.ts

@@ -41,7 +41,7 @@ async function waitForScrollStatePersisted(page: Page) {
 
 // The virtual list renders only the visible rows. Scrolling causes new pages
 // to be fetched and new rows to be inserted into the DOM. With 200 items and a
-// min page size of 100, there are at least 2 pages to load.
+// min page size of 50, there are at least 2 pages to load.
 
 test.describe('Scroll / paging', () => {
   test.beforeEach(async ({page}) => {
@@ -50,7 +50,7 @@ test.describe('Scroll / paging', () => {
 
   test('initial render shows the correct item count', async ({page}) => {
     // The virtualizer lazy-loads pages, so the initial count is an estimate
-    // based on the first page only (e.g. "(~100)"). Verify a count appears.
+    // based on the first page only (e.g. "(~50)"). Verify a count appears.
     await expect(page.getByText(/\(~?\d+\)/)).toBeVisible({timeout: TIMEOUT});
   });
 
@@ -61,14 +61,17 @@ test.describe('Scroll / paging', () => {
 
     // The virtualizer lazy-loads pages, so we need to scroll to the bottom
     // repeatedly — each scroll triggers loading the next page, which extends
-    // the scrollable area.
+    // the scrollable area. The per-attempt check is kept short so the retry
+    // loop gets enough scroll rounds to walk every page (200 items over a
+    // 50-row min page size), rather than burning the budget on a few long
+    // waits.
     await expect(async () => {
       await viewportEl.evaluate(el => {
         el.scrollTop = el.scrollHeight;
       });
       await expect(
         page.locator(`a[href="#${TEST_ITEMS[TEST_ITEMS.length - 1].id}"]`),
-      ).toBeVisible();
+      ).toBeVisible({timeout: 1_000});
     }).toPass({timeout: TIMEOUT});
   });
 

src/core/virtualizer.dom.test.ts

@@ -110,6 +110,10 @@ function createHarness({
     getRowKey: row => row.id,
     listContextParams: 'ctx',
     anchoring: 'native',
+    // Pinned so the paging expectations below (page lengths, anchor indices,
+    // spaceBefore) stay fixed to a 100-row page rather than tracking the
+    // minPageSize default.
+    minPageSize: 100,
     observeElementRect: (_instance, cb) => {
       cb({width: 300, height: viewportHeight});
     },

src/core/virtualizer.test.ts

@@ -411,9 +411,9 @@ describe('ZeroVirtualizer wrapper contract', () => {
 });
 
 describe('minPageSize', () => {
-  test('defaults the query page size to 100', () => {
+  test('defaults the query page size to 50', () => {
     const v = new ZeroVirtualizer(makeOptions());
-    expect(v.getQueryInputs().pageSize).toBe(100);
+    expect(v.getQueryInputs().pageSize).toBe(50);
   });
 
   test('lowers the floor for tall rows', () => {

src/core/virtualizer.ts

@@ -26,7 +26,7 @@ import type {
 } from './types.ts';
 
 // Make sure this is even since we half it for scroll state loading
-const MIN_PAGE_SIZE = 100;
+const MIN_PAGE_SIZE = 50;
 
 const NUM_ROWS_FOR_LOADING_SKELETON = 1;
 
@@ -122,8 +122,8 @@ export type VirtualizerOptions<TListContextParams, TRow, TStartRow> = {
   /**
    * Floor for the query page size. The page size is derived from the viewport
    * (about three viewports' worth of rows at `estimateSize`), but never drops
-   * below this floor. Defaults to 100 — sized for short rows; lower it for
-   * tall rows (cards, comments) where 100 rows is many viewports of content.
+   * below this floor. Defaults to 50 — sized for short rows; lower it for
+   * tall rows (cards, comments) where 50 rows is many viewports of content.
    * Rounded up to an even number (paging halves pages around permalinks).
    */
   minPageSize?: number | undefined;

src/solid/create-zero-virtualizer.test.ts

@@ -163,7 +163,7 @@ describe('createZeroVirtualizer (solid wrapper wiring)', () => {
         kind: 'forward',
         startRow: undefined,
       });
-      expect(inputs().pageSize).toBeGreaterThanOrEqual(100);
+      expect(inputs().pageSize).toBeGreaterThanOrEqual(50);
       expect(inputs().settled).toBe(false);
       dispose();
     });