diff --git a/docs/technical-debt.md b/docs/technical-debt.md
index d643dfad..bd94a804 100644
--- a/docs/technical-debt.md
+++ b/docs/technical-debt.md
@@ -14,6 +14,16 @@ Dług dotyczący całego systemu (backend, deploy, dane) żyje w `sklepik/docs/r
 
 ## Dług techniczny
 
+### 2026-07-07 — CountrySwitcher zastąpiony LanguageSwitcher — Market switcher jeszcze nie istnieje
+
+**Status:** w toku (krok 0+1 planu zamknięte, kroki 2-4 czekają na realny drugi rynek)
+
+**Skrót:** `CountrySwitcher.tsx` mieszał język i walutę w jednym dropdownie i linkował wg usuniętego schematu URL `/{country}/{locale}/...` → 404 na wyborze kraju + wizualny duplikat "PL PL | PLN". Usunięty (razem z `useCountrySwitch.ts`) i zastąpiony `LanguageSwitcher.tsx` — czysto językowym przełącznikiem (pl/en dziś, de/es/fr gotowe strukturalnie w `messages/*.json`, ale niewystawione dopóki ktoś nie zweryfikuje ich jakości), niezależnym od waluty/rynku. Ten sam fix zastosowany w `MobileMenu.tsx` (panel "country" → "language").
+
+**Co trzeba zrobić:** zbudować `MarketSwitcher` (waluta + wysyłka, oparty o cookie, nie URL) — dopiero gdy w adminie powstanie realny drugi `Market` (np. Eurozone/EUR). `updateCartMarket` (`src/lib/data/checkout.ts`) zostawiony nieużywany celowo — gotowa, przetestowana funkcja do reużycia w tym kroku.
+
+**Warunek zamknięcia:** pełny plan w `sklepik/docs/plans/market-language-switcher.md` zrealizowany (kroki 2-4).
+
 ### 2026-07-07 — Zdjęcie główne na stronie produktu czasem się nie wyświetla (mitygacja, nie fix)
 
 **Status:** otwarte (frontowa mitygacja wdrożona, przyczyna po stronie backendu/infra pozostaje)
diff --git a/messages/de.json b/messages/de.json
index 373c3b77..77601bc8 100644
--- a/messages/de.json
+++ b/messages/de.json
@@ -18,6 +18,7 @@
     "continueShopping": "Weiter einkaufen",
     "orderSummary": "Bestellübersicht",
     "selectCountry": "Land auswählen",
+    "selectLanguage": "Sprache auswählen",
     "myAccount": "Mein Konto",
     "giftCard": "Geschenkkarte",
     "storeCredit": "Guthaben",
@@ -31,6 +32,7 @@
     "openMenu": "Menü öffnen",
     "menu": "Menü",
     "selectCountry": "Land auswählen",
+    "selectLanguage": "Sprache auswählen",
     "home": "Startseite",
     "allProducts": "Alle Produkte",
     "contact": "Kontakt",
diff --git a/messages/en.json b/messages/en.json
index 5dd69a47..cafbca0e 100644
--- a/messages/en.json
+++ b/messages/en.json
@@ -18,6 +18,7 @@
     "continueShopping": "Continue Shopping",
     "orderSummary": "Order Summary",
     "selectCountry": "Select Country",
+    "selectLanguage": "Select Language",
     "myAccount": "My Account",
     "giftCard": "Gift card",
     "storeCredit": "Store credit",
@@ -31,6 +32,7 @@
     "openMenu": "Open menu",
     "menu": "Menu",
     "selectCountry": "Select Country",
+    "selectLanguage": "Select Language",
     "home": "Home",
     "allProducts": "All Products",
     "contact": "Contact",
diff --git a/messages/es.json b/messages/es.json
index 8e7610ce..b83ac324 100644
--- a/messages/es.json
+++ b/messages/es.json
@@ -18,6 +18,7 @@
     "continueShopping": "Seguir comprando",
     "orderSummary": "Resumen del pedido",
     "selectCountry": "Seleccionar pais",
+    "selectLanguage": "Seleccionar idioma",
     "myAccount": "Mi cuenta",
     "giftCard": "Tarjeta regalo",
     "storeCredit": "Credito de la tienda",
@@ -31,6 +32,7 @@
     "openMenu": "Abrir menu",
     "menu": "Menu",
     "selectCountry": "Seleccionar pais",
+    "selectLanguage": "Seleccionar idioma",
     "home": "Inicio",
     "allProducts": "Todos los productos",
     "contact": "Contacto",
diff --git a/messages/fr.json b/messages/fr.json
index f36c9878..2e4059d9 100644
--- a/messages/fr.json
+++ b/messages/fr.json
@@ -18,6 +18,7 @@
     "continueShopping": "Continuer les achats",
     "orderSummary": "Recapitulatif de la commande",
     "selectCountry": "Choisir le pays",
+    "selectLanguage": "Choisir la langue",
     "myAccount": "Mon compte",
     "giftCard": "Carte cadeau",
     "storeCredit": "Credit boutique",
@@ -31,6 +32,7 @@
     "openMenu": "Ouvrir le menu",
     "menu": "Menu",
     "selectCountry": "Choisir le pays",
+    "selectLanguage": "Choisir la langue",
     "home": "Accueil",
     "allProducts": "Tous les produits",
     "contact": "Contact",
diff --git a/messages/pl.json b/messages/pl.json
index 86bd1c51..b670a3c6 100644
--- a/messages/pl.json
+++ b/messages/pl.json
@@ -18,6 +18,7 @@
     "continueShopping": "Kontynuuj zakupy",
     "orderSummary": "Podsumowanie zamówienia",
     "selectCountry": "Wybierz kraj",
+    "selectLanguage": "Wybierz język",
     "myAccount": "Moje konto",
     "giftCard": "Karta podarunkowa",
     "storeCredit": "Kredyt sklepowy",
@@ -31,6 +32,7 @@
     "openMenu": "Otwórz menu",
     "menu": "Menu",
     "selectCountry": "Wybierz kraj",
+    "selectLanguage": "Wybierz język",
     "home": "Strona główna",
     "allProducts": "Wszystkie produkty",
     "contact": "Kontakt",
diff --git a/src/components/layout/Header.tsx b/src/components/layout/Header.tsx
index 6840da9f..c359483a 100644
--- a/src/components/layout/Header.tsx
+++ b/src/components/layout/Header.tsx
@@ -20,10 +20,10 @@ const LazyMobileMenu = dynamic(
   },
 );
 
