Remember to use language choice between browser sessions

application/account-management/Core/Features/Signups/Commands/CompleteSignup.cs

@@ -15,6 +15,8 @@ public sealed record CompleteSignupCommand(string OneTimePassword) : ICommand, I
 {
     [JsonIgnore] // Removes this property from the API contract
     public SignupId Id { get; init; } = null!;
+
+    public string? PreferredLocale { get; init; }
 }
 
 public sealed class CompleteSignupHandler(
@@ -65,7 +67,10 @@ public async Task<Result> Handle(CompleteSignupCommand command, CancellationToke
             return Result.BadRequest("The code is no longer valid, please request a new code.", true);
         }
 
-        var result = await mediator.Send(new CreateTenantCommand(signup.TenantId, signup.Email, true), cancellationToken);
+        var result = await mediator.Send(
+            new CreateTenantCommand(signup.TenantId, signup.Email, true, command.PreferredLocale),
+            cancellationToken
+        );
 
         var user = await userRepository.GetByIdAsync(result.Value!, cancellationToken);
         authenticationTokenService.CreateAndSetAuthenticationTokens(user!.Adapt<UserInfo>());

application/account-management/Core/Features/Tenants/Commands/CreateTenant.cs

@@ -9,7 +9,7 @@
 namespace PlatformPlatform.AccountManagement.Features.Tenants.Commands;
 
 [PublicAPI]
-public sealed record CreateTenantCommand(TenantId Id, string OwnerEmail, bool EmailConfirmed)
+public sealed record CreateTenantCommand(TenantId Id, string OwnerEmail, bool EmailConfirmed, string? Locale)
     : ICommand, IRequest<Result<UserId>>;
 
 public sealed class CreateTenantHandler(ITenantRepository tenantRepository, IMediator mediator, ITelemetryEventsCollector events)
@@ -23,8 +23,8 @@ public async Task<Result<UserId>> Handle(CreateTenantCommand command, Cancellati
         events.CollectEvent(new TenantCreated(tenant.Id, tenant.State));
 
         var result = await mediator.Send(
-            new CreateUserCommand(tenant.Id, command.OwnerEmail, UserRole.Owner, command.EmailConfirmed)
-            , cancellationToken
+            new CreateUserCommand(tenant.Id, command.OwnerEmail, UserRole.Owner, command.EmailConfirmed, command.Locale),
+            cancellationToken
         );
 
         return result.Value!;

application/account-management/Core/Features/Users/Commands/CreateUser.cs

@@ -7,13 +7,20 @@
 using PlatformPlatform.SharedKernel.Cqrs;
 using PlatformPlatform.SharedKernel.Domain;
 using PlatformPlatform.SharedKernel.ExecutionContext;
+using PlatformPlatform.SharedKernel.SinglePageApp;
 using PlatformPlatform.SharedKernel.Telemetry;
 using PlatformPlatform.SharedKernel.Validation;
 
 namespace PlatformPlatform.AccountManagement.Features.Users.Commands;
 
 [PublicAPI]
-public sealed record CreateUserCommand(TenantId TenantId, string Email, UserRole UserRole, bool EmailConfirmed)
+public sealed record CreateUserCommand(
+    TenantId TenantId,
+    string Email,
+    UserRole UserRole,
+    bool EmailConfirmed,
+    string? PreferredLocale
+)
     : ICommand, IRequest<Result<UserId>>;
 
 public sealed class CreateUserValidator : AbstractValidator<CreateUserCommand>
@@ -50,7 +57,10 @@ public async Task<Result<UserId>> Handle(CreateUserCommand command, Cancellation
             throw new UnreachableException("Only when signing up a new tenant, is the TenantID allowed to different than the current tenant.");
         }
 
-        var user = User.Create(command.TenantId, command.Email, command.UserRole, command.EmailConfirmed);
+        var locale = SinglePageAppConfiguration.SupportedLocalizations.Contains(command.PreferredLocale)
+            ? command.PreferredLocale
+            : string.Empty;
+        var user = User.Create(command.TenantId, command.Email, command.UserRole, command.EmailConfirmed, locale);
 
         await userRepository.AddAsync(user, cancellationToken);
         var gravatar = await gravatarClient.GetGravatar(user.Id, user.Email, cancellationToken);

application/account-management/Core/Features/Users/Commands/InviteUser.cs

@@ -41,7 +41,10 @@ public async Task<Result> Handle(InviteUserCommand command, CancellationToken ca
             return Result.Forbidden("Only owners are allowed to invite other users.");
         }
 
-        var result = await mediator.Send(new CreateUserCommand(executionContext.TenantId!, command.Email, UserRole.Member, false), cancellationToken);
+        var result = await mediator.Send(
+            new CreateUserCommand(executionContext.TenantId!, command.Email, UserRole.Member, false, null),
+            cancellationToken
+        );
 
         events.CollectEvent(new UserInvited(result.Value!));
 

application/account-management/Core/Features/Users/Domain/User.cs

@@ -6,13 +6,14 @@ public sealed class User : AggregateRoot<UserId>, ITenantScopedEntity
 {
     private string _email = string.Empty;
 
