fix(grid): restore scroll after transpose

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

@@ -1,5 +1,5 @@
 import { describe, expect, it } from "vitest";
-import { dataGridBottomScrollTop, isDataGridAtScrollBottom } from "@/lib/dataGrid/dataGridInfiniteScroll";
+import { dataGridBottomScrollTop, isDataGridAtScrollBottom, restoredDataGridScrollLeft } from "@/lib/dataGrid/dataGridInfiniteScroll";
 
 describe("data grid bottom anchoring", () => {
   it("keeps DOM rows anchored when scrollbar padding increases the scroll height", () => {
@@ -30,3 +30,17 @@ describe("data grid bottom anchoring", () => {
     expect(isDataGridAtScrollBottom({ scrollTop: 700, scrollHeight: 1000, clientHeight: 260 })).toBe(false);
   });
 });
+
+describe("data grid horizontal restoration", () => {
+  it("restores the previous horizontal position after the grid remounts", () => {
+    expect(restoredDataGridScrollLeft(320, 1200, 600)).toBe(320);
+  });
+
+  it("clamps the previous position when the scrollable width shrinks", () => {
+    expect(restoredDataGridScrollLeft(720, 1000, 600)).toBe(400);
+  });
+
+  it("resets the position when the rebuilt grid no longer overflows", () => {
+    expect(restoredDataGridScrollLeft(320, 500, 600)).toBe(0);
+  });
+});

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

@@ -16,6 +16,10 @@ export function dataGridScrollPosition(top: number, left: number): DataGridScrol
   };
 }
 
+export function restoredDataGridScrollLeft(scrollLeft: number, scrollWidth: number, clientWidth: number): number {
+  return Math.max(0, Math.min(Math.max(0, scrollWidth - clientWidth), scrollLeft));
+}
+
 export function shouldCheckInfiniteScrollAfterScroll(previous: DataGridScrollPosition | undefined, current: DataGridScrollPosition): boolean {
   if (!previous) return false;
   // Shift+wheel horizontal scrolling changes scrollLeft only and must not paginate.