fix(web): persist docs language selection (#32551)

packages/web/astro.config.mjs

@@ -299,6 +299,7 @@ export default defineConfig({
         Head: "./src/components/Head.astro",
         Header: "./src/components/Header.astro",
         Footer: "./src/components/Footer.astro",
+        LanguageSelect: "./src/components/LanguageSelect.astro",
         SiteTitle: "./src/components/SiteTitle.astro",
       },
       plugins: [

packages/web/src/components/Footer.astro

@@ -1,6 +1,6 @@
 ---
 import config from "virtual:starlight/user-config"
-import LanguageSelect from "@astrojs/starlight/components/LanguageSelect.astro"
+import LanguageSelect from "./LanguageSelect.astro"
 import { Icon } from "@astrojs/starlight/components"
 
 const { lang, editUrl, lastUpdated, entry } = Astro.locals.starlightRoute

packages/web/src/components/LanguageSelect.astro

@@ -0,0 +1,29 @@
+---
+import config from "virtual:starlight/user-config"
+import StarlightLanguageSelect from "@astrojs/starlight/components/LanguageSelect.astro"
+
+const locales = Object.keys(config.locales ?? {})
+---
+
+<opencode-language-select data-locales={JSON.stringify(locales)}>
+  <StarlightLanguageSelect />
+</opencode-language-select>
+
+<script>
+  document.addEventListener("change", (event) => {
+    if (!(event.target instanceof HTMLSelectElement)) return
+    const wrapper = event.target.closest("opencode-language-select")
+    if (!(wrapper instanceof HTMLElement)) return
+
+    const locales = JSON.parse(wrapper.dataset.locales ?? "[]") as string[]
+    const locale = locales[event.target.selectedIndex]
+    if (!locale) return
+    document.cookie = `oc_locale=${encodeURIComponent(locale === "root" ? "en" : locale)}; Path=/; Max-Age=31536000; SameSite=Lax`
+  })
+</script>
+
+<style>
+  opencode-language-select {
+    display: contents;
+  }
+</style>