fix(web): sideways swipes over a terminal scroll the pane strip

apps/web/src/terminal/ghostty/surface.test.ts

@@ -522,6 +522,22 @@ describe("GhosttyTerminalSurface visibility", () => {
     expect(surface.getSelection()).toBe("row 6\nrow 7\nrow 8");
   });
 
+  it("leaves mostly sideways wheel events to the scroller around it", async () => {
+    const harness = createHarness();
+    await harness.create();
+    const wheel = (deltaX: number, deltaY: number) => {
+      const event = Object.assign(new Event("wheel", { cancelable: true }), {
+        deltaX,
+        deltaY,
+        deltaMode: 0,
+      });
+      harness.canvas.dispatchEvent(event);
+      return event.defaultPrevented;
+    };
+    expect(wheel(-20, 1)).toBe(false);
+    expect(wheel(2, -60)).toBe(true);
+  });
+
   it("does not activate a link replaced before pointer release", async () => {
     const harness = createHarness();
     const onLinkActivate = vi.fn();

apps/web/src/terminal/ghostty/surface.ts

@@ -1674,7 +1674,7 @@ export class GhosttyTerminalSurface {
   };
 
   private readonly onWheel = (event: WheelEvent) => {
-    if (event.deltaY === 0) return;
+    if (event.deltaY === 0 || Math.abs(event.deltaY) < Math.abs(event.deltaX)) return;
     event.preventDefault();
     const delta = terminalWheelDeltaRows(
       event,