-const LazyCountrySwitcher = dynamic(
+const LazyLanguageSwitcher = dynamic(
   () =>
-    import("@/components/layout/CountrySwitcher").then((mod) => ({
-      default: mod.CountrySwitcher,
+    import("@/components/layout/LanguageSwitcher").then((mod) => ({
+      default: mod.LanguageSwitcher,
     })),
   {
     loading: () => (
@@ -64,7 +64,7 @@ export async function Header({
       }
       rightStart={
         <div className="hidden lg:block">
-          <LazyCountrySwitcher />
+          <LazyLanguageSwitcher />
         </div>
       }
       rightEnd={
diff --git a/src/components/layout/LanguageSwitcher.tsx b/src/components/layout/LanguageSwitcher.tsx
new file mode 100644
index 00000000..79c9fcf7
--- /dev/null
+++ b/src/components/layout/LanguageSwitcher.tsx
@@ -0,0 +1,76 @@
+"use client";
+
+import { Check, ChevronDown, Globe } from "lucide-react";
+import { usePathname, useRouter } from "next/navigation";
+import { useLocale, useTranslations } from "next-intl";
+import { Button } from "@/components/ui/button";
+import {
+  DropdownMenu,
+  DropdownMenuContent,
+  DropdownMenuItem,
+  DropdownMenuLabel,
+  DropdownMenuTrigger,
+} from "@/components/ui/dropdown-menu";
+import { getDefaultLocale, getPrefixedLocales } from "@/lib/store";
+import { LANGUAGE_NAMES } from "@/lib/utils/language-names";
+import { buildBasePath, getPathWithoutPrefix } from "@/lib/utils/path";
+
+/**
+ * Purely a UI-language control — independent of currency/market (see
+ * docs/plans/market-language-switcher.md). Rewrites only the /{locale}
+ * URL segment via a soft client navigation; never touches cart, currency,
+ * or cookies.
+ */
+export function LanguageSwitcher() {
+  const currentLocale = useLocale();
+  const pathname = usePathname();
+  const router = useRouter();
+  const t = useTranslations("common");
+
+  const locales = [
+    getDefaultLocale() as Locale,
+    ...getPrefixedLocales().map((l) => l as Locale),
+  ];
+
+  // Nothing to switch between — don't render a dropdown with one option.
+  if (locales.length <= 1) return null;
+
+  const handleSelect = (locale: Locale) => {
+    if (locale === currentLocale) return;
+    const pathRest = getPathWithoutPrefix(pathname);
+    router.push(`${buildBasePath(locale)}${pathRest}`);
+  };
+
+  return (
+    <DropdownMenu>
+      <DropdownMenuTrigger asChild>
+        <Button variant="ghost">
+          <Globe className="w-4 h-4 text-gray-400" />
+          <span className="font-medium">
+            {LANGUAGE_NAMES[currentLocale as Locale] ??
+              currentLocale.toUpperCase()}
+          </span>
+          <ChevronDown className="w-4 h-4 text-gray-400" />
+        </Button>
+      </DropdownMenuTrigger>
+
+      <DropdownMenuContent align="end" className="w-48">
+        <DropdownMenuLabel>{t("selectLanguage")}</DropdownMenuLabel>
+        {locales.map((locale) => {
+          const isSelected = locale === currentLocale;
+          return (
+            <DropdownMenuItem
+              key={locale}
+              onSelect={() => handleSelect(locale)}
+            >
+              <span className="flex-1 font-medium">
+                {LANGUAGE_NAMES[locale] ?? locale.toUpperCase()}
+              </span>
+              {isSelected && <Check className="w-4 h-4" />}
+            </DropdownMenuItem>
+          );
+        })}
+      </DropdownMenuContent>
+    </DropdownMenu>
+  );
+}
diff --git a/src/components/layout/MobileMenu.tsx b/src/components/layout/MobileMenu.tsx
index 877cf61a..71b778ea 100644
--- a/src/components/layout/MobileMenu.tsx
+++ b/src/components/layout/MobileMenu.tsx
@@ -1,9 +1,10 @@
 "use client";
 
