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GitHub proxies external images through Camo, which fetched the demo GIF while the CDN was mid-refresh and cached the truncated result: 1801375 of 4149835 bytes, 66 of 133 frames, and a broken LZW stream, so the animation stopped partway through. Camo keys its cache on an HMAC of the source URL and holds it for a year, so replacing the file in place could never dislodge it. Point both READMEs at demo1-v2.gif, which gives Camo a new URL to fetch. The file is also re-encoded at 900x506 and 8fps to keep terminal text legible while staying well under Camo's 5 MiB proxy limit, which the original 7.5 MB upload had exceeded.
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背景
README 里的 StepPage 演示 GIF 在 GitHub 上只播一半就断了。逐层排查后定位到 GitHub 的图片代理 Camo：
Camo 在 CDN 刷新过程中抓取，拿到一个传输中断的残缺文件并缓存了下来(
x-cache: HIT,max-age=31536000)。它的缓存键是源地址的 HMAC，所以原地覆盖同名文件永远无法让它回源 —— 这也是先前多次刷新 CDN 都无效的原因。首次上传的 7.5 MB 文件还另外触发了一个问题:超过 Camo 的 5 MiB 代理上限,直接返回 404。
修复
两个 README 的图片地址改为
demo1-v2.gif,给 Camo 一个全新的 URL 去抓取。新文件同时重新编码为 900x506 / 8fps,在保证终端文字可读的前提下留出充足的体积余量。验证
改 README 之前先确认源站返回完整文件,避免 Camo 再缓存一个坏副本:
content-length4352323,且无age头(回源新鲜响应)c7db1a9b0e415ccf6e0795de4798abc7与本地文件逐字节一致ffprobe读出 900x506 / 133 帧,无解码报错npm run check通过。边界
本次只改图片地址,不动文案与其他内容。旧的
demo1-small.gif仍留在 CDN 上,其对应的 Camo 缓存要到一年后才过期,不再被引用。