diff --git a/.agents/notes/implemented/feature/2026-07-31-browser-derived-initial-locale.i18n.yaml b/.agents/notes/implemented/feature/2026-07-31-browser-derived-initial-locale.i18n.yaml
index c1ac4af1e9..f1168d973c 100644
--- a/.agents/notes/implemented/feature/2026-07-31-browser-derived-initial-locale.i18n.yaml
+++ b/.agents/notes/implemented/feature/2026-07-31-browser-derived-initial-locale.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/feature/2026-07-31-browser-derived-initial-locale.md
-2026-07-31-browser-derived-initial-locale.md: 94f32b136f20c7ab7fb8241a0ac9adf6249a4380
-2026-07-31-browser-derived-initial-locale.zh.md: 8d879b9b11ad42feed9ffd2ec3e5a16d1dcd9b8c
+2026-07-31-browser-derived-initial-locale.md: 6fcd799b9c3e6ec898725e0ef72106b63f613bee
+2026-07-31-browser-derived-initial-locale.zh.md: 73f2c825e11bb0380fe172b4b4522295d419e9a5
diff --git a/.agents/notes/implemented/feature/2026-07-31-browser-derived-initial-locale.md b/.agents/notes/implemented/feature/2026-07-31-browser-derived-initial-locale.md
index 94f32b136f..6fcd799b9c 100644
--- a/.agents/notes/implemented/feature/2026-07-31-browser-derived-initial-locale.md
+++ b/.agents/notes/implemented/feature/2026-07-31-browser-derived-initial-locale.md
@@ -22,6 +22,8 @@ Reading the browser fixed the readers whose browser names a language this app sh
 
 **An explicit choice is durable.** `setLocale` writes through the Host settings API, so a user who picked a language keeps it across browser origins and system languages that share the same DSH home. Nothing writes the detected locale back: detection is re-derived every boot and stays invisible to the “has the user chosen?” question.
 
+**`<html lang>` follows the resolved locale, and the served markup cannot.** `apps/web/index.html` is one static file serving every visitor, so whatever it declares is wrong for somebody: resolution happens in the client, after the document is parsed. The locale plugin therefore sets `document.documentElement.lang` from the active locale — once at activation, because detection or an adopted Host preference may already disagree with the markup, and again on every switch. The markup declares the product default (`en`) so the pre-boot document is not actively misleading. Assistive technology and browser features (pronunciation rules, translation offers, font fallback, spell check) read this attribute, so a stale value misreports the document language rather than merely looking untidy. The attribute carries a BCP 47 tag rather than the app's locale id: `zh` alone leaves the script ambiguous, so the shipped Chinese copy declares `zh-CN`.
+
 **The browser e2e lane pins browser language.** Scenarios asserting Chinese copy (`access-confirmation`, `models-settings`, `onboarding-deepseek-config`, `settings-chrome`) open their page with `locale: ZH_BROWSER_LOCALE` from `apps/web/tests/support.ts`; `newEnglishPage` advertises `en-US`. `settings-chrome.e2e.ts` opens a fresh Host home with no explicit locale twice: an `en-US` browser and an `fr-FR` one both reach an English surface. The `fr-FR` scenario is the one that pins the fallback — an `en-US` browser would land on English under detection or fallback alike, so only an unshipped language distinguishes them, and the zh scenarios prove detection still overrides the fallback.
 
 ## Alternatives considered
@@ -33,10 +35,12 @@ Reading the browser fixed the readers whose browser names a language this app sh
 - **Two constants, one for the opening locale and one for the dictionary fallback**: it separates two genuinely different questions, and would be required if the answers differed. They do not: the dictionaries are symmetric, so both are `en`, and a second constant would be two names for one value plus a rule nothing enforces. The symmetry itself is worth enforcing, so it is gated directly instead.
 - **Keeping `zh` as the dictionary fallback while opening in `en`**: it reads as the conservative choice, but with symmetric dictionaries it never resolves a key that `en` would not, so it buys nothing; and where it would matter — a key present only in `zh` — rendering Chinese text inside an otherwise English UI is worse than the bare key a reviewer would notice.
 - **Keeping the e2e lane's zh scenarios on storage pinning (`dsh.locale=zh`)**: it would keep the suite green while removing the only place the browser-derived path runs in an assembled app; pinning the browser language instead exercises the new resolution end to end.
+- **Serving `<html lang>` per request, or leaving the static attribute alone**: computing it server-side would need the request's `Accept-Language` to re-derive what the client resolves anyway, duplicating the rule in two places and still losing to a stored preference the server does not read. Leaving it static is what made the attribute permanently wrong for one language or the other. Setting it from the resolved locale keeps one source of truth.
 
