fix(grid): preserve row selection during infinite-scroll append

apps/desktop/src/components/grid/DataGrid.vue

@@ -141,7 +141,7 @@ import { isCancelSearchShortcut, isCopyCurrentRowShortcut, isDeleteCurrentRowSho
 import { dataGridHeaderContentWidth, scrollbarGutterWidth } from "@/lib/dataGrid/dataGridScrollGutter";
 import { canFetchNextDataGridSegment, canGoNextDataGridPage, dataGridTotalRowCountLabelKey, hasCompleteLocalDataGridResult, resolveDataGridPaginationTotal, type DataGridInexactTotalRowCountMode } from "@/lib/dataGrid/dataGridPagination";
 import { dataGridCountQueryOptions } from "@/lib/dataGrid/dataGridQueryOptions";
-import { dataGridBottomScrollTop, dataGridScrollPosition, isDataGridAtScrollBottom, isDataGridNearScrollBottom, shouldCheckInfiniteScrollAfterScroll, type DataGridScrollPosition } from "@/lib/dataGrid/dataGridInfiniteScroll";
+import { dataGridBottomScrollTop, dataGridScrollPosition, isDataGridAtScrollBottom, isDataGridNearScrollBottom, isDataGridPrefixAppend, shouldCheckInfiniteScrollAfterScroll, type DataGridScrollPosition } from "@/lib/dataGrid/dataGridInfiniteScroll";
 import { CANVAS_DATA_GRID_ROW_HEIGHT, canvasDataGridActionOverlayWidth, canvasDataGridActionReservedWidth, dataGridSearchMatchKey, drawCanvasDataGrid, type CanvasDevicePixelSize } from "@/lib/dataGrid/canvasDataGridRenderer";
 import { DATA_GRID_DARK_STRIPED_ROW_BG, DATA_GRID_LIGHT_STRIPED_ROW_BG, dataGridActiveRowBackground } from "@/lib/dataGrid/dataGridPaintTheme";
 import { createRowLowerTextCache } from "@/lib/dataGrid/dataGridRowLowerText";
@@ -7112,9 +7112,10 @@ watch(isTransposeMode, (active) => {
 
 watch(
   () => props.result,
-  () => {
+  (result, previousResult) => {
     const shouldPreserveTranspose = preserveTransposeOnNextResult.value;
     preserveTransposeOnNextResult.value = false;
+    if (isDataGridPrefixAppend(previousResult, result)) return;
     if (getResetScrollAfterResult()) {
       clearResetScrollAfterResult();
       resetGridVerticalScroll();

apps/desktop/src/lib/dataGrid/dataGridInfiniteScroll.ts

@@ -9,6 +9,11 @@ export interface DataGridScrollMetrics {
   clientHeight: number;
 }
 
+export interface DataGridAppendResult {
+  rows: readonly unknown[];
+  appended_from_row_count?: number;
+}
+
 export function dataGridScrollPosition(top: number, left: number): DataGridScrollPosition {
   return {
     top: Math.max(0, top),
@@ -30,6 +35,11 @@ export function isDataGridNearScrollBottom(metrics: DataGridScrollMetrics, thres
   return metrics.scrollHeight - metrics.scrollTop - metrics.clientHeight < threshold;
 }
 
+export function isDataGridPrefixAppend(previous: DataGridAppendResult | undefined, next: DataGridAppendResult): boolean {
+  if (!previous || next.appended_from_row_count !== previous.rows.length || next.rows.length < previous.rows.length) return false;
+  return previous.rows.every((row, index) => row === next.rows[index]);
+}
+
 export function isDataGridAtScrollBottom(metrics: DataGridScrollMetrics, tolerance = 1): boolean {
   const maxScrollTop = Math.max(0, metrics.scrollHeight - metrics.clientHeight);
   return maxScrollTop - metrics.scrollTop <= tolerance;

packages/app-tests/dataGridInfiniteScroll.test.ts

@@ -1,7 +1,7 @@
 import { strict as assert } from "node:assert";
 import { readFileSync } from "node:fs";
 import { test } from "vitest";
-import { dataGridScrollPosition, isDataGridNearScrollBottom, shouldCheckInfiniteScrollAfterScroll } from "../../apps/desktop/src/lib/dataGrid/dataGridInfiniteScroll.ts";
+import { dataGridScrollPosition, isDataGridNearScrollBottom, isDataGridPrefixAppend, shouldCheckInfiniteScrollAfterScroll } from "../../apps/desktop/src/lib/dataGrid/dataGridInfiniteScroll.ts";
 
 test("horizontal-only scroll does not check infinite scroll", () => {
   assert.equal(shouldCheckInfiniteScrollAfterScroll(dataGridScrollPosition(240, 0), dataGridScrollPosition(240, 180)), false);
@@ -25,6 +25,21 @@ test("near-bottom check matches the grid threshold", () => {
   assert.equal(isDataGridNearScrollBottom({ scrollTop: 800, scrollHeight: 1000, clientHeight: 100 }), false);
 });
 
+test("prefix-only append preserves the existing result identity", () => {
+  const first = [1, "Ada"];
+  const second = [2, "Linus"];
+  const previous = { rows: [first, second] };
+  assert.equal(isDataGridPrefixAppend(previous, { rows: [first, second, [3, "Grace"]], appended_from_row_count: 2 }), true);
+});
+
+test("append marker does not preserve state when an existing row was replaced", () => {
+  const first = [1, "Ada"];
+  const second = [2, "Linus"];
+  const previous = { rows: [first, second] };
+  assert.equal(isDataGridPrefixAppend(previous, { rows: [first, [...second], [3, "Grace"]], appended_from_row_count: 2 }), false);
+  assert.equal(isDataGridPrefixAppend(previous, { rows: [first, second, [3, "Grace"]] }), false);
+});
+
 test("infinite scroll requests only the next bounded segment", () => {
   const source = readFileSync("apps/desktop/src/components/grid/DataGrid.vue", "utf8");
   assert.match(source, /function infiniteScrollNextPage\(\) \{[\s\S]*?if \(!canFetchNextInfiniteScrollSegment\.value\) \{[\s\S]*?infiniteScrollAllLoaded = true;[\s\S]*?return;[\s\S]*?\}/);