diff --git a/Cargo.lock b/Cargo.lock
index 168fa25..b0dd278 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -92,6 +92,7 @@ dependencies = [
  "async-trait",
  "bytes",
  "domain",
+ "serde",
  "thiserror",
  "tokio",
  "uuid",
diff --git a/crates/api-types/src/requests.rs b/crates/api-types/src/requests.rs
index 5e67edf..cc45379 100644
--- a/crates/api-types/src/requests.rs
+++ b/crates/api-types/src/requests.rs
@@ -1,5 +1,6 @@
 #[derive(Debug, serde::Deserialize, utoipa::ToSchema)]
 pub struct RegisterRequest {
+    pub username: String,
     pub email: String,
     pub password: String,
 }
@@ -9,3 +10,8 @@ pub struct LoginRequest {
     pub email: String,
     pub password: String,
 }
+
+#[derive(Debug, serde::Deserialize, utoipa::ToSchema)]
+pub struct CreateAlbumRequest {
+    pub title: String,
+}
diff --git a/crates/api-types/src/responses.rs b/crates/api-types/src/responses.rs
index 3c11ac4..cb26e9a 100644
--- a/crates/api-types/src/responses.rs
+++ b/crates/api-types/src/responses.rs
@@ -4,6 +4,7 @@ use uuid::Uuid;
 #[derive(Debug, serde::Serialize, utoipa::ToSchema)]
 pub struct UserResponse {
     pub id: Uuid,
+    pub username: String,
     pub email: String,
     pub created_at: DateTime<Utc>,
 }
@@ -18,8 +19,30 @@ impl UserResponse {
     pub fn from_domain(user: &domain::entities::User) -> Self {
         Self {
             id: *user.id.as_uuid(),
+            username: user.username.clone(),
             email: user.email.to_string(),
             created_at: user.created_at,
         }
     }
 }
+
+#[derive(Debug, serde::Serialize, utoipa::ToSchema)]
+pub struct AlbumResponse {
+    pub id: Uuid,
+    pub title: String,
+    pub description: String,
+    pub creator_id: Uuid,
+    pub created_at: DateTime<Utc>,
+}
+
+impl AlbumResponse {
+    pub fn from_domain(album: &domain::entities::Album) -> Self {
+        Self {
+            id: *album.album_id.as_uuid(),
+            title: album.title.clone(),
+            description: album.description.clone(),
+            creator_id: *album.creator_user_id.as_uuid(),
+            created_at: *album.created_at.as_datetime(),
+        }
+    }
+}
diff --git a/crates/application/Cargo.toml b/crates/application/Cargo.toml
index 4fb737f..d0784d3 100644
--- a/crates/application/Cargo.toml
+++ b/crates/application/Cargo.toml
@@ -11,3 +11,4 @@ thiserror   = { workspace = true }
 uuid        = { workspace = true }
 tokio       = { workspace = true }
 bytes       = { workspace = true }
+serde       = { workspace = true }
diff --git a/crates/application/src/catalog/mod.rs b/crates/application/src/catalog/mod.rs
new file mode 100644
index 0000000..2c9940a
--- /dev/null
+++ b/crates/application/src/catalog/mod.rs
@@ -0,0 +1 @@
+// Catalog commands/queries (future: SearchAssets, UpdateMetadata, etc.)
diff --git a/crates/application/src/use_cases/identity/login_user.rs b/crates/application/src/identity/commands/login_user.rs
similarity index 66%
rename from crates/application/src/use_cases/identity/login_user.rs
rename to crates/application/src/identity/commands/login_user.rs
index 5fcbf54..69676e5 100644
--- a/crates/application/src/use_cases/identity/login_user.rs
+++ b/crates/application/src/identity/commands/login_user.rs
@@ -6,13 +6,19 @@ use domain::{
     value_objects::Email,
 };
 
-pub struct LoginUser {
+#[derive(Debug, Clone, serde::Serialize, serde::Deserialize)]
+pub struct LoginUserCommand {
+    pub email: String,
+    pub password: String,
+}
+
+pub struct LoginUserHandler {
     repo: Arc<dyn UserRepository>,
     hasher: Arc<dyn PasswordHasher>,
     issuer: Arc<dyn TokenIssuer>,
 }
 
-impl LoginUser {
+impl LoginUserHandler {
     pub fn new(
         repo: Arc<dyn UserRepository>,
         hasher: Arc<dyn PasswordHasher>,
@@ -21,11 +27,11 @@ impl LoginUser {
         Self { repo, hasher, issuer }
     }
 