 ## Consequences
 
 - A first visit from an English browser lands in English, a Chinese browser in Chinese, and a browser naming neither lands in English rather than Chinese. The Language row still shows the same two self-described options, so the escape hatch is unchanged in either direction.
 - Dictionary resolution reverses direction: a key missing from the active locale now falls to `en`, not `zh`. With symmetric dictionaries no shipped key changes behavior, which is why the parity gate exists — it is the assumption that reversal rests on.
+- `<html lang>` now reports the language on screen in both directions, which closes [#2160](https://github.com/deepseek-harness/deepseek-harness/issues/2160). A client that never activates the locale plugin keeps the served default, so the attribute degrades to the old static behavior rather than to a blank value.
 - Non-browser runs of the client tree (node boots, the non-jsdom unit lane) now open in `en`. Specs that assert shipped Chinese copy must set `setLocale('zh')` explicitly on the runtime they construct; a suite-level `usePinnedBrowserLanguages('zh-CN')` only works in files that also declare `@vitest-environment jsdom`, because without a `window` the detection path never reads `navigator` at all. Seven `*.client.spec.ts` files carried such a dead pin and were relying on the old `zh` fallback instead.
 - Detection cost is one array walk per service construction and no implicit settings write; an explicit Host preference may cause one live convergence after plugin activation.
diff --git a/.agents/notes/implemented/feature/2026-07-31-browser-derived-initial-locale.zh.md b/.agents/notes/implemented/feature/2026-07-31-browser-derived-initial-locale.zh.md
index 8d879b9b11..73f2c825e1 100644
--- a/.agents/notes/implemented/feature/2026-07-31-browser-derived-initial-locale.zh.md
+++ b/.agents/notes/implemented/feature/2026-07-31-browser-derived-initial-locale.zh.md
@@ -22,6 +22,8 @@ Status: implemented
 
 **显式选择具有持久性。** `setLocale` 通过 Host settings API 写入，因此选过语言的用户可在共享同一 DSH home 的不同浏览器 origin 与系统语言之间保留原选择。没有任何代码把探测到的 locale 写回：探测在每次启动时重新推导，对「用户是否做过选择」这一问题始终不可见。
 
+**`<html lang>` 跟随解析出的 locale，而所服务的 markup 做不到这一点。** `apps/web/index.html` 是一份静态文件，服务所有访问者，因此它声明什么都必然对某些人是错的：解析发生在客户端，在文档被解析之后。于是由 locale 插件依据当前 locale 设置 `document.documentElement.lang`——激活时设置一次，因为探测结果或已采纳的 Host 偏好可能已与 markup 不一致；此后每次切换再设置一次。markup 声明产品默认值（`en`），使启动前的文档不至于主动误导。无障碍技术与浏览器功能（发音规则、翻译提示、字体回退、拼写检查）都读取该属性，因此陈旧的值是在误报文档语言，而不只是看起来不整齐。该属性承载 BCP 47 标签而非应用内部的 locale id：单独的 `zh` 会使文字（script）含义不明，因此已提供的中文文案声明 `zh-CN`。
+
 **浏览器 e2e 车道固定浏览器语言。** 断言中文文案的场景（`access-confirmation`、`models-settings`、`onboarding-deepseek-config`、`settings-chrome`）以 `apps/web/tests/support.ts` 的 `locale: ZH_BROWSER_LOCALE` 打开页面；`newEnglishPage` 声明 `en-US`。`settings-chrome.e2e.ts` 两次使用没有显式 locale 的全新 Host home：`en-US` 浏览器与 `fr-FR` 浏览器都会抵达英文界面。真正钉住回落值的是 `fr-FR` 那个场景——`en-US` 浏览器无论走探测还是走回落都会落在英文，因此只有本应用不提供的语言才能区分二者，而中文场景则证明探测仍然覆盖回落值。
 
