refactor(application): fix 4 code smells — validate username input, extract ownership guard and dedup helpers

crates/application/src/services/federation_event.rs

@@ -2,8 +2,9 @@ use std::sync::Arc;
 use domain::{
     errors::DomainError,
     events::DomainEvent,
-    models::thought::Visibility,
+    models::thought::{Thought, Visibility},
     ports::{OutboundFederationPort, ThoughtRepository, UserRepository},
+    value_objects::ThoughtId,
 };
 
 pub struct FederationEventService {
@@ -14,6 +15,12 @@ pub struct FederationEventService {
 }
 
 impl FederationEventService {
+    fn object_ap_id(&self, thought: &Thought, thought_id: &ThoughtId) -> String {
+        thought.ap_id.clone().unwrap_or_else(|| {
+            format!("{}/thoughts/{}", self.base_url, thought_id)
+        })
+    }
+
     pub async fn process(&self, event: &DomainEvent) -> Result<(), DomainError> {
         match event {
             DomainEvent::ThoughtCreated { thought_id, user_id, .. } => {
@@ -52,9 +59,7 @@ impl FederationEventService {
                     Some(t) => t,
                     None => return Ok(()),
                 };
-                let object_ap_id = thought.ap_id.clone().unwrap_or_else(|| {
-                    format!("{}/thoughts/{}", self.base_url, thought_id)
-                });
+                let object_ap_id = self.object_ap_id(&thought, thought_id);
                 self.ap.broadcast_announce(user_id, &object_ap_id).await
             }
 
@@ -63,9 +68,7 @@ impl FederationEventService {
                     Some(t) => t,
                     None => return Ok(()),
                 };
-                let object_ap_id = thought.ap_id.clone().unwrap_or_else(|| {
-                    format!("{}/thoughts/{}", self.base_url, thought_id)
-                });
+                let object_ap_id = self.object_ap_id(&thought, thought_id);
                 self.ap.broadcast_undo_announce(user_id, &object_ap_id).await
             }
 

crates/application/src/services/notification_event.rs

@@ -5,7 +5,7 @@ use domain::{
     events::DomainEvent,
     models::notification::{Notification, NotificationType},
     ports::{NotificationRepository, ThoughtRepository},
-    value_objects::NotificationId,
+    value_objects::{NotificationId, UserId},
 };
 
 pub struct NotificationEventService {
@@ -13,6 +13,10 @@ pub struct NotificationEventService {
     pub notifications: Arc<dyn NotificationRepository>,
 }
 
+fn is_self_action(thought_author: &UserId, actor: &UserId) -> bool {
+    thought_author == actor
+}
+
 impl NotificationEventService {
     pub async fn process(&self, event: &DomainEvent) -> Result<(), DomainError> {
         match event {
@@ -21,7 +25,7 @@ impl NotificationEventService {
                     Some(t) => t,
                     None => return Ok(()),
                 };
-                if thought.user_id == *user_id { return Ok(()); }
+                if is_self_action(&thought.user_id, user_id) { return Ok(()); }
                 self.notifications.save(&Notification {
                     id: NotificationId::new(),
                     user_id: thought.user_id,
@@ -37,7 +41,7 @@ impl NotificationEventService {
                     Some(t) => t,
                     None => return Ok(()),
                 };
-                if thought.user_id == *user_id { return Ok(()); }
+                if is_self_action(&thought.user_id, user_id) { return Ok(()); }
                 self.notifications.save(&Notification {
                     id: NotificationId::new(),
                     user_id: thought.user_id,
@@ -68,7 +72,7 @@ impl NotificationEventService {
                     Some(t) => t,
                     None => return Ok(()),
                 };
-                if original.user_id == *user_id { return Ok(()); }
+                if is_self_action(&original.user_id, user_id) { return Ok(()); }
                 self.notifications.save(&Notification {
                     id: NotificationId::new(),
                     user_id: original.user_id,

crates/application/src/use_cases/profile.rs

@@ -10,7 +10,7 @@ pub async fn get_user(users: &dyn UserRepository, user_id: &UserId) -> Result<Us
 }
 
 pub async fn get_user_by_username(users: &dyn UserRepository, username: &str) -> Result<User, DomainError> {
-    let username = Username::from_trusted(username.to_string());
+    let username = Username::new(username).map_err(|_| DomainError::NotFound)?;
     users.find_by_username(&username).await?.ok_or(DomainError::NotFound)
 }
 

crates/application/src/use_cases/thoughts.rs

@@ -6,6 +6,13 @@ use domain::{
     value_objects::{Content, ThoughtId, UserId},
 };
 
+fn require_owner(thought: &Thought, user_id: &UserId) -> Result<(), DomainError> {
+    if thought.user_id != *user_id {
+        return Err(DomainError::NotFound);
+    }
+    Ok(())
+}
+
 pub struct CreateThoughtInput {
     pub user_id: UserId,
     pub content: String,
@@ -45,7 +52,7 @@ pub async fn delete_thought(
     user_id: &UserId,
 ) -> Result<(), DomainError> {
     let thought = thoughts.find_by_id(id).await?.ok_or(DomainError::NotFound)?;
-    if thought.user_id != *user_id { return Err(DomainError::NotFound); }
+    require_owner(&thought, user_id)?;
     thoughts.delete(id, user_id).await?;
     events.publish(&DomainEvent::ThoughtDeleted { thought_id: id.clone(), user_id: user_id.clone() }).await?;
     Ok(())
@@ -59,7 +66,7 @@ pub async fn edit_thought(
     new_content: String,
 ) -> Result<(), DomainError> {
     let thought = thoughts.find_by_id(id).await?.ok_or(DomainError::NotFound)?;
-    if thought.user_id != *user_id { return Err(DomainError::NotFound); }
+    require_owner(&thought, user_id)?;
     let content = Content::new_local(new_content)?;
     thoughts.update_content(id, &content).await?;
     events.publish(&DomainEvent::ThoughtUpdated { thought_id: id.clone(), user_id: user_id.clone() }).await?;