feat: event infrastructure — payload, transport, NATS adapter

- EventPublisher now takes &DomainEvent (11 call sites + 3 impls updated)
- EventEnvelope + EventConsumer port in domain
- event-payload: serializable DomainEvent mirror with subject routing
- event-transport: generic Transport/MessageSource traits, publisher/consumer adapters
- adapters-nats: JetStream publish + durable pull consumer

crates/adapters/nats/src/lib.rs

@@ -0,0 +1,214 @@
+use async_nats::jetstream::{self, AckKind, stream::Config as StreamConfig};
+use async_trait::async_trait;
+use domain::errors::DomainError;
+use event_transport::{MessageSource, RawMessage, Transport};
+use futures::stream::BoxStream;
+use std::sync::Arc;
+
+const STREAM_NAME: &str = "KPHOTOS_EVENTS";
+const STREAM_SUBJECT: &str = "kphotos-events.>";
+const CONSUMER_NAME: &str = "worker";
+const MAX_MESSAGES: i64 = 100_000;
+
+pub const CONSUMER_MAX_DELIVER: i64 = 5;
+const CONSUMER_ACK_WAIT_SECS: u64 = 30;
+const ACK_TASK_TIMEOUT_SECS: u64 = 5;
+
+fn stream_config() -> StreamConfig {
+    StreamConfig {
+        name: STREAM_NAME.to_string(),
+        subjects: vec![STREAM_SUBJECT.to_string()],
+        max_messages: MAX_MESSAGES,
+        ..Default::default()
+    }
+}
+
+pub async fn ensure_stream(client: &async_nats::Client) -> Result<(), DomainError> {
+    let js = jetstream::new(client.clone());
+
+    if js.update_stream(stream_config()).await.is_ok() {
+        tracing::info!(subject = STREAM_SUBJECT, "JetStream stream updated");
+        return Ok(());
+    }
+
+    tracing::warn!(
+        "JetStream stream update failed (incompatible config), deleting '{STREAM_NAME}' and recreating"
+    );
+    let _ = js.delete_stream(STREAM_NAME).await;
+
+    js.create_stream(stream_config())
+        .await
+        .map(|_| ())
+        .map_err(|e| DomainError::Internal(format!("JetStream stream create failed: {e}")))
+}
+
+pub struct NatsTransport {
+    jetstream: jetstream::Context,
+}
+
+impl NatsTransport {
+    pub fn new(client: async_nats::Client) -> Self {
+        Self {
+            jetstream: jetstream::new(client),
+        }
+    }
+}
+
+#[async_trait]
+impl Transport for NatsTransport {
+    async fn publish_bytes(&self, subject: &str, bytes: &[u8]) -> Result<(), DomainError> {
+        let full_subject = format!("kphotos-events.{subject}");
+        self.jetstream
+            .publish(full_subject, bytes.to_vec().into())
+            .await
+            .map_err(|e| DomainError::Internal(e.to_string()))?
+            .await
+            .map_err(|e| DomainError::Internal(e.to_string()))?;
+        Ok(())
+    }
+}
+
+pub struct NatsMessageSource {
+    jetstream: jetstream::Context,
+}
+
+impl NatsMessageSource {
+    pub fn new(client: async_nats::Client) -> Self {
+        Self {
+            jetstream: jetstream::new(client),
+        }
+    }
+}
+
+impl MessageSource for NatsMessageSource {
+    fn messages(&self) -> BoxStream<'_, Result<RawMessage, DomainError>> {
+        use futures::stream;
+        use tokio::sync::Mutex as TokioMutex;
+
+        let js = self.jetstream.clone();
+        let (tx, rx) = tokio::sync::mpsc::channel::<Result<RawMessage, DomainError>>(128);
+
+        tokio::spawn(async move {
+            let stream = match js.get_stream(STREAM_NAME).await {
+                Ok(s) => s,
+                Err(e) => {
+                    let _ = tx.send(Err(DomainError::Internal(e.to_string()))).await;
+                    return;
+                }
+            };
+
+            if let Ok(info) = stream.consumer_info(CONSUMER_NAME).await
+                && info.config.deliver_subject.is_some()
+            {
+                tracing::info!(
+                    "deleting old push consumer '{CONSUMER_NAME}', replacing with pull"
+                );
+                let _ = stream.delete_consumer(CONSUMER_NAME).await;
+            }
+
+            let consumer = match stream
+                .get_or_create_consumer(
+                    CONSUMER_NAME,
+                    jetstream::consumer::pull::Config {
+                        durable_name: Some(CONSUMER_NAME.to_string()),
+                        deliver_policy: jetstream::consumer::DeliverPolicy::New,
