feat: add broadcast_move to ActivityPubService; bump to v0.1.9

Cargo.lock

@@ -1368,7 +1368,7 @@ dependencies = [
 
 [[package]]
 name = "k-ap"
-version = "0.1.7"
+version = "0.1.9"
 dependencies = [
  "activitypub_federation",
  "anyhow",

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "k-ap"
-version = "0.1.8"
+version = "0.1.9"
 edition = "2024"
 description = "Generic ActivityPub protocol layer"
 license = "MIT"

src/activities.rs

@@ -837,10 +837,86 @@ impl Activity for MoveActivity {
         if data.federation_repo.is_domain_blocked(domain).await? {
             return Ok(());
         }
+
+        // Fetch the target actor via signed request.
+        let target = ObjectId::<DbActor>::from(self.target.clone())
+            .dereference(data)
+            .await
+            .map_err(|e| Error::from(anyhow::anyhow!("{e}")))?;
+
+        // Verify the new actor claims the old identity via alsoKnownAs.
+        let old_url = self.object.as_str();
+        if target.also_known_as.as_deref() != Some(old_url) {
+            return Err(Error::bad_request(anyhow::anyhow!(
+                "Move target alsoKnownAs does not reference old actor"
+            )));
+        }
+
+        // Migrate DB records; get user IDs that need a re-follow.
+        let affected = data
+            .federation_repo
+            .migrate_follower_actor(old_url, self.target.as_str())
+            .await
+            .map_err(|e| Error::from(anyhow::anyhow!("{e}")))?;
+
+        let affected_count = affected.len();
+
+        // Re-follow on behalf of each affected local user.
+        for local_user_id in &affected {
+            let local_actor = match crate::actors::get_local_actor(*local_user_id, data).await {
+                Ok(a) => a,
+                Err(e) => {
+                    tracing::warn!(error = %e, %local_user_id, "Move: failed to load local actor for re-follow");
+                    continue;
+                }
+            };
+
+            let follow_id = match crate::urls::activity_url(&data.base_url) {
+                Ok(u) => u,
+                Err(e) => {
+                    tracing::warn!(error = %e, "Move: failed to generate follow activity URL");
+                    continue;
+                }
+            };
+
+            let follow = FollowActivity {
+                id: follow_id,
+                kind: Default::default(),
+                actor: activitypub_federation::fetch::object_id::ObjectId::from(
+                    local_actor.ap_id.clone(),
+                ),
+                object: activitypub_federation::fetch::object_id::ObjectId::from(
+                    self.target.clone(),
+                ),
+            };
+
+            let sends = match activitypub_federation::activity_sending::SendActivityTask::prepare(
+                &activitypub_federation::protocol::context::WithContext::new_default(follow),
+                &local_actor,
+                vec![target.inbox_url.clone()],
+                data,
+            )
+            .await
+            {
+                Ok(s) => s,
+                Err(e) => {
+                    tracing::warn!(error = %e, "Move: failed to prepare re-follow");
+                    continue;
+                }
+            };
+
+            for send in sends {
+                if let Err(e) = send.sign_and_send(data).await {
+                    tracing::warn!(error = %e, %local_user_id, "Move: re-follow delivery failed");
+                }
+            }
+        }
+
         tracing::info!(
             actor = %self.actor.inner(),
             target = %self.target,
-            "received Move (account migration) — target noted"
+            affected = affected_count,
+            "received Move — migrated follower relationships"
         );
         Ok(())
     }

src/repository.rs

@@ -131,4 +131,12 @@ pub trait FederationRepository: Send + Sync {
     async fn remove_blocked_actor(&self, local_user_id: uuid::Uuid, actor_url: &str) -> Result<()>;
     async fn get_blocked_actors(&self, local_user_id: uuid::Uuid) -> Result<Vec<String>>;
     async fn is_actor_blocked(&self, local_user_id: uuid::Uuid, actor_url: &str) -> Result<bool>;
+    /// Migrate all local following records from old_actor_url to new_actor_url.
+    /// Returns the local user IDs whose records were migrated (excludes users
+    /// already following the new actor — they need no re-follow).
+    async fn migrate_follower_actor(
+        &self,
+        old_actor_url: &str,
+        new_actor_url: &str,
+    ) -> Result<Vec<uuid::Uuid>>;
 }

src/service.rs

@@ -1203,6 +1203,74 @@ impl ActivityPubService {
         Ok(())
     }
 
+    /// Broadcast a Move activity to all accepted followers, signalling that this
+    /// actor is migrating to `new_actor_url`.
+    ///
+    /// **Pre-condition (caller's responsibility):**
+    /// Before calling this, the application must persist `also_known_as = [new_actor_url]`
+    /// in the local actor's row so the old actor JSON already advertises the new URL
+    /// when remote servers fetch it to verify the cross-reference.
+    pub async fn broadcast_move(
+        &self,
+        user_id: uuid::Uuid,
+        new_actor_url: url::Url,
+    ) -> anyhow::Result<()> {
+        let data = self.federation_config.to_request_data();
+        let local_actor = get_local_actor(user_id, &data)
+            .await
+            .map_err(|e| anyhow::anyhow!("{e}"))?;
+
+        let followers = data.federation_repo.get_followers(user_id).await?;
+        let accepted: Vec<_> = followers
+            .into_iter()
+            .filter(|f| f.status == FollowerStatus::Accepted)
+            .collect();
+
+        if accepted.is_empty() {
+            tracing::info!(
+                %user_id,
+                "broadcast_move: no accepted followers, nothing to send"
+            );
+            return Ok(());
+        }
+
+        let inboxes = collect_inboxes(&accepted);
+
+        let move_id =
+            crate::urls::activity_url(&self.base_url).map_err(|e| anyhow::anyhow!("{e}"))?;
+
+        let move_activity = crate::activities::MoveActivity {
+            id: move_id,
+            kind: Default::default(),
+            actor: ObjectId::from(local_actor.ap_id.clone()),
+            object: local_actor.ap_id.clone(),
+            target: new_actor_url.clone(),
+        };
+
+        let sends = SendActivityTask::prepare(
+            &WithContext::new_default(move_activity),
+            &local_actor,
+            inboxes,
+            &data,
+        )
+        .await?;
+
+        let failures = send_with_retry(sends, &data).await;
+        if !failures.is_empty() {
+            tracing::warn!(
+                count = failures.len(),
+                "some Move deliveries failed permanently"
+            );
+        }
+
+        tracing::info!(
+            %user_id,
+            target = %new_actor_url,
+            "broadcast_move: delivered to all accepted followers"
+        );
+        Ok(())
+    }
+
     pub async fn block_actor(
         &self,
         local_user_id: uuid::Uuid,