-    pub async fn execute(&self, email: &str, password: &str) -> Result<(User, String), DomainError> {
-        let email = Email::new(email)?;
+    pub async fn execute(&self, cmd: LoginUserCommand) -> Result<(User, String), DomainError> {
+        let email = Email::new(&cmd.email)?;
         let user = self.repo.find_by_email(&email).await?
             .ok_or_else(|| DomainError::Unauthorized("Invalid credentials".to_string()))?;
-        let valid = self.hasher.verify(password, &user.password_hash).await?;
+        let valid = self.hasher.verify(&cmd.password, &user.password_hash).await?;
         if !valid {
             return Err(DomainError::Unauthorized("Invalid credentials".to_string()));
         }
diff --git a/crates/application/src/identity/commands/mod.rs b/crates/application/src/identity/commands/mod.rs
new file mode 100644
index 0000000..4ece247
--- /dev/null
+++ b/crates/application/src/identity/commands/mod.rs
@@ -0,0 +1,5 @@
+pub mod register_user;
+pub mod login_user;
+
+pub use register_user::{RegisterUserCommand, RegisterUserHandler};
+pub use login_user::{LoginUserCommand, LoginUserHandler};
diff --git a/crates/application/src/identity/commands/register_user.rs b/crates/application/src/identity/commands/register_user.rs
new file mode 100644
index 0000000..41e01c2
--- /dev/null
+++ b/crates/application/src/identity/commands/register_user.rs
@@ -0,0 +1,45 @@
+use std::sync::Arc;
+use domain::{
+    entities::User,
+    errors::DomainError,
+    ports::{PasswordHasher, UserRepository},
+    value_objects::Email,
+};
+
+#[derive(Debug, Clone, serde::Serialize, serde::Deserialize)]
+pub struct RegisterUserCommand {
+    pub username: String,
+    pub email: String,
+    pub password: String,
+}
+
+pub struct RegisterUserHandler {
+    user_repo: Arc<dyn UserRepository>,
+    hasher: Arc<dyn PasswordHasher>,
+}
+
+impl RegisterUserHandler {
+    pub fn new(user_repo: Arc<dyn UserRepository>, hasher: Arc<dyn PasswordHasher>) -> Self {
+        Self { user_repo, hasher }
+    }
+
+    pub async fn execute(&self, cmd: RegisterUserCommand) -> Result<User, DomainError> {
+        if cmd.username.is_empty() {
+            return Err(DomainError::Validation("Username must not be empty".to_string()));
+        }
+        if cmd.password.len() < 8 {
+            return Err(DomainError::Validation("Password must be at least 8 characters".to_string()));
+        }
+        let email = Email::new(&cmd.email)?;
+        if self.user_repo.find_by_email(&email).await?.is_some() {
+            return Err(DomainError::Conflict(format!("Email {} is already registered", email.as_str())));
+        }
+        if self.user_repo.find_by_username(&cmd.username).await?.is_some() {
+            return Err(DomainError::Conflict(format!("Username {} is already taken", cmd.username)));
+        }
+        let hash = self.hasher.hash(&cmd.password).await?;
+        let user = User::new(&cmd.username, email, hash);
+        self.user_repo.save(&user).await?;
+        Ok(user)
+    }
+}
diff --git a/crates/application/src/identity/mod.rs b/crates/application/src/identity/mod.rs
new file mode 100644
index 0000000..00c5710
--- /dev/null
+++ b/crates/application/src/identity/mod.rs
@@ -0,0 +1,5 @@
+pub mod commands;
+pub mod queries;
+
+pub use commands::{RegisterUserCommand, RegisterUserHandler, LoginUserCommand, LoginUserHandler};
+pub use queries::{GetProfileQuery, GetProfileHandler};
diff --git a/crates/application/src/identity/queries/get_profile.rs b/crates/application/src/identity/queries/get_profile.rs
new file mode 100644
index 0000000..2d7bdce
--- /dev/null
+++ b/crates/application/src/identity/queries/get_profile.rs
@@ -0,0 +1,22 @@
+use std::sync::Arc;
+use domain::{entities::User, errors::DomainError, ports::UserRepository, value_objects::SystemId};
+
+#[derive(Debug, Clone, serde::Serialize, serde::Deserialize)]
+pub struct GetProfileQuery {
+    pub user_id: SystemId,
+}
+
+pub struct GetProfileHandler {
+    repo: Arc<dyn UserRepository>,
+}
+
+impl GetProfileHandler {
+    pub fn new(repo: Arc<dyn UserRepository>) -> Self {
+        Self { repo }
+    }
+
+    pub async fn execute(&self, query: GetProfileQuery) -> Result<User, DomainError> {
+        self.repo.find_by_id(&query.user_id).await?
+            .ok_or_else(|| DomainError::NotFound(format!("User {} not found", query.user_id)))
+    }
+}
diff --git a/crates/application/src/identity/queries/mod.rs b/crates/application/src/identity/queries/mod.rs
new file mode 100644
index 0000000..8855048
--- /dev/null
+++ b/crates/application/src/identity/queries/mod.rs
@@ -0,0 +1,3 @@
+pub mod get_profile;
+
+pub use get_profile::{GetProfileQuery, GetProfileHandler};
diff --git a/crates/application/src/lib.rs b/crates/application/src/lib.rs
index 0435007..514d8fe 100644
--- a/crates/application/src/lib.rs
+++ b/crates/application/src/lib.rs
@@ -1,2 +1,8 @@
+pub mod identity;
+pub mod organization;
+pub mod storage;
+pub mod catalog;
+pub mod sharing;
+pub mod sidecar;
+pub mod processing;
 pub mod testing;
-pub mod use_cases;
diff --git a/crates/application/src/use_cases/organization/create_album.rs b/crates/application/src/organization/commands/create_album.rs
similarity index 54%
rename from crates/application/src/use_cases/organization/create_album.rs
rename to crates/application/src/organization/commands/create_album.rs
index 0082906..67b2e0c 100644
--- a/crates/application/src/use_cases/organization/create_album.rs
+++ b/crates/application/src/organization/commands/create_album.rs
@@ -6,20 +6,26 @@ use domain::{
     value_objects::SystemId,
 };
 
