# Audit Gap Fixes 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:** Close the three gaps found in the architectural audit: `unblock_user` publishing a `UserUnblocked` event, `register` publishing a `UserRegistered` event, and the worker creating Reply notifications when a thought is a reply.

**Architecture:** Two new `DomainEvent` variants (`UserUnblocked`, `UserRegistered`) ripple through the event pipeline: added to `events.rs`, serialised in `event-payload`, published in the affected use cases. The worker `NotificationHandler` gains a new arm for `ThoughtCreated` with an `in_reply_to_id`.

**Tech Stack:** Rust, existing domain/event-payload/application/worker crates

---

## File Map

```
Modify: crates/domain/src/events.rs                           ← add UserUnblocked + UserRegistered variants
Modify: crates/adapters/event-payload/src/lib.rs              ← add variants + From<&DomainEvent> + TryFrom arms
Modify: crates/application/src/use_cases/social.rs            ← unblock_user accepts events, publishes UserUnblocked
Modify: crates/application/src/use_cases/auth.rs              ← register publishes UserRegistered
Modify: crates/presentation/src/handlers/social.rs            ← delete_block passes &*s.events
Modify: crates/worker/src/handlers.rs                         ← ThoughtCreated arm → Reply notification
```

---

### Task 1: New DomainEvent variants + event-payload + use case fixes

**Files:**
- Modify: `crates/domain/src/events.rs`
- Modify: `crates/adapters/event-payload/src/lib.rs`
- Modify: `crates/application/src/use_cases/social.rs`
- Modify: `crates/application/src/use_cases/auth.rs`
- Modify: `crates/presentation/src/handlers/social.rs`

- [ ] **Write failing tests** — add to `crates/application/src/use_cases/social.rs` test module (bottom of existing `#[cfg(test)] mod tests`):

```rust
    #[tokio::test]
    async fn unblock_user_publishes_event() {
        let store = TestStore::default();
        let alice = user("alice");
        let bob   = user("bob");
        // block first so we can unblock
        block_user(&store, &store, &alice.id, &bob.id).await.unwrap();
        store.events.lock().unwrap().clear(); // reset after block event
        unblock_user(&store, &store, &alice.id, &bob.id).await.unwrap();
        let events = store.events.lock().unwrap();
        assert_eq!(events.len(), 1);
        assert!(matches!(events[0], DomainEvent::UserUnblocked { .. }));
    }
```

Add to `crates/application/src/use_cases/auth.rs` test module:

```rust
    #[tokio::test]
    async fn register_publishes_user_registered_event() {
        let store = TestStore::default();
        register(&store, &FakeHasher, &FakeAuth, &store, input()).await.unwrap();
        let events = store.events.lock().unwrap();
        assert_eq!(events.len(), 1);
        assert!(matches!(events[0], DomainEvent::UserRegistered { .. }));
    }
```

Note: in the auth test, `&store` is passed as the `events` argument (TestStore implements EventPublisher). The existing tests use `&NoOpEventPublisher` — leave those unchanged, they still pass. Only the new test passes `&store` to capture events.

- [ ] **Run:** `cargo test -p application` — Expected: FAIL (UserUnblocked + UserRegistered not defined).

- [ ] **Add variants to `crates/domain/src/events.rs`** — append two variants to the `DomainEvent` enum, after `UserBlocked`:

```rust
    UserUnblocked { blocker_id: UserId, blocked_id: UserId },
    UserRegistered { user_id: UserId },
```

- [ ] **Add variants to `crates/adapters/event-payload/src/lib.rs`**:

**In the `EventPayload` enum** — append after `UserBlocked`:

```rust
    UserUnblocked {
        blocker_id: String,
        blocked_id: String,
    },
    UserRegistered {
        user_id: String,
    },
```

**In `subject()`** — append after the `Self::UserBlocked` arm:

```rust
            Self::UserUnblocked { .. } => "users.unblocked",
            Self::UserRegistered { .. } => "users.registered",
```

**In `impl From<&DomainEvent> for EventPayload`** — append after the `DomainEvent::UserBlocked` arm:

```rust
            DomainEvent::UserUnblocked { blocker_id, blocked_id } => Self::UserUnblocked {
                blocker_id: blocker_id.to_string(),
                blocked_id: blocked_id.to_string(),
            },
            DomainEvent::UserRegistered { user_id } => Self::UserRegistered {
                user_id: user_id.to_string(),
            },
```

