diff --git a/crates/domain/src/ports.rs b/crates/domain/src/ports.rs
index 8457d24..36f8dda 100644
--- a/crates/domain/src/ports.rs
+++ b/crates/domain/src/ports.rs
@@ -233,3 +233,38 @@ pub trait ActivityPubRepository: Send + Sync {
     /// Total locally-authored thought count for NodeInfo responses.
     async fn count_local_notes(&self) -> Result<u64, DomainError>;
 }
+
+#[async_trait]
+pub trait OutboundFederationPort: Send + Sync {
+    /// Fan out a new local Note to all accepted followers.
+    async fn broadcast_create(
+        &self,
+        author_user_id: &UserId,
+        thought: &Thought,
+        author_username: &str,
+    ) -> Result<(), DomainError>;
+
+    /// Fan out a Delete tombstone for a now-deleted local Note.
+    /// `thought_ap_id` is pre-constructed by the caller because the thought
+    /// has already been deleted from the DB when this fires.
+    async fn broadcast_delete(
+        &self,
+        author_user_id: &UserId,
+        thought_ap_id: &str,
+    ) -> Result<(), DomainError>;
+
+    /// Fan out an Update(Note) for an edited local thought.
+    async fn broadcast_update(
+        &self,
+        author_user_id: &UserId,
+        thought: &Thought,
+        author_username: &str,
+    ) -> Result<(), DomainError>;
+
+    /// Fan out an Announce(object_ap_id) for a boost.
+    async fn broadcast_announce(
+        &self,
+        booster_user_id: &UserId,
+        object_ap_id: &str,
+    ) -> Result<(), DomainError>;
+}