-pub struct CreateAlbum {
+#[derive(Debug, Clone, serde::Serialize, serde::Deserialize)]
+pub struct CreateAlbumCommand {
+    pub title: String,
+    pub creator_id: SystemId,
+}
+
+pub struct CreateAlbumHandler {
     album_repo: Arc<dyn AlbumRepository>,
 }
 
-impl CreateAlbum {
+impl CreateAlbumHandler {
     pub fn new(album_repo: Arc<dyn AlbumRepository>) -> Self {
         Self { album_repo }
     }
 
-    pub async fn execute(&self, title: &str, creator_id: SystemId) -> Result<Album, DomainError> {
-        if title.is_empty() {
+    pub async fn execute(&self, cmd: CreateAlbumCommand) -> Result<Album, DomainError> {
+        if cmd.title.is_empty() {
             return Err(DomainError::Validation("Album title must not be empty".to_string()));
         }
-        let album = Album::new(title, creator_id);
+        let album = Album::new(&cmd.title, cmd.creator_id);
         self.album_repo.save(&album).await?;
         Ok(album)
     }
diff --git a/crates/application/src/organization/commands/mod.rs b/crates/application/src/organization/commands/mod.rs
new file mode 100644
index 0000000..f576691
--- /dev/null
+++ b/crates/application/src/organization/commands/mod.rs
@@ -0,0 +1,3 @@
+pub mod create_album;
+
+pub use create_album::{CreateAlbumCommand, CreateAlbumHandler};
diff --git a/crates/application/src/organization/mod.rs b/crates/application/src/organization/mod.rs
new file mode 100644
index 0000000..9520a46
--- /dev/null
+++ b/crates/application/src/organization/mod.rs
@@ -0,0 +1,3 @@
+pub mod commands;
+
+pub use commands::{CreateAlbumCommand, CreateAlbumHandler};
diff --git a/crates/application/src/processing/mod.rs b/crates/application/src/processing/mod.rs
new file mode 100644
index 0000000..eec5f1e
--- /dev/null
+++ b/crates/application/src/processing/mod.rs
@@ -0,0 +1 @@
+// Processing commands/queries (future: EnqueueJob, ProcessBatch, etc.)
diff --git a/crates/application/src/sharing/mod.rs b/crates/application/src/sharing/mod.rs
new file mode 100644
index 0000000..e115d4f
--- /dev/null
+++ b/crates/application/src/sharing/mod.rs
@@ -0,0 +1 @@
+// Sharing commands/queries (future: CreateShareLink, ManageAccess, etc.)
diff --git a/crates/application/src/sidecar/mod.rs b/crates/application/src/sidecar/mod.rs
new file mode 100644
index 0000000..f2c54f4
--- /dev/null
+++ b/crates/application/src/sidecar/mod.rs
@@ -0,0 +1 @@
+// Sidecar commands/queries (future: SyncSidecar, ExportMetadata, etc.)
diff --git a/crates/application/src/storage/mod.rs b/crates/application/src/storage/mod.rs
new file mode 100644
index 0000000..180ec5a
--- /dev/null
+++ b/crates/application/src/storage/mod.rs
@@ -0,0 +1 @@
+// Storage commands/queries (future: IngestAsset, ManageVolume, etc.)
diff --git a/crates/application/src/use_cases/catalog/mod.rs b/crates/application/src/use_cases/catalog/mod.rs
deleted file mode 100644
index 2bc57f3..0000000
--- a/crates/application/src/use_cases/catalog/mod.rs
+++ /dev/null
@@ -1 +0,0 @@
-// Catalog use cases (future: SearchAssets, UpdateMetadata, etc.)
diff --git a/crates/application/src/use_cases/identity/get_profile.rs b/crates/application/src/use_cases/identity/get_profile.rs
deleted file mode 100644
index 3631c9a..0000000
--- a/crates/application/src/use_cases/identity/get_profile.rs
+++ /dev/null
@@ -1,15 +0,0 @@
-use std::sync::Arc;
-use domain::{entities::User, errors::DomainError, ports::UserRepository, value_objects::SystemId};
-
-pub struct GetProfile {
-    repo: Arc<dyn UserRepository>,
-}
-
-impl GetProfile {
-    pub fn new(repo: Arc<dyn UserRepository>) -> Self { Self { repo } }
-
-    pub async fn execute(&self, user_id: &SystemId) -> Result<User, DomainError> {
-        self.repo.find_by_id(user_id).await?
-            .ok_or_else(|| DomainError::NotFound(format!("User {user_id} not found")))
-    }
-}
diff --git a/crates/application/src/use_cases/identity/mod.rs b/crates/application/src/use_cases/identity/mod.rs
deleted file mode 100644
index cff7e22..0000000
--- a/crates/application/src/use_cases/identity/mod.rs
+++ /dev/null
@@ -1,7 +0,0 @@
-pub mod register_user;
-pub mod login_user;
-pub mod get_profile;
-
-pub use register_user::RegisterUser;
-pub use login_user::LoginUser;
-pub use get_profile::GetProfile;
diff --git a/crates/application/src/use_cases/identity/register_user.rs b/crates/application/src/use_cases/identity/register_user.rs
deleted file mode 100644
index c881c32..0000000
--- a/crates/application/src/use_cases/identity/register_user.rs
+++ /dev/null
@@ -1,38 +0,0 @@
-use std::sync::Arc;
-use domain::{
-    entities::User,
-    errors::DomainError,
-    ports::{PasswordHasher, UserRepository},
-    value_objects::Email,