-    private User(TenantId tenantId, string email, UserRole role, bool emailConfirmed)
+    private User(TenantId tenantId, string email, UserRole role, bool emailConfirmed, string? locale)
         : base(UserId.NewId())
     {
         Email = email;
         TenantId = tenantId;
         Role = role;
         EmailConfirmed = emailConfirmed;
+        Locale = locale ?? string.Empty;
         Avatar = new Avatar();
     }
 
@@ -34,13 +35,13 @@ public string Email
 
     public Avatar Avatar { get; private set; }
 
-    public string Locale { get; private set; } = string.Empty;
+    public string Locale { get; private set; }
 
     public TenantId TenantId { get; }
 
-    public static User Create(TenantId tenantId, string email, UserRole role, bool emailConfirmed)
+    public static User Create(TenantId tenantId, string email, UserRole role, bool emailConfirmed, string? locale)
     {
-        return new User(tenantId, email, role, emailConfirmed);
+        return new User(tenantId, email, role, emailConfirmed, locale);
     }
 
     public void Update(string firstName, string lastName, string title)

application/account-management/Tests/DatabaseSeeder.cs

@@ -14,7 +14,7 @@ public DatabaseSeeder(AccountManagementDbContext accountManagementDbContext)
     {
         Tenant1 = Tenant.Create(new TenantId("tenant-1"), "[email protected]");
         accountManagementDbContext.Tenants.AddRange(Tenant1);
-        User1 = User.Create(Tenant1.Id, "[email protected]", UserRole.Owner, true);
+        User1 = User.Create(Tenant1.Id, "[email protected]", UserRole.Owner, true, null);
         accountManagementDbContext.Users.AddRange(User1);
 
         accountManagementDbContext.SaveChanges();

application/account-management/Tests/Users/CreateUserTests.cs

@@ -18,7 +18,7 @@ public async Task CreateUser_WhenValid_ShouldCreateUser()
     {
         // Arrange
         var existingTenantId = DatabaseSeeder.Tenant1.Id;
-        var command = new CreateUserCommand(existingTenantId, Faker.Internet.Email(), UserRole.Member, false);
+        var command = new CreateUserCommand(existingTenantId, Faker.Internet.Email(), UserRole.Member, false, null);
 
         // Act
         var response = await AuthenticatedHttpClient.PostAsJsonAsync("/api/account-management/users", command);
@@ -34,7 +34,7 @@ public async Task CreateUser_WhenInvalidEmail_ShouldReturnBadRequest()
         // Arrange
         var existingTenantId = DatabaseSeeder.Tenant1.Id;
         var invalidEmail = Faker.InvalidEmail();
-        var command = new CreateUserCommand(existingTenantId, invalidEmail, UserRole.Member, false);
+        var command = new CreateUserCommand(existingTenantId, invalidEmail, UserRole.Member, false, null);
 
         // Act
         var response = await AuthenticatedHttpClient.PostAsJsonAsync("/api/account-management/users", command);
@@ -53,7 +53,7 @@ public async Task CreateUser_WhenUserExists_ShouldReturnBadRequest()
         // Arrange
         var existingTenantId = DatabaseSeeder.Tenant1.Id;
         var existingUserEmail = DatabaseSeeder.User1.Email;
-        var command = new CreateUserCommand(existingTenantId, existingUserEmail, UserRole.Member, false);
+        var command = new CreateUserCommand(existingTenantId, existingUserEmail, UserRole.Member, false, null);
 
         // Act
         var response = await AuthenticatedHttpClient.PostAsJsonAsync("/api/account-management/users", command);
@@ -71,7 +71,7 @@ public async Task CreateUser_WhenTenantDoesNotExists_ShouldReturnBadRequest()
     {
         // Arrange
         var unknownTenantId = new TenantId(Faker.Subdomain());
-        var command = new CreateUserCommand(unknownTenantId, Faker.Internet.Email(), UserRole.Member, false);
+        var command = new CreateUserCommand(unknownTenantId, Faker.Internet.Email(), UserRole.Member, false, null);
 