 ## Alternatives considered
@@ -33,10 +35,12 @@ Status: implemented
 - **拆成两个常量，一个管开场 locale、一个管字典回落**：它区分了两个确实不同的问题，若两个答案不同也确有必要。但它们并不不同：字典是对称的，因此两者都是 `en`，第二个常量只会是同一个值的两个名字，外加一条无人强制的规则。对称性本身值得强制，所以直接为它设门禁。
 - **开场用 `en`、字典回落仍保留 `zh`**：这看起来是保守选择，但在字典对称的前提下，它能解析的 key 与 `en` 完全相同，因此毫无收益；而在它真正会起作用的情形——某个 key 只存在于 `zh`——在整体英文的界面里渲染出中文文本，比让 reviewer 一眼看见裸 key 更糟。
 - **让 e2e 车道的中文场景继续钉存储项（`dsh.locale=zh`）**：那会让套件保持绿色，却抹掉浏览器推导路径在组装后应用中唯一的运行处；改钉浏览器语言才能端到端地演练新的解析过程。
+- **按请求服务 `<html lang>`，或干脆不管这个静态属性**：在服务端计算它需要用请求的 `Accept-Language` 去重新推导客户端本就会解析的结果，使同一条规则在两处重复，而且仍会输给服务端并不读取的存储偏好。放任其保持静态，正是该属性对某一种语言永远错误的原因。依据解析出的 locale 来设置，可保持单一真源。
 
 ## Consequences
 
 - 来自英文浏览器的首访落在英文界面，中文浏览器落在中文界面，而两者皆未声明的浏览器落在英文而非中文界面。语言行依然呈现同样两个以自身语言自述的选项，两个方向的脱身通道都未改变。
 - 字典解析方向发生反转：当前 locale 缺失的 key 现在回落到 `en` 而非 `zh`。在字典对称的前提下，没有任何已提供的 key 行为发生变化——这正是那道对称性门禁存在的原因：它是这次反转所依赖的前提。
+- `<html lang>` 现在在两个方向上都如实报告屏幕上的语言，这也关闭了 [#2160](https://github.com/deepseek-harness/deepseek-harness/issues/2160)。若某个客户端从未激活 locale 插件，则保留所服务的默认值，因此该属性退化为旧的静态行为，而不会退化为空值。
 - 客户端树的非浏览器运行（node 启动、非 jsdom 单测车道）现在以 `en` 开场。断言已提供中文文案的用例必须在其构造的 runtime 上显式调用 `setLocale('zh')`；套件级的 `usePinnedBrowserLanguages('zh-CN')` 仅在同时声明了 `@vitest-environment jsdom` 的文件中生效，因为没有 `window` 时探测路径根本不会读取 `navigator`。此前有七个 `*.client.spec.ts` 文件带着这样一条失效的固定语句，实际依赖的是旧的 `zh` 回落值。
 - 探测的代价是每次服务构造遍历一次数组，且不会隐式写入 settings；插件激活后，显式 Host 偏好可能引发一次实时收敛。
diff --git a/packages/client/locale/src/client/index.ts b/packages/client/locale/src/client/index.ts
index abea65ac9e..ab84f054ad 100644
--- a/packages/client/locale/src/client/index.ts
+++ b/packages/client/locale/src/client/index.ts
@@ -107,6 +107,28 @@ const LOCALES: readonly LocaleDefinition[] = Object.freeze([
   { id: 'en', label: 'English' },
 ])
 
