refactor(activities): split into per-activity files with check_guards DRY helper

src/activities/accept.rs

@@ -0,0 +1,59 @@
+use activitypub_federation::{
+    config::Data,
+    fetch::object_id::ObjectId,
+    kinds::activity::AcceptType,
+    traits::Activity,
+};
+use serde::{Deserialize, Serialize};
+use url::Url;
+
+use crate::actors::DbActor;
+use crate::data::FederationData;
+use crate::error::Error;
+use crate::repository::FollowingStatus;
+
+use super::follow::FollowActivity;
+use super::helpers::check_guards;
+
+#[derive(Debug, Deserialize, Serialize)]
+#[serde(rename_all = "camelCase")]
+pub struct AcceptActivity {
+    pub(crate) id: Url,
+    #[serde(rename = "type", default)]
+    pub(crate) kind: AcceptType,
+    pub(crate) actor: ObjectId<DbActor>,
+    pub(crate) object: FollowActivity,
+}
+
+#[async_trait::async_trait]
+impl Activity for AcceptActivity {
+    type DataType = FederationData;
+    type Error = Error;
+
+    fn id(&self) -> &Url { &self.id }
+    fn actor(&self) -> &Url { self.actor.inner() }
+
+    async fn verify(&self, _data: &Data<Self::DataType>) -> Result<(), Self::Error> {
+        if self.actor.inner() != self.object.object.inner() {
+            return Err(Error::bad_request(anyhow::anyhow!("Accept actor does not match Follow target")));
+        }
+        Ok(())
+    }
+
+    async fn receive(self, data: &Data<Self::DataType>) -> Result<(), Self::Error> {
+        if check_guards(&self.id, self.actor.inner(), data).await? {
+            return Ok(());
+        }
+        let local_user_id = crate::urls::extract_user_id_from_url(self.object.actor.inner())
+            .ok_or_else(|| Error::bad_request(anyhow::anyhow!("invalid actor URL in Follow")))?;
+        data.federation_repo
+            .update_following_status(
+                local_user_id,
+                self.actor.inner().as_str(),
+                FollowingStatus::Accepted,
+            )
+            .await?;
+        tracing::info!(remote_actor = %self.actor.inner(), "follow accepted by remote");
+        Ok(())
+    }
+}

src/activities/add.rs

@@ -0,0 +1,66 @@
+use activitypub_federation::{
+    config::Data,
+    fetch::object_id::ObjectId,
+    traits::Activity,
+};
+use serde::{Deserialize, Serialize};
+use url::Url;
+
+use crate::actors::DbActor;
+use crate::data::FederationData;
+use crate::error::Error;
+
+use super::helpers::check_guards;
+
+#[derive(Clone, Default, Debug, Serialize, Deserialize)]
+#[serde(rename = "Add")]
+pub struct AddType;
+
+#[derive(Debug, Deserialize, Serialize)]
+#[serde(rename_all = "camelCase")]
+pub struct AddActivity {
+    pub(crate) id: Url,
+    #[serde(rename = "type", default)]
+    pub(crate) kind: AddType,
+    pub(crate) actor: ObjectId<DbActor>,
+    pub(crate) object: serde_json::Value,
+    #[serde(skip_serializing_if = "Vec::is_empty", default)]
+    pub(crate) to: Vec<String>,
+    #[serde(skip_serializing_if = "Vec::is_empty", default)]
+    pub(crate) cc: Vec<String>,
+}
+
+#[async_trait::async_trait]
+impl Activity for AddActivity {
+    type DataType = FederationData;
+    type Error = Error;
+
+    fn id(&self) -> &Url { &self.id }
+    fn actor(&self) -> &Url { self.actor.inner() }
+
+    async fn verify(&self, _data: &Data<Self::DataType>) -> Result<(), Self::Error> {
+        if let Some(attributed_to) = self.object.get("attributedTo").and_then(|v| v.as_str())
+            && let Ok(attributed_url) = Url::parse(attributed_to)
+            && &attributed_url != self.actor.inner()
+        {
+            return Err(Error::bad_request(anyhow::anyhow!(
+                "Add actor does not match object attributedTo"
+            )));
+        }
+        Ok(())
+    }
+
+    async fn receive(self, data: &Data<Self::DataType>) -> Result<(), Self::Error> {
+        if check_guards(&self.id, self.actor.inner(), data).await? {
+            return Ok(());
+        }
+        let ap_id = self.id.clone();
+        let actor_url = self.actor.inner().clone();
+        data.object_handler
+            .on_create(&ap_id, &actor_url, self.object)
+            .await
+            .map_err(|e| Error::from(anyhow::anyhow!(e)))?;
+        tracing::info!(actor = %actor_url, "received Add activity");
+        Ok(())
+    }
+}

