diff --git a/src/main/java/alpl/backend/web/AplpBackendWebApplication.java b/src/main/java/aplp/backend/web/AplpBackendWebApplication.java
similarity index 100%
rename from src/main/java/alpl/backend/web/AplpBackendWebApplication.java
rename to src/main/java/aplp/backend/web/AplpBackendWebApplication.java
diff --git a/src/main/java/alpl/backend/web/common/api/GlobalExceptionHandler.java b/src/main/java/aplp/backend/web/common/api/GlobalExceptionHandler.java
similarity index 100%
rename from src/main/java/alpl/backend/web/common/api/GlobalExceptionHandler.java
rename to src/main/java/aplp/backend/web/common/api/GlobalExceptionHandler.java
diff --git a/src/main/java/alpl/backend/web/common/config/CommonConfig.java b/src/main/java/aplp/backend/web/common/config/CommonConfig.java
similarity index 100%
rename from src/main/java/alpl/backend/web/common/config/CommonConfig.java
rename to src/main/java/aplp/backend/web/common/config/CommonConfig.java
diff --git a/src/main/java/alpl/backend/web/common/config/OpenApiConfig.java b/src/main/java/aplp/backend/web/common/config/OpenApiConfig.java
similarity index 100%
rename from src/main/java/alpl/backend/web/common/config/OpenApiConfig.java
rename to src/main/java/aplp/backend/web/common/config/OpenApiConfig.java
diff --git a/src/main/java/alpl/backend/web/common/security/AuthenticatedUser.java b/src/main/java/aplp/backend/web/common/security/AuthenticatedUser.java
similarity index 100%
rename from src/main/java/alpl/backend/web/common/security/AuthenticatedUser.java
rename to src/main/java/aplp/backend/web/common/security/AuthenticatedUser.java
diff --git a/src/main/java/alpl/backend/web/common/security/CorsProperties.java b/src/main/java/aplp/backend/web/common/security/CorsProperties.java
similarity index 100%
rename from src/main/java/alpl/backend/web/common/security/CorsProperties.java
rename to src/main/java/aplp/backend/web/common/security/CorsProperties.java
diff --git a/src/main/java/alpl/backend/web/common/security/JwtAuthenticationFilter.java b/src/main/java/aplp/backend/web/common/security/JwtAuthenticationFilter.java
similarity index 100%
rename from src/main/java/alpl/backend/web/common/security/JwtAuthenticationFilter.java
rename to src/main/java/aplp/backend/web/common/security/JwtAuthenticationFilter.java
diff --git a/src/main/java/alpl/backend/web/common/security/JwtClaims.java b/src/main/java/aplp/backend/web/common/security/JwtClaims.java
similarity index 100%
rename from src/main/java/alpl/backend/web/common/security/JwtClaims.java
rename to src/main/java/aplp/backend/web/common/security/JwtClaims.java
diff --git a/src/main/java/alpl/backend/web/common/security/JwtProperties.java b/src/main/java/aplp/backend/web/common/security/JwtProperties.java
similarity index 100%
rename from src/main/java/alpl/backend/web/common/security/JwtProperties.java
rename to src/main/java/aplp/backend/web/common/security/JwtProperties.java
diff --git a/src/main/java/alpl/backend/web/common/security/JwtTokenProvider.java b/src/main/java/aplp/backend/web/common/security/JwtTokenProvider.java
similarity index 100%
rename from src/main/java/alpl/backend/web/common/security/JwtTokenProvider.java
rename to src/main/java/aplp/backend/web/common/security/JwtTokenProvider.java
diff --git a/src/main/java/alpl/backend/web/common/security/SecurityConfig.java b/src/main/java/aplp/backend/web/common/security/SecurityConfig.java
similarity index 100%
rename from src/main/java/alpl/backend/web/common/security/SecurityConfig.java
rename to src/main/java/aplp/backend/web/common/security/SecurityConfig.java
diff --git a/src/main/java/alpl/backend/web/common/security/SecurityErrorHandlers.java b/src/main/java/aplp/backend/web/common/security/SecurityErrorHandlers.java
similarity index 100%
rename from src/main/java/alpl/backend/web/common/security/SecurityErrorHandlers.java
rename to src/main/java/aplp/backend/web/common/security/SecurityErrorHandlers.java
diff --git a/src/main/java/alpl/backend/web/common/security/SecurityUtils.java b/src/main/java/aplp/backend/web/common/security/SecurityUtils.java
similarity index 100%
rename from src/main/java/alpl/backend/web/common/security/SecurityUtils.java
rename to src/main/java/aplp/backend/web/common/security/SecurityUtils.java
diff --git a/src/main/java/alpl/backend/web/common/web/RequestIdFilter.java b/src/main/java/aplp/backend/web/common/web/RequestIdFilter.java
similarity index 100%
rename from src/main/java/alpl/backend/web/common/web/RequestIdFilter.java
rename to src/main/java/aplp/backend/web/common/web/RequestIdFilter.java
diff --git a/src/main/java/alpl/backend/web/identity/api/controller/AuthController.java b/src/main/java/aplp/backend/web/identity/api/controller/AuthController.java
similarity index 89%
rename from src/main/java/alpl/backend/web/identity/api/controller/AuthController.java
rename to src/main/java/aplp/backend/web/identity/api/controller/AuthController.java
index b4078cb..1929024 100644
--- a/src/main/java/alpl/backend/web/identity/api/controller/AuthController.java
+++ b/src/main/java/aplp/backend/web/identity/api/controller/AuthController.java
@@ -26,12 +26,12 @@ public class AuthController {
     @PostMapping("/register")
     @ResponseStatus(HttpStatus.CREATED)
     public AuthResponse register(@Valid @RequestBody RegisterRequest request) {
-        return authService.register(request.email(), request.password(), request.displayName());
+        return authService.register(request.username(), request.email(), request.password(), request.displayName());
     }
 
