feat(presentation): NatsEventPublisher with no-op fallback when NATS_URL unset

crates/presentation/Cargo.toml

@@ -14,6 +14,8 @@ api-types   = { workspace = true }
 postgres    = { workspace = true }
 postgres-search = { workspace = true }
 auth        = { workspace = true }
+nats        = { workspace = true }
+async-nats  = { workspace = true }
 axum        = { workspace = true }
 sqlx        = { workspace = true }
 tower-http  = { workspace = true }

crates/presentation/src/lib.rs

@@ -5,23 +5,36 @@ pub mod routes;
 pub mod state;
 
 use std::sync::Arc;
-use sqlx::PgPool;
-use state::AppState;
-use postgres_search::PgSearchRepository;
-
 use async_trait::async_trait;
+use sqlx::PgPool;
 use domain::{errors::DomainError, events::DomainEvent, ports::EventPublisher};
+use postgres_search::PgSearchRepository;
+use state::AppState;
 
 struct NoOpEventPublisher;
-
 #[async_trait]
 impl EventPublisher for NoOpEventPublisher {
-    async fn publish(&self, _e: &DomainEvent) -> Result<(), DomainError> {
-        Ok(())
-    }
+    async fn publish(&self, _e: &DomainEvent) -> Result<(), DomainError> { Ok(()) }
 }
 
-pub fn build_state(pool: PgPool, jwt_secret: String) -> AppState {
+pub async fn build_state(pool: PgPool, jwt_secret: String) -> AppState {
+    let event_publisher: Arc<dyn EventPublisher> = match std::env::var("NATS_URL") {
+        Ok(url) => match async_nats::connect(&url).await {
+            Ok(client) => {
+                tracing::info!("Connected to NATS at {url}");
+                Arc::new(nats::NatsEventPublisher::new(client))
+            }
+            Err(e) => {
+                tracing::warn!("Failed to connect to NATS at {url}: {e} — using no-op publisher");
+                Arc::new(NoOpEventPublisher)
+            }
+        },
+        Err(_) => {
+            tracing::info!("NATS_URL not set — using no-op event publisher");
+            Arc::new(NoOpEventPublisher)
+        }
+    };
+
     AppState {
         users:         Arc::new(postgres::user::PgUserRepository::new(pool.clone())),
         thoughts:      Arc::new(postgres::thought::PgThoughtRepository::new(pool.clone())),
@@ -38,6 +51,6 @@ pub fn build_state(pool: PgPool, jwt_secret: String) -> AppState {
         search:        Arc::new(PgSearchRepository::new(pool.clone())),
         auth:          Arc::new(auth::JwtAuthService::new(jwt_secret, 86400 * 30)),
         hasher:        Arc::new(auth::Argon2PasswordHasher),
-        events:        Arc::new(NoOpEventPublisher),
+        events:        event_publisher,
     }
 }

crates/presentation/src/main.rs

@@ -16,7 +16,7 @@ async fn main() {
     let pool = PgPool::connect(&database_url).await.expect("DB connect failed");
     sqlx::migrate!("../adapters/postgres/migrations").run(&pool).await.expect("Migrations failed");
 
-    let state = presentation::build_state(pool, jwt_secret);
+    let state = presentation::build_state(pool, jwt_secret).await;
     let app = presentation::routes::router()
         .with_state(state)
         .layer(CorsLayer::permissive());