src/activities/announce.rs

@@ -0,0 +1,75 @@
+use activitypub_federation::{
+    config::Data,
+    fetch::object_id::ObjectId,
+    protocol::verification::verify_domains_match,
+    traits::Activity,
+};
+use serde::{Deserialize, Serialize};
+use url::Url;
+
+use crate::actors::DbActor;
+use crate::data::FederationData;
+use crate::error::Error;
+
+use super::helpers::check_guards;
+
+#[derive(Clone, Default, Debug, Serialize, Deserialize)]
+#[serde(rename = "Announce")]
+pub struct AnnounceType;
+
+#[derive(Debug, Deserialize, Serialize)]
+#[serde(rename_all = "camelCase")]
+pub struct AnnounceActivity {
+    pub(crate) id: Url,
+    #[serde(rename = "type", default)]
+    pub(crate) kind: AnnounceType,
+    pub(crate) actor: ObjectId<DbActor>,
+    pub(crate) object: Url,
+    pub(crate) published: Option<chrono::DateTime<chrono::Utc>>,
+    #[serde(skip_serializing_if = "Vec::is_empty", default)]
+    pub(crate) to: Vec<String>,
+    #[serde(skip_serializing_if = "Vec::is_empty", default)]
+    pub(crate) cc: Vec<String>,
+}
+
+#[async_trait::async_trait]
+impl Activity for AnnounceActivity {
+    type DataType = FederationData;
+    type Error = Error;
+
+    fn id(&self) -> &Url { &self.id }
+    fn actor(&self) -> &Url { self.actor.inner() }
+
+    async fn verify(&self, _data: &Data<Self::DataType>) -> Result<(), Self::Error> {
+        verify_domains_match(&self.id, self.actor.inner())?;
+        Ok(())
+    }
+
+    async fn receive(self, data: &Data<Self::DataType>) -> Result<(), Self::Error> {
+        if check_guards(&self.id, self.actor.inner(), data).await? {
+            return Ok(());
+        }
+        if self.object.host_str().unwrap_or("") != data.domain {
+            data.object_handler
+                .on_announce_of_remote(&self.object, self.actor.inner())
+                .await
+                .unwrap_or_else(|e| tracing::warn!(error = %e, "failed to process cross-server announce"));
+            tracing::debug!(actor = %self.actor.inner(), object = %self.object, "received Announce of non-local object");
+            return Ok(());
+        }
+        data.federation_repo
+            .add_announce(
+                self.id.as_str(),
+                self.object.as_str(),
+                self.actor.inner().as_str(),
+                self.published.unwrap_or_else(chrono::Utc::now),
+            )
+            .await?;
+        data.object_handler
+            .on_announce_received(&self.object, self.actor.inner())
+            .await
+            .unwrap_or_else(|e| tracing::warn!(error = %e, "failed to process announce notification"));
+        tracing::info!(actor = %self.actor.inner(), object = %self.object, "received announce");
+        Ok(())
+    }
+}

src/activities/block.rs

@@ -0,0 +1,54 @@
+use activitypub_federation::{
+    config::Data,
+    fetch::object_id::ObjectId,
+    protocol::verification::verify_domains_match,
+    traits::Activity,
+};
+use serde::{Deserialize, Serialize};
+use url::Url;
+
+use crate::actors::DbActor;
+use crate::data::FederationData;
+use crate::error::Error;
+
+use super::helpers::check_guards;
+
+#[derive(Clone, Default, Debug, Serialize, Deserialize)]
+#[serde(rename = "Block")]
+pub struct BlockType;
+
+#[derive(Debug, Deserialize, Serialize)]
+#[serde(rename_all = "camelCase")]
+pub struct BlockActivity {
+    pub(crate) id: Url,
+    #[serde(rename = "type", default)]
+    pub(crate) kind: BlockType,
+    pub(crate) actor: ObjectId<DbActor>,
+    pub(crate) object: Url,
+}
+
+#[async_trait::async_trait]
+impl Activity for BlockActivity {
+    type DataType = FederationData;
+    type Error = Error;
+
+    fn id(&self) -> &Url { &self.id }
+    fn actor(&self) -> &Url { self.actor.inner() }
+
+    async fn verify(&self, _data: &Data<Self::DataType>) -> Result<(), Self::Error> {
+        verify_domains_match(&self.id, self.actor.inner())?;
+        Ok(())
+    }
+
+    async fn receive(self, data: &Data<Self::DataType>) -> Result<(), Self::Error> {
+        if check_guards(&self.id, self.actor.inner(), data).await? {
+            return Ok(());
+        }
+        if let Some(local_user_id) = crate::urls::extract_user_id_from_url(&self.object) {
+            let _ = data.federation_repo.remove_following(local_user_id, self.actor.inner().as_str()).await;
+            let _ = data.federation_repo.remove_follower(local_user_id, self.actor.inner().as_str()).await;
+        }
+        tracing::info!(actor = %self.actor.inner(), "received block — removed following and follower");
+        Ok(())
+    }
+}