     @PostMapping("/login")
     public AuthResponse login(@Valid @RequestBody LoginRequest request) {
-        return authService.login(request.email(), request.password());
+        return authService.login(request.username(), request.password());
     }
 
     @PostMapping("/refresh")
diff --git a/src/main/java/alpl/backend/web/identity/application/dtos/AuthResponse.java b/src/main/java/aplp/backend/web/identity/application/dtos/AuthResponse.java
similarity index 100%
rename from src/main/java/alpl/backend/web/identity/application/dtos/AuthResponse.java
rename to src/main/java/aplp/backend/web/identity/application/dtos/AuthResponse.java
diff --git a/src/main/java/alpl/backend/web/identity/application/dtos/LoginRequest.java b/src/main/java/aplp/backend/web/identity/application/dtos/LoginRequest.java
similarity index 58%
rename from src/main/java/alpl/backend/web/identity/application/dtos/LoginRequest.java
rename to src/main/java/aplp/backend/web/identity/application/dtos/LoginRequest.java
index 0178012..5093c7c 100644
--- a/src/main/java/alpl/backend/web/identity/application/dtos/LoginRequest.java
+++ b/src/main/java/aplp/backend/web/identity/application/dtos/LoginRequest.java
@@ -1,10 +1,10 @@
 package aplp.backend.web.identity.application.dtos;
 
-import jakarta.validation.constraints.Email;
 import jakarta.validation.constraints.NotBlank;
+import jakarta.validation.constraints.Size;
 
 public record LoginRequest(
-        @NotBlank @Email(message = "must be a valid email") String email,
+        @NotBlank @Size(min = 3, max = 50) String username,
         @NotBlank String password
 ) {
 }
diff --git a/src/main/java/alpl/backend/web/identity/application/dtos/RefreshTokenRequest.java b/src/main/java/aplp/backend/web/identity/application/dtos/RefreshTokenRequest.java
similarity index 100%
rename from src/main/java/alpl/backend/web/identity/application/dtos/RefreshTokenRequest.java
rename to src/main/java/aplp/backend/web/identity/application/dtos/RefreshTokenRequest.java
diff --git a/src/main/java/alpl/backend/web/identity/application/dtos/RegisterRequest.java b/src/main/java/aplp/backend/web/identity/application/dtos/RegisterRequest.java
similarity index 88%
rename from src/main/java/alpl/backend/web/identity/application/dtos/RegisterRequest.java
rename to src/main/java/aplp/backend/web/identity/application/dtos/RegisterRequest.java
index bfc5894..0dc54c4 100644
--- a/src/main/java/alpl/backend/web/identity/application/dtos/RegisterRequest.java
+++ b/src/main/java/aplp/backend/web/identity/application/dtos/RegisterRequest.java
@@ -5,6 +5,7 @@ import jakarta.validation.constraints.NotBlank;
 import jakarta.validation.constraints.Size;
 