+                        ack_policy: jetstream::consumer::AckPolicy::Explicit,
+                        ack_wait: std::time::Duration::from_secs(CONSUMER_ACK_WAIT_SECS),
+                        max_deliver: CONSUMER_MAX_DELIVER,
+                        ..Default::default()
+                    },
+                )
+                .await
+            {
+                Ok(c) => c,
+                Err(e) => {
+                    let _ = tx.send(Err(DomainError::Internal(e.to_string()))).await;
+                    return;
+                }
+            };
+
+            tracing::info!("NATS pull consumer ready");
+
+            loop {
+                let mut messages = match consumer.messages().await {
+                    Ok(m) => m,
+                    Err(e) => {
+                        tracing::error!("NATS messages() failed: {e}");
+                        let _ = tx.send(Err(DomainError::Internal(e.to_string()))).await;
+                        return;
+                    }
+                };
+
+                use futures::StreamExt;
+                while let Some(result) = messages.next().await {
+                    let msg = match result {
+                        Ok(m) => m,
+                        Err(e) => {
+                            tracing::warn!("NATS message error: {e}");
+                            continue;
+                        }
+                    };
+
+                    let subject = msg.subject.to_string();
+                    let payload = msg.payload.to_vec();
+                    let delivery_count = msg
+                        .info()
+                        .map(|info| info.delivered.max(0) as u64)
+                        .unwrap_or(1);
+                    let msg = Arc::new(msg);
+                    let msg_nack = Arc::clone(&msg);
+
+                    let raw = RawMessage {
+                        subject,
+                        payload,
+                        delivery_count,
+                        ack: Box::new(move || {
+                            let m = Arc::clone(&msg);
+                            tokio::spawn(async move {
+                                let result = tokio::time::timeout(
+                                    std::time::Duration::from_secs(ACK_TASK_TIMEOUT_SECS),
+                                    m.ack(),
+                                )
+                                .await;
+                                match result {
+                                    Ok(Ok(())) => {}
+                                    Ok(Err(e)) => tracing::warn!("NATS ack failed: {e}"),
+                                    Err(_) => tracing::warn!(
+                                        "NATS ack timed out after {ACK_TASK_TIMEOUT_SECS}s"
+                                    ),
+                                }
+                            });
+                        }),
+                        nack: Box::new(move || {
+                            let m = Arc::clone(&msg_nack);
+                            tokio::spawn(async move {
+                                let result = tokio::time::timeout(
+                                    std::time::Duration::from_secs(ACK_TASK_TIMEOUT_SECS),
+                                    m.ack_with(AckKind::Nak(None)),
+                                )
+                                .await;
+                                match result {
+                                    Ok(Ok(())) => {}
+                                    Ok(Err(e)) => tracing::warn!("NATS nack failed: {e}"),
+                                    Err(_) => tracing::warn!(
+                                        "NATS nack timed out after {ACK_TASK_TIMEOUT_SECS}s"
+                                    ),
+                                }
+                            });
+                        }),
+                    };
+
+                    if tx.send(Ok(raw)).await.is_err() {
+                        return;
+                    }
+                }
+            }
+        });
+
+        let rx = Arc::new(TokioMutex::new(rx));
+        Box::pin(stream::unfold(rx, |rx| async move {
+            let item = rx.lock().await.recv().await?;
+            Some((item, rx))
+        }))
+    }
+}