# Federation Handler Implementation Plan

> **For agentic workers:** REQUIRED SUB-SKILL: Use superpowers:subagent-driven-development (recommended) or superpowers:executing-plans to implement this plan task-by-task. Steps use checkbox (`- [ ]`) syntax for tracking.

**Goal:** Replace the `FederationHandler` stub with a real implementation that fans out content events (ThoughtCreated/Deleted/Updated, BoostAdded) as ActivityPub activities, while simultaneously refactoring both worker handlers to be thin adapters over application-layer event services.

**Architecture:** Domain defines `OutboundFederationPort`; application holds `FederationEventService` and `NotificationEventService` (business logic); `activitypub-base`'s `ActivityPubService` implements the port; worker handlers are one-liners that call the services. A new `worker/src/factory.rs` owns all dependency construction; `main.rs` stays tiny.

**Dependency chain after refactor:**
```
domain ← application ← worker
domain ← activitypub-base (impl OutboundFederationPort)
bootstrap/worker → postgres, postgres-federation, activitypub, activitypub-base (composition roots only)
```

**Events handled in FederationHandler (async fan-out only):**
- `ThoughtCreated` → `Create(Note)` to local-user followers (local thoughts only)
- `ThoughtDeleted` → `Delete(Note)` to followers
- `ThoughtUpdated` → `Update(Note)` to followers
- `BoostAdded`    → `Announce` to followers
- All others      → no-op (Follow/Accept/Reject/Block dispatched synchronously in HTTP handlers)

---

## File Map

```
Modify: crates/domain/src/ports.rs
  + OutboundFederationPort trait (4 methods)

Create: crates/application/src/services/mod.rs
Create: crates/application/src/services/notification_event.rs
Create: crates/application/src/services/federation_event.rs
Modify: crates/application/src/lib.rs
  + pub mod services

Modify: crates/adapters/activitypub-base/src/activities.rs
  + to/cc fields on AnnounceActivity

Modify: crates/adapters/activitypub-base/src/service.rs
  + broadcast_announce_to_followers()
  + impl OutboundFederationPort for ActivityPubService

Modify: crates/worker/src/handlers.rs
  — remove all business logic, keep thin delegation wrappers

Create: crates/worker/src/factory.rs
  + build() → builds all deps and returns (consumer, handlers)

Modify: crates/worker/src/main.rs
  — call factory::build(), keep event loop only

Modify: crates/worker/Cargo.toml
  + activitypub-base, activitypub, postgres-federation, application
```

---

### Task 1: OutboundFederationPort in domain

**Files:**
- Modify: `crates/domain/src/ports.rs`

- [ ] **Add `OutboundFederationPort` to `crates/domain/src/ports.rs`** — insert after the `ActivityPubRepository` trait:

```rust
#[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>;
}
```

- [ ] **Run:** `cargo check -p domain` — Expected: no errors.

- [ ] **Commit:**

```bash
git add crates/domain/src/ports.rs
git commit -m "feat(domain): OutboundFederationPort — thin AP broadcast abstraction"
```

---

### Task 2: NotificationEventService in application

**Files:**
- Create: `crates/application/src/services/mod.rs`
- Create: `crates/application/src/services/notification_event.rs`
- Modify: `crates/application/src/lib.rs`