-};
-
-pub struct RegisterUser {
-    repo: Arc<dyn UserRepository>,
-    hasher: Arc<dyn PasswordHasher>,
-}
-
-impl RegisterUser {
-    pub fn new(repo: Arc<dyn UserRepository>, hasher: Arc<dyn PasswordHasher>) -> Self {
-        Self { repo, hasher }
-    }
-
-    pub async fn execute(&self, username: &str, email: &str, password: &str) -> Result<User, DomainError> {
-        if username.is_empty() {
-            return Err(DomainError::Validation("Username must not be empty".to_string()));
-        }
-        if password.len() < 8 {
-            return Err(DomainError::Validation("Password must be at least 8 characters".to_string()));
-        }
-        let email = Email::new(email)?;
-        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(username, email, hash);
-        self.repo.save(&user).await?;
-        Ok(user)
-    }
-}
diff --git a/crates/application/src/use_cases/mod.rs b/crates/application/src/use_cases/mod.rs
deleted file mode 100644
index b1cff67..0000000
--- a/crates/application/src/use_cases/mod.rs
+++ /dev/null
@@ -1,10 +0,0 @@
-pub mod identity;
-pub mod organization;
-pub mod storage;
-pub mod catalog;
-pub mod sharing;
-pub mod sidecar;
-pub mod processing;
-
-pub use identity::{RegisterUser, LoginUser, GetProfile};
-pub use organization::CreateAlbum;
diff --git a/crates/application/src/use_cases/organization/mod.rs b/crates/application/src/use_cases/organization/mod.rs
deleted file mode 100644
index e4e2af8..0000000
--- a/crates/application/src/use_cases/organization/mod.rs
+++ /dev/null
@@ -1,3 +0,0 @@
-pub mod create_album;
-
-pub use create_album::CreateAlbum;
diff --git a/crates/application/src/use_cases/processing/mod.rs b/crates/application/src/use_cases/processing/mod.rs
deleted file mode 100644
index 1e0331f..0000000
--- a/crates/application/src/use_cases/processing/mod.rs
+++ /dev/null
@@ -1 +0,0 @@
-// Processing use cases (future: EnqueueJob, ProcessBatch, etc.)
diff --git a/crates/application/src/use_cases/sharing/mod.rs b/crates/application/src/use_cases/sharing/mod.rs
deleted file mode 100644
index 0a99ff7..0000000
--- a/crates/application/src/use_cases/sharing/mod.rs
+++ /dev/null
@@ -1 +0,0 @@
-// Sharing use cases (future: CreateShareLink, ManageAccess, etc.)
diff --git a/crates/application/src/use_cases/sidecar/mod.rs b/crates/application/src/use_cases/sidecar/mod.rs
deleted file mode 100644
index e7282ca..0000000
--- a/crates/application/src/use_cases/sidecar/mod.rs
+++ /dev/null
@@ -1 +0,0 @@
-// Sidecar Sync use cases (future: SyncSidecar, ExportMetadata, etc.)
diff --git a/crates/application/src/use_cases/storage/mod.rs b/crates/application/src/use_cases/storage/mod.rs
deleted file mode 100644
index d786366..0000000
--- a/crates/application/src/use_cases/storage/mod.rs
+++ /dev/null
@@ -1 +0,0 @@
-// Storage use cases (future: IngestAsset, ManageVolume, etc.)
diff --git a/crates/application/tests/app_tests.rs b/crates/application/tests/app_tests.rs
index 64707d9..6b57d05 100644
--- a/crates/application/tests/app_tests.rs
+++ b/crates/application/tests/app_tests.rs
@@ -1 +1,2 @@
-mod use_cases;
+mod identity;
+mod organization;
diff --git a/crates/application/tests/use_cases/identity/mod.rs b/crates/application/tests/identity/commands/mod.rs
similarity index 100%
rename from crates/application/tests/use_cases/identity/mod.rs
rename to crates/application/tests/identity/commands/mod.rs
diff --git a/crates/application/tests/identity/commands/register_user.rs b/crates/application/tests/identity/commands/register_user.rs
new file mode 100644
index 0000000..4a35be9
--- /dev/null
+++ b/crates/application/tests/identity/commands/register_user.rs
@@ -0,0 +1,77 @@
+use std::sync::Arc;
+use application::testing::{InMemoryUserRepository, StubPasswordHasher};
+use application::identity::{RegisterUserCommand, RegisterUserHandler};
+use domain::errors::DomainError;
+
+#[tokio::test]
+async fn registers_new_user() {
+    let repo = Arc::new(InMemoryUserRepository::new());
+    let handler = RegisterUserHandler::new(repo.clone(), Arc::new(StubPasswordHasher));
+    let cmd = RegisterUserCommand {
+        username: "testuser".into(),
+        email: "test@example.com".into(),
+        password: "password123".into(),
+    };
+    let user = handler.execute(cmd).await.unwrap();
+    assert_eq!(user.username, "testuser");
+    assert_eq!(user.email.as_str(), "test@example.com");
+    assert_eq!(repo.all().await.len(), 1);
+}
+
+#[tokio::test]
+async fn rejects_duplicate_email() {
+    let repo = Arc::new(InMemoryUserRepository::new());
+    let handler = RegisterUserHandler::new(repo.clone(), Arc::new(StubPasswordHasher));
