fix(console): take the page language from the URL only (#56564)

packages/console/app/src/context/language.tsx

@@ -11,7 +11,7 @@ import {
   dir as localeDir,
   label as localeLabel,
   localeFromCookieHeader,
-  localeFromRequest,
+  pageLocale,
   parseLocale,
   route as localeRoute,
   tag as localeTag,
@@ -19,7 +19,7 @@ import {
 
 function initial() {
   const evt = getRequestEvent()
-  if (evt) return localeFromRequest(evt.request)
+  if (evt) return pageLocale(evt.request)
 
   if (typeof document === "object") {
     const fromDom = parseLocale(document.documentElement.dataset.locale)

packages/console/app/src/entry-server.tsx

@@ -1,7 +1,7 @@
 // @refresh reload
 import { createHandler, StartServer } from "@solidjs/start/server"
 import { getRequestEvent } from "solid-js/web"
-import { dir, localeFromRequest, tag } from "~/lib/language"
+import { dir, pageLocale, tag } from "~/lib/language"
 
 const criticalCSS = `[data-component="top"]{min-height:80px;display:flex;align-items:center}`
 
@@ -10,7 +10,7 @@ export default createHandler(
     <StartServer
       document={({ assets, children, scripts }) => {
         const evt = getRequestEvent()
-        const locale = evt ? localeFromRequest(evt.request) : "en"
+        const locale = evt ? pageLocale(evt.request) : "en"
 
         return (
           <html lang={tag(locale)} dir={dir(locale)} data-locale={locale}>

packages/console/app/src/lib/language.ts

@@ -325,6 +325,17 @@ export function localeFromRequest(request: Request) {
   )
 }
 
+// Pages take their language from the URL alone, so one URL serves the same language to people, crawlers and caches.
+export function pageLocale(request: Request) {
+  const pathname = new URL(request.url).pathname
+  return (
+    parseLocale(request.headers.get(LOCALE_HEADER)) ??
+    fromPathname(pathname) ??
+    fromDocsPathname(pathname) ??
+    ("en" satisfies Locale)
+  )
+}
+
 export function cookie(locale: Locale) {
   return `${LOCALE_COOKIE}=${encodeURIComponent(locale)}; Path=/; Max-Age=31536000; SameSite=Lax`
 }

packages/console/app/src/routes/docs/[...path].ts

@@ -1,6 +1,6 @@
 import type { APIEvent } from "@solidjs/start/server"
 import { Resource } from "@opencode/console-resource"
-import { cookie, docs, localeFromRequest, tag } from "~/lib/language"
+import { docs, pageLocale, tag } from "~/lib/language"
 
 async function handler(evt: APIEvent) {
   const req = evt.request.clone()
@@ -10,7 +10,7 @@ async function handler(evt: APIEvent) {
     return Response.redirect(new URL(moved[1] === "go" ? "/v2/docs/console/go/" : "/v2/docs/console/models/", url), 302)
   }
 
-  const locale = localeFromRequest(req)
+  const locale = pageLocale(req)
   const host = Resource.App.stage === "production" ? "docs.opencode.ai" : "docs.dev.opencode.ai"
   const targetUrl = `https://${host}${docs(locale, url.pathname)}${url.search}`
 
@@ -22,9 +22,7 @@ async function handler(evt: APIEvent) {
     headers,
     body: req.body,
   })
-  const next = new Response(response.body, response)
-  next.headers.append("set-cookie", cookie(locale))
-  return next
+  return new Response(response.body, response)
 }
 
 export const GET = handler

packages/console/app/src/routes/docs/index.ts

@@ -1,11 +1,11 @@
 import type { APIEvent } from "@solidjs/start/server"
 import { Resource } from "@opencode/console-resource"
-import { cookie, docs, localeFromRequest, tag } from "~/lib/language"
+import { docs, pageLocale, tag } from "~/lib/language"
 
 async function handler(evt: APIEvent) {
   const req = evt.request.clone()
   const url = new URL(req.url)
-  const locale = localeFromRequest(req)
+  const locale = pageLocale(req)
   const host = Resource.App.stage === "production" ? "docs.opencode.ai" : "docs.dev.opencode.ai"
   const targetUrl = `https://${host}${docs(locale, url.pathname)}${url.search}`
 
@@ -17,9 +17,7 @@ async function handler(evt: APIEvent) {
     headers,
     body: req.body,
   })
-  const next = new Response(response.body, response)
-  next.headers.append("set-cookie", cookie(locale))
-  return next
+  return new Response(response.body, response)
 }
 
 export const GET = handler

packages/console/app/test/language.test.ts

@@ -1,5 +1,5 @@
 import { describe, expect, test } from "bun:test"
-import { route } from "../src/lib/language"
+import { LOCALE_HEADER, pageLocale, route } from "../src/lib/language"
 
 describe("language.route", () => {
   test("keeps the changelog unprefixed for every locale", () => {
@@ -11,3 +11,19 @@ describe("language.route", () => {
     expect(route("de", "/download")).toBe("/de/download")
   })
 })
+
+describe("pageLocale", () => {
+  const request = (path: string, headers: Record<string, string> = {}) =>
+    new Request(`https://opencode.ai${path}`, { headers })
+  const german = { "accept-language": "de-DE,de;q=0.9", cookie: "oc_locale=de" }
+
+  test("ignores the browser language and cookie on unprefixed pages", () => {
+    expect(pageLocale(request("/", german))).toBe("en")
+    expect(pageLocale(request("/docs/agents/", german))).toBe("en")
+  })
+
+  test("uses the locale in the URL", () => {
+    expect(pageLocale(request("/", { [LOCALE_HEADER]: "de" }))).toBe("de")
+    expect(pageLocale(request("/docs/de/agents/"))).toBe("de")
+  })
+})