feat(core): implement event outbox persistence

Add domain_events migration and SeaORM entity. Modify EventBus::publish
to persist events before broadcasting (best-effort: DB failure logs
warning but still broadcasts in-memory). Update all 19 publish call
sites across 4 crates to pass db reference.

Add outbox relay background task that polls pending events every 5s
and re-broadcasts them, ensuring no events are lost on server restart.

crates/erp-server/src/main.rs

@@ -2,6 +2,7 @@ mod config;
 mod db;
 mod handlers;
 mod middleware;
+mod outbox;
 mod state;
 
 /// OpenAPI 规范定义（预留，未来可通过 utoipa derive 合并各模块 schema）。
@@ -142,6 +143,10 @@ async fn main() -> anyhow::Result<()> {
     erp_message::MessageModule::start_event_listener(db.clone(), event_bus.clone());
     tracing::info!("Message event listener started");
 
+    // Start outbox relay (re-publish pending domain events)
+    outbox::start_outbox_relay(db.clone(), event_bus.clone());
+    tracing::info!("Outbox relay started");
+
     let host = config.server.host.clone();
     let port = config.server.port;
 

crates/erp-server/src/outbox.rs

@@ -0,0 +1,58 @@
+use chrono::Utc;
+use sea_orm::{ActiveModelTrait, ColumnTrait, EntityTrait, QueryFilter, Set};
+use std::time::Duration;
+
+use erp_core::entity::domain_event;
+use erp_core::events::{DomainEvent, EventBus};
+
+/// 启动 outbox relay 后台任务。
+///
+/// 定期扫描 domain_events 表中 status = 'pending' 的事件，
+/// 重新广播并标记为 published。
+pub fn start_outbox_relay(db: sea_orm::DatabaseConnection, event_bus: EventBus) {
+    tokio::spawn(async move {
+        let mut interval = tokio::time::interval(Duration::from_secs(5));
+        loop {
+            interval.tick().await;
+            if let Err(e) = process_pending_events(&db, &event_bus).await {
+                tracing::warn!(error = %e, "Outbox relay 处理失败");
+            }
+        }
+    });
+}
+
+async fn process_pending_events(
+    db: &sea_orm::DatabaseConnection,
+    event_bus: &EventBus,
+) -> Result<(), sea_orm::DbErr> {
+    let pending = domain_event::Entity::find()
+        .filter(domain_event::Column::Status.eq("pending"))
+        .filter(domain_event::Column::Attempts.lt(3))
+        .all(db)
+        .await?;
+
+    if pending.is_empty() {
+        return Ok(());
+    }
+
+    tracing::info!(count = pending.len(), "处理待发领域事件");
+
+    for event_model in pending {
+        // 重建 DomainEvent 并广播
+        let domain_event = DomainEvent::new(
+            &event_model.event_type,
+            event_model.tenant_id,
+            event_model.payload.clone().unwrap_or(serde_json::json!({})),
+        );
+
+        event_bus.broadcast(domain_event);
+
+        // 标记为 published
+        let mut active: domain_event::ActiveModel = event_model.into();
+        active.status = Set("published".to_string());
+        active.published_at = Set(Some(Utc::now()));
+        active.update(db).await?;
+    }
+
+    Ok(())
+}