src/activities/create.rs

@@ -0,0 +1,73 @@
+use activitypub_federation::{
+    config::Data,
+    fetch::object_id::ObjectId,
+    kinds::activity::CreateType,
+    traits::Activity,
+};
+use serde::{Deserialize, Serialize};
+use url::Url;
+
+use crate::actors::DbActor;
+use crate::data::FederationData;
+use crate::error::Error;
+
+use super::helpers::{check_guards, extract_and_dispatch_mentions};
+
+#[derive(Debug, Deserialize, Serialize)]
+#[serde(rename_all = "camelCase")]
+pub struct CreateActivity {
+    pub(crate) id: Url,
+    #[serde(rename = "type", default)]
+    pub(crate) kind: CreateType,
+    pub(crate) actor: ObjectId<DbActor>,
+    pub(crate) object: serde_json::Value,
+    #[serde(skip_serializing_if = "Vec::is_empty", default)]
+    pub(crate) to: Vec<String>,
+    #[serde(skip_serializing_if = "Vec::is_empty", default)]
+    pub(crate) cc: Vec<String>,
+    #[serde(skip_serializing_if = "Vec::is_empty", default)]
+    pub(crate) bto: Vec<String>,
+    #[serde(skip_serializing_if = "Vec::is_empty", default)]
+    pub(crate) bcc: Vec<String>,
+}
+
+#[async_trait::async_trait]
+impl Activity for CreateActivity {
+    type DataType = FederationData;
+    type Error = Error;
+
+    fn id(&self) -> &Url { &self.id }
+    fn actor(&self) -> &Url { self.actor.inner() }
+
+    async fn verify(&self, _data: &Data<Self::DataType>) -> Result<(), Self::Error> {
+        if let Some(attributed_to) = self.object.get("attributedTo").and_then(|v| v.as_str())
+            && let Ok(attributed_url) = Url::parse(attributed_to)
+            && &attributed_url != self.actor.inner()
+        {
+            return Err(Error::bad_request(anyhow::anyhow!(
+                "Create actor does not match object attributedTo"
+            )));
+        }
+        Ok(())
+    }
+
+    async fn receive(self, data: &Data<Self::DataType>) -> Result<(), Self::Error> {
+        if check_guards(&self.id, self.actor.inner(), data).await? {
+            return Ok(());
+        }
+        let ap_id = self
+            .object
+            .get("id")
+            .and_then(|v| v.as_str())
+            .and_then(|s| Url::parse(s).ok())
+            .unwrap_or_else(|| self.id.clone());
+        let actor_url = self.actor.inner().clone();
+        extract_and_dispatch_mentions(&ap_id, &actor_url, &self.object, data).await;
+        data.object_handler
+            .on_create(&ap_id, &actor_url, self.object)
+            .await
+            .map_err(|e| Error::from(anyhow::anyhow!(e)))?;
+        tracing::info!(actor = %actor_url, "received create activity");
+        Ok(())
+    }
+}

