feat: worker relays outbox to nats

crates/adapters/nats/src/lib.rs

@@ -1,52 +1,41 @@
 mod config;
 mod consumer;
 mod payload;
-mod publisher;
+mod relay;
 mod subject;
 
 pub use config::{NatsConfig, NatsMode};
 pub use consumer::{NatsCoreConsumer, NatsJetStreamConsumer};
-pub use publisher::NatsEventPublisher;
+pub use relay::NatsRelaySink;
 
 use std::sync::Arc;
 
-use domain::ports::{EventConsumer, EventPublisher};
+use domain::ports::{EventConsumer, EventRelaySink};
 
-pub async fn create_publisher(cfg: NatsConfig) -> anyhow::Result<Arc<dyn EventPublisher>> {
-    let client = async_nats::connect(&cfg.url).await?;
-    let publisher: Arc<dyn EventPublisher> = match cfg.mode {
-        NatsMode::Core => Arc::new(NatsEventPublisher::new_core(client, cfg.subject_prefix)),
-        NatsMode::JetStream => Arc::new(NatsEventPublisher::new_jetstream(
-            client,
-            cfg.subject_prefix,
-        )),
-    };
-
-    tracing::info!("NATS publisher created (mode: {:?})", cfg.mode);
-    Ok(publisher)
-}
-
-pub async fn create_channel(
+/// The worker's NATS side: where handlers read events from, and where the
+/// outbox relay writes them to.
+pub async fn create_bus(
     cfg: NatsConfig,
-) -> anyhow::Result<(Arc<dyn EventPublisher>, Arc<dyn EventConsumer>)> {
+) -> anyhow::Result<(Arc<dyn EventConsumer>, Arc<dyn EventRelaySink>)> {
     let client = async_nats::connect(&cfg.url).await?;
 
-    let publisher: Arc<dyn EventPublisher> = match cfg.mode {
-        NatsMode::Core => Arc::new(NatsEventPublisher::new_core(
-            client.clone(),
-            cfg.subject_prefix.clone(),
-        )),
-        NatsMode::JetStream => Arc::new(NatsEventPublisher::new_jetstream(
-            client.clone(),
-            cfg.subject_prefix.clone(),
-        )),
+    let (consumer, sink): (Arc<dyn EventConsumer>, Arc<dyn EventRelaySink>) = match cfg.mode {
+        NatsMode::Core => {
+            tracing::info!(
+                "core NATS mode: no broker-side dedup or redelivery; relying on consumer ledger"
+            );
+            (
+                Arc::new(NatsCoreConsumer::create(&cfg, client.clone()).await?),
+                Arc::new(NatsRelaySink::new_core(client, cfg.subject_prefix)),
+            )
+        }
+        // The consumer creates the stream the relay publishes into.
+        NatsMode::JetStream => (
+            Arc::new(NatsJetStreamConsumer::create(&cfg, client.clone()).await?),
+            Arc::new(NatsRelaySink::new_jetstream(client, cfg.subject_prefix)),
+        ),
     };
 
-    let consumer: Arc<dyn EventConsumer> = match cfg.mode {
-        NatsMode::Core => Arc::new(NatsCoreConsumer::create(&cfg, client).await?),
-        NatsMode::JetStream => Arc::new(NatsJetStreamConsumer::create(&cfg, client).await?),
-    };
-
-    tracing::info!("NATS channel created (mode: {:?})", cfg.mode);
-    Ok((publisher, consumer))
+    tracing::info!("NATS bus created (mode: {:?})", cfg.mode);
+    Ok((consumer, sink))
 }