**In `impl TryFrom<EventPayload> for DomainEvent`** — append after the `EventPayload::UserBlocked` arm:

```rust
            EventPayload::UserUnblocked { blocker_id, blocked_id } => DomainEvent::UserUnblocked {
                blocker_id: UserId::from_uuid(parse_uuid(&blocker_id, "blocker_id")?),
                blocked_id: UserId::from_uuid(parse_uuid(&blocked_id, "blocked_id")?),
            },
            EventPayload::UserRegistered { user_id } => DomainEvent::UserRegistered {
                user_id: UserId::from_uuid(parse_uuid(&user_id, "user_id")?),
            },
```

- [ ] **Update `unblock_user` in `crates/application/src/use_cases/social.rs`**:

Replace the current function (which takes only `blocks` and two UserId params):

```rust
pub async fn unblock_user(blocks: &dyn BlockRepository, blocker_id: &UserId, blocked_id: &UserId) -> Result<(), DomainError> {
    blocks.delete(blocker_id, blocked_id).await?;
    Ok(())
}
```

With:

```rust
pub async fn unblock_user(
    blocks: &dyn BlockRepository,
    events: &dyn EventPublisher,
    blocker_id: &UserId,
    blocked_id: &UserId,
) -> Result<(), DomainError> {
    blocks.delete(blocker_id, blocked_id).await?;
    events.publish(&DomainEvent::UserUnblocked {
        blocker_id: blocker_id.clone(),
        blocked_id: blocked_id.clone(),
    }).await?;
    Ok(())
}
```

- [ ] **Update `register` in `crates/application/src/use_cases/auth.rs`**:

Change the parameter from `_events` to `events` (remove the underscore) and add one line after `users.save(&user).await?;`:

```rust
pub async fn register(
    users: &dyn UserRepository,
    hasher: &dyn PasswordHasher,
    auth: &dyn AuthService,
    events: &dyn EventPublisher,    // ← remove leading underscore
    input: RegisterInput,
) -> Result<RegisterOutput, DomainError> {
    let username = Username::new(input.username)?;
    let email = Email::new(input.email)?;
    if users.find_by_username(&username).await?.is_some() {
        return Err(DomainError::Conflict("username taken".into()));
    }
    if users.find_by_email(&email).await?.is_some() {
        return Err(DomainError::Conflict("email taken".into()));
    }
    let hash = hasher.hash(&input.password).await?;
    let user = User::new_local(UserId::new(), username, email, hash);
    users.save(&user).await?;
    events.publish(&DomainEvent::UserRegistered { user_id: user.id.clone() }).await?;  // ← new
    let token = auth.generate_token(&user.id)?;
    Ok(RegisterOutput { user, token: token.token })
}
```

- [ ] **Update `delete_block` handler in `crates/presentation/src/handlers/social.rs`**:

The handler currently calls `unblock_user(&*s.blocks, &uid, &UserId::from_uuid(target))`. Add `&*s.events` as the second argument:

```rust
pub async fn delete_block(State(s): State<AppState>, AuthUser(uid): AuthUser, Path(target): Path<Uuid>) -> Result<StatusCode, ApiError> {
    unblock_user(&*s.blocks, &*s.events, &uid, &UserId::from_uuid(target)).await?;
    Ok(StatusCode::NO_CONTENT)
}
```

- [ ] **Run:** `cargo test -p application` — Expected: all tests pass including 2 new ones.

- [ ] **Run:** `cargo check --workspace` — Expected: no errors (the handler change + event-payload additions must compile).

- [ ] **Commit:**

```bash
git add crates/domain/src/events.rs \
        crates/adapters/event-payload/src/lib.rs \
        crates/application/src/use_cases/social.rs \
        crates/application/src/use_cases/auth.rs \
        crates/presentation/src/handlers/social.rs
git commit -m "feat: UserUnblocked + UserRegistered events, fix unblock_user and register signatures"
```

