fix(grid): stabilize row drag selection gestures

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

@@ -4601,6 +4601,10 @@ const selection = useDataGridSelection({
   cellFromClientPoint: dataGridCellFromClientPoint,
   rowFromClientPoint: dataGridRowFromClientPoint,
   onUserCellSelection: invalidateSyntheticContextSelection,
+  // Canvas schedules its draw before the document-level mousemove handler runs,
+  // so its row state must be current before that frame is painted.
+  shouldUpdateDraggedRowsImmediately: () => useCanvasGridRows.value,
+  onDraggedRowSelectionChange: scheduleCanvasDraw,
   runtimeScope: dataGridRuntimeScope,
 });
 
@@ -4915,7 +4919,22 @@ const domSelectionDragOverlayStyle = computed((): CSSProperties | undefined => {
   };
 });
 
-function onCellMouseenter(rowIndex: number, visibleColIdx: number, actualColIdx: number) {
+function stopReleasedSelectionGesture(event: MouseEvent): boolean {
+  if ((event.buttons & 1) !== 0) return false;
+  let stopped = false;
+  if (isSelectingCells.value) {
+    finishCellSelection();
+    stopped = true;
+  }
+  if (selection.isSelectingRows.value) {
+    selection.finishRowSelection();
+    stopped = true;
+  }
+  return stopped;
+}
+
+function onCellMouseenter(rowIndex: number, visibleColIdx: number, actualColIdx: number, event: MouseEvent) {
+  stopReleasedSelectionGesture(event);
   if (!isSelectingCells.value) {
     quickDownloadMenuCell.value = retainBinaryCellDownloadMenuForHover(quickDownloadMenuCell.value, { rowIndex, col: actualColIdx });
     if (!isScrolling.value) hoveredDetailCell.value = { rowIndex, col: actualColIdx };
@@ -6261,6 +6280,7 @@ function onDomGridWheel(event: WheelEvent) {
 }
 
 function onCanvasMouseMove(event: MouseEvent) {
+  stopReleasedSelectionGesture(event);
   if (columnHeaderPointerInteractionActive()) {
     if (canvasRef.value) canvasRef.value.style.cursor = "default";
     onCanvasMouseLeave();
@@ -6290,7 +6310,7 @@ function onCanvasMouseMove(event: MouseEvent) {
     if (previousActualColIdx !== undefined) onCellMouseleave(previous.rowIndex, previousActualColIdx);
   }
   canvasHoverCell.value = next;
-  if (next && actualColIdx !== undefined) onCellMouseenter(next.rowIndex, next.visibleColIdx, actualColIdx);
+  if (next && actualColIdx !== undefined) onCellMouseenter(next.rowIndex, next.visibleColIdx, actualColIdx, event);
   scheduleCanvasDraw();
 }
 
@@ -11758,7 +11778,7 @@ function currentGridContextMenuItems(): ContextMenuItem[] {
                           prepareDataCellMouseDown(item, col.actualColIdx);
                           handleDataCellMousedown(item.displayIndex, col.visibleColIdx, item.id, $event);
                         "
-                        @mouseenter="onCellMouseenter(item.displayIndex, col.visibleColIdx, col.actualColIdx)"
+                        @mouseenter="onCellMouseenter(item.displayIndex, col.visibleColIdx, col.actualColIdx, $event)"
                         @mouseleave="onCellMouseleave(item.displayIndex, col.actualColIdx)"
                         @dblclick="onDomCellDblClick(item, col.actualColIdx, $event)"
                         :data-visible-col-index="col.visibleColIdx"

apps/desktop/src/components/grid/__tests__/DataGridSelectionGesture.spec.ts

@@ -0,0 +1,16 @@
+import { readFileSync } from "node:fs";
+import { describe, expect, it } from "vitest";
+
+const source = readFileSync(new URL("../DataGrid.vue", import.meta.url), "utf8");
+
+describe("DataGrid selection gesture ownership", () => {
+  it("stops released gestures before DOM hover or canvas movement extends them", () => {
+    expect(source).toContain("function stopReleasedSelectionGesture(event: MouseEvent)");
+    expect(source).toContain("if ((event.buttons & 1) !== 0) return false;");
+    expect(source).toContain("function onCellMouseenter(rowIndex: number, visibleColIdx: number, actualColIdx: number, event: MouseEvent)");
+    expect(source).toContain('@mouseenter="onCellMouseenter(item.displayIndex, col.visibleColIdx, col.actualColIdx, $event)"');
+
+    const canvasMove = source.slice(source.indexOf("function onCanvasMouseMove"), source.indexOf("function onCanvasMouseLeave"));
+    expect(canvasMove).toContain("stopReleasedSelectionGesture(event);");
+  });
+});