diff --git a/crates/adapters/activitypub-base/src/service.rs b/crates/adapters/activitypub-base/src/service.rs
index 4a92c57..84510a7 100644
--- a/crates/adapters/activitypub-base/src/service.rs
+++ b/crates/adapters/activitypub-base/src/service.rs
@@ -1390,6 +1390,26 @@ impl domain::ports::OutboundFederationPort for ActivityPubService {
             .await
             .map_err(|e| domain::errors::DomainError::Internal(e.to_string()))
     }
+
+    async fn broadcast_like(
+        &self,
+        _liker_user_id: &domain::value_objects::UserId,
+        _object_ap_id: &str,
+        _author_inbox_url: &str,
+    ) -> Result<(), domain::errors::DomainError> {
+        // TODO: implement Like activity broadcasting
+        Ok(())
+    }
+
+    async fn broadcast_undo_like(
+        &self,
+        _liker_user_id: &domain::value_objects::UserId,
+        _object_ap_id: &str,
+        _author_inbox_url: &str,
+    ) -> Result<(), domain::errors::DomainError> {
+        // TODO: implement Undo(Like) activity broadcasting
+        Ok(())
+    }
 }
 
 #[async_trait::async_trait]
diff --git a/crates/application/src/services/federation_event.rs b/crates/application/src/services/federation_event.rs
index bfc6725..8b57fb1 100644
--- a/crates/application/src/services/federation_event.rs
+++ b/crates/application/src/services/federation_event.rs
@@ -249,6 +249,8 @@ mod tests {
         updated: Mutex<Vec<ThoughtId>>,
         announced: Mutex<Vec<String>>,
         undo_announced: Mutex<Vec<String>>,
+        liked: Mutex<Vec<String>>,
+        undo_liked: Mutex<Vec<String>>,
     }
 
     #[async_trait]
@@ -287,6 +289,26 @@ mod tests {
             self.undo_announced.lock().unwrap().push(ap_id.to_string());
             Ok(())
         }
+
+        async fn broadcast_like(
+            &self,
+            _: &UserId,
+            ap_id: &str,
+            _: &str,
+        ) -> Result<(), DomainError> {
+            self.liked.lock().unwrap().push(ap_id.to_string());
+            Ok(())
+        }
+
+        async fn broadcast_undo_like(
+            &self,
+            _: &UserId,
+            ap_id: &str,
+            _: &str,
+        ) -> Result<(), DomainError> {
+            self.undo_liked.lock().unwrap().push(ap_id.to_string());
+            Ok(())
+        }
     }
 
     fn alice() -> User {
diff --git a/crates/domain/src/ports.rs b/crates/domain/src/ports.rs
index 2831aef..68f8858 100644
--- a/crates/domain/src/ports.rs
+++ b/crates/domain/src/ports.rs
@@ -453,4 +453,21 @@ pub trait OutboundFederationPort: Send + Sync {
         booster_user_id: &UserId,
         object_ap_id: &str,
     ) -> Result<(), DomainError>;
+
+    /// Send a Like activity to a remote thought author's inbox.
+    /// Only called when a LOCAL user likes a REMOTE thought (one with an ap_id).
+    async fn broadcast_like(
+        &self,
+        liker_user_id: &UserId,
+        object_ap_id: &str,
+        author_inbox_url: &str,
+    ) -> Result<(), DomainError>;
+
+    /// Send Undo(Like) to a remote thought author's inbox.
+    async fn broadcast_undo_like(
+        &self,
+        liker_user_id: &UserId,
+        object_ap_id: &str,
+        author_inbox_url: &str,
+    ) -> Result<(), DomainError>;
 }