domain: add Identity & Access ports (UserRepo, RoleRepo, GroupRepo, EventPublisher)

crates/application/src/testing.rs

@@ -38,6 +38,12 @@ impl UserRepository for InMemoryUserRepository {
             .cloned())
     }
 
+    async fn find_by_username(&self, username: &str) -> Result<Option<User>, DomainError> {
+        Ok(self.users.lock().await.values()
+            .find(|u| u.username == username)
+            .cloned())
+    }
+
     async fn save(&self, user: &User) -> Result<(), DomainError> {
         self.users.lock().await.insert(user.id.to_string(), user.clone());
         Ok(())

crates/application/src/use_cases/get_profile.rs

@@ -24,7 +24,7 @@ mod tests {
     async fn get_profile_returns_existing_user() {
         let repo = Arc::new(InMemoryUserRepository::new());
         let r = RegisterUser::new(repo.clone(), Arc::new(StubPasswordHasher));
-        let user = r.execute("user@example.com", "password123").await.unwrap();
+        let user = r.execute("testuser", "user@example.com", "password123").await.unwrap();
         let uc = GetProfile::new(repo);
         let found = uc.execute(&user.id).await.unwrap();
         assert_eq!(found.id, user.id);

crates/application/src/use_cases/login.rs

@@ -43,7 +43,7 @@ mod tests {
     async fn seeded_repo() -> Arc<InMemoryUserRepository> {
         let repo = Arc::new(InMemoryUserRepository::new());
         let r = RegisterUser::new(repo.clone(), Arc::new(StubPasswordHasher));
-        r.execute("user@example.com", "password123").await.unwrap();
+        r.execute("testuser", "user@example.com", "password123").await.unwrap();
         repo
     }
 

crates/application/src/use_cases/register.rs

@@ -3,7 +3,7 @@ use domain::{
     entities::User,
     errors::DomainError,
     ports::{PasswordHasher, UserRepository},
-    value_objects::{Email, SystemId},
+    value_objects::Email,
 };
 
 pub struct RegisterUser {
@@ -16,7 +16,7 @@ impl RegisterUser {
         Self { repo, hasher }
     }
 
-    pub async fn execute(&self, email: &str, password: &str) -> Result<User, DomainError> {
+    pub async fn execute(&self, username: &str, email: &str, password: &str) -> Result<User, DomainError> {
         if password.len() < 8 {
             return Err(DomainError::Validation("Password must be at least 8 characters".to_string()));
         }
@@ -24,8 +24,11 @@ impl RegisterUser {
         if self.repo.find_by_email(&email).await?.is_some() {
             return Err(DomainError::Conflict(format!("Email {} is already registered", email.as_str())));
         }
+        if self.repo.find_by_username(username).await?.is_some() {
+            return Err(DomainError::Conflict(format!("Username {username} is already taken")));
+        }
         let hash = self.hasher.hash(password).await?;
-        let user = User::new(SystemId::new(), email, hash);
+        let user = User::new(username, email, hash);
         self.repo.save(&user).await?;
         Ok(user)
     }
@@ -40,8 +43,9 @@ mod tests {
     async fn register_creates_user() {
         let repo = Arc::new(InMemoryUserRepository::new());
         let uc = RegisterUser::new(repo.clone(), Arc::new(StubPasswordHasher));
-        let user = uc.execute("test@example.com", "password123").await.unwrap();
+        let user = uc.execute("testuser", "test@example.com", "password123").await.unwrap();
         assert_eq!(user.email.as_str(), "test@example.com");
+        assert_eq!(user.username, "testuser");
         assert_eq!(repo.all().await.len(), 1);
     }
 
@@ -49,8 +53,17 @@ mod tests {
     async fn register_rejects_duplicate_email() {
         let repo = Arc::new(InMemoryUserRepository::new());
         let uc = RegisterUser::new(repo.clone(), Arc::new(StubPasswordHasher));
-        uc.execute("test@example.com", "password123").await.unwrap();
-        let result = uc.execute("test@example.com", "different1").await;
+        uc.execute("user1", "test@example.com", "password123").await.unwrap();
+        let result = uc.execute("user2", "test@example.com", "different1").await;
+        assert!(matches!(result, Err(DomainError::Conflict(_))));
+    }
+
+    #[tokio::test]
+    async fn register_rejects_duplicate_username() {
+        let repo = Arc::new(InMemoryUserRepository::new());
+        let uc = RegisterUser::new(repo.clone(), Arc::new(StubPasswordHasher));
+        uc.execute("sameuser", "a@example.com", "password123").await.unwrap();
+        let result = uc.execute("sameuser", "b@example.com", "password123").await;
         assert!(matches!(result, Err(DomainError::Conflict(_))));
     }
 
@@ -58,7 +71,7 @@ mod tests {
     async fn register_rejects_short_password() {
         let repo = Arc::new(InMemoryUserRepository::new());
         let uc = RegisterUser::new(repo, Arc::new(StubPasswordHasher));
-        let result = uc.execute("test@example.com", "short").await;
+        let result = uc.execute("user", "test@example.com", "short").await;
         assert!(matches!(result, Err(DomainError::Validation(_))));
     }
 
@@ -66,7 +79,7 @@ mod tests {
     async fn register_rejects_invalid_email() {
         let repo = Arc::new(InMemoryUserRepository::new());
         let uc = RegisterUser::new(repo, Arc::new(StubPasswordHasher));
-        let result = uc.execute("notanemail", "password123").await;
+        let result = uc.execute("user", "notanemail", "password123").await;
         assert!(matches!(result, Err(DomainError::Validation(_))));
     }
 }