feat(worker): handle FetchActorConnections — resolve and cache remote actor connections

crates/application/src/services/federation_event.rs

@@ -14,6 +14,7 @@ pub struct FederationEventService {
     pub base_url: String,
     pub federation_action: Arc<dyn domain::ports::FederationActionPort>,
     pub ap_repo: Arc<dyn ActivityPubRepository>,
+    pub remote_actor_connections: Arc<dyn domain::ports::RemoteActorConnectionRepository>,
 }
 
 impl FederationEventService {
@@ -157,6 +158,52 @@ impl FederationEventService {
                 Ok(())
             }
 
+            DomainEvent::FetchActorConnections {
+                actor_ap_url,
+                collection_url,
+                connection_type,
+                page,
+            } => {
+                let urls = match self
+                    .federation_action
+                    .fetch_actor_urls_from_collection(collection_url)
+                    .await
+                {
+                    Ok(u) => u,
+                    Err(e) => {
+                        tracing::warn!(
+                            collection_url,
+                            error = %e,
+                            "failed to fetch actor connections collection"
+                        );
+                        return Ok(());
+                    }
+                };
+
+                if urls.is_empty() {
+                    return Ok(());
+                }
+
+                let summaries = self.federation_action.resolve_actor_profiles(urls).await;
+
+                if summaries.is_empty() {
+                    return Ok(());
+                }
+
+                tracing::info!(
+                    count = summaries.len(),
+                    connection_type,
+                    actor = actor_ap_url,
+                    "caching actor connections"
+                );
+
+                self.remote_actor_connections
+                    .upsert_connections(actor_ap_url, connection_type, *page, &summaries)
+                    .await?;
+
+                Ok(())
+            }
+
             _ => Ok(()),
         }
     }
@@ -255,6 +302,7 @@ mod tests {
             base_url: "https://example.com".to_string(),
             federation_action: Arc::new(store.clone()),
             ap_repo: Arc::new(store.clone()),
+            remote_actor_connections: Arc::new(store.clone()),
         }
     }
 
@@ -592,4 +640,19 @@ mod tests {
             .unwrap();
         // TestStore.fetch_outbox_page returns Ok(vec![]) — no notes, no error
     }
+
+    #[tokio::test]
+    async fn fetch_actor_connections_is_noop_when_collection_empty() {
+        let store = TestStore::default();
+        let spy = Arc::new(SpyPort::default());
+        svc(&store, spy.clone())
+            .process(&DomainEvent::FetchActorConnections {
+                actor_ap_url: "https://mastodon.social/users/alice".into(),
+                collection_url: "https://mastodon.social/users/alice/followers".into(),
+                connection_type: "followers".into(),
+                page: 1,
+            })
+            .await
+            .unwrap();
+    }
 }