src/activities/delete.rs

@@ -0,0 +1,94 @@
+use activitypub_federation::{
+    config::Data,
+    fetch::object_id::ObjectId,
+    kinds::activity::DeleteType,
+    traits::Activity,
+};
+use serde::{Deserialize, Serialize};
+use url::Url;
+
+use crate::actors::DbActor;
+use crate::data::FederationData;
+use crate::error::Error;
+
+use super::helpers::check_guards;
+
+#[derive(Debug, Deserialize, Serialize)]
+#[serde(rename_all = "camelCase")]
+pub struct DeleteActivity {
+    pub(crate) id: Url,
+    #[serde(rename = "type", default)]
+    pub(crate) kind: DeleteType,
+    pub(crate) actor: ObjectId<DbActor>,
+    pub(crate) object: serde_json::Value,
+    #[serde(skip_serializing_if = "Vec::is_empty", default)]
+    pub(crate) to: Vec<String>,
+    #[serde(skip_serializing_if = "Vec::is_empty", default)]
+    pub(crate) cc: Vec<String>,
+}
+
+#[async_trait::async_trait]
+impl Activity for DeleteActivity {
+    type DataType = FederationData;
+    type Error = Error;
+
+    fn id(&self) -> &Url { &self.id }
+    fn actor(&self) -> &Url { self.actor.inner() }
+
+    async fn verify(&self, _data: &Data<Self::DataType>) -> Result<(), Self::Error> {
+        let actor_domain = self.actor.inner().host_str().unwrap_or("");
+        let object_domain = match &self.object {
+            serde_json::Value::String(s) => Url::parse(s)
+                .ok()
+                .and_then(|u| u.host_str().map(|h| h.to_string()))
+                .unwrap_or_default(),
+            serde_json::Value::Object(o) => o
+                .get("id")
+                .and_then(|v| v.as_str())
+                .and_then(|s| Url::parse(s).ok())
+                .and_then(|u| u.host_str().map(|h| h.to_string()))
+                .unwrap_or_default(),
+            _ => String::new(),
+        };
+        if !object_domain.is_empty() && actor_domain != object_domain {
+            return Err(Error::bad_request(anyhow::anyhow!(
+                "Delete actor domain does not match object domain"
+            )));
+        }
+        Ok(())
+    }
+
+    async fn receive(self, data: &Data<Self::DataType>) -> Result<(), Self::Error> {
+        if check_guards(&self.id, self.actor.inner(), data).await? {
+            return Ok(());
+        }
+        let actor_url = self.actor.inner().clone();
+        let object_url_str = match &self.object {
+            serde_json::Value::String(s) => s.clone(),
+            serde_json::Value::Object(o) => o
+                .get("id")
+                .and_then(|v| v.as_str())
+                .map(|s| s.to_string())
+                .unwrap_or_default(),
+            _ => String::new(),
+        };
+        let Ok(object_url) = Url::parse(&object_url_str) else {
+            tracing::warn!(actor = %actor_url, "Delete has unparseable object, ignoring");
+            return Ok(());
+        };
+        if object_url == *self.actor.inner() {
+            data.object_handler
+                .on_actor_removed(&actor_url)
+                .await
+                .map_err(|e| Error::from(anyhow::anyhow!(e)))?;
+            tracing::info!(actor = %actor_url, "received Delete(actor) — remote account deleted");
+            return Ok(());
+        }
+        data.object_handler
+            .on_delete(&object_url, &actor_url)
+            .await
+            .map_err(|e| Error::from(anyhow::anyhow!(e)))?;
+        tracing::info!(object = %object_url, "received Delete(note)");
+        Ok(())
+    }
+}

src/activities/follow.rs

@@ -0,0 +1,85 @@
+use activitypub_federation::{
+    config::Data,
+    fetch::object_id::ObjectId,
+    kinds::activity::FollowType,
+    traits::Activity,
+};
+use serde::{Deserialize, Serialize};
+use url::Url;
+
+use crate::actors::DbActor;
+use crate::data::FederationData;
+use crate::error::Error;
+use crate::repository::FollowerStatus;
+
+use super::helpers::check_guards;
+
+#[derive(Debug, Clone, Deserialize, Serialize)]
+#[serde(rename_all = "camelCase")]
+pub struct FollowActivity {
+    pub(crate) id: Url,
+    #[serde(rename = "type", default)]
+    pub(crate) kind: FollowType,
+    pub(crate) actor: ObjectId<DbActor>,
+    pub(crate) object: ObjectId<DbActor>,
+}
+
+#[async_trait::async_trait]
+impl Activity for FollowActivity {
+    type DataType = FederationData;
+    type Error = Error;
+
+    fn id(&self) -> &Url { &self.id }
+    fn actor(&self) -> &Url { self.actor.inner() }
+
+    async fn verify(&self, data: &Data<Self::DataType>) -> Result<(), Self::Error> {
+        let target_url = self.object.inner();
+        let target_domain = match (target_url.host_str(), target_url.port()) {
+            (Some(host), Some(port)) => format!("{}:{}", host, port),
+            (Some(host), None) => host.to_string(),
+            _ => return Err(Error::bad_request(anyhow::anyhow!("invalid follow target URL"))),
+        };
+        if target_domain == data.domain {
+            return Ok(());
+        }
+        if let Some(uuid) = crate::urls::extract_user_id_from_url(target_url) {
+            if data.user_repo.find_by_id(uuid).await.ok().flatten().is_some() {
+                tracing::debug!(target = %target_url, "accepting follow for migrated actor URL");
+                return Ok(());
+            }
+        }
+        Err(Error::bad_request(anyhow::anyhow!("follow target is not a local actor")))
+    }
+
+    async fn receive(self, data: &Data<Self::DataType>) -> Result<(), Self::Error> {
+        if check_guards(&self.id, self.actor.inner(), data).await? {
+            return Ok(());
+        }
+        // Actor block checked BEFORE any outbound HTTP fetch.
+        if let Some(target_user_id) = crate::urls::extract_user_id_from_url(self.object.inner()) {
+            if data.federation_repo
+                .is_actor_blocked(target_user_id, self.actor.inner().as_str())
+                .await?
+            {
+                tracing::info!(actor = %self.actor.inner(), "ignoring follow from blocked actor");
+                return Ok(());
+            }
+        }
+        let _follower = self.actor.dereference(data).await?;
+        let local_actor = self.object.dereference(data).await?;
+        data.federation_repo
+            .add_follower(
+                local_actor.user_id,
+                self.actor.inner().as_str(),
+                FollowerStatus::Pending,
+                self.id.as_str(),
+            )
+            .await?;
+        tracing::info!(
+            follower = %self.actor.inner(),
+            local_user = %local_actor.user_id,
+            "follow request pending approval"
+        );
+        Ok(())
+    }
+}