+/**
+ * `<html lang>` tag per shipped locale. The locale id is the app's own
+ * vocabulary (primary subtag); the document attribute wants a BCP 47 tag,
+ * which assistive technology and browser features (pronunciation rules,
+ * translation offers, font fallback, spell check) read to pick their own
+ * behavior. `zh` alone leaves the script ambiguous, so the shipped Chinese
+ * copy names the variant it actually is.
+ */
+const DOCUMENT_LANGUAGE: Record<LocaleId, string> = { zh: 'zh-CN', en: 'en' }
+
+/**
+ * Point `<html lang>` at the active locale. Called on every locale change,
+ * so the attribute tracks the UI instead of standing at whatever the served
+ * markup happened to declare.
+ * @param active - the active locale id.
+ */
+function syncDocumentLanguage(active: LocaleId): void {
+  // Non-browser runs (node boots of the client tree) have no document.
+  if (typeof document === 'undefined') return
+  document.documentElement.lang = DOCUMENT_LANGUAGE[active]
+}
+
 /**
  * Dictionary registry plus locale preference. Lookup chain per key: the
  * entry's namespace in the active locale -> that namespace's en fallback ->
@@ -371,6 +393,7 @@ export function apply(ctx: ClientContext): void {
   const store = createLanguageRowStore()
   let bound: BoundActions<typeof store> | undefined
   const sync = (snapshot: LocaleSnapshot): void => {
+    syncDocumentLanguage(snapshot.active)
     bound?.sync(
       snapshot.active,
       snapshot.locales.map(l => ({ id: l.id, label: l.label })),
@@ -378,6 +401,10 @@ export function apply(ctx: ClientContext): void {
     )
   }
   ctx.on('locale/change', sync)
+  // The served markup declares one language; the resolved locale may differ
+  // (browser detection, or a stored preference adopted after activation), so
+  // state it once at activation rather than waiting for the first change.
+  syncDocumentLanguage(locale.getLocale().active)
   const injected = (actions: BoundActions<typeof store>): LanguageRowInjected => {
     bound = actions
     // Re-sync from the getter so no event is lost between registration and
diff --git a/packages/client/locale/tests/document-language.client.spec.ts b/packages/client/locale/tests/document-language.client.spec.ts
index 891e22e5f5..b10a3e8e69 100644
--- a/packages/client/locale/tests/document-language.client.spec.ts
+++ b/packages/client/locale/tests/document-language.client.spec.ts
@@ -11,7 +11,8 @@
 import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest'
 import { Context } from '@deepseek-ai/cordis'
 import { SlotRegistry } from '@deepseek-ai/dsh-client-runtime/client'
-import { SettingsScopeBinder } from '@deepseek-ai/dsh-client-ui-settings/client'
+import { SettingsSchemaService } from '@deepseek-ai/dsh-client-ui-settings/src/client/schema.ts'
+import { SettingsScopeBinder } from '@deepseek-ai/dsh-client-ui-settings/src/client/settings-scope.ts'
 import { TestRemote } from '@deepseek-ai/dsh-client-test-runtime'
 import { apply, inject } from '@deepseek-ai/dsh-client-locale/client'
 import type { LocaleRuntime } from '@deepseek-ai/dsh-client-locale/client'
@@ -43,7 +44,7 @@ async function bench(preference?: string) {
   ctx.provide('connection', { api: { settings: { describe: describeRpc, mutate } }, isLoopback: true } as never)
   // The settings transport and the forwarded-event port the plugin injects.
   new TestRemote(ctx)
-  await ctx.plugin(SettingsScopeBinder).await()
+  await ctx.plugin(SettingsScopeBinder, new SettingsSchemaService(ctx)).await()
   await ctx.plugin({ inject: [...inject], apply }).await()
   return { ctx, locale: ctx.get('locale') as LocaleRuntime }
 }
diff --git a/packages/client/ui-settings-general/package.json b/packages/client/ui-settings-general/package.json
index 59a7694633..14e826630e 100644
--- a/packages/client/ui-settings-general/package.json
+++ b/packages/client/ui-settings-general/package.json
@@ -67,7 +67,6 @@
     "@deepseek-ai/dsh-client-connection": "workspace:^",
     "@deepseek-ai/dsh-client-locale": "workspace:^",
     "@deepseek-ai/dsh-client-runtime": "workspace:^",
-    "@deepseek-ai/dsh-client-test-runtime": "workspace:^",
     "@deepseek-ai/dsh-client-ui-primitives": "workspace:^",
     "@deepseek-ai/dsh-client-ui-settings": "workspace:^",
     "@deepseek-ai/dsh-client-ui-sidebar": "workspace:^",
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index ce67604757..154a76c92f 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -2490,9 +2490,6 @@ importers:
       '@deepseek-ai/dsh-client-runtime':
         specifier: workspace:^
         version: link:../runtime
-      '@deepseek-ai/dsh-client-test-runtime':
-        specifier: workspace:^
-        version: link:../../test-support/client-runtime
       '@deepseek-ai/dsh-client-ui-primitives':
         specifier: workspace:^
         version: link:../ui-primitives