 public record RegisterRequest(
+        @NotBlank @Size(min = 3, max = 50) String username,
         @NotBlank @Email(message = "must be a valid email") @Size(max = 320) String email,
         @NotBlank @Size(min = 8, max = 128, message = "must be between 8 and 128 characters") String password,
         @NotBlank @Size(max = 100) String displayName
diff --git a/src/main/java/alpl/backend/web/identity/application/mappers/AuthMapper.java b/src/main/java/aplp/backend/web/identity/application/mappers/AuthMapper.java
similarity index 100%
rename from src/main/java/alpl/backend/web/identity/application/mappers/AuthMapper.java
rename to src/main/java/aplp/backend/web/identity/application/mappers/AuthMapper.java
diff --git a/src/main/java/alpl/backend/web/identity/application/services/AuthService.java b/src/main/java/aplp/backend/web/identity/application/services/AuthService.java
similarity index 90%
rename from src/main/java/alpl/backend/web/identity/application/services/AuthService.java
rename to src/main/java/aplp/backend/web/identity/application/services/AuthService.java
index 0160950..f28a602 100644
--- a/src/main/java/alpl/backend/web/identity/application/services/AuthService.java
+++ b/src/main/java/aplp/backend/web/identity/application/services/AuthService.java
@@ -9,6 +9,7 @@ import aplp.backend.web.identity.application.dtos.AuthResponse;
 import aplp.backend.web.identity.application.mappers.AuthMapper;
 import aplp.backend.web.identity.domain.exceptions.EmailAlreadyExistsException;
 import aplp.backend.web.identity.domain.exceptions.InvalidCredentialsException;
+import aplp.backend.web.identity.domain.exceptions.UsernameAlreadyExistsException;
 import aplp.backend.web.identity.domain.entities.RefreshToken;
 import aplp.backend.web.identity.domain.exceptions.RefreshTokenInvalidException;
 import aplp.backend.web.identity.domain.repositories.RefreshTokenRepository;
@@ -53,22 +54,24 @@ public class AuthService {
     }
 
     @Transactional
-    public AuthResponse register(String email, String rawPassword, String displayName) {
+    public AuthResponse register(String username, String email, String rawPassword, String displayName) {
         Instant now = clock.instant();
         String normalizedEmail = email.trim().toLowerCase();
         if (userRepository.existsByEmail(normalizedEmail)) {
             throw new EmailAlreadyExistsException(normalizedEmail);
         }
-        User user = User.register(normalizedEmail, passwordEncoder.encode(rawPassword), displayName, now);
+        if (userRepository.existsByUsername(username)) {
+            throw new UsernameAlreadyExistsException(username);
+        }
+        User user = User.register(username, normalizedEmail, passwordEncoder.encode(rawPassword), displayName, now);
         User saved = userRepository.save(user);
         learnerProvisioner.provision(saved.id(), displayName);
         return issueTokens(saved);
     }
 
     @Transactional
-    public AuthResponse login(String email, String rawPassword) {
-        String normalizedEmail = email.trim().toLowerCase();
-        User user = userRepository.findByEmail(normalizedEmail).orElseThrow(InvalidCredentialsException::new);
+    public AuthResponse login(String username, String rawPassword) {
+        User user = userRepository.findByUsername(username).orElseThrow(InvalidCredentialsException::new);
         if (!passwordEncoder.matches(rawPassword, user.passwordHash())) {
             throw new InvalidCredentialsException();
         }
diff --git a/src/main/java/alpl/backend/web/identity/domain/entities/RefreshToken.java b/src/main/java/aplp/backend/web/identity/domain/entities/RefreshToken.java
similarity index 100%
rename from src/main/java/alpl/backend/web/identity/domain/entities/RefreshToken.java
rename to src/main/java/aplp/backend/web/identity/domain/entities/RefreshToken.java
diff --git a/src/main/java/alpl/backend/web/identity/domain/entities/User.java b/src/main/java/aplp/backend/web/identity/domain/entities/User.java
similarity index 76%
rename from src/main/java/alpl/backend/web/identity/domain/entities/User.java
rename to src/main/java/aplp/backend/web/identity/domain/entities/User.java
index 16a194a..9538518 100644
--- a/src/main/java/alpl/backend/web/identity/domain/entities/User.java
+++ b/src/main/java/aplp/backend/web/identity/domain/entities/User.java
@@ -21,6 +21,9 @@ public class User {
     @GeneratedValue(strategy = GenerationType.IDENTITY)
     private Long id;
 
+    @Column(nullable = false, unique = true, length = 50)
+    private String username;
+
     @Column(nullable = false, unique = true, length = 320)
     private String email;
 
@@ -43,9 +46,10 @@ public class User {
     protected User() {
     }
 
-    private User(Long id, String email, String passwordHash, String displayName,
+    private User(Long id, String username, String email, String passwordHash, String displayName,
                  UserStatus status, Instant createdAt, Instant updatedAt) {
         this.id = id;
+        this.username = username;
         this.email = email;
         this.passwordHash = passwordHash;
         this.displayName = displayName;
@@ -54,13 +58,13 @@ public class User {
         this.updatedAt = updatedAt;
     }
 