---

### Task 2: Reply notifications in worker

**Files:**
- Modify: `crates/worker/src/handlers.rs`

- [ ] **Write the failing test** — add to the existing `#[cfg(test)] mod tests` block in `crates/worker/src/handlers.rs`, after `follow_accepted_creates_notification`:

```rust
    #[tokio::test]
    async fn reply_creates_notification_for_original_author() {
        let store = TestStore::default();
        let alice = alice(); // author of the original thought
        let bob_id = UserId::new(); // author of the reply

        let original = Thought::new_local(
            ThoughtId::new(), alice.id.clone(),
            Content::new_local("original thought").unwrap(),
            None, Visibility::Public, None, false,
        );
        store.users.lock().unwrap().push(alice.clone());
        store.thoughts.lock().unwrap().push(original.clone());

        let reply_id = ThoughtId::new();
        let handler = NotificationHandler {
            thoughts:      Arc::new(store.clone()),
            notifications: Arc::new(store.clone()),
        };

        // ThoughtCreated with in_reply_to_id pointing at alice's thought
        handler.handle(&DomainEvent::ThoughtCreated {
            thought_id: reply_id,
            user_id: bob_id.clone(),
            in_reply_to_id: Some(original.id.clone()),
        }).await.unwrap();

        let notifs = store.notifications.lock().unwrap();
        assert_eq!(notifs.len(), 1);
        assert_eq!(notifs[0].user_id, alice.id);
        assert!(matches!(notifs[0].notification_type, NotificationType::Reply));
    }

    #[tokio::test]
    async fn self_reply_does_not_create_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.users.lock().unwrap().push(alice.clone());
        store.thoughts.lock().unwrap().push(original.clone());

        let handler = NotificationHandler {
            thoughts:      Arc::new(store.clone()),
            notifications: Arc::new(store.clone()),
        };

        handler.handle(&DomainEvent::ThoughtCreated {
            thought_id: ThoughtId::new(),
            user_id: alice.id.clone(), // alice replying to herself
            in_reply_to_id: Some(original.id.clone()),
        }).await.unwrap();

        assert!(store.notifications.lock().unwrap().is_empty());
    }

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

        let handler = NotificationHandler {
            thoughts:      Arc::new(store.clone()),
            notifications: Arc::new(store.clone()),
        };

        handler.handle(&DomainEvent::ThoughtCreated {
            thought_id: ThoughtId::new(),
            user_id: alice.id.clone(),
            in_reply_to_id: None, // not a reply
        }).await.unwrap();

        assert!(store.notifications.lock().unwrap().is_empty());
    }
```

- [ ] **Run:** `DATABASE_URL=postgres://postgres:postgres@localhost:5434/postgres cargo test -p worker` — Expected: FAIL on 3 new tests (reply handling not implemented).

- [ ] **Add the `ThoughtCreated` arm** to `NotificationHandler::handle` in `crates/worker/src/handlers.rs` — insert before the final `_ => Ok(()),` arm:

```rust
            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(()), // not a reply — no notification needed
                };
                let original = match self.thoughts.find_by_id(reply_to_id).await? {
                    Some(t) => t,
                    None => return Ok(()), // original thought deleted — skip
                };
                if original.user_id == *user_id { return Ok(()); } // no self-notifications
                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
            }
```

- [ ] **Run:** `cargo test -p worker` — Expected: all 6 tests pass (3 existing + 3 new).

- [ ] **Run full suite:** `DATABASE_URL=postgres://postgres:postgres@localhost:5434/postgres cargo test --workspace 2>&1 | tail -3` — Expected: all tests pass.

- [ ] **Commit:**

```bash
git add crates/worker/src/handlers.rs
git commit -m "feat(worker): Reply notification when ThoughtCreated has in_reply_to_id"
```

---

## Self-Review

**Spec coverage:**
- ✅ `UserUnblocked` added to DomainEvent (Task 1)
- ✅ `UserRegistered` added to DomainEvent (Task 1)
- ✅ Both variants added to EventPayload with subject routing (Task 1)
- ✅ Both variants covered in From<&DomainEvent> and TryFrom<EventPayload> (Task 1)
- ✅ `unblock_user` now accepts `events` and publishes `UserUnblocked` (Task 1)
- ✅ `register` now publishes `UserRegistered` (Task 1)
- ✅ `delete_block` handler passes `&*s.events` (Task 1)
- ✅ `ThoughtCreated` with `in_reply_to_id` triggers Reply notification (Task 2)
- ✅ Self-reply suppressed (Task 2)
- ✅ Plain thought (no reply) triggers no notification (Task 2)

**Placeholder scan:** None.

**Type consistency:**
- `DomainEvent::UserUnblocked { blocker_id: UserId, blocked_id: UserId }` — matches use case publish call and EventPayload From arm
- `DomainEvent::UserRegistered { user_id: UserId }` — matches use case publish call and EventPayload From arm
- `NotificationType::Reply` — already exists in `domain/src/models/notification.rs`
- `unblock_user(blocks, events, blocker_id, blocked_id)` — matches updated handler call in `delete_block`

**Notes:**
- `NotificationType::Reply` was already defined in domain models (Plan 1) — no domain model change needed
- The `event-payload` `all_subjects_are_unique` test will catch duplicate NATS subjects — the new subjects "users.unblocked" and "users.registered" are unique