+    handler.execute(RegisterUserCommand {
+        username: "user1".into(),
+        email: "test@example.com".into(),
+        password: "password123".into(),
+    }).await.unwrap();
+    let result = handler.execute(RegisterUserCommand {
+        username: "user2".into(),
+        email: "test@example.com".into(),
+        password: "different1".into(),
+    }).await;
+    assert!(matches!(result, Err(DomainError::Conflict(_))));
+}
+
+#[tokio::test]
+async fn rejects_duplicate_username() {
+    let repo = Arc::new(InMemoryUserRepository::new());
+    let handler = RegisterUserHandler::new(repo.clone(), Arc::new(StubPasswordHasher));
+    handler.execute(RegisterUserCommand {
+        username: "sameuser".into(),
+        email: "a@example.com".into(),
+        password: "password123".into(),
+    }).await.unwrap();
+    let result = handler.execute(RegisterUserCommand {
+        username: "sameuser".into(),
+        email: "b@example.com".into(),
+        password: "password123".into(),
+    }).await;
+    assert!(matches!(result, Err(DomainError::Conflict(_))));
+}
+
+#[tokio::test]
+async fn rejects_short_password() {
+    let repo = Arc::new(InMemoryUserRepository::new());
+    let handler = RegisterUserHandler::new(repo, Arc::new(StubPasswordHasher));
+    let result = handler.execute(RegisterUserCommand {
+        username: "user".into(),
+        email: "test@example.com".into(),
+        password: "short".into(),
+    }).await;
+    assert!(matches!(result, Err(DomainError::Validation(_))));
+}
+
+#[tokio::test]
+async fn rejects_empty_username() {
+    let repo = Arc::new(InMemoryUserRepository::new());
+    let handler = RegisterUserHandler::new(repo, Arc::new(StubPasswordHasher));
+    let result = handler.execute(RegisterUserCommand {
+        username: "".into(),
+        email: "test@example.com".into(),
+        password: "password123".into(),
+    }).await;
+    assert!(matches!(result, Err(DomainError::Validation(_))));
+}
diff --git a/crates/application/tests/identity/mod.rs b/crates/application/tests/identity/mod.rs
new file mode 100644
index 0000000..2406e7d
--- /dev/null
+++ b/crates/application/tests/identity/mod.rs
@@ -0,0 +1,2 @@
+mod commands;
+mod queries;
diff --git a/crates/application/tests/identity/queries/get_profile.rs b/crates/application/tests/identity/queries/get_profile.rs
new file mode 100644
index 0000000..bdcab1f
--- /dev/null
+++ b/crates/application/tests/identity/queries/get_profile.rs
@@ -0,0 +1,28 @@
+use std::sync::Arc;
+use application::testing::{InMemoryUserRepository, StubPasswordHasher};
+use application::identity::{RegisterUserCommand, RegisterUserHandler, GetProfileQuery, GetProfileHandler};
+use domain::errors::DomainError;
+use domain::value_objects::SystemId;
+
+#[tokio::test]
+async fn returns_existing_user() {
+    let repo = Arc::new(InMemoryUserRepository::new());
+    let reg = RegisterUserHandler::new(repo.clone(), Arc::new(StubPasswordHasher));
+    let user = reg.execute(RegisterUserCommand {
+        username: "alice".into(),
+        email: "alice@example.com".into(),
+        password: "password123".into(),
+    }).await.unwrap();
+
+    let handler = GetProfileHandler::new(repo);
+    let found = handler.execute(GetProfileQuery { user_id: user.id }).await.unwrap();
+    assert_eq!(found.username, "alice");
+}
+
+#[tokio::test]
+async fn returns_not_found_for_missing_user() {
+    let repo = Arc::new(InMemoryUserRepository::new());
+    let handler = GetProfileHandler::new(repo);
+    let result = handler.execute(GetProfileQuery { user_id: SystemId::new() }).await;
+    assert!(matches!(result, Err(DomainError::NotFound(_))));
+}
diff --git a/crates/application/tests/identity/queries/mod.rs b/crates/application/tests/identity/queries/mod.rs
new file mode 100644
index 0000000..5eecfed
--- /dev/null
+++ b/crates/application/tests/identity/queries/mod.rs
@@ -0,0 +1 @@
+mod get_profile;
diff --git a/crates/application/tests/use_cases/organization/create_album.rs b/crates/application/tests/organization/commands/create_album.rs
similarity index 56%
rename from crates/application/tests/use_cases/organization/create_album.rs
rename to crates/application/tests/organization/commands/create_album.rs
index 38d471f..859f381 100644
--- a/crates/application/tests/use_cases/organization/create_album.rs
+++ b/crates/application/tests/organization/commands/create_album.rs
@@ -1,15 +1,18 @@
 use std::sync::Arc;
 use application::testing::InMemoryAlbumRepository;
-use application::use_cases::CreateAlbum;
+use application::organization::{CreateAlbumCommand, CreateAlbumHandler};
 use domain::errors::DomainError;
 use domain::value_objects::SystemId;
 