-    public static User register(String email, String passwordHash, String displayName, Instant now) {
-        return new User(null, normalizeEmail(email), passwordHash, displayName, UserStatus.ACTIVE, now, now);
+    public static User register(String username, String email, String passwordHash, String displayName, Instant now) {
+        return new User(null, username, normalizeEmail(email), passwordHash, displayName, UserStatus.ACTIVE, now, now);
     }
 
-    public static User reconstruct(Long id, String email, String passwordHash, String displayName,
+    public static User reconstruct(Long id, String username, String email, String passwordHash, String displayName,
                                    UserStatus status, Instant createdAt, Instant updatedAt) {
-        return new User(id, email, passwordHash, displayName, status, createdAt, updatedAt);
+        return new User(id, username, email, passwordHash, displayName, status, createdAt, updatedAt);
     }
 
     public void updatePasswordHash(String newHash, Instant now) {
@@ -81,6 +85,10 @@ public class User {
         return id;
     }
 
+    public String username() {
+        return username;
+    }
+
     public String email() {
         return email;
     }
diff --git a/src/main/java/alpl/backend/web/identity/domain/entities/UserStatus.java b/src/main/java/aplp/backend/web/identity/domain/entities/UserStatus.java
similarity index 100%
rename from src/main/java/alpl/backend/web/identity/domain/entities/UserStatus.java
rename to src/main/java/aplp/backend/web/identity/domain/entities/UserStatus.java
diff --git a/src/main/java/alpl/backend/web/identity/domain/exceptions/EmailAlreadyExistsException.java b/src/main/java/aplp/backend/web/identity/domain/exceptions/EmailAlreadyExistsException.java
similarity index 100%
rename from src/main/java/alpl/backend/web/identity/domain/exceptions/EmailAlreadyExistsException.java
rename to src/main/java/aplp/backend/web/identity/domain/exceptions/EmailAlreadyExistsException.java
diff --git a/src/main/java/alpl/backend/web/identity/domain/exceptions/InvalidCredentialsException.java b/src/main/java/aplp/backend/web/identity/domain/exceptions/InvalidCredentialsException.java
similarity index 100%
rename from src/main/java/alpl/backend/web/identity/domain/exceptions/InvalidCredentialsException.java
rename to src/main/java/aplp/backend/web/identity/domain/exceptions/InvalidCredentialsException.java
diff --git a/src/main/java/alpl/backend/web/identity/domain/exceptions/RefreshTokenInvalidException.java b/src/main/java/aplp/backend/web/identity/domain/exceptions/RefreshTokenInvalidException.java
similarity index 100%
rename from src/main/java/alpl/backend/web/identity/domain/exceptions/RefreshTokenInvalidException.java
rename to src/main/java/aplp/backend/web/identity/domain/exceptions/RefreshTokenInvalidException.java
diff --git a/src/main/java/aplp/backend/web/identity/domain/exceptions/UsernameAlreadyExistsException.java b/src/main/java/aplp/backend/web/identity/domain/exceptions/UsernameAlreadyExistsException.java
new file mode 100644
index 0000000..c71fc12
--- /dev/null
+++ b/src/main/java/aplp/backend/web/identity/domain/exceptions/UsernameAlreadyExistsException.java
@@ -0,0 +1,11 @@
+package aplp.backend.web.identity.domain.exceptions;
+
+import aplp.backend.core.common.exception.DomainException;
+import aplp.backend.core.common.exception.ErrorCode;
+
+public class UsernameAlreadyExistsException extends DomainException {
+
+    public UsernameAlreadyExistsException(String username) {
+        super(ErrorCode.USERNAME_ALREADY_EXISTS, "Username is already taken: " + username);
+    }
+}
diff --git a/src/main/java/alpl/backend/web/identity/domain/repositories/RefreshTokenRepository.java b/src/main/java/aplp/backend/web/identity/domain/repositories/RefreshTokenRepository.java
similarity index 100%
rename from src/main/java/alpl/backend/web/identity/domain/repositories/RefreshTokenRepository.java
rename to src/main/java/aplp/backend/web/identity/domain/repositories/RefreshTokenRepository.java
diff --git a/src/main/java/alpl/backend/web/identity/domain/repositories/UserRepository.java b/src/main/java/aplp/backend/web/identity/domain/repositories/UserRepository.java
similarity index 76%
rename from src/main/java/alpl/backend/web/identity/domain/repositories/UserRepository.java
rename to src/main/java/aplp/backend/web/identity/domain/repositories/UserRepository.java
index caad2e3..dffb166 100644
--- a/src/main/java/alpl/backend/web/identity/domain/repositories/UserRepository.java
+++ b/src/main/java/aplp/backend/web/identity/domain/repositories/UserRepository.java
@@ -8,9 +8,13 @@ public interface UserRepository {
 
