feat(presentation): /federation/lookup and /federation/follow endpoints

crates/api-types/src/requests.rs

@@ -80,3 +80,9 @@ pub struct SearchQuery {
     pub page: Option<u64>,
     pub per_page: Option<u64>,
 }
+
+#[derive(serde::Deserialize, utoipa::ToSchema)]
+#[serde(rename_all = "camelCase")]
+pub struct FollowRemoteRequest {
+    pub handle: String,
+}

crates/api-types/src/responses.rs

@@ -87,3 +87,12 @@ pub struct CreatedApiKeyResponse {
     /// Raw API key — shown only once at creation
     pub key: String,
 }
+
+#[derive(Serialize, utoipa::ToSchema)]
+#[serde(rename_all = "camelCase")]
+pub struct RemoteActorResponse {
+    pub handle: String,
+    pub display_name: Option<String>,
+    pub avatar_url: Option<String>,
+    pub url: String,
+}

crates/presentation/src/handlers/federation.rs

@@ -0,0 +1,130 @@
+use axum::{
+    extract::{Query, State},
+    http::StatusCode,
+    Json,
+};
+use serde::Deserialize;
+
+use api_types::{requests::FollowRemoteRequest, responses::RemoteActorResponse};
+
+use crate::{errors::ApiError, extractors::AuthUser, state::AppState};
+
+#[derive(Deserialize)]
+pub struct LookupQuery {
+    pub handle: String,
+}
+
+pub async fn lookup_handler(
+    State(s): State<AppState>,
+    Query(q): Query<LookupQuery>,
+) -> Result<Json<RemoteActorResponse>, ApiError> {
+    let actor = s.federation.lookup_actor(&q.handle).await?;
+    Ok(Json(RemoteActorResponse {
+        handle: actor.handle,
+        display_name: actor.display_name,
+        avatar_url: actor.avatar_url,
+        url: actor.url,
+    }))
+}
+
+pub async fn follow_remote_handler(
+    State(s): State<AppState>,
+    AuthUser(uid): AuthUser,
+    Json(body): Json<FollowRemoteRequest>,
+) -> Result<StatusCode, ApiError> {
+    s.federation.follow_remote(&uid, &body.handle).await?;
+    Ok(StatusCode::NO_CONTENT)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use async_trait::async_trait;
+    use axum::{
+        body::Body,
+        http::{Request, StatusCode},
+        routing::{get, post},
+        Router,
+    };
+    use domain::{
+        errors::DomainError,
+        ports::{AuthService, GeneratedToken, PasswordHasher},
+        testing::TestStore,
+        value_objects::{PasswordHash, UserId},
+    };
+    use std::sync::Arc;
+    use tower::ServiceExt;
+
+    struct NoOpAuth;
+    impl AuthService for NoOpAuth {
+        fn generate_token(&self, _uid: &UserId) -> Result<GeneratedToken, DomainError> {
+            Err(DomainError::Internal("noop".into()))
+        }
+        fn validate_token(&self, _token: &str) -> Result<UserId, DomainError> {
+            Err(DomainError::Unauthorized)
+        }
+    }
+
+    struct NoOpHasher;
+    #[async_trait]
+    impl PasswordHasher for NoOpHasher {
+        async fn hash(&self, _plain: &str) -> Result<PasswordHash, DomainError> {
+            Err(DomainError::Internal("noop".into()))
+        }
+        async fn verify(&self, _plain: &str, _hash: &PasswordHash) -> Result<bool, DomainError> {
+            Ok(false)
+        }
+    }
+
+    fn make_state() -> crate::state::AppState {
+        let store = Arc::new(TestStore::default());
+        crate::state::AppState {
+            users: store.clone(),
+            thoughts: store.clone(),
+            likes: store.clone(),
+            boosts: store.clone(),
+            follows: store.clone(),
+            blocks: store.clone(),
+            tags: store.clone(),
+            api_keys: store.clone(),
+            top_friends: store.clone(),
+            notifications: store.clone(),
+            remote_actors: store.clone(),
+            feed: store.clone(),
+            search: store.clone(),
+            auth: Arc::new(NoOpAuth),
+            hasher: Arc::new(NoOpHasher),
+            events: store.clone(),
+            federation: store.clone(),
+        }
+    }
+
+    fn app() -> Router {
+        Router::new()
+            .route("/federation/lookup", get(lookup_handler))
+            .route("/federation/follow", post(follow_remote_handler))
+            .with_state(make_state())
+    }
+
+    #[tokio::test]
+    async fn lookup_unknown_handle_returns_404() {
+        let req = Request::builder()
+            .uri("/federation/lookup?handle=%40alice%40example.com")
+            .body(Body::empty())
+            .unwrap();
+        let resp = app().oneshot(req).await.unwrap();
+        assert_eq!(resp.status(), StatusCode::NOT_FOUND);
+    }
+
+    #[tokio::test]
+    async fn follow_remote_without_auth_returns_401() {
+        let req = Request::builder()
+            .method("POST")
+            .uri("/federation/follow")
+            .header("content-type", "application/json")
+            .body(Body::from(r#"{"handle":"@alice@example.com"}"#))
+            .unwrap();
+        let resp = app().oneshot(req).await.unwrap();
+        assert_eq!(resp.status(), StatusCode::UNAUTHORIZED);
+    }
+}

crates/presentation/src/handlers/mod.rs

@@ -1,5 +1,6 @@
 pub mod api_keys;
 pub mod auth;
+pub mod federation;
 pub mod feed;
 pub mod health;
 pub mod notifications;

crates/presentation/src/routes.rs

@@ -92,7 +92,13 @@ pub fn router() -> Router<AppState> {
             "/api-keys",
             get(api_keys::get_api_keys).post(api_keys::post_api_key),
         )
-        .route("/api-keys/{id}", delete(api_keys::delete_api_key_handler));
+        .route("/api-keys/{id}", delete(api_keys::delete_api_key_handler))
+        // federation
+        .route("/federation/lookup", get(federation::lookup_handler))
+        .route(
+            "/federation/follow",
+            post(federation::follow_remote_handler),
+        );
 
     openapi::serve(api_routes)
 }