- [ ] **Write failing tests** at the bottom of `crates/application/src/services/notification_event.rs` (file doesn't exist yet — create it):

```rust
#[cfg(test)]
mod tests {
    use super::*;
    use domain::{
        models::{thought::{Thought, Visibility}, user::User},
        testing::TestStore,
        value_objects::*,
    };
    use std::sync::Arc;

    fn alice() -> User {
        User::new_local(
            UserId::new(),
            Username::new("alice").unwrap(),
            Email::new("alice@ex.com").unwrap(),
            PasswordHash("h".into()),
        )
    }

    #[tokio::test]
    async fn like_creates_notification_for_thought_author() {
        let store = TestStore::default();
        let alice = alice();
        let bob_id = UserId::new();
        let thought = Thought::new_local(
            ThoughtId::new(), alice.id.clone(),
            Content::new_local("hello").unwrap(),
            None, Visibility::Public, None, false,
        );
        store.thoughts.lock().unwrap().push(thought.clone());
        let svc = NotificationEventService {
            thoughts: Arc::new(store.clone()),
            notifications: Arc::new(store.clone()),
        };
        svc.process(&DomainEvent::LikeAdded {
            like_id: LikeId::new(),
            user_id: bob_id,
            thought_id: thought.id.clone(),
        }).await.unwrap();
        let notifs = store.notifications.lock().unwrap();
        assert_eq!(notifs.len(), 1);
        assert!(matches!(notifs[0].notification_type, NotificationType::Like));
    }

    #[tokio::test]
    async fn self_like_creates_no_notification() {
        let store = TestStore::default();
        let alice = alice();
        let thought = Thought::new_local(
            ThoughtId::new(), alice.id.clone(),
            Content::new_local("hello").unwrap(),
            None, Visibility::Public, None, false,
        );
        store.thoughts.lock().unwrap().push(thought.clone());
        let svc = NotificationEventService {
            thoughts: Arc::new(store.clone()),
            notifications: Arc::new(store.clone()),
        };
        svc.process(&DomainEvent::LikeAdded {
            like_id: LikeId::new(),
            user_id: alice.id.clone(),
            thought_id: thought.id.clone(),
        }).await.unwrap();
        assert!(store.notifications.lock().unwrap().is_empty());
    }

    #[tokio::test]
    async fn follow_accepted_creates_notification() {
        let store = TestStore::default();
        let alice = alice();
        let bob_id = UserId::new();
        let svc = NotificationEventService {
            thoughts: Arc::new(store.clone()),
            notifications: Arc::new(store.clone()),
        };
        svc.process(&DomainEvent::FollowAccepted {
            follower_id: bob_id,
            following_id: alice.id.clone(),
        }).await.unwrap();
        let notifs = store.notifications.lock().unwrap();
        assert_eq!(notifs.len(), 1);
        assert!(matches!(notifs[0].notification_type, NotificationType::Follow));
    }

    #[tokio::test]
    async fn reply_creates_notification_for_original_author() {
        let store = TestStore::default();
        let alice = alice();
        let bob_id = UserId::new();
        let original = Thought::new_local(
            ThoughtId::new(), alice.id.clone(),
            Content::new_local("original").unwrap(),
            None, Visibility::Public, None, false,
        );
        store.thoughts.lock().unwrap().push(original.clone());
        let svc = NotificationEventService {
            thoughts: Arc::new(store.clone()),
            notifications: Arc::new(store.clone()),
        };
        svc.process(&DomainEvent::ThoughtCreated {
            thought_id: ThoughtId::new(),
            user_id: bob_id,
            in_reply_to_id: Some(original.id.clone()),
        }).await.unwrap();
        let notifs = store.notifications.lock().unwrap();
        assert_eq!(notifs.len(), 1);
        assert!(matches!(notifs[0].notification_type, NotificationType::Reply));
    }

    #[tokio::test]
    async fn self_reply_creates_no_notification() {
        let store = TestStore::default();
        let alice = alice();
        let original = Thought::new_local(
            ThoughtId::new(), alice.id.clone(),
            Content::new_local("original").unwrap(),
            None, Visibility::Public, None, false,
        );
        store.thoughts.lock().unwrap().push(original.clone());
        let svc = NotificationEventService {
            thoughts: Arc::new(store.clone()),
            notifications: Arc::new(store.clone()),
        };
        svc.process(&DomainEvent::ThoughtCreated {
            thought_id: ThoughtId::new(),
            user_id: alice.id.clone(),
            in_reply_to_id: Some(original.id.clone()),
        }).await.unwrap();
        assert!(store.notifications.lock().unwrap().is_empty());
    }
}
```

- [ ] **Run:** `cargo test -p application` — Expected: FAIL (no implementation yet).

- [ ] **Create `crates/application/src/services/notification_event.rs`:**

```rust
use std::sync::Arc;
use chrono::Utc;
use domain::{
    errors::DomainError,
    events::DomainEvent,
    models::notification::{Notification, NotificationType},
    ports::{NotificationRepository, ThoughtRepository},
    value_objects::NotificationId,
};

pub struct NotificationEventService {
    pub thoughts:      Arc<dyn ThoughtRepository>,
    pub notifications: Arc<dyn NotificationRepository>,
}

impl NotificationEventService {
    pub async fn process(&self, event: &DomainEvent) -> Result<(), DomainError> {
        match event {
            DomainEvent::LikeAdded { like_id: _, user_id, thought_id } => {
                let thought = match self.thoughts.find_by_id(thought_id).await? {
                    Some(t) => t,
                    None => return Ok(()),
                };
                if thought.user_id == *user_id { return Ok(()); }
                self.notifications.save(&Notification {
                    id: NotificationId::new(),
                    user_id: thought.user_id,
                    notification_type: NotificationType::Like,
                    from_user_id: Some(user_id.clone()),
                    thought_id: Some(thought_id.clone()),
                    read: false,
                    created_at: Utc::now(),
                }).await
            }
            DomainEvent::BoostAdded { boost_id: _, user_id, thought_id } => {
                let thought = match self.thoughts.find_by_id(thought_id).await? {
                    Some(t) => t,
                    None => return Ok(()),
                };
                if thought.user_id == *user_id { return Ok(()); }
                self.notifications.save(&Notification {
                    id: NotificationId::new(),
                    user_id: thought.user_id,
                    notification_type: NotificationType::Boost,
                    from_user_id: Some(user_id.clone()),
                    thought_id: Some(thought_id.clone()),
                    read: false,
                    created_at: Utc::now(),
                }).await
            }
            DomainEvent::FollowAccepted { follower_id, following_id } => {
                self.notifications.save(&Notification {
                    id: NotificationId::new(),
                    user_id: following_id.clone(),
                    notification_type: NotificationType::Follow,
                    from_user_id: Some(follower_id.clone()),
                    thought_id: None,
                    read: false,
                    created_at: Utc::now(),
                }).await
            }
            DomainEvent::ThoughtCreated { thought_id, user_id, in_reply_to_id } => {
                let reply_to_id = match in_reply_to_id {
                    Some(id) => id,
                    None => return Ok(()),
                };
                let original = match self.thoughts.find_by_id(reply_to_id).await? {
                    Some(t) => t,
                    None => return Ok(()),
                };
                if original.user_id == *user_id { return Ok(()); }
                self.notifications.save(&Notification {
                    id: NotificationId::new(),
                    user_id: original.user_id,
                    notification_type: NotificationType::Reply,
                    from_user_id: Some(user_id.clone()),
                    thought_id: Some(thought_id.clone()),
                    read: false,
                    created_at: Utc::now(),
                }).await
            }
            _ => Ok(()),
        }
    }
}
```

