What gesture conflict exists in a scrollable list with horizontal swipes?

This tests Flutter's gesture arena and directional slop mechanics when nested recognizers compete. The conflict is that diagonal pointer movement can satisfy both vertical scroll and horizontal swipe touch slop, creating intent ambiguity. Flutter places competing recognizers in an arena where each tracks deltas; the recognizer whose primary axis exceeds slop first accepts the gesture and the other rejects. A red flag is asserting a fixed parent-wins strategy or that both handlers fire simultaneously.