     Optional<User> findByEmail(String email);
 
+    Optional<User> findByUsername(String username);
+
     Optional<User> findById(Long id);
 
     boolean existsByEmail(String email);
 
+    boolean existsByUsername(String username);
+
     User save(User user);
 }
diff --git a/src/main/java/alpl/backend/web/identity/infrastructure/persistence/RefreshTokenJpaRepository.java b/src/main/java/aplp/backend/web/identity/infrastructure/persistence/RefreshTokenJpaRepository.java
similarity index 100%
rename from src/main/java/alpl/backend/web/identity/infrastructure/persistence/RefreshTokenJpaRepository.java
rename to src/main/java/aplp/backend/web/identity/infrastructure/persistence/RefreshTokenJpaRepository.java
diff --git a/src/main/java/alpl/backend/web/identity/infrastructure/persistence/RefreshTokenRepositoryImpl.java b/src/main/java/aplp/backend/web/identity/infrastructure/persistence/RefreshTokenRepositoryImpl.java
similarity index 100%
rename from src/main/java/alpl/backend/web/identity/infrastructure/persistence/RefreshTokenRepositoryImpl.java
rename to src/main/java/aplp/backend/web/identity/infrastructure/persistence/RefreshTokenRepositoryImpl.java
diff --git a/src/main/java/alpl/backend/web/identity/infrastructure/persistence/UserJpaRepository.java b/src/main/java/aplp/backend/web/identity/infrastructure/persistence/UserJpaRepository.java
similarity index 76%
rename from src/main/java/alpl/backend/web/identity/infrastructure/persistence/UserJpaRepository.java
rename to src/main/java/aplp/backend/web/identity/infrastructure/persistence/UserJpaRepository.java
index ea21d3a..8325be4 100644
--- a/src/main/java/alpl/backend/web/identity/infrastructure/persistence/UserJpaRepository.java
+++ b/src/main/java/aplp/backend/web/identity/infrastructure/persistence/UserJpaRepository.java
@@ -7,5 +7,9 @@ public interface UserJpaRepository extends JpaRepository<User, Long> {
 
     boolean existsByEmail(String email);
 
+    boolean existsByUsername(String username);
+
     java.util.Optional<User> findByEmail(String email);
+
+    java.util.Optional<User> findByUsername(String username);
 }
\ No newline at end of file
diff --git a/src/main/java/alpl/backend/web/identity/infrastructure/persistence/UserRepositoryImpl.java b/src/main/java/aplp/backend/web/identity/infrastructure/persistence/UserRepositoryImpl.java
similarity index 78%
rename from src/main/java/alpl/backend/web/identity/infrastructure/persistence/UserRepositoryImpl.java
rename to src/main/java/aplp/backend/web/identity/infrastructure/persistence/UserRepositoryImpl.java
index 83da823..aaf332d 100644
--- a/src/main/java/alpl/backend/web/identity/infrastructure/persistence/UserRepositoryImpl.java
+++ b/src/main/java/aplp/backend/web/identity/infrastructure/persistence/UserRepositoryImpl.java
@@ -20,6 +20,11 @@ public class UserRepositoryImpl implements UserRepository {
         return jpaRepository.findByEmail(email);
     }
 
+    @Override
+    public Optional<User> findByUsername(String username) {
+        return jpaRepository.findByUsername(username);
+    }
+
     @Override
     public Optional<User> findById(Long id) {
         return jpaRepository.findById(id);
@@ -30,6 +35,11 @@ public class UserRepositoryImpl implements UserRepository {
         return jpaRepository.existsByEmail(email);
     }
 