- [ ] **Create `crates/application/src/services/mod.rs`:**

```rust
pub mod federation_event;
pub mod notification_event;

pub use federation_event::FederationEventService;
pub use notification_event::NotificationEventService;
```

- [ ] **Modify `crates/application/src/lib.rs`** — add `pub mod services;`:

```rust
pub mod services;
pub mod use_cases;
```

- [ ] **Run:** `cargo test -p application` — Expected: 5 notification tests pass.

- [ ] **Commit:**

```bash
git add crates/application/
git commit -m "feat(application): NotificationEventService — move notification business logic out of worker"
```

---

### Task 3: FederationEventService in application

**Files:**
- Create: `crates/application/src/services/federation_event.rs`
- Modify: `crates/application/src/services/mod.rs` (re-export)

- [ ] **Write failing tests** inside `crates/application/src/services/federation_event.rs`:

```rust
#[cfg(test)]
mod tests {
    use super::*;
    use async_trait::async_trait;
    use domain::{
        errors::DomainError,
        events::DomainEvent,
        models::thought::{Thought, Visibility},
        models::user::User,
        ports::OutboundFederationPort,
        testing::TestStore,
        value_objects::*,
    };
    use std::sync::{Arc, Mutex};

    // ── Spy port ─────────────────────────────────────────────────────────────

    #[derive(Default)]
    struct SpyPort {
        created:   Mutex<Vec<ThoughtId>>,
        deleted:   Mutex<Vec<String>>,
        updated:   Mutex<Vec<ThoughtId>>,
        announced: Mutex<Vec<String>>,
    }

    #[async_trait]
    impl OutboundFederationPort for SpyPort {
        async fn broadcast_create(&self, _: &UserId, thought: &Thought, _: &str) -> Result<(), DomainError> {
            self.created.lock().unwrap().push(thought.id.clone());
            Ok(())
        }
        async fn broadcast_delete(&self, _: &UserId, ap_id: &str) -> Result<(), DomainError> {
            self.deleted.lock().unwrap().push(ap_id.to_string());
            Ok(())
        }
        async fn broadcast_update(&self, _: &UserId, thought: &Thought, _: &str) -> Result<(), DomainError> {
            self.updated.lock().unwrap().push(thought.id.clone());
            Ok(())
        }
        async fn broadcast_announce(&self, _: &UserId, ap_id: &str) -> Result<(), DomainError> {
            self.announced.lock().unwrap().push(ap_id.to_string());
            Ok(())
        }
    }

    fn alice() -> User {
        User::new_local(
            UserId::new(),
            Username::new("alice").unwrap(),
            Email::new("alice@ex.com").unwrap(),
            PasswordHash("h".into()),
        )
    }

    fn local_thought(author_id: UserId) -> Thought {
        Thought::new_local(
            ThoughtId::new(), author_id,
            Content::new_local("hello").unwrap(),
            None, Visibility::Public, None, false,
        )
    }

    fn svc(store: &TestStore, spy: Arc<SpyPort>) -> FederationEventService {
        FederationEventService {
            thoughts: Arc::new(store.clone()),
            users: Arc::new(store.clone()),
            ap: spy,
            base_url: "https://example.com".to_string(),
        }
    }

    #[tokio::test]
    async fn thought_created_broadcasts_create() {
        let store = TestStore::default();
        let alice = alice();
        let thought = local_thought(alice.id.clone());
        store.users.lock().unwrap().push(alice.clone());
        store.thoughts.lock().unwrap().push(thought.clone());

        let spy = Arc::new(SpyPort::default());
        svc(&store, spy.clone())
            .process(&DomainEvent::ThoughtCreated {
                thought_id: thought.id.clone(),
                user_id: alice.id.clone(),
                in_reply_to_id: None,
            })
            .await
            .unwrap();

        assert_eq!(spy.created.lock().unwrap().len(), 1);
        assert_eq!(spy.created.lock().unwrap()[0], thought.id);
    }

    #[tokio::test]
    async fn remote_thought_created_does_not_broadcast() {
        let store = TestStore::default();
        let alice = alice();
        // Remote thought: local = false, ap_id = Some(...)
        let mut thought = local_thought(alice.id.clone());
        thought.local = false;
