docs(website): derive navigation targets from the publication manifest

The navigation bar named `/guide/` while the manifest published the guide's
first page at `guide/quickstart.md`, so the item served a 404 in both locales.

`landingLink` resolves each item against `orderedPages`, the ordering the
sidebar already renders, and a test asserts every navigation target is a route
the manifest publishes.

.agents/notes/implemented/process/2026-08-12-documentation-site-navigation-and-chrome.i18n.yaml

@@ -2,5 +2,5 @@
 # side as of the last confirmed-consistent state. Both languages carry equal authority;
 # after editing either side, bring the other along and re-record with:
 #   pnpm run verify-translation-pairing --write .agents/notes/implemented/process/2026-08-12-documentation-site-navigation-and-chrome.md
-2026-08-12-documentation-site-navigation-and-chrome.md: 1b1868a011744decf1c0a25a825fd022ea3609ab
-2026-08-12-documentation-site-navigation-and-chrome.zh.md: 0fd685ec8c6b7f3f2fd93013ebaf9266a70b2c81
+2026-08-12-documentation-site-navigation-and-chrome.md: 07f88d303a96676806cce0801bce5d478fb5406e
+2026-08-12-documentation-site-navigation-and-chrome.zh.md: ca605e2a890bac4bcff9f22a6c6ab8928d1a8aa8

.agents/notes/implemented/process/2026-08-12-documentation-site-navigation-and-chrome.md

@@ -8,6 +8,8 @@ English | [中文](2026-08-12-documentation-site-navigation-and-chrome.zh.md)
 
 The reference sidebar rendered its 43 subsystem pages first, ahead of every other group: `sectionOrder` in the VitePress config listed no position for `子系统`/`Subsystems` — nor for `其他接口`/`Other interfaces` — so `indexOf` returned `-1` and sorted them ahead of the ordered sections. Clicking the `参考` navigation item landed on the architecture page whose own sidebar entry was link 44 of 62, 1549px down a 2478px sidebar — outside the viewport. Four subsystem pages carried `order` values already taken by other pages in the same section, resolved only by `Array.prototype.sort` stability and the order the manifest's arrays happened to be concatenated.
 
+The navigation bar named `/guide/` while the manifest published the guide's first page at `guide/quickstart.md`, so that item served a 404: written-down navigation targets drift from the routes the manifest publishes.
+
 Separately, every canonical page carries lines written for its GitHub reader — a language switcher under the heading, and for some, a repository badge — which the site projected verbatim even though its navigation bar already offers both.
 
 ## Decision
@@ -16,6 +18,8 @@ Separately, every canonical page carries lines written for its GitHub reader —
 
 Subsystem pages are grouped by concern — overview, core and scopes, sessions and persistence, model and context, execution and tools, policy and interaction, platform and access — and the six topical groups render collapsed until one holds the page being read. The groups sort last within the reference sidebar: expanded, they outnumber every other group combined, so anything placed after them is reachable only by scrolling past the whole list. Page `order` derives from array position rather than a hand-written number.
 
+`landingLink(locale, collection)` derives each navigation item's target from `orderedPages`, the same ordering the sidebar renders, so an item always opens its collection's first published page.
+
 `projectedPageContent` in [scripts/project-doc-site.ts](../../../../scripts/project-doc-site.ts) drops the language-switcher line and the repository badge. The switcher match is confined to the first eight lines so a tutorial that shows the convention still renders its example.
 
 The navigation-bar title is the DeepSeek wordmark inlined into `siteTitle`, which VitePress renders as HTML. Inlining is what lets the mark's `currentColor` fills follow the active theme; `themeConfig.logo` renders an `<img>`, which freezes the mark at the colors its file declares and would need one asset per theme. The sidebar scrollbar rests invisible and appears while scrolling, marked by a `data-` attribute rather than a class because Vue rewrites `class` wholesale when it patches the element.

.agents/notes/implemented/process/2026-08-12-documentation-site-navigation-and-chrome.zh.md

@@ -8,6 +8,8 @@ Status: implemented
 
 参考侧边栏把 43 个子系统页排在了所有其他分组之前：VitePress 配置中的 `sectionOrder` 既没有为 `子系统`/`Subsystems` 也没有为 `其他接口`/`Other interfaces` 声明位置，`indexOf` 返回 `-1`，于是它们排到了所有已排序分区的前面。点击 `参考` 导航项落在架构页，而该页自己的侧边栏条目是 62 条中的第 44 条，位于 2478px 侧边栏的 1549px 处——在视口之外。四个子系统页所用的 `order` 值已被同一分区内的其他页占用，只靠 `Array.prototype.sort` 的稳定性和 manifest 数组恰好的拼接顺序才没有错乱。
 
+顶栏把 `入门` 指向 `/guide/`，而 manifest 已把入门首页发布在 `guide/quickstart.md`，该导航项因此返回 404：写死的导航目标会与 manifest 实际发布的路由脱节。
+
 另外，每个规范页面都带有写给 GitHub 读者的行——标题下的语言切换行，部分页面还有仓库徽章——站点原样投影了它们，尽管其导航栏已经提供了这两者。
 
 ## 决定
@@ -16,6 +18,8 @@ Status: implemented
 
 子系统页按关注点分组——总览、内核与作用域、会话与持久化、模型与上下文、执行与工具、策略与交互、平台与接入——其中六个主题组保持折叠，直到某一组包含正在阅读的页面。这些分组排在参考侧边栏的最后：展开时它们的数量超过其余所有分组之和，因此排在它们之后的任何内容都只能靠滚过整个列表才能到达。页面 `order` 由数组位置推导，不再手写数字。
 
+`landingLink(locale, collection)` 依据 `orderedPages`——即侧边栏所用的同一套排序——推导每个导航项的目标，因此导航项始终打开该分区已发布的首个页面。
+
 [scripts/project-doc-site.ts](../../../../scripts/project-doc-site.ts) 中的 `projectedPageContent` 会丢弃语言切换行和仓库徽章。切换行的匹配被限制在前八行内，因此展示该约定的教程仍能渲染出它的示例。
 
 导航栏标题是内联进 `siteTitle` 的 DeepSeek 字标，VitePress 会将其按 HTML 渲染。内联正是让字标的 `currentColor` 填充跟随当前主题的原因；`themeConfig.logo` 渲染为 `<img>`，会把字标固定为文件声明的颜色，并且需要为每套主题各准备一份资源。侧边栏滚动条平时不可见，滚动时出现，通过 `data-` 属性而非 class 标记，因为 Vue 在 patch 该元素时会整体重写 `class`。