+    @Override
+    public boolean existsByUsername(String username) {
+        return jpaRepository.existsByUsername(username);
+    }
+
     @Override
     public User save(User user) {
         return jpaRepository.save(user);
diff --git a/src/main/java/alpl/backend/web/learner/api/controller/LearnerController.java b/src/main/java/aplp/backend/web/learner/api/controller/LearnerController.java
similarity index 100%
rename from src/main/java/alpl/backend/web/learner/api/controller/LearnerController.java
rename to src/main/java/aplp/backend/web/learner/api/controller/LearnerController.java
diff --git a/src/main/java/alpl/backend/web/learner/application/dtos/LearnerProfileResponse.java b/src/main/java/aplp/backend/web/learner/application/dtos/LearnerProfileResponse.java
similarity index 100%
rename from src/main/java/alpl/backend/web/learner/application/dtos/LearnerProfileResponse.java
rename to src/main/java/aplp/backend/web/learner/application/dtos/LearnerProfileResponse.java
diff --git a/src/main/java/alpl/backend/web/learner/application/dtos/UpdateLearnerProfileRequest.java b/src/main/java/aplp/backend/web/learner/application/dtos/UpdateLearnerProfileRequest.java
similarity index 100%
rename from src/main/java/alpl/backend/web/learner/application/dtos/UpdateLearnerProfileRequest.java
rename to src/main/java/aplp/backend/web/learner/application/dtos/UpdateLearnerProfileRequest.java
diff --git a/src/main/java/alpl/backend/web/learner/application/mappers/LearnerMapper.java b/src/main/java/aplp/backend/web/learner/application/mappers/LearnerMapper.java
similarity index 100%
rename from src/main/java/alpl/backend/web/learner/application/mappers/LearnerMapper.java
rename to src/main/java/aplp/backend/web/learner/application/mappers/LearnerMapper.java
diff --git a/src/main/java/alpl/backend/web/learner/application/services/LearnerProvisioner.java b/src/main/java/aplp/backend/web/learner/application/services/LearnerProvisioner.java
similarity index 100%
rename from src/main/java/alpl/backend/web/learner/application/services/LearnerProvisioner.java
rename to src/main/java/aplp/backend/web/learner/application/services/LearnerProvisioner.java
diff --git a/src/main/java/alpl/backend/web/learner/application/services/LearnerService.java b/src/main/java/aplp/backend/web/learner/application/services/LearnerService.java
similarity index 100%
rename from src/main/java/alpl/backend/web/learner/application/services/LearnerService.java
rename to src/main/java/aplp/backend/web/learner/application/services/LearnerService.java
diff --git a/src/main/java/alpl/backend/web/learner/domain/entities/Learner.java b/src/main/java/aplp/backend/web/learner/domain/entities/Learner.java
similarity index 100%
rename from src/main/java/alpl/backend/web/learner/domain/entities/Learner.java
rename to src/main/java/aplp/backend/web/learner/domain/entities/Learner.java
diff --git a/src/main/java/alpl/backend/web/learner/domain/exceptions/LearnerNotFoundException.java b/src/main/java/aplp/backend/web/learner/domain/exceptions/LearnerNotFoundException.java
similarity index 100%
rename from src/main/java/alpl/backend/web/learner/domain/exceptions/LearnerNotFoundException.java
rename to src/main/java/aplp/backend/web/learner/domain/exceptions/LearnerNotFoundException.java
diff --git a/src/main/java/alpl/backend/web/learner/domain/repositories/LearnerRepository.java b/src/main/java/aplp/backend/web/learner/domain/repositories/LearnerRepository.java
similarity index 100%
rename from src/main/java/alpl/backend/web/learner/domain/repositories/LearnerRepository.java
rename to src/main/java/aplp/backend/web/learner/domain/repositories/LearnerRepository.java
diff --git a/src/main/java/alpl/backend/web/learner/infrastructure/persistence/LearnerJpaRepository.java b/src/main/java/aplp/backend/web/learner/infrastructure/persistence/LearnerJpaRepository.java
similarity index 100%
rename from src/main/java/alpl/backend/web/learner/infrastructure/persistence/LearnerJpaRepository.java
rename to src/main/java/aplp/backend/web/learner/infrastructure/persistence/LearnerJpaRepository.java
diff --git a/src/main/java/alpl/backend/web/learner/infrastructure/persistence/LearnerRepositoryImpl.java b/src/main/java/aplp/backend/web/learner/infrastructure/persistence/LearnerRepositoryImpl.java
similarity index 100%
rename from src/main/java/alpl/backend/web/learner/infrastructure/persistence/LearnerRepositoryImpl.java
rename to src/main/java/aplp/backend/web/learner/infrastructure/persistence/LearnerRepositoryImpl.java
diff --git a/src/main/resources/application-dev.yml b/src/main/resources/application-dev.yml
index ba84567..83186e4 100644
--- a/src/main/resources/application-dev.yml
+++ b/src/main/resources/application-dev.yml
@@ -1,6 +1,6 @@
 spring:
   datasource:
-    url: ${DB_URL:jdbc:postgresql://localhost:5432/aplp}
+    url: ${DB_URL:jdbc:postgresql://192.168.2.100:5432/aplp}
     username: ${DB_USERNAME:postgres}
     password: ${DB_PASSWORD:Pa55w0rd}
     hikari:
diff --git a/src/main/resources/application.yml b/src/main/resources/application.yml
index 0844323..bed9fa6 100644
--- a/src/main/resources/application.yml
+++ b/src/main/resources/application.yml
@@ -6,10 +6,15 @@ spring:
   jpa:
     hibernate:
       ddl-auto: validate
+    properties:
+      hibernate:
+        default_schema: web
     open-in-view: false
   flyway:
     enabled: true
     locations: classpath:db/migration
+    schemas: web
+    default-schema: web
   jackson:
     default-property-inclusion: non_null
 