        thought.ap_id = Some("https://remote.example/notes/1".into());
        store.users.lock().unwrap().push(alice.clone());
        store.thoughts.lock().unwrap().push(thought.clone());

        let spy = Arc::new(SpyPort::default());
        svc(&store, spy.clone())
            .process(&DomainEvent::ThoughtCreated {
                thought_id: thought.id.clone(),
                user_id: alice.id.clone(),
                in_reply_to_id: None,
            })
            .await
            .unwrap();

        assert!(spy.created.lock().unwrap().is_empty());
    }

    #[tokio::test]
    async fn thought_deleted_broadcasts_delete_with_constructed_ap_id() {
        let store = TestStore::default();
        let alice = alice();
        let tid = ThoughtId::new();

        let spy = Arc::new(SpyPort::default());
        svc(&store, spy.clone())
            .process(&DomainEvent::ThoughtDeleted {
                thought_id: tid.clone(),
                user_id: alice.id.clone(),
            })
            .await
            .unwrap();

        let deleted = spy.deleted.lock().unwrap();
        assert_eq!(deleted.len(), 1);
        assert_eq!(deleted[0], format!("https://example.com/thoughts/{}", tid));
    }

    #[tokio::test]
    async fn thought_updated_broadcasts_update() {
        let store = TestStore::default();
        let alice = alice();
        let thought = local_thought(alice.id.clone());
        store.users.lock().unwrap().push(alice.clone());
        store.thoughts.lock().unwrap().push(thought.clone());

        let spy = Arc::new(SpyPort::default());
        svc(&store, spy.clone())
            .process(&DomainEvent::ThoughtUpdated {
                thought_id: thought.id.clone(),
                user_id: alice.id.clone(),
            })
            .await
            .unwrap();

        assert_eq!(spy.updated.lock().unwrap().len(), 1);
    }

    #[tokio::test]
    async fn boost_of_local_thought_announces_constructed_url() {
        let store = TestStore::default();
        let alice = alice();
        let thought = local_thought(alice.id.clone()); // ap_id = None
        store.thoughts.lock().unwrap().push(thought.clone());

        let spy = Arc::new(SpyPort::default());
        svc(&store, spy.clone())
            .process(&DomainEvent::BoostAdded {
                boost_id: BoostId::new(),
                user_id: alice.id.clone(),
                thought_id: thought.id.clone(),
            })
            .await
            .unwrap();

        let announced = spy.announced.lock().unwrap();
        assert_eq!(announced.len(), 1);
        assert_eq!(announced[0], format!("https://example.com/thoughts/{}", thought.id));
    }

    #[tokio::test]
    async fn boost_of_remote_thought_announces_remote_ap_id() {
        let store = TestStore::default();
        let alice = alice();
        let mut thought = local_thought(alice.id.clone());
        thought.local = false;
        thought.ap_id = Some("https://mastodon.social/users/bob/statuses/123".into());
        store.thoughts.lock().unwrap().push(thought.clone());

        let spy = Arc::new(SpyPort::default());
        svc(&store, spy.clone())
            .process(&DomainEvent::BoostAdded {
                boost_id: BoostId::new(),
                user_id: alice.id.clone(),
                thought_id: thought.id.clone(),
            })
            .await
            .unwrap();

        let announced = spy.announced.lock().unwrap();
        assert_eq!(announced[0], "https://mastodon.social/users/bob/statuses/123");
    }

    #[tokio::test]
    async fn unrelated_events_are_noop() {
        let store = TestStore::default();
        let spy = Arc::new(SpyPort::default());
        let svc = svc(&store, spy.clone());

        svc.process(&DomainEvent::UserBlocked {
            blocker_id: UserId::new(),
            blocked_id: UserId::new(),
        }).await.unwrap();

        assert!(spy.created.lock().unwrap().is_empty());
        assert!(spy.deleted.lock().unwrap().is_empty());
        assert!(spy.updated.lock().unwrap().is_empty());
        assert!(spy.announced.lock().unwrap().is_empty());
    }
}
```

- [ ] **Run:** `cargo test -p application -- services::federation_event` — Expected: FAIL (no implementation).

