refactor: remove LocaleSwitcher component and update locale handling

- Removed LocaleSwitcher from NavUser, SiteHeader, and WorkbenchHeader components.
- Updated tests to reflect the removal of LocaleSwitcher.
- Changed default locale from "en-US" to "zh-CN" in i18n configuration.
- Refactored locale resolution logic to read configured locale without relying on browser language detection.
- Updated AgentDesk SDK to support language configuration from public API.
- Cleaned up unused auth options fetching in the auth API.

web/i18n/config.test.mjs

@@ -25,7 +25,7 @@ async function loadConfig() {
 test("normalizes supported locale aliases", async () => {
   const { DEFAULT_LOCALE, normalizeLocale } = await loadConfig()
 
-  assert.equal(DEFAULT_LOCALE, "en-US")
+  assert.equal(DEFAULT_LOCALE, "zh-CN")
   assert.equal(normalizeLocale("zh-CN"), "zh-CN")
   assert.equal(normalizeLocale("zh_CN"), "zh-CN")
   assert.equal(normalizeLocale("zh"), "zh-CN")
@@ -35,26 +35,11 @@ test("normalizes supported locale aliases", async () => {
   assert.equal(normalizeLocale("fr-FR"), DEFAULT_LOCALE)
 })
 
-test("resolves browser locale from stored value before navigator languages", async () => {
-  const { resolveBrowserLocale } = await loadConfig()
+test("reads the configured locale without browser language detection", async () => {
+  const { configureLocale, readStoredLocale } = await loadConfig()
 
-  assert.equal(
-    resolveBrowserLocale({
-      storedLocale: "en-US",
-      navigatorLanguages: ["zh-CN"],
-    }),
-    "en-US"
-  )
-})
-
-test("falls back through navigator languages", async () => {
-  const { resolveBrowserLocale } = await loadConfig()
-
-  assert.equal(
-    resolveBrowserLocale({
-      storedLocale: "",
-      navigatorLanguages: ["fr-FR", "en"],
-    }),
-    "en-US"
-  )
+  assert.equal(readStoredLocale(), "zh-CN")
+
+  configureLocale("en-US")
+  assert.equal(readStoredLocale(), "en-US")
 })

web/i18n/config.ts

@@ -1,8 +1,7 @@
 export const SUPPORTED_LOCALES = ["zh-CN", "en-US"] as const
 export type AppLocale = (typeof SUPPORTED_LOCALES)[number]
 
-export const DEFAULT_LOCALE: AppLocale = "en-US"
-export const LOCALE_STORAGE_KEY = "cs_ai_agent_locale"
+export const DEFAULT_LOCALE: AppLocale = "zh-CN"
 
 const LOCALE_ALIASES: Record<string, AppLocale> = {
   zh: "zh-CN",
@@ -37,40 +36,13 @@ export function isSupportedLocale(
   return SUPPORTED_LOCALES.includes(value as AppLocale)
 }
 
-export function resolveBrowserLocale({
-  storedLocale,
-  navigatorLanguages,
-}: {
-  storedLocale?: string | null
-  navigatorLanguages?: readonly string[] | null
-}): AppLocale {
-  if (isSupportedLocale(storedLocale)) {
-    return storedLocale
-  }
-
-  for (const locale of navigatorLanguages ?? []) {
-    const normalized = normalizeSupportedLocale(locale)
-    if (normalized) {
-      return normalized
-    }
-  }
-
-  return DEFAULT_LOCALE
-}
+let configuredLocale: AppLocale = DEFAULT_LOCALE
 
 export function readStoredLocale(): AppLocale {
-  if (typeof window === "undefined") {
-    return DEFAULT_LOCALE
-  }
-  return resolveBrowserLocale({
-    storedLocale: window.localStorage.getItem(LOCALE_STORAGE_KEY),
-    navigatorLanguages: window.navigator.languages,
-  })
+  return configuredLocale
 }
 
-export function writeStoredLocale(locale: AppLocale) {
-  if (typeof window === "undefined") {
-    return
-  }
-  window.localStorage.setItem(LOCALE_STORAGE_KEY, locale)
+export function configureLocale(locale: string | null | undefined): AppLocale {
+  configuredLocale = normalizeLocale(locale)
+  return configuredLocale
 }

web/i18n/provider.tsx

@@ -12,10 +12,10 @@ import {
 import {
   DEFAULT_LOCALE,
   type AppLocale,
-  readStoredLocale,
-  writeStoredLocale,
+  configureLocale,
 } from "@/i18n/config"
 import { translateMessage } from "@/i18n/messages"
+import { fetchPublicConfig } from "@/lib/api/config"
 
 type LocaleContextValue = {
   locale: AppLocale
@@ -34,11 +34,24 @@ export function AppI18nProvider({ children }: { children: ReactNode }) {
   const [isLocaleReady, setIsLocaleReady] = useState(false)
 
   useEffect(() => {
-    const storedLocale = readStoredLocale()
-    setLocaleState(storedLocale)
-    document.documentElement.lang = storedLocale
-    document.title = translateMessage(storedLocale, "app.metadataTitle")
-    setIsLocaleReady(true)
+    let cancelled = false
+
+    fetchPublicConfig()
+      .then((config) => configureLocale(config.language))
+      .catch(() => configureLocale(DEFAULT_LOCALE))
+      .then((configuredLocale) => {
+        if (cancelled) {
+          return
+        }
+        setLocaleState(configuredLocale)
+        document.documentElement.lang = configuredLocale
+        document.title = translateMessage(configuredLocale, "app.metadataTitle")
+        setIsLocaleReady(true)
+      })
+
+    return () => {
+      cancelled = true
+    }
   }, [])
 
   useEffect(() => {
@@ -49,12 +62,7 @@ export function AppI18nProvider({ children }: { children: ReactNode }) {
     () => ({
       locale,
       t: (key, values) => translateMessage(locale, key, values),
-      setLocale: (nextLocale) => {
-        setLocaleState(nextLocale)
-        writeStoredLocale(nextLocale)
-        document.documentElement.lang = nextLocale
-        document.title = translateMessage(nextLocale, "app.metadataTitle")
-      },
+      setLocale: () => {},
     }),
     [locale]
   )