         // Act
         var response = await AuthenticatedHttpClient.PostAsJsonAsync("/api/account-management/users", command);

application/account-management/WebApp/routes/__root.tsx

@@ -4,6 +4,7 @@ import { NotFound } from "@repo/infrastructure/errorComponents/NotFoundPage";
 import { AuthenticationProvider } from "@repo/infrastructure/auth/AuthenticationProvider";
 import { ReactAriaRouterProvider } from "@repo/infrastructure/router/ReactAriaRouterProvider";
 import { ThemeModeProvider } from "@repo/ui/theme/mode/ThemeMode";
+import { useInitializeLocale } from "@repo/infrastructure/translations/useInitializeLocale";
 
 export const Route = createRootRoute({
   component: Root,
@@ -13,6 +14,7 @@ export const Route = createRootRoute({
 
 function Root() {
   const navigate = useNavigate();
+  useInitializeLocale();
 
   return (
     <ThemeModeProvider>

application/account-management/WebApp/routes/signup/verify.tsx

@@ -15,6 +15,7 @@ import { getSignupState, setSignupState } from "./-shared/signupState";
 import { api } from "@/shared/lib/api/client";
 import { FormErrorMessage } from "@repo/ui/components/FormErrorMessage";
 import { loggedInPath, signedUpPath } from "@repo/infrastructure/auth/constants";
+import { preferredLocaleKey } from "@repo/infrastructure/translations/constants";
 import { useActionState, useEffect } from "react";
 import { useIsAuthenticated } from "@repo/infrastructure/auth/hooks";
 
@@ -80,6 +81,7 @@ export function CompleteSignupForm() {
     <div className="w-full max-w-sm space-y-3">
       <Form action={action} validationErrors={errors} validationBehavior="aria">
         <input type="hidden" name="id" value={signupId} />
+        <input type="hidden" name="preferredLocale" value={localStorage.getItem(preferredLocaleKey) ?? ""} />
         <div className="flex w-full flex-col gap-4 rounded-lg px-6 pt-8 pb-4">
           <div className="flex justify-center">
             <Link href="/">

application/account-management/WebApp/shared/lib/api/AccountManagement.Api.json

@@ -834,6 +834,10 @@
         "properties": {
           "oneTimePassword": {
             "type": "string"
+          },
+          "preferredLocale": {
+            "type": "string",
+            "nullable": true
           }
         }
       },
@@ -1129,6 +1133,10 @@
           },
           "emailConfirmed": {
             "type": "boolean"
+          },
+          "preferredLocale": {
+            "type": "string",
+            "nullable": true
           }
         }
       },

application/back-office/WebApp/routes/__root.tsx

@@ -4,6 +4,7 @@ import { NotFound } from "@repo/infrastructure/errorComponents/NotFoundPage";
 import { AuthenticationProvider } from "@repo/infrastructure/auth/AuthenticationProvider";
 import { ReactAriaRouterProvider } from "@repo/infrastructure/router/ReactAriaRouterProvider";
 import { ThemeModeProvider } from "@repo/ui/theme/mode/ThemeMode";
+import { useInitializeLocale } from "@repo/infrastructure/translations/useInitializeLocale";
 
 export const Route = createRootRoute({
   component: Root,
@@ -13,6 +14,8 @@ export const Route = createRootRoute({
 
 function Root() {
   const navigate = useNavigate();
+  useInitializeLocale();
+
   return (
     <ThemeModeProvider>
       <ReactAriaRouterProvider>

application/shared-webapp/infrastructure/translations/LocaleSwitcher.tsx

@@ -8,6 +8,7 @@ import { Popover } from "@repo/ui/components/Popover";
 import { DialogTrigger } from "@repo/ui/components/Dialog";
 import type { Selection } from "react-aria-components";
 import { AuthenticationContext } from "@repo/infrastructure/auth/AuthenticationProvider";
+import { preferredLocaleKey } from "./constants";
 
 export function LocaleSwitcher() {
   const [isOpen, setIsOpen] = useState(false);
@@ -35,10 +36,12 @@ export function LocaleSwitcher() {
         })
           .then(async (_) => {
             await setLocale(newLocale);
+            localStorage.setItem(preferredLocaleKey, newLocale);
           })
           .catch((error) => console.error("Failed to update locale:", error));
       } else {
         await setLocale(newLocale);
+        localStorage.setItem(preferredLocaleKey, newLocale);
       }
 
       setIsOpen(false);

application/shared-webapp/infrastructure/translations/constants.ts

@@ -0,0 +1 @@
+export const preferredLocaleKey = "preferred-locale";

application/shared-webapp/infrastructure/translations/useInitializeLocale.ts

@@ -0,0 +1,22 @@
+import { useEffect, useContext } from "react";
+import { preferredLocaleKey } from "./constants";
+import { AuthenticationContext } from "../auth/AuthenticationProvider";
+import { translationContext } from "./TranslationContext";
+import type { Locale } from "./Translation";
+
+export function useInitializeLocale() {
+  const { userInfo } = useContext(AuthenticationContext);
+  const { setLocale } = useContext(translationContext);
+
+  useEffect(() => {
+    if (userInfo?.isAuthenticated) {
+      localStorage.setItem(preferredLocaleKey, document.documentElement.lang);
+    } else {
+      const storedLocale = localStorage.getItem(preferredLocaleKey) as Locale;
+      if (storedLocale) {
+        document.documentElement.lang = storedLocale;
+        setLocale(storedLocale);
+      }
+    }
+  }, [userInfo?.isAuthenticated, setLocale]);
+}