- [ ] **Write `crates/application/src/services/federation_event.rs`** — full file including tests already added above:

```rust
use std::sync::Arc;
use domain::{
    errors::DomainError,
    events::DomainEvent,
    models::thought::Thought,
    ports::{OutboundFederationPort, ThoughtRepository, UserRepository},
    value_objects::UserId,
};

pub struct FederationEventService {
    pub thoughts:  Arc<dyn ThoughtRepository>,
    pub users:     Arc<dyn UserRepository>,
    pub ap:        Arc<dyn OutboundFederationPort>,
    pub base_url:  String,
}

impl FederationEventService {
    pub async fn process(&self, event: &DomainEvent) -> Result<(), DomainError> {
        match event {
            DomainEvent::ThoughtCreated { thought_id, user_id, .. } => {
                let thought = match self.thoughts.find_by_id(thought_id).await? {
                    Some(t) if t.local => t,
                    _ => return Ok(()),
                };
                let user = match self.users.find_by_id(user_id).await? {
                    Some(u) => u,
                    None => return Ok(()),
                };
                self.ap.broadcast_create(user_id, &thought, user.username.as_str()).await
            }

            DomainEvent::ThoughtDeleted { thought_id, user_id } => {
                let ap_id = format!("{}/thoughts/{}", self.base_url, thought_id);
                self.ap.broadcast_delete(user_id, &ap_id).await
            }

            DomainEvent::ThoughtUpdated { thought_id, user_id } => {
                let thought = match self.thoughts.find_by_id(thought_id).await? {
                    Some(t) if t.local => t,
                    _ => return Ok(()),
                };
                let user = match self.users.find_by_id(user_id).await? {
                    Some(u) => u,
                    None => return Ok(()),
                };
                self.ap.broadcast_update(user_id, &thought, user.username.as_str()).await
            }

            DomainEvent::BoostAdded { boost_id: _, user_id, thought_id } => {
                let thought = match self.thoughts.find_by_id(thought_id).await? {
                    Some(t) => t,
                    None => return Ok(()),
                };
                let object_ap_id = thought.ap_id.clone().unwrap_or_else(|| {
                    format!("{}/thoughts/{}", self.base_url, thought_id)
                });
                self.ap.broadcast_announce(user_id, &object_ap_id).await
            }

            _ => Ok(()),
        }
    }
}
```

- [ ] **Update `crates/application/src/services/mod.rs`** to re-export both services:

```rust
pub mod federation_event;
pub mod notification_event;

pub use federation_event::FederationEventService;
pub use notification_event::NotificationEventService;
```

- [ ] **Run:** `cargo test -p application` — Expected: all 12 tests pass (5 notification + 7 federation).

- [ ] **Commit:**

```bash
git add crates/application/src/services/federation_event.rs crates/application/src/services/mod.rs
git commit -m "feat(application): FederationEventService — content fan-out business logic"
```

---

### Task 4: AnnounceActivity to/cc + impl OutboundFederationPort for ActivityPubService

**Files:**
- Modify: `crates/adapters/activitypub-base/src/activities.rs`
- Modify: `crates/adapters/activitypub-base/src/service.rs`

- [ ] **Add `to`/`cc` to `AnnounceActivity`** in `crates/adapters/activitypub-base/src/activities.rs` — replace the struct definition (fields only; leave `impl Activity` intact):

```rust
#[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>,
}
```

- [ ] **Run:** `cargo check -p activitypub-base` — Expected: no errors (fields are optional in deserialization due to `default`).

- [ ] **Add `broadcast_announce_to_followers`** to `ActivityPubService` in `crates/adapters/activitypub-base/src/service.rs` — insert before the `follow` method:

```rust
/// Fan out an Announce activity to all accepted followers.
pub async fn broadcast_announce_to_followers(
    &self,
    local_user_id: uuid::Uuid,
    object_ap_id: url::Url,
) -> anyhow::Result<()> {
    let data = self.federation_config.to_request_data();
    let local_actor = get_local_actor(local_user_id, &data)
        .await
        .map_err(|e| anyhow::anyhow!("{e}"))?;

    let followers = data.federation_repo.get_followers(local_user_id).await?;
    let blocked = data.federation_repo.get_blocked_actors(local_user_id).await.unwrap_or_default();
    let blocked_set: std::collections::HashSet<String> = blocked.into_iter().collect();
    let blocked_domains = data.federation_repo.get_blocked_domains().await.unwrap_or_default();
    let blocked_domain_set: std::collections::HashSet<String> =
        blocked_domains.into_iter().map(|d| d.domain).collect();

    let accepted: Vec<_> = followers
        .into_iter()
        .filter(|f| f.status == FollowerStatus::Accepted)
        .filter(|f| !blocked_set.contains(&f.actor.url))
        .filter(|f| {
            let domain = url::Url::parse(&f.actor.inbox_url)
                .ok()
                .and_then(|u| u.host_str().map(|s| s.to_string()))
                .unwrap_or_default();
            !blocked_domain_set.contains(&domain)
        })
        .collect();

    if accepted.is_empty() {
        return Ok(());
    }

    let announce = AnnounceActivity {
        id: crate::urls::activity_url(&self.base_url).map_err(|e| anyhow::anyhow!("{e}"))?,
        kind: Default::default(),
        actor: activitypub_federation::fetch::object_id::ObjectId::from(local_actor.ap_id.clone()),
        object: object_ap_id,
        published: Some(chrono::Utc::now()),
        to: vec![crate::urls::AS_PUBLIC.to_string()],
        cc: vec![local_actor.followers_url.to_string()],
    };

    let inboxes = collect_inboxes(&accepted);
    let sends = activitypub_federation::activity_sending::SendActivityTask::prepare(
        &activitypub_federation::protocol::context::WithContext::new_default(announce),
        &local_actor,
        inboxes,
        &data,
    )
    .await?;
    let failures = send_with_retry(sends, &data).await;
    if !failures.is_empty() {
        tracing::warn!(count = failures.len(), "some Announce deliveries failed");
    }
    Ok(())
}
```