 #[tokio::test]
 async fn creates_album() {
     let repo = Arc::new(InMemoryAlbumRepository::new());
-    let uc = CreateAlbum::new(repo);
+    let handler = CreateAlbumHandler::new(repo);
     let creator = SystemId::new();
-    let album = uc.execute("Vacation 2024", creator).await.unwrap();
+    let album = handler.execute(CreateAlbumCommand {
+        title: "Vacation 2024".into(),
+        creator_id: creator,
+    }).await.unwrap();
     assert_eq!(album.title, "Vacation 2024");
     assert_eq!(album.creator_user_id, creator);
     assert_eq!(album.asset_count(), 0);
@@ -18,7 +21,10 @@ async fn creates_album() {
 #[tokio::test]
 async fn rejects_empty_title() {
     let repo = Arc::new(InMemoryAlbumRepository::new());
-    let uc = CreateAlbum::new(repo);
-    let result = uc.execute("", SystemId::new()).await;
+    let handler = CreateAlbumHandler::new(repo);
+    let result = handler.execute(CreateAlbumCommand {
+        title: "".into(),
+        creator_id: SystemId::new(),
+    }).await;
     assert!(matches!(result, Err(DomainError::Validation(_))));
 }
diff --git a/crates/application/tests/use_cases/organization/mod.rs b/crates/application/tests/organization/commands/mod.rs
similarity index 100%
rename from crates/application/tests/use_cases/organization/mod.rs
rename to crates/application/tests/organization/commands/mod.rs
diff --git a/crates/application/tests/organization/mod.rs b/crates/application/tests/organization/mod.rs
new file mode 100644
index 0000000..f3d4468
--- /dev/null
+++ b/crates/application/tests/organization/mod.rs
@@ -0,0 +1 @@
+mod commands;
diff --git a/crates/application/tests/use_cases/identity/register_user.rs b/crates/application/tests/use_cases/identity/register_user.rs
deleted file mode 100644
index d2eed0e..0000000
--- a/crates/application/tests/use_cases/identity/register_user.rs
+++ /dev/null
@@ -1,48 +0,0 @@
-use std::sync::Arc;
-use application::testing::{InMemoryUserRepository, StubPasswordHasher};
-use application::use_cases::RegisterUser;
-use domain::errors::DomainError;
-
-#[tokio::test]
-async fn registers_new_user() {
-    let repo = Arc::new(InMemoryUserRepository::new());
-    let uc = RegisterUser::new(repo.clone(), Arc::new(StubPasswordHasher));
-    let user = uc.execute("testuser", "test@example.com", "password123").await.unwrap();
-    assert_eq!(user.username, "testuser");
-    assert_eq!(user.email.as_str(), "test@example.com");
-    assert_eq!(repo.all().await.len(), 1);
-}
-
-#[tokio::test]
-async fn rejects_duplicate_email() {
-    let repo = Arc::new(InMemoryUserRepository::new());
-    let uc = RegisterUser::new(repo.clone(), Arc::new(StubPasswordHasher));
-    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 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(_))));
-}
-
-#[tokio::test]
-async fn rejects_short_password() {
-    let repo = Arc::new(InMemoryUserRepository::new());
-    let uc = RegisterUser::new(repo, Arc::new(StubPasswordHasher));
-    let result = uc.execute("user", "test@example.com", "short").await;
-    assert!(matches!(result, Err(DomainError::Validation(_))));
-}
-
-#[tokio::test]
-async fn rejects_empty_username() {
-    let repo = Arc::new(InMemoryUserRepository::new());
-    let uc = RegisterUser::new(repo, Arc::new(StubPasswordHasher));
-    let result = uc.execute("", "test@example.com", "password123").await;
-    assert!(matches!(result, Err(DomainError::Validation(_))));
-}
diff --git a/crates/application/tests/use_cases/mod.rs b/crates/application/tests/use_cases/mod.rs
deleted file mode 100644
index 6b57d05..0000000
--- a/crates/application/tests/use_cases/mod.rs
+++ /dev/null
@@ -1,2 +0,0 @@
-mod identity;
-mod organization;
diff --git a/crates/bootstrap/src/factory.rs b/crates/bootstrap/src/factory.rs
index 0c2597b..75d7d01 100644
--- a/crates/bootstrap/src/factory.rs
+++ b/crates/bootstrap/src/factory.rs
@@ -12,7 +12,7 @@ use adapters_postgres::{connect, run_migrations, PostgresUserRepository};
 
