Fix NaN coordinates in mouse wheel reports from touch fling inertia

src/browser/scrollable/touch.ts

@@ -434,6 +434,15 @@ export class Gesture extends Disposable {
       const evt = this._newGestureEvent(EventType.CHANGE);
       evt.translationX = deltaPosX;
       evt.translationY = deltaPosY;
+      // Carry the extrapolated position on inertia frames. Real touchmove
+      // CHANGE events (_handleTouchMove) always stamp coordinates and
+      // consumers like the mouse-report wheel path read event.clientX/clientY.
+      // Without these, momentum frames yield NaN coordinates (undefined
+      // arithmetic), which ends up serialized into mouse reports.
+      evt.pageX = x + deltaPosX;
+      evt.pageY = y + deltaPosY;
+      evt.clientX = x + deltaPosX - targetWindow.scrollX;
+      evt.clientY = y + deltaPosY - targetWindow.scrollY;
       dispatchTo.forEach(d => d.dispatchEvent(evt));
 
       if (!stopped) {

src/browser/services/MouseService.ts

@@ -344,6 +344,15 @@ export class MouseService implements IMouseService {
       return;
     }
 
+    // Wheel reports carry the cell the "wheel" happened over, so a gesture
+    // event without usable coordinates must not be reported: NaN passes
+    // through getMouseReportCoords' clamping untouched and ends up serialized
+    // into the report sequence (e.g. `CSI < 64 ; NaN ; NaN M`), which the
+    // application then reads as garbage input.
+    if (!isFinite(e.clientX) || !isFinite(e.clientY)) {
+      return;
+    }
+
     this._touchScrollAccumulator -= e.translationY;
     const lines = Math.trunc(this._touchScrollAccumulator / cellHeight);
     if (lines === 0) {