- [ ] **Add `impl OutboundFederationPort for ActivityPubService`** at the bottom of `crates/adapters/activitypub-base/src/service.rs`, after the existing `impl ActivityPubService` block:

```rust
#[async_trait::async_trait]
impl domain::ports::OutboundFederationPort for ActivityPubService {
    async fn broadcast_create(
        &self,
        author_user_id: &domain::value_objects::UserId,
        thought: &domain::models::thought::Thought,
        author_username: &str,
    ) -> Result<(), domain::errors::DomainError> {
        let user_uuid = author_user_id.as_uuid();
        let data = self.federation_config.to_request_data();
        let local_actor = get_local_actor(user_uuid, &data)
            .await
            .map_err(|e| domain::errors::DomainError::Internal(e.to_string()))?;

        let ap_id = url::Url::parse(&format!("{}/thoughts/{}", self.base_url, thought.id))
            .map_err(|e| domain::errors::DomainError::Internal(e.to_string()))?;

        let mut note = serde_json::json!({
            "type": "Note",
            "id": ap_id.to_string(),
            "attributedTo": local_actor.ap_id.to_string(),
            "content": thought.content.as_str(),
            "published": thought.created_at.to_rfc3339(),
            "to": [crate::urls::AS_PUBLIC],
            "cc": [local_actor.followers_url.to_string()],
            "sensitive": thought.sensitive,
        });
        if let Some(ref cw) = thought.content_warning {
            note["summary"] = serde_json::json!(cw);
        }
        if let Some(ref reply_url) = thought.in_reply_to_url {
            note["inReplyTo"] = serde_json::json!(reply_url);
        }

        self.broadcast_to_followers(user_uuid, ap_id, note)
            .await
            .map_err(|e| domain::errors::DomainError::Internal(e.to_string()))
    }

    async fn broadcast_delete(
        &self,
        author_user_id: &domain::value_objects::UserId,
        thought_ap_id: &str,
    ) -> Result<(), domain::errors::DomainError> {
        let user_uuid = author_user_id.as_uuid();
        let ap_id = url::Url::parse(thought_ap_id)
            .map_err(|e| domain::errors::DomainError::Internal(e.to_string()))?;
        self.broadcast_delete_to_followers(user_uuid, ap_id)
            .await
            .map_err(|e| domain::errors::DomainError::Internal(e.to_string()))
    }

    async fn broadcast_update(
        &self,
        author_user_id: &domain::value_objects::UserId,
        thought: &domain::models::thought::Thought,
        author_username: &str,
    ) -> Result<(), domain::errors::DomainError> {
        let user_uuid = author_user_id.as_uuid();
        let data = self.federation_config.to_request_data();
        let local_actor = get_local_actor(user_uuid, &data)
            .await
            .map_err(|e| domain::errors::DomainError::Internal(e.to_string()))?;

        let ap_id = format!("{}/thoughts/{}", self.base_url, thought.id);

        let mut note = serde_json::json!({
            "type": "Note",
            "id": ap_id,
            "attributedTo": local_actor.ap_id.to_string(),
            "content": thought.content.as_str(),
            "published": thought.created_at.to_rfc3339(),
            "to": [crate::urls::AS_PUBLIC],
            "cc": [local_actor.followers_url.to_string()],
            "sensitive": thought.sensitive,
        });
        if let Some(ref cw) = thought.content_warning {
            note["summary"] = serde_json::json!(cw);
        }
        if let Some(ref reply_url) = thought.in_reply_to_url {
            note["inReplyTo"] = serde_json::json!(reply_url);
        }

        self.broadcast_update_to_followers(user_uuid, note)
            .await
            .map_err(|e| domain::errors::DomainError::Internal(e.to_string()))
    }

    async fn broadcast_announce(
        &self,
        booster_user_id: &domain::value_objects::UserId,
        object_ap_id: &str,
    ) -> Result<(), domain::errors::DomainError> {
        let user_uuid = booster_user_id.as_uuid();
        let ap_id = url::Url::parse(object_ap_id)
            .map_err(|e| domain::errors::DomainError::Internal(e.to_string()))?;
        self.broadcast_announce_to_followers(user_uuid, ap_id)
            .await
            .map_err(|e| domain::errors::DomainError::Internal(e.to_string()))
    }
}
```

- [ ] **Run:** `cargo check -p activitypub-base` — Expected: no errors.

