Stage M5 and Stage M6

apps/api/src/modules/search/search-index.subscriber.ts

@@ -0,0 +1,52 @@
+import { Injectable, Logger, type OnModuleInit } from '@nestjs/common';
+
+import { DOMAIN_EVENTS } from '@/infrastructure/events/domain-event';
+import { EventBusService } from '@/infrastructure/events/event-bus.service';
+
+import { SearchIndexerService } from './search-indexer.service';
+
+/**
+ * Keeps the index in step with the catalog, by subscription rather than by call.
+ *
+ * This is the direction the dependency has to run: SearchModule knows about
+ * products, products knows nothing about search. When this module is extracted,
+ * this file is the only thing that changes — an in-process subscription becomes
+ * a queue consumer, and the producer never learns the difference.
+ *
+ * Failures are logged, not rethrown. A search index that missed one update is a
+ * degraded search; an exception escaping here would take down the write that
+ * triggered it, which is a far worse trade.
+ */
+@Injectable()
+export class SearchIndexSubscriber implements OnModuleInit {
+  private readonly logger = new Logger(SearchIndexSubscriber.name);
+
+  constructor(
+    private readonly events: EventBusService,
+    private readonly indexer: SearchIndexerService,
+  ) {}
+
+  onModuleInit(): void {
+    for (const event of [
+      DOMAIN_EVENTS.PRODUCT_UPDATED,
+      DOMAIN_EVENTS.PRODUCT_PUBLISHED,
+      DOMAIN_EVENTS.PRODUCT_ARCHIVED,
+    ]) {
+      this.events.on<{ productId: string }>(event).subscribe((message) => {
+        void this.reindex(message.payload.productId, event);
+      });
+    }
+  }
+
+  private async reindex(productId: string, event: string): Promise<void> {
+    try {
+      await this.indexer.reindexProduct(productId);
+    } catch (error) {
+      this.logger.error(
+        `Reindex failed for ${productId} after ${event}: ${
+          error instanceof Error ? error.message : String(error)
+        }`,
+      );
+    }
+  }
+}