 use adapters_storage::{ObjectStorageAdapter, StorageConfig, build_store};
 
-use application::use_cases::{GetProfile, LoginUser, RegisterUser};
+use application::identity::{RegisterUserHandler, LoginUserHandler, GetProfileHandler};
 use presentation::{routes::app_router, state::AppState};
 
 use crate::config::Config;
@@ -21,26 +21,24 @@ pub async fn build_app(config: &Config) -> Result<Router> {
     let pool = connect(&config.database_url).await?;
     run_migrations(&pool).await?;
 
-    
-    
+
+
     let user_repo = Arc::new(PostgresUserRepository::new(pool));
-    
+
     let hasher = Arc::new(BcryptPasswordHasher);
     let issuer = Arc::new(JwtTokenIssuer::new(&config.jwt_secret));
 
-    let register_uc = Arc::new(RegisterUser::new(user_repo.clone(), hasher.clone()));
-    let login_uc = Arc::new(LoginUser::new(user_repo.clone(), hasher, issuer.clone()));
-    let get_profile_uc = Arc::new(GetProfile::new(user_repo));
+    let register_handler = Arc::new(RegisterUserHandler::new(user_repo.clone(), hasher.clone()));
+    let login_handler = Arc::new(LoginUserHandler::new(user_repo.clone(), hasher, issuer.clone()));
+    let get_profile_handler = Arc::new(GetProfileHandler::new(user_repo));
+
 
