fix: vitrine/marketing pages use visitor's browser locale, not always English (v0.78.0)

getMarketingLocale() only ever read the marketing_locale cookie, defaulting anonymous first-time visitors to English until they manually used the language switcher — even though the switcher and a full French translation already existed. Now falls back to parsing Accept-Language when no cookie is set; an explicit switcher choice still wins on every later visit.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

CHANGELOG.md

@@ -2,6 +2,11 @@
 
 All notable changes to Epicure are documented here. This file is mirrored in-app at `/changelog` (and in the admin dashboard) via `apps/web/lib/changelog.ts` — update both together.
 
+## 0.78.0 — 2026-07-24 13:40
+
+### Fixed
+- Marketing/vitrine pages now honor a first-time visitor's browser language (Accept-Language) instead of always defaulting to English until they manually switch. An explicit choice from the language switcher still wins on every later visit.
+
 ## 0.77.0 — 2026-07-24 13:00
 
 ### Added

FEATURE_AUDIT.md

@@ -12,6 +12,8 @@ Status legend: **Exists** (fully working) · **Partial** (works but with a real
 
 **Model Prefs gating (closed 2026-07-24):** `Settings → AI`'s Model Prefs section previously had zero gate — every user could pick a raw provider + model ID with no fencing. Now behind `isByokEnabled` (same gate as BYOK itself, since picking a specific provider/model only makes sense once you have your own key to route it to) — hidden entirely for non-BYOK users, not just locked-and-teased. `GET`/`PUT /api/v1/users/me/model-prefs` gated server-side via `requireByok()` too.
 
+**Marketing/vitrine locale (closed 2026-07-24):** `getMarketingLocale()` (`apps/web/lib/marketing-locale.ts`) previously hard-defaulted anonymous visitors to English until they clicked the language switcher, even though the switcher's `marketing_locale` cookie mechanism and a fully French-translated marketing site both already existed. Now falls back to parsing the `Accept-Language` header (first supported tag in the browser's stated preference order) when no cookie is set; an explicit switcher choice still wins on every later visit, and logged-in visitors still get their saved `users.locale` first, unchanged.
+
 | Feature | Status | Description | Key files |
 |---|---|---|---|
 | Recipe CRUD | Exists | Create/get/list/update/delete; update snapshots the prior version first (`recipeSnapshots`) | `apps/web/app/api/v1/recipes/**` |

apps/web/lib/changelog.ts

@@ -1,5 +1,5 @@
 // Mirrors CHANGELOG.md at the repo root — update both together.
-export const APP_VERSION = "0.77.0";
+export const APP_VERSION = "0.78.0";
 
 export type ChangelogEntry = {
   version: string;
@@ -11,6 +11,13 @@ export type ChangelogEntry = {
 };
 
 export const CHANGELOG: ChangelogEntry[] = [
+  {
+    version: "0.78.0",
+    date: "2026-07-24 13:40",
+    fixed: [
+      "Marketing/vitrine pages now honor a first-time visitor's browser language (Accept-Language) instead of always defaulting to English until they manually switch. An explicit choice from the language switcher still wins on every later visit.",
+    ],
+  },
   {
     version: "0.77.0",
     date: "2026-07-24 13:00",

apps/web/lib/marketing-locale.ts

@@ -12,10 +12,31 @@ export { MARKETING_LOCALE_COOKIE };
  * which persists to `users.locale` via an authenticated PATCH that would
  * just 401 for an anonymous visitor and revert the UI.
  */
+/** Parses an `Accept-Language` header and returns the first supported
+ * locale it lists, in the browser's stated preference order — ignoring
+ * unsupported languages (e.g. "de", "es") rather than stopping at them. */
+function localeFromAcceptLanguage(header: string | null): Locale | null {
+  if (!header) return null;
+  const tags = header
+    .split(",")
+    .map((part) => part.split(";")[0]!.trim().toLowerCase())
+    .filter(Boolean);
+  for (const tag of tags) {
+    if (tag.startsWith("fr")) return "fr";
+    if (tag.startsWith("en")) return "en";
+  }
+  return null;
+}
+
 export async function getMarketingLocale(): Promise<Locale> {
   const store = await cookies();
-  const value = store.get(MARKETING_LOCALE_COOKIE)?.value;
+  const cookieValue = store.get(MARKETING_LOCALE_COOKIE)?.value;
-  return value === "fr" ? "fr" : "en";
+  if (cookieValue === "fr" || cookieValue === "en") return cookieValue;
+
+  // No explicit choice saved yet (first visit, or cookies cleared) — honor
+  // the visitor's browser language instead of always defaulting to English.
+  const headerStore = await headers();
+  return localeFromAcceptLanguage(headerStore.get("accept-language")) ?? "en";
 }
 
 /** A logged-in visitor's own saved locale wins (matches what they see

apps/web/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@epicure/web",
-  "version": "0.77.0",
+  "version": "0.78.0",
   "private": true,
   "scripts": {
     "dev": "next dev",

package.json

@@ -1,6 +1,6 @@
 {
   "name": "epicure",
-  "version": "0.77.0",
+  "version": "0.78.0",
   "private": true,
   "scripts": {
     "dev": "pnpm --filter web dev",