 import type { Category } from "@spree/sdk";
-import { ArrowLeft, Check, ChevronRight, User, X } from "lucide-react";
+import { ArrowLeft, Check, ChevronRight, Globe, User, X } from "lucide-react";
 import Link from "next/link";
-import { useTranslations } from "next-intl";
+import { usePathname, useRouter } from "next/navigation";
+import { useLocale, useTranslations } from "next-intl";
 import { useRef, useState } from "react";
 import { flushSync } from "react-dom";
 import { Button } from "@/components/ui/button";
@@ -14,22 +15,14 @@ import {
   SheetFooter,
   SheetTitle,
 } from "@/components/ui/sheet";
-import { useStore } from "@/contexts/StoreContext";
-import { useCountrySwitch } from "@/hooks/useCountrySwitch";
-
-// Convert ISO country code to flag emoji
-function countryToFlag(countryCode: string): string {
-  const code = countryCode.toUpperCase();
-  if (code.length !== 2) return "";
-  const firstChar = code.charCodeAt(0) - 65 + 0x1f1e6;
-  const secondChar = code.charCodeAt(1) - 65 + 0x1f1e6;
-  return String.fromCodePoint(firstChar, secondChar);
-}
+import { getDefaultLocale, getPrefixedLocales } from "@/lib/store";
+import { LANGUAGE_NAMES } from "@/lib/utils/language-names";
+import { buildBasePath, getPathWithoutPrefix } from "@/lib/utils/path";
 
 type PanelType =
   | { kind: "main" }
   | { kind: "category"; category: Category }
-  | { kind: "country" };
+  | { kind: "language" };
 
 interface MobileMenuProps {
   rootCategories: Category[];
@@ -46,11 +39,20 @@ export function MobileMenu({ rootCategories, basePath }: MobileMenuProps) {
   const rafRef = useRef<number | null>(null);
   const timeoutRef = useRef<NodeJS.Timeout | null>(null);
 
-  const { country, currency, countries } = useStore();
-  const { isCountryNavigating, handleCountrySelect } = useCountrySwitch({
-    currentCountry: country,
-    onBeforeNavigate: () => setOpen(false),
-  });
+  const currentLocale = useLocale();
+  const pathname = usePathname();
+  const router = useRouter();
+  const locales = [
+    getDefaultLocale() as Locale,
+    ...getPrefixedLocales().map((l) => l as Locale),
+  ];
+
+  const handleLanguageSelect = (locale: Locale) => {
+    setOpen(false);
+    if (locale === currentLocale) return;
+    const pathRest = getPathWithoutPrefix(pathname);
+    router.push(`${buildBasePath(locale)}${pathRest}`);
+  };
 
   const currentPanel = panelStack[panelStack.length - 1];
 
@@ -191,8 +193,8 @@ export function MobileMenu({ rootCategories, basePath }: MobileMenuProps) {
             <span>
               {currentPanel.kind === "category"
                 ? currentPanel.category.name
-                : currentPanel.kind === "country"
-                  ? t("selectCountry")
+                : currentPanel.kind === "language"
+                  ? t("selectLanguage")
                   : ""}
             </span>
           </button>
@@ -262,21 +264,22 @@ export function MobileMenu({ rootCategories, basePath }: MobileMenuProps) {
               </Link>
             </nav>
 