src/activities/helpers.rs

@@ -0,0 +1,84 @@
+use activitypub_federation::config::Data;
+use url::Url;
+
+use crate::data::FederationData;
+use crate::error::Error;
+
+/// Returns `true` if the activity was already processed.
+/// Marks it processed before returning `false`.
+/// On repo error, skips the check rather than silently dropping the activity.
+pub(crate) async fn already_processed(activity_id: &Url, data: &Data<FederationData>) -> bool {
+    let id = activity_id.as_str();
+    match data.federation_repo.is_activity_processed(id).await {
+        Ok(true) => {
+            tracing::debug!(activity_id = id, "duplicate activity, skipping");
+            true
+        }
+        Ok(false) => {
+            if let Err(e) = data.federation_repo.mark_activity_processed(id).await {
+                tracing::warn!(activity_id = id, error = %e, "failed to mark activity processed");
+            }
+            false
+        }
+        Err(e) => {
+            tracing::warn!(error = %e, "idempotency check failed, processing anyway");
+            false
+        }
+    }
+}
+
+/// Returns `true` when the activity should be skipped:
+/// already processed, or the sender's domain is blocked.
+/// Call this at the top of every `receive()` impl.
+pub(crate) async fn check_guards(
+    id: &Url,
+    actor: &Url,
+    data: &Data<FederationData>,
+) -> Result<bool, Error> {
+    if already_processed(id, data).await {
+        return Ok(true);
+    }
+    let domain = actor.host_str().unwrap_or("");
+    if data.federation_repo.is_domain_blocked(domain).await? {
+        tracing::info!(actor = %actor, "ignoring activity from blocked domain");
+        return Ok(true);
+    }
+    Ok(false)
+}
+
+/// Parse `object["tag"]` for `Mention` entries and notify each tagged local user.
+/// Failures are logged and never propagated — a broken mention must not fail the activity.
+pub(crate) async fn extract_and_dispatch_mentions(
+    ap_id: &Url,
+    actor_url: &Url,
+    object: &serde_json::Value,
+    data: &Data<FederationData>,
+) {
+    let Some(tags) = object.get("tag").and_then(|t| t.as_array()) else {
+        return;
+    };
+    for tag in tags {
+        if tag.get("type").and_then(|v| v.as_str()) != Some("Mention") {
+            continue;
+        }
+        let Some(href) = tag.get("href").and_then(|v| v.as_str()) else {
+            continue;
+        };
+        let Ok(href_url) = Url::parse(href) else { continue };
+        let Some(mentioned_user_id) = crate::urls::extract_user_id_from_url(&href_url) else {
+            continue;
+        };
+        if let Err(e) = data
+            .object_handler
+            .on_mention(ap_id, mentioned_user_id, actor_url)
+            .await
+        {
+            tracing::warn!(
+                ap_id = %ap_id,
+                mentioned_user = %mentioned_user_id,
+                error = %e,
+                "failed to dispatch mention notification"
+            );
+        }
+    }
+}

src/activities/like.rs

@@ -0,0 +1,61 @@
+use activitypub_federation::{
+    config::Data,
+    fetch::object_id::ObjectId,
+    protocol::verification::verify_domains_match,
+    traits::Activity,
+};
+use serde::{Deserialize, Serialize};
+use url::Url;
+
+use crate::actors::DbActor;
+use crate::data::FederationData;
+use crate::error::Error;
+
+use super::helpers::check_guards;
+
+#[derive(Clone, Debug, Deserialize, Serialize)]
+#[serde(rename = "Like")]
+pub struct LikeType;
+
+impl Default for LikeType {
+    fn default() -> Self { Self }
+}
+
+#[derive(Clone, Debug, Deserialize, Serialize)]
+#[serde(rename_all = "camelCase")]
+pub struct LikeActivity {
+    pub id: Url,
+    #[serde(rename = "type")]
+    pub kind: LikeType,
+    pub actor: ObjectId<DbActor>,
+    pub object: Url,
+}
+
+#[async_trait::async_trait]
+impl Activity for LikeActivity {
+    type DataType = FederationData;
+    type Error = Error;
+
+    fn id(&self) -> &Url { &self.id }
+    fn actor(&self) -> &Url { self.actor.inner() }
+
+    async fn verify(&self, _data: &Data<Self::DataType>) -> Result<(), Self::Error> {
+        verify_domains_match(&self.id, self.actor.inner())?;
+        Ok(())
+    }
+
+    async fn receive(self, data: &Data<Self::DataType>) -> Result<(), Self::Error> {
+        if check_guards(&self.id, self.actor.inner(), data).await? {
+            return Ok(());
+        }
+        if self.object.host_str().unwrap_or("") != data.domain {
+            return Ok(());
+        }
+        data.object_handler
+            .on_like(&self.object, self.actor.inner())
+            .await
+            .map_err(|e| Error::from(anyhow::anyhow!(e)))?;
+        tracing::info!(actor = %self.actor.inner(), object = %self.object, "received like");
+        Ok(())
+    }
+}