diff --git a/src/main/resources/db/migration/V1__init_schema.sql b/src/main/resources/db/migration/V1__init_schema.sql
index 3c8416c..230cde2 100644
--- a/src/main/resources/db/migration/V1__init_schema.sql
+++ b/src/main/resources/db/migration/V1__init_schema.sql
@@ -1,12 +1,14 @@
 CREATE TABLE users (
     id            BIGINT GENERATED BY DEFAULT AS IDENTITY PRIMARY KEY,
     email         VARCHAR(320)                 NOT NULL,
+    username      VARCHAR(50)                  NOT NULL,
     password_hash VARCHAR(255)                 NOT NULL,
     display_name  VARCHAR(100)                 NOT NULL,
     status        VARCHAR(20)                  NOT NULL DEFAULT 'ACTIVE',
     created_at    TIMESTAMP WITH TIME ZONE     NOT NULL DEFAULT CURRENT_TIMESTAMP,
     updated_at    TIMESTAMP WITH TIME ZONE     NOT NULL DEFAULT CURRENT_TIMESTAMP,
-    CONSTRAINT uq_users_email UNIQUE (email)
+    CONSTRAINT uq_users_email UNIQUE (email),
+    CONSTRAINT uq_users_username UNIQUE (username)
 );
 
 CREATE TABLE refresh_token (
@@ -32,3 +34,4 @@ CREATE TABLE learner (
 
 CREATE INDEX idx_refresh_token_user_id ON refresh_token (user_id);
 CREATE INDEX idx_users_email ON users (email);
+CREATE INDEX idx_users_username ON users (username);
diff --git a/src/test/java/aplp/backend/web/AuthFlowIntegrationTest.java b/src/test/java/aplp/backend/web/AuthFlowIntegrationTest.java
index 74f914c..0cbb706 100644
--- a/src/test/java/aplp/backend/web/AuthFlowIntegrationTest.java
+++ b/src/test/java/aplp/backend/web/AuthFlowIntegrationTest.java
@@ -38,10 +38,10 @@ class AuthFlowIntegrationTest {
 
     @Test
     void fullAuthFlow() throws Exception {
-        TokenPair registered = register(EMAIL, PASSWORD, "Learner One");
+        TokenPair registered = register("learnerone", EMAIL, PASSWORD, "Learner One");
         viewMyProfile(registered.accessToken());
 
-        TokenPair loggedIn = login(EMAIL, PASSWORD);
+        TokenPair loggedIn = login("learnerone", PASSWORD);
         viewMyProfile(loggedIn.accessToken());
 
         TokenPair refreshed = refresh(loggedIn.refreshToken());
@@ -54,7 +54,7 @@ class AuthFlowIntegrationTest {
     void registrationSetsXRequestIdAndRejectsDuplicate() throws Exception {
         MvcResult first = mockMvc.perform(post("/api/v1/auth/register")
                         .contentType(MediaType.APPLICATION_JSON)
-                        .content(json("email", "dup@aplp.dev", "password", PASSWORD, "displayName", "Dup")))
+                        .content(json("username", "dupuser", "email", "dup@aplp.dev", "password", PASSWORD, "displayName", "Dup")))
                 .andExpect(status().isCreated())
                 .andExpect(header().exists("X-Request-Id"))
                 .andReturn();
@@ -62,7 +62,7 @@ class AuthFlowIntegrationTest {
 
         mockMvc.perform(post("/api/v1/auth/register")
                         .contentType(MediaType.APPLICATION_JSON)
-                        .content(json("email", "dup@aplp.dev", "password", PASSWORD, "displayName", "Dup")))
+                        .content(json("username", "dupuser2", "email", "dup@aplp.dev", "password", PASSWORD, "displayName", "Dup")))
                 .andExpect(status().isConflict())
                 .andExpect(jsonPath("$.code").value("EMAIL_ALREADY_EXISTS"));
     }
@@ -80,10 +80,10 @@ class AuthFlowIntegrationTest {
 