-            {/* Footer: Country switcher (mobile + tablet) + Account (mobile only) */}
+            {/* Footer: Language switcher (mobile + tablet) + Account (mobile only) */}
             <SheetFooter className="lg:hidden border-t border-gray-200 pt-4 gap-2">
-              <button
-                type="button"
-                onClick={() => pushPanel({ kind: "country" })}
-                className="flex items-center gap-2 px-4 py-2.5 text-base text-gray-700 hover:bg-gray-50 rounded-lg transition-colors w-full"
-              >
-                <span className="text-lg leading-none">
-                  {countryToFlag(country)}
-                </span>
-                <span className="font-medium">{country.toUpperCase()}</span>
-                <span className="text-gray-400">|</span>
-                <span>{currency}</span>
-                <ChevronRight className="w-4 h-4 text-gray-400 ml-auto" />
-              </button>
+              {locales.length > 1 && (
+                <button
+                  type="button"
+                  onClick={() => pushPanel({ kind: "language" })}
+                  className="flex items-center gap-2 px-4 py-2.5 text-base text-gray-700 hover:bg-gray-50 rounded-lg transition-colors w-full"
+                >
+                  <Globe className="w-4 h-4 text-gray-400" />
+                  <span className="font-medium">
+                    {LANGUAGE_NAMES[currentLocale as Locale] ??
+                      currentLocale.toUpperCase()}
+                  </span>
+                  <ChevronRight className="w-4 h-4 text-gray-400 ml-auto" />
+                </button>
+              )}
 
               <SheetClose asChild className="md:hidden">
                 <Link
@@ -358,10 +361,10 @@ export function MobileMenu({ rootCategories, basePath }: MobileMenuProps) {
             );
           })}
 
-          {/* Country selector panel */}
+          {/* Language selector panel */}
           <div
             className={`absolute inset-0 flex flex-col bg-white transition-transform duration-300 ease-in-out ${
-              currentPanel.kind === "country" &&
+              currentPanel.kind === "language" &&
               animatedIndex === panelStack.length - 1
                 ? "translate-x-0"
                 : "translate-x-full"
@@ -374,33 +377,27 @@ export function MobileMenu({ rootCategories, basePath }: MobileMenuProps) {
                 className="flex items-center gap-2 text-gray-700 hover:text-gray-900 py-2 text-base font-medium"
               >
                 <ArrowLeft className="w-5 h-5" />
-                <span>{t("selectCountry")}</span>
+                <span>{t("selectLanguage")}</span>
               </button>
             </div>
 
             <div className="flex-1 overflow-y-auto px-4 py-2">
-              {countries.map((c) => {
-                const isSelected =
-                  c.iso.toLowerCase() === country.toLowerCase();
+              {locales.map((locale) => {
+                const isSelected = locale === currentLocale;
                 return (
                   <button
-                    key={c.iso}
+                    key={locale}
                     type="button"
-                    disabled={isCountryNavigating}
-                    onClick={() => handleCountrySelect(c)}
+                    onClick={() => handleLanguageSelect(locale)}
                     className={`w-full flex items-center gap-3 px-3 py-3 rounded-lg text-base transition-colors ${
                       isSelected
                         ? "bg-gray-100 font-medium"
                         : "hover:bg-gray-50"
                     }`}
                   >
-                    <span className="text-lg leading-none">
-                      {countryToFlag(c.iso)}
-                    </span>
                     <span className="flex-1 text-left font-medium">
-                      {c.name}
+                      {LANGUAGE_NAMES[locale] ?? locale.toUpperCase()}
                     </span>
-                    <span className="text-sm text-gray-500">{c.currency}</span>
                     {isSelected && <Check className="w-4 h-4 text-black" />}
                   </button>
                 );
diff --git a/src/lib/utils/language-names.ts b/src/lib/utils/language-names.ts
new file mode 100644
index 00000000..0da38b48
--- /dev/null
+++ b/src/lib/utils/language-names.ts
@@ -0,0 +1,10 @@
+// Each language's own name in its own language (endonym) — a language
+// switcher should stay legible regardless of which UI language is
+// currently active, so labels are never run through next-intl.
+export const LANGUAGE_NAMES: Record<Locale, string> = {
+  pl: "Polski",
+  en: "English",
+  de: "Deutsch",
+  es: "Español",
+  fr: "Français",
+};