feat(domain): add list_mutual to FollowRepository, add remote actor storage to TestStore

crates/adapters/postgres/src/follow/mod.rs

@@ -187,6 +187,50 @@ impl FollowRepository for PgFollowRepository {
         .into_domain()?;
         Ok(ids.into_iter().map(UserId::from_uuid).collect())
     }
+
+    async fn list_mutual(
+        &self,
+        user_id: &UserId,
+        page: &PageParams,
+    ) -> Result<Paginated<User>, DomainError> {
+        let total: i64 = sqlx::query_scalar(
+            "SELECT COUNT(DISTINCT u.id)
+             FROM users u
+             WHERE EXISTS (
+               SELECT 1 FROM follows f1 WHERE f1.follower_id=$1 AND f1.following_id=u.id AND f1.state='accepted'
+             ) AND EXISTS (
+               SELECT 1 FROM follows f2 WHERE f2.following_id=$1 AND f2.follower_id=u.id AND f2.state='accepted'
+             )",
+        )
+        .bind(user_id.as_uuid())
+        .fetch_one(&self.pool)
+        .await
+        .into_domain()?;
+
+        let rows = sqlx::query_as::<_, crate::user::UserRow>(
+            "SELECT u.id,u.username,u.email,u.password_hash,u.display_name,u.bio,u.avatar_url,u.header_url,u.custom_css,u.local,u.ap_id,u.inbox_url,u.created_at,u.updated_at
+             FROM users u
+             WHERE EXISTS (
+               SELECT 1 FROM follows f1 WHERE f1.follower_id=$1 AND f1.following_id=u.id AND f1.state='accepted'
+             ) AND EXISTS (
+               SELECT 1 FROM follows f2 WHERE f2.following_id=$1 AND f2.follower_id=u.id AND f2.state='accepted'
+             )
+             ORDER BY u.created_at DESC LIMIT $2 OFFSET $3"
+        )
+        .bind(user_id.as_uuid())
+        .bind(page.limit())
+        .bind(page.offset())
+        .fetch_all(&self.pool)
+        .await
+        .into_domain()?;
+
+        Ok(Paginated {
+            items: rows.into_iter().map(User::from).collect(),
+            total,
+            page: page.page,
+            per_page: page.per_page,
+        })
+    }
 }
 
 #[cfg(test)]

crates/domain/src/ports.rs

@@ -171,6 +171,11 @@ pub trait FollowRepository: Send + Sync {
         &self,
         user_id: &UserId,
     ) -> Result<Vec<UserId>, DomainError>;
+    async fn list_mutual(
+        &self,
+        user_id: &UserId,
+        page: &PageParams,
+    ) -> Result<Paginated<User>, DomainError>;
 }
 
 #[async_trait]

crates/domain/src/testing/mod.rs

@@ -37,6 +37,8 @@ pub struct TestStore {
     pub actor_ap_ids: Arc<Mutex<HashMap<String, UserId>>>,
     /// ThoughtId → AP object URL (used by get_thought_ap_id)
     pub thought_ap_ids: Arc<Mutex<HashMap<ThoughtId, String>>>,
+    pub remote_following: Arc<Mutex<Vec<RemoteActor>>>,
+    pub remote_followers: Arc<Mutex<Vec<RemoteActor>>>,
 }
 
 #[async_trait]
@@ -452,6 +454,40 @@ impl FollowRepository for TestStore {
             .map(|f| f.following_id.clone())
             .collect())
     }
+    async fn list_mutual(
+        &self,
+        user_id: &UserId,
+        page: &PageParams,
+    ) -> Result<Paginated<User>, DomainError> {
+        use std::collections::HashSet;
+        let follows = self.follows.lock().unwrap();
+        let following_ids: HashSet<UserId> = follows
+            .iter()
+            .filter(|f| &f.follower_id == user_id && f.state == FollowState::Accepted)
+            .map(|f| f.following_id.clone())
+            .collect();
+        let follower_ids: HashSet<UserId> = follows
+            .iter()
+            .filter(|f| &f.following_id == user_id && f.state == FollowState::Accepted)
+            .map(|f| f.follower_id.clone())
+            .collect();
+        let mutual_ids: HashSet<UserId> =
+            following_ids.intersection(&follower_ids).cloned().collect();
+        drop(follows);
+        let users = self.users.lock().unwrap();
+        let items: Vec<User> = users
+            .iter()
+            .filter(|u| mutual_ids.contains(&u.id))
+            .cloned()
+            .collect();
+        let total = items.len() as i64;
+        Ok(Paginated {
+            items,
+            total,
+            page: page.page,
+            per_page: page.per_page,
+        })
+    }
 }
 
 #[async_trait]
@@ -710,7 +746,7 @@ impl FederationFollowPort for TestStore {
         &self,
         _user_id: &UserId,
     ) -> Result<Vec<RemoteActor>, DomainError> {
-        Ok(vec![])
+        Ok(self.remote_following.lock().unwrap().clone())
     }
 
     async fn broadcast_move(
@@ -751,7 +787,7 @@ impl FederationFollowRequestPort for TestStore {
         &self,
         _user_id: &UserId,
     ) -> Result<Vec<RemoteActor>, DomainError> {
-        Ok(vec![])
+        Ok(self.remote_followers.lock().unwrap().clone())
     }
 
     async fn remove_remote_follower(