src/activities/mod.rs

@@ -0,0 +1,60 @@
+mod accept;
+mod add;
+mod announce;
+mod block;
+mod create;
+mod delete;
+mod follow;
+pub(crate) mod helpers;
+mod like;
+mod move_act;
+mod reject;
+mod undo;
+mod update;
+
+pub use accept::AcceptActivity;
+pub use add::{AddActivity, AddType};
+pub use announce::{AnnounceActivity, AnnounceType};
+pub use block::{BlockActivity, BlockType};
+pub use create::CreateActivity;
+pub use delete::DeleteActivity;
+pub use follow::FollowActivity;
+pub use like::{LikeActivity, LikeType};
+pub use move_act::{MoveActivity, MoveType};
+pub use reject::RejectActivity;
+pub use undo::UndoActivity;
+pub use update::UpdateActivity;
+
+use activitypub_federation::config::Data;
+use serde::{Deserialize, Serialize};
+use url::Url;
+
+#[derive(Debug, Deserialize, Serialize)]
+#[serde(tag = "type")]
+#[enum_delegate::implement(activitypub_federation::traits::Activity)]
+pub enum InboxActivities {
+    #[serde(rename = "Follow")]
+    Follow(FollowActivity),
+    #[serde(rename = "Accept")]
+    Accept(AcceptActivity),
+    #[serde(rename = "Reject")]
+    Reject(RejectActivity),
+    #[serde(rename = "Undo")]
+    Undo(UndoActivity),
+    #[serde(rename = "Create")]
+    Create(CreateActivity),
+    #[serde(rename = "Delete")]
+    Delete(DeleteActivity),
+    #[serde(rename = "Update")]
+    Update(UpdateActivity),
+    #[serde(rename = "Announce")]
+    Announce(AnnounceActivity),
+    #[serde(rename = "Add")]
+    Add(AddActivity),
+    #[serde(rename = "Block")]
+    Block(BlockActivity),
+    #[serde(rename = "Like")]
+    Like(LikeActivity),
+    #[serde(rename = "Move")]
+    Move(MoveActivity),
+}

src/activities/move_act.rs

@@ -0,0 +1,105 @@
+use activitypub_federation::{
+    activity_sending::SendActivityTask,
+    config::Data,
+    fetch::object_id::ObjectId,
+    protocol::context::WithContext,
+    traits::Activity,
+};
+use serde::{Deserialize, Serialize};
+use url::Url;
+
+use crate::actors::DbActor;
+use crate::data::FederationData;
+use crate::error::Error;
+
+use super::follow::FollowActivity;
+use super::helpers::check_guards;
+
+#[derive(Clone, Default, Debug, Serialize, Deserialize)]
+#[serde(rename = "Move")]
+pub struct MoveType;
+
+#[derive(Debug, Deserialize, Serialize)]
+#[serde(rename_all = "camelCase")]
+pub struct MoveActivity {
+    pub(crate) id: Url,
+    #[serde(rename = "type", default)]
+    pub(crate) kind: MoveType,
+    pub(crate) actor: ObjectId<DbActor>,
+    pub(crate) object: Url,
+    pub(crate) target: Url,
+}
+
+#[async_trait::async_trait]
+impl Activity for MoveActivity {
+    type DataType = FederationData;
+    type Error = Error;
+
+    fn id(&self) -> &Url { &self.id }
+    fn actor(&self) -> &Url { self.actor.inner() }
+
+    async fn verify(&self, _data: &Data<Self::DataType>) -> Result<(), Self::Error> {
+        if &self.object != self.actor.inner() {
+            return Err(Error::bad_request(anyhow::anyhow!("Move object must be the actor itself")));
+        }
+        Ok(())
+    }
+
+    async fn receive(self, data: &Data<Self::DataType>) -> Result<(), Self::Error> {
+        if check_guards(&self.id, self.actor.inner(), data).await? {
+            return Ok(());
+        }
+        let target = ObjectId::<DbActor>::from(self.target.clone())
+            .dereference(data)
+            .await
+            .map_err(|e| Error::from(anyhow::anyhow!("{e}")))?;
+        if target.also_known_as.as_deref() != Some(self.object.as_str()) {
+            return Err(Error::bad_request(anyhow::anyhow!(
+                "Move target alsoKnownAs does not reference old actor"
+            )));
+        }
+        let affected = data
+            .federation_repo
+            .migrate_follower_actor(self.object.as_str(), self.target.as_str())
+            .await
+            .map_err(|e| Error::from(anyhow::anyhow!("{e}")))?;
+        let affected_count = affected.len();
+        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"); 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: ObjectId::from(local_actor.ap_id.clone()),
+                object: ObjectId::from(self.target.clone()),
+            };
+            let sends = match SendActivityTask::prepare(
+                &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,
+            affected = affected_count,
+            "received Move — migrated follower relationships"
+        );
+        Ok(())
+    }
+}