     @Test
     void loginWithWrongPasswordIsRejected() throws Exception {
-        register("wrong@aplp.dev", PASSWORD, "Wrong");
+        register("wronguser", "wrong@aplp.dev", PASSWORD, "Wrong");
         mockMvc.perform(post("/api/v1/auth/login")
                         .contentType(MediaType.APPLICATION_JSON)
-                        .content(json("email", "wrong@aplp.dev", "password", "not-the-password")))
+                        .content(json("username", "wronguser", "password", "not-the-password")))
                 .andExpect(status().isUnauthorized())
                 .andExpect(jsonPath("$.code").value("INVALID_CREDENTIALS"));
     }
@@ -92,14 +92,14 @@ class AuthFlowIntegrationTest {
     void validationErrorsReturnUniformShape() throws Exception {
         mockMvc.perform(post("/api/v1/auth/register")
                         .contentType(MediaType.APPLICATION_JSON)
-                        .content("{\"email\":\"not-an-email\",\"password\":\"x\",\"displayName\":\"\"}"))
+                        .content("{\"username\":\"\",\"email\":\"not-an-email\",\"password\":\"x\",\"displayName\":\"\"}"))
                 .andExpect(status().isBadRequest())
                 .andExpect(jsonPath("$.code").value("VALIDATION_FAILED"));
     }
 
     @Test
     void updateLearnerDisplayName() throws Exception {
-        TokenPair pair = register("update-me@aplp.dev", PASSWORD, "Old Name");
+        TokenPair pair = register("updateme", "update-me@aplp.dev", PASSWORD, "Old Name");
         mockMvc.perform(patch("/api/v1/learners/me")
                         .header("Authorization", "Bearer " + pair.accessToken())
                         .contentType(MediaType.APPLICATION_JSON)
@@ -110,7 +110,7 @@ class AuthFlowIntegrationTest {
 
     @Test
     void refreshWithRevokedTokenIsRejected() throws Exception {
-        TokenPair pair = loginOrRegister("revoked@aplp.dev");
+        TokenPair pair = loginOrRegister("revokeduser", "revoked@aplp.dev");
 
         mockMvc.perform(post("/api/v1/auth/logout")
                         .header("Authorization", "Bearer " + pair.accessToken())
@@ -141,10 +141,10 @@ class AuthFlowIntegrationTest {
                 .andExpect(jsonPath("$.status").value("UP"));
     }
 
-    private TokenPair register(String email, String password, String displayName) throws Exception {
+    private TokenPair register(String username, String email, String password, String displayName) throws Exception {
         MvcResult result = mockMvc.perform(post("/api/v1/auth/register")
                         .contentType(MediaType.APPLICATION_JSON)
-                        .content(json("email", email, "password", password, "displayName", displayName)))
+                        .content(json("username", username, "email", email, "password", password, "displayName", displayName)))
                 .andExpect(status().isCreated())
                 .andReturn();
         JsonNode body = bodyOf(result);
@@ -152,22 +152,21 @@ class AuthFlowIntegrationTest {
         return new TokenPair(body.get("accessToken").asText(), body.get("refreshToken").asText());
     }
 
-    private TokenPair login(String email, String password) throws Exception {
+    private TokenPair login(String username, String password) throws Exception {
         MvcResult result = mockMvc.perform(post("/api/v1/auth/login")
                         .contentType(MediaType.APPLICATION_JSON)
-                        .content(json("email", email, "password", password)))
+                        .content(json("username", username, "password", password)))
                 .andExpect(status().isOk())
                 .andReturn();
         JsonNode body = bodyOf(result);
-        assertThat(body.get("user").get("email").asText()).isEqualTo(email);
         return new TokenPair(body.get("accessToken").asText(), body.get("refreshToken").asText());
     }
 
-    private TokenPair loginOrRegister(String email) throws Exception {
+    private TokenPair loginOrRegister(String username, String email) throws Exception {
         try {
-            return register(email, PASSWORD, "Revoked");
+            return register(username, email, PASSWORD, "Revoked");
         } catch (AssertionError ignored) {
-            return login(email, PASSWORD);
+            return login(username, PASSWORD);
         }
     }
 
diff --git a/src/test/resources/application-test.yml b/src/test/resources/application-test.yml
index 23adfb7..c763d36 100644
--- a/src/test/resources/application-test.yml
+++ b/src/test/resources/application-test.yml
@@ -7,8 +7,13 @@ spring:
   jpa:
     hibernate:
       ddl-auto: validate
+    properties:
+      hibernate:
+        default_schema: web
   flyway:
     enabled: true
+    schemas: web
+    default-schema: web
 
 app:
   jwt: