refactor(nats): strip NatsEventPublisher, add NatsTransport implementing Transport

crates/adapters/nats/Cargo.toml

@@ -6,6 +6,7 @@ edition = "2021"
 [dependencies]
 domain           = { workspace = true }
 event-payload    = { workspace = true }
+event-publisher  = { workspace = true }
 async-nats       = { workspace = true }
 async-stream     = { workspace = true }
 serde_json       = { workspace = true }

crates/adapters/nats/src/lib.rs

@@ -2,36 +2,33 @@ use async_trait::async_trait;
 use domain::{
     errors::DomainError,
     events::{DomainEvent, EventEnvelope},
-    ports::{EventConsumer, EventPublisher},
+    ports::EventConsumer,
 };
 use event_payload::EventPayload;
+use event_publisher::Transport;
 use futures::stream::BoxStream;
 
-// ── NatsEventPublisher ────────────────────────────────────────────────────
+// ── NatsTransport — raw NATS publish backend ────────────────────────────────
 
-pub struct NatsEventPublisher {
+pub struct NatsTransport {
     client: async_nats::Client,
 }
 
-impl NatsEventPublisher {
+impl NatsTransport {
     pub fn new(client: async_nats::Client) -> Self { Self { client } }
 }
 
 #[async_trait]
-impl EventPublisher for NatsEventPublisher {
-    async fn publish(&self, event: &DomainEvent) -> Result<(), DomainError> {
-        let payload = EventPayload::from(event);
-        let subject = payload.subject();
-        let bytes = serde_json::to_vec(&payload)
-            .map_err(|e| DomainError::Internal(e.to_string()))?;
+impl Transport for NatsTransport {
+    async fn publish_bytes(&self, subject: &str, bytes: &[u8]) -> Result<(), DomainError> {
         self.client
-            .publish(subject, bytes.into())
+            .publish(subject.to_string(), bytes.to_vec().into())
             .await
             .map_err(|e| DomainError::Internal(e.to_string()))
     }
 }
 
-// ── NatsEventConsumer ─────────────────────────────────────────────────────
+// ── NatsEventConsumer — subscribes and yields EventEnvelopes ────────────────
 
 pub struct NatsEventConsumer {
     client: async_nats::Client,
@@ -66,7 +63,6 @@ impl EventConsumer for NatsEventConsumer {
                         continue;
                     }
                 };
-                // Basic NATS: no ack/nack (at-most-once delivery)
                 yield EventEnvelope {
                     event,
                     ack:  Box::new(|| {}),