- [ ] **Run:** `cargo check --workspace` — Expected: no errors.

- [ ] **Commit:**

```bash
git add crates/adapters/activitypub-base/
git commit -m "feat(activitypub-base): Announce broadcast + impl OutboundFederationPort for ActivityPubService"
```

---

### Task 5: Thin worker handlers + factory + main

**Files:**
- Modify: `crates/worker/Cargo.toml`
- Modify: `crates/worker/src/handlers.rs`
- Create: `crates/worker/src/factory.rs`
- Modify: `crates/worker/src/main.rs`

- [ ] **Update `crates/worker/Cargo.toml`** — add missing deps:

```toml
[package]
name = "worker"
version = "0.1.0"
edition = "2021"

[[bin]]
name = "thoughts-worker"
path = "src/main.rs"

[dependencies]
domain              = { workspace = true }
application         = { workspace = true }
nats                = { workspace = true }
event-payload       = { workspace = true }
event-transport     = { workspace = true }
activitypub-base    = { workspace = true }
activitypub         = { workspace = true }
postgres            = { workspace = true }
postgres-federation = { workspace = true }
async-nats          = { workspace = true }
tokio               = { workspace = true, features = ["full"] }
futures             = { workspace = true }
async-trait         = { workspace = true }
tracing             = { workspace = true }
tracing-subscriber  = { workspace = true }
dotenvy             = { workspace = true }
serde_json          = { workspace = true }
chrono              = { workspace = true }
sqlx                = { workspace = true }

[dev-dependencies]
domain = { workspace = true, features = ["test-helpers"] }
```

- [ ] **Rewrite `crates/worker/src/handlers.rs`** — thin delegation wrappers only, all tests removed (they now live in `application`):

```rust
use std::sync::Arc;
use application::services::{FederationEventService, NotificationEventService};
use domain::{errors::DomainError, events::DomainEvent};

pub struct NotificationHandler {
    pub service: Arc<NotificationEventService>,
}

impl NotificationHandler {
    pub async fn handle(&self, event: &DomainEvent) -> Result<(), DomainError> {
        self.service.process(event).await
    }
}

pub struct FederationHandler {
    pub service: Arc<FederationEventService>,
}

impl FederationHandler {
    pub async fn handle(&self, event: &DomainEvent) -> Result<(), DomainError> {
        self.service.process(event).await
    }
}
```

- [ ] **Create `crates/worker/src/factory.rs`:**

```rust
use std::sync::Arc;
use sqlx::PgPool;

use activitypub::ThoughtsObjectHandler;
use activitypub_base::ActivityPubService;
use application::services::{FederationEventService, NotificationEventService};
use postgres::activitypub::PgActivityPubRepository;
use postgres_federation::{PostgresApUserRepository, PostgresFederationRepository};

use crate::handlers::{FederationHandler, NotificationHandler};

pub struct WorkerHandlers {
    pub notification: NotificationHandler,
    pub federation:   FederationHandler,
}

pub async fn build(
    database_url: &str,
    base_url: &str,
    nats_url: &str,
) -> (
    event_transport::EventConsumerAdapter<nats::NatsMessageSource>,
    WorkerHandlers,
) {
    let pool = PgPool::connect(database_url)
        .await
        .expect("DB connect failed");

    // Repos
    let thoughts      = Arc::new(postgres::thought::PgThoughtRepository::new(pool.clone()));
    let users         = Arc::new(postgres::user::PgUserRepository::new(pool.clone()));
    let notifications = Arc::new(postgres::notification::PgNotificationRepository::new(pool.clone()));

    // ActivityPub service (for federation fan-out)
    let ap_service: Arc<dyn domain::ports::OutboundFederationPort> = Arc::new(
        ActivityPubService::new(
            Arc::new(PostgresFederationRepository::new(pool.clone())),
            Arc::new(PostgresApUserRepository::new(pool.clone(), base_url.to_string())),
            Arc::new(ThoughtsObjectHandler::new(
                Arc::new(PgActivityPubRepository::new(pool.clone())),
                base_url,
            )),
            base_url.to_string(),
            false,
            "thoughts".to_string(),
            false,
            None,
        )
        .await
        .expect("ActivityPubService build failed"),
    );

    // Application services
    let notification_svc = Arc::new(NotificationEventService {
        thoughts: thoughts.clone(),
        notifications,
    });
    let federation_svc = Arc::new(FederationEventService {
        thoughts,
        users,
        ap: ap_service,
        base_url: base_url.to_string(),
    });

    // Thin handlers
    let handlers = WorkerHandlers {
        notification: NotificationHandler { service: notification_svc },
        federation:   FederationHandler   { service: federation_svc   },
    };

    // NATS consumer
    let nats_client = async_nats::connect(nats_url)
        .await
        .expect("NATS connect failed");
    let consumer = event_transport::EventConsumerAdapter::new(
        nats::NatsMessageSource::new(nats_client),
    );

    (consumer, handlers)
}
```

