frontend/angular/src/app/session-route-context.spec.ts

@@ -69,6 +69,7 @@ describe('session route context', () => {
       sessionCode: 'AB12',
       playerId: 5,
       token: 'tok-5',
+      locale: 'en',
     });
   });
 
@@ -80,7 +81,25 @@ describe('session route context', () => {
       sessionCode: 'AB12',
       playerId: null,
       token: null,
+      locale: 'en',
     });
     expect(sessionStorage.setItem).toHaveBeenCalledWith('wpp.host-session-code', 'AB12');
   });
+
+  it('resolvers normalize and expose locale from lang query param', () => {
+    setWindow(storageMock(), storageMock());
+
+    expect(hostRouteContextResolver(route({}, { lang: 'da-DK' }) as never, {} as never).locale).toBe('da');
+    expect(playerRouteContextResolver(route({}, { lang: 'EN' }) as never, {} as never).locale).toBe('en');
+  });
+
+  it('does not reset persisted preferred locale when lang query param is absent', () => {
+    const localStorage = storageMock({ 'wpp.locale': 'da' });
+    setWindow(localStorage, storageMock());
+
+    expect(hostRouteContextResolver(route({}, { lang: 'da' }) as never, {} as never).locale).toBe('da');
+    expect(hostRouteContextResolver(route({}, {}) as never, {} as never).locale).toBe('da');
+    expect(localStorage.setItem).toHaveBeenCalledTimes(1);
+    expect(localStorage.setItem).toHaveBeenCalledWith('wpp.locale', 'da');
+  });
 });

frontend/angular/src/app/session-route-context.ts

@@ -2,11 +2,13 @@ import { inject } from '@angular/core';
 import { type ActivatedRouteSnapshot, type CanActivateFn, type ResolveFn, Router, type UrlTree } from '@angular/router';
 
 import { createSessionContextStore } from '../../../src/spa/session-context-store';
+import { normalizeLocale, resolvePreferredLocale, setPreferredLocale } from './lobby-i18n';
 
 export interface RouteSessionContext {
   sessionCode: string | null;
   playerId: number | null;
   token: string | null;
+  locale: string;
 }
 
 const HOST_STORAGE_KEY = 'wpp.host-session-code';
@@ -61,6 +63,17 @@ export function resolveSessionCode(route: ActivatedRouteSnapshot, mode: 'host' |
   return null;
 }
 
+function resolveRouteLocale(route: ActivatedRouteSnapshot): string {
+  const langParam = route.queryParamMap.get('lang');
+  if (langParam !== null) {
+    const locale = normalizeLocale(langParam);
+    setPreferredLocale(locale);
+    return locale;
+  }
+
+  return resolvePreferredLocale();
+}
+
 async function sessionExists(code: string): Promise<boolean> {
   const response = await fetch(`/lobby/sessions/${encodeURIComponent(code)}`, {
     method: 'GET',
@@ -118,23 +131,26 @@ export const playerRouteGuard: CanActivateFn = (route) => guard('player', route)
 
 export const hostRouteContextResolver: ResolveFn<RouteSessionContext> = (route) => {
   const code = resolveSessionCode(route, 'host');
+  const locale = resolveRouteLocale(route);
   if (code) {
     window.sessionStorage.setItem(HOST_STORAGE_KEY, code);
   }
-  return { sessionCode: code, playerId: null, token: null };
+  return { sessionCode: code, playerId: null, token: null, locale };
 };
 
 export const playerRouteContextResolver: ResolveFn<RouteSessionContext> = (route) => {
   const code = resolveSessionCode(route, 'player');
+  const locale = resolveRouteLocale(route);
   const context = createSessionContextStore(window.localStorage).get();
 
   if (!code || !context || normalizeCode(context.sessionCode) !== code) {
-    return { sessionCode: code, playerId: null, token: null };
+    return { sessionCode: code, playerId: null, token: null, locale };
   }
 
   return {
     sessionCode: code,
     playerId: Number.isInteger(context.playerId) && context.playerId > 0 ? context.playerId : null,
     token: context.token.trim() || null,
+    locale,
   };
 };