-    
     let storage_cfg = StorageConfig::from_env()?;
     let store = build_store(&storage_cfg)?;
-    // To inject storage into a use case, clone it into the constructor:
-    // let my_uc = Arc::new(MyUseCase::new(repo, storage.clone()));
     let storage = Arc::new(ObjectStorageAdapter::new(store, &storage_cfg.prefix)?);
-    
 
-    let state = AppState::new(register_uc, login_uc, get_profile_uc, issuer, storage);
+
+    let state = AppState::new(register_handler, login_handler, get_profile_handler, issuer, storage);
 
     let cors = CorsLayer::new()
         .allow_origin(
diff --git a/crates/presentation/src/handlers/auth.rs b/crates/presentation/src/handlers/auth.rs
index f60da05..2dc98a0 100644
--- a/crates/presentation/src/handlers/auth.rs
+++ b/crates/presentation/src/handlers/auth.rs
@@ -3,6 +3,7 @@ use api_types::{
     requests::{LoginRequest, RegisterRequest},
     responses::{AuthResponse, UserResponse},
 };
+use application::identity::{RegisterUserCommand, LoginUserCommand, GetProfileQuery};
 use crate::{errors::AppError, extractors::{JwtClaims, ValidatedJson}, state::AppState};
 
 #[utoipa::path(
@@ -18,7 +19,12 @@ pub async fn register(
     State(state): State<AppState>,
     ValidatedJson(req): ValidatedJson<RegisterRequest>,
 ) -> Result<(StatusCode, Json<AuthResponse>), AppError> {
-    let user = state.register_uc.execute(&req.email, &req.password).await?;
+    let cmd = RegisterUserCommand {
+        username: req.username,
+        email: req.email,
+        password: req.password,
+    };
+    let user = state.register_handler.execute(cmd).await?;
     let token = state.token_issuer.issue(&user.id, "user").await.map_err(AppError::from)?;
     Ok((StatusCode::CREATED, Json(AuthResponse { token, user: UserResponse::from_domain(&user) })))
 }
@@ -35,7 +41,11 @@ pub async fn login(
     State(state): State<AppState>,
     ValidatedJson(req): ValidatedJson<LoginRequest>,
 ) -> Result<Json<AuthResponse>, AppError> {
-    let (user, token) = state.login_uc.execute(&req.email, &req.password).await?;
+    let cmd = LoginUserCommand {
+        email: req.email,
+        password: req.password,
+    };
+    let (user, token) = state.login_handler.execute(cmd).await?;
     Ok(Json(AuthResponse { token, user: UserResponse::from_domain(&user) }))
 }
 
@@ -51,6 +61,7 @@ pub async fn me(
     State(state): State<AppState>,
     claims: JwtClaims,
 ) -> Result<Json<UserResponse>, AppError> {
-    let user = state.get_profile_uc.execute(&claims.user_id).await?;
+    let query = GetProfileQuery { user_id: claims.user_id };
+    let user = state.get_profile_handler.execute(query).await?;
     Ok(Json(UserResponse::from_domain(&user)))
 }
diff --git a/crates/presentation/src/state.rs b/crates/presentation/src/state.rs
index 2509add..16a4365 100644
--- a/crates/presentation/src/state.rs
+++ b/crates/presentation/src/state.rs
@@ -1,26 +1,26 @@
 use std::sync::Arc;
-use application::use_cases::{GetProfile, LoginUser, RegisterUser};
+use application::identity::{RegisterUserHandler, LoginUserHandler, GetProfileHandler};
 
 use domain::ports::{StoragePort, TokenIssuer};
 
 
 #[derive(Clone)]
 pub struct AppState {
-    pub register_uc: Arc<RegisterUser>,
-    pub login_uc: Arc<LoginUser>,
-    pub get_profile_uc: Arc<GetProfile>,
+    pub register_handler: Arc<RegisterUserHandler>,
+    pub login_handler: Arc<LoginUserHandler>,
+    pub get_profile_handler: Arc<GetProfileHandler>,
     pub token_issuer: Arc<dyn TokenIssuer>,
     pub storage: Arc<dyn StoragePort>,
 }
 
 impl AppState {
     pub fn new(
-        register_uc: Arc<RegisterUser>,
-        login_uc: Arc<LoginUser>,
-        get_profile_uc: Arc<GetProfile>,
+        register_handler: Arc<RegisterUserHandler>,
+        login_handler: Arc<LoginUserHandler>,
+        get_profile_handler: Arc<GetProfileHandler>,
         token_issuer: Arc<dyn TokenIssuer>,
         storage: Arc<dyn StoragePort>,
     ) -> Self {
-        Self { register_uc, login_uc, get_profile_uc, token_issuer, storage }
+        Self { register_handler, login_handler, get_profile_handler, token_issuer, storage }
     }
 }