- [ ] **Rewrite `crates/worker/src/main.rs`:**

```rust
mod factory;
mod handlers;

use futures::StreamExt;
use domain::ports::EventConsumer;

#[tokio::main]
async fn main() {
    dotenvy::dotenv().ok();
    tracing_subscriber::fmt()
        .with_env_filter(tracing_subscriber::EnvFilter::from_default_env())
        .init();

    let database_url = std::env::var("DATABASE_URL").expect("DATABASE_URL required");
    let nats_url     = std::env::var("NATS_URL").unwrap_or_else(|_| "nats://localhost:4222".into());
    let base_url     = std::env::var("BASE_URL").expect("BASE_URL required");

    tracing::info!("Building worker...");
    let (consumer, handlers) = factory::build(&database_url, &base_url, &nats_url).await;

    tracing::info!("Worker started, consuming events...");
    let mut stream = consumer.consume();
    while let Some(result) = stream.next().await {
        match result {
            Ok(envelope) => {
                let event = &envelope.event;
                tracing::debug!(?event, "received event");

                let n = handlers.notification.handle(event).await;
                let f = handlers.federation.handle(event).await;

                if n.is_ok() && f.is_ok() {
                    (envelope.ack)();
                } else {
                    if let Err(e) = n { tracing::error!("notification handler: {e}"); }
                    if let Err(e) = f { tracing::error!("federation handler: {e}");   }
                    (envelope.nack)();
                }
            }
            Err(e) => tracing::error!("consumer error: {e}"),
        }
    }
}
```

- [ ] **Run:** `cargo check -p worker` — Expected: no errors.

- [ ] **Run:** `cargo check --workspace` — Expected: no errors.

- [ ] **Run full test suite:**

```bash
DATABASE_URL=postgres://postgres:postgres@localhost:5434/postgres cargo test --workspace 2>&1 | tail -5
```

Expected: all tests pass including the 12 new application service tests.

- [ ] **Commit:**

```bash
git add crates/worker/
git commit -m "refactor(worker): thin handlers + factory — move all business logic to application services"
```

---

## Self-Review

**Spec coverage:**
- ✅ `OutboundFederationPort` in domain, 4 methods in domain language (Task 1)
- ✅ `NotificationEventService` in application, business logic out of worker (Task 2)
- ✅ 5 notification tests in application crate (Task 2)
- ✅ `FederationEventService` in application: ThoughtCreated/Deleted/Updated/BoostAdded (Task 3)
- ✅ Remote thought guard: `local == false` → skip broadcast (Task 3)
- ✅ 7 federation event tests including remote thought guard and remote-boost AP ID (Task 3)
- ✅ `to`/`cc` added to `AnnounceActivity` for AP compliance (Task 4)
- ✅ `broadcast_announce_to_followers` respects blocked actors/domains (Task 4)
- ✅ `impl OutboundFederationPort for ActivityPubService` builds Note JSON with `inReplyTo`, `summary`, `sensitive` (Task 4)
- ✅ `worker/src/factory.rs` owns all composition — main.rs stays tiny (Task 5)
- ✅ Worker handlers are one-liner delegations (Task 5)
- ✅ Follow/Accept/Reject/Block remain synchronous in HTTP handlers — unchanged

**Placeholder scan:** None.

**Type consistency:**
- `UserId::as_uuid()` used in impl — confirmed available in `value_objects.rs:11`
- `Content::as_str()`, `Username::as_str()` — confirmed available
- `Thought.local: bool` — used for guard in `FederationEventService`
- `Thought.ap_id: Option<String>` — used for boost AP ID construction
- `ActivityPubService::broadcast_to_followers(uuid::Uuid, Url, Value)` — matches existing signature
- `broadcast_update_to_followers(uuid::Uuid, Value)` — matches existing signature
- `ThoughtsObjectHandler::new(Arc<dyn ActivityPubRepository>, &str)` — matches bootstrap factory usage
- `PostgresApUserRepository::new(PgPool, String)` — matches bootstrap factory usage