src/activities/reject.rs

@@ -0,0 +1,54 @@
+use activitypub_federation::{
+    config::Data,
+    fetch::object_id::ObjectId,
+    kinds::activity::RejectType,
+    traits::Activity,
+};
+use serde::{Deserialize, Serialize};
+use url::Url;
+
+use crate::actors::DbActor;
+use crate::data::FederationData;
+use crate::error::Error;
+
+use super::follow::FollowActivity;
+use super::helpers::check_guards;
+
+#[derive(Debug, Deserialize, Serialize)]
+#[serde(rename_all = "camelCase")]
+pub struct RejectActivity {
+    pub(crate) id: Url,
+    #[serde(rename = "type", default)]
+    pub(crate) kind: RejectType,
+    pub(crate) actor: ObjectId<DbActor>,
+    pub(crate) object: FollowActivity,
+}
+
+#[async_trait::async_trait]
+impl Activity for RejectActivity {
+    type DataType = FederationData;
+    type Error = Error;
+
+    fn id(&self) -> &Url { &self.id }
+    fn actor(&self) -> &Url { self.actor.inner() }
+
+    async fn verify(&self, _data: &Data<Self::DataType>) -> Result<(), Self::Error> {
+        if self.actor.inner() != self.object.object.inner() {
+            return Err(Error::bad_request(anyhow::anyhow!("Reject actor does not match Follow target")));
+        }
+        Ok(())
+    }
+
+    async fn receive(self, data: &Data<Self::DataType>) -> Result<(), Self::Error> {
+        if check_guards(&self.id, self.actor.inner(), data).await? {
+            return Ok(());
+        }
+        if let Some(user_id) = crate::urls::extract_user_id_from_url(self.object.actor.inner()) {
+            data.federation_repo
+                .remove_following(user_id, self.actor.inner().as_str())
+                .await?;
+        }
+        tracing::info!(actor = %self.actor.inner(), "follow rejected");
+        Ok(())
+    }
+}

src/activities/undo.rs

@@ -0,0 +1,101 @@
+use activitypub_federation::{
+    config::Data,
+    fetch::object_id::ObjectId,
+    kinds::activity::UndoType,
+    traits::Activity,
+};
+use serde::{Deserialize, Serialize};
+use url::Url;
+
+use crate::actors::DbActor;
+use crate::data::FederationData;
+use crate::error::Error;
+
+use super::helpers::check_guards;
+
+#[derive(Debug, Deserialize, Serialize)]
+#[serde(rename_all = "camelCase")]
+pub struct UndoActivity {
+    pub(crate) id: Url,
+    #[serde(rename = "type", default)]
+    pub(crate) kind: UndoType,
+    pub(crate) actor: ObjectId<DbActor>,
+    pub(crate) object: serde_json::Value,
+}
+
+#[async_trait::async_trait]
+impl Activity for UndoActivity {
+    type DataType = FederationData;
+    type Error = Error;
+
+    fn id(&self) -> &Url { &self.id }
+    fn actor(&self) -> &Url { self.actor.inner() }
+
+    async fn verify(&self, _data: &Data<Self::DataType>) -> Result<(), Self::Error> {
+        if let Some(inner_actor) = self.object.get("actor").and_then(|v| v.as_str())
+            && inner_actor != self.actor.inner().as_str()
+        {
+            return Err(Error::bad_request(anyhow::anyhow!(
+                "Undo actor does not match inner activity actor"
+            )));
+        }
+        Ok(())
+    }
+
+    async fn receive(self, data: &Data<Self::DataType>) -> Result<(), Self::Error> {
+        if check_guards(&self.id, self.actor.inner(), data).await? {
+            return Ok(());
+        }
+        let obj_type = self.object.get("type").and_then(|t| t.as_str()).unwrap_or("");
+        match obj_type {
+            "Follow" => {
+                if let Some(obj_url) = self.object.get("object").and_then(|o| o.as_str())
+                    && let Ok(url) = Url::parse(obj_url)
+                    && let Some(user_id) = crate::urls::extract_user_id_from_url(&url)
+                {
+                    data.federation_repo
+                        .remove_follower(user_id, self.actor.inner().as_str())
+                        .await?;
+                }
+                data.object_handler
+                    .on_actor_removed(self.actor.inner())
+                    .await
+                    .map_err(|e| Error::from(anyhow::anyhow!(e)))?;
+                tracing::info!(actor = %self.actor.inner(), "unfollowed");
+            }
+            "Add" => {
+                let ap_id_str = self
+                    .object
+                    .get("object")
+                    .and_then(|o| o.get("id"))
+                    .and_then(|id| id.as_str())
+                    .or_else(|| self.object.get("id").and_then(|id| id.as_str()));
+                if let Some(ap_id_str) = ap_id_str
+                    && let Ok(ap_id) = Url::parse(ap_id_str)
+                {
+                    data.object_handler
+                        .on_delete(&ap_id, self.actor.inner())
+                        .await
+                        .map_err(|e| Error::from(anyhow::anyhow!(e)))?;
+                    tracing::info!(ap_id = %ap_id_str, "undo Add (watchlist remove)");
+                }
+            }
+            "Like" => {
+                if let Some(obj_url_str) = self.object.get("object").and_then(|o| o.as_str())
+                    && let Ok(obj_url) = Url::parse(obj_url_str)
+                    && obj_url.host_str().unwrap_or("") == data.domain
+                {
+                    data.object_handler
+                        .on_unlike(&obj_url, self.actor.inner())
+                        .await
+                        .unwrap_or_else(|e| tracing::warn!(error = %e, "failed to process unlike"));
+                }
+                tracing::info!(actor = %self.actor.inner(), "received Undo(Like)");
+            }
+            other => {
+                tracing::debug!(kind = %other, "ignoring Undo of unknown activity type");
+            }
+        }
+        Ok(())
+    }
+}

src/activities/update.rs

@@ -0,0 +1,69 @@
+use activitypub_federation::{
+    config::Data,
+    fetch::object_id::ObjectId,
+    kinds::activity::UpdateType,
+    traits::Activity,
+};
+use serde::{Deserialize, Serialize};
+use url::Url;
+
+use crate::actors::DbActor;
+use crate::data::FederationData;
+use crate::error::Error;
+
+use super::helpers::{check_guards, extract_and_dispatch_mentions};
+
+#[derive(Debug, Deserialize, Serialize)]
+#[serde(rename_all = "camelCase")]
+pub struct UpdateActivity {
+    pub(crate) id: Url,
+    #[serde(rename = "type", default)]
+    pub(crate) kind: UpdateType,
+    pub(crate) actor: ObjectId<DbActor>,
+    pub(crate) object: serde_json::Value,
+    #[serde(skip_serializing_if = "Vec::is_empty", default)]
+    pub(crate) to: Vec<String>,
+    #[serde(skip_serializing_if = "Vec::is_empty", default)]
+    pub(crate) cc: Vec<String>,
+}
+
+#[async_trait::async_trait]
+impl Activity for UpdateActivity {
+    type DataType = FederationData;
+    type Error = Error;
+
+    fn id(&self) -> &Url { &self.id }
+    fn actor(&self) -> &Url { self.actor.inner() }
+
+    async fn verify(&self, _data: &Data<Self::DataType>) -> Result<(), Self::Error> {
+        if let Some(attributed_to) = self.object.get("attributedTo").and_then(|v| v.as_str())
+            && let Ok(attributed_url) = Url::parse(attributed_to)
+            && &attributed_url != self.actor.inner()
+        {
+            return Err(Error::bad_request(anyhow::anyhow!(
+                "Update actor does not match object attributedTo"
+            )));
+        }
+        Ok(())
+    }
+
+    async fn receive(self, data: &Data<Self::DataType>) -> Result<(), Self::Error> {
+        if check_guards(&self.id, self.actor.inner(), data).await? {
+            return Ok(());
+        }
+        let ap_id = self
+            .object
+            .get("id")
+            .and_then(|v| v.as_str())
+            .and_then(|s| Url::parse(s).ok())
+            .unwrap_or_else(|| self.id.clone());
+        let actor_url = self.actor.inner().clone();
+        extract_and_dispatch_mentions(&ap_id, &actor_url, &self.object, data).await;
+        data.object_handler
+            .on_update(&ap_id, &actor_url, self.object)
+            .await
+            .map_err(|e| Error::from(anyhow::anyhow!(e)))?;
+        tracing::info!(actor = %actor_url